[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Proposed Rules]
[Pages 61896-61949]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19008]
[[Page 61895]]
Vol. 88
Thursday,
No. 172
September 7, 2023
Part VI
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 572
Anthropomorphic Test Devices; THOR 50th Percentile Adult Male Test
Dummy; Incorporation by Reference; Proposed Rule
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 /
Proposed Rules
[[Page 61896]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 572
[Docket No. NHTSA-2023-0031]
RIN 2127-AM20
Anthropomorphic Test Devices; THOR 50th Percentile Adult Male
Test Dummy; Incorporation by Reference
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes to amend NHTSA's regulations to include
an advanced crash test dummy, the Test Device for Human Occupant
Restraint (THOR) 50th percentile adult male (THOR-50M). The dummy
represents an adult male of roughly average height and weight and is
designed for use in frontal crash tests. NHTSA plans to issue a
separate NPRM to amend Federal Motor Vehicle Safety Standard (FMVSS)
No. 208, ``Occupant crash protection,'' to specify the THOR-50M as an
alternative (at the vehicle manufacturer's option) to the 50th
percentile adult male dummy currently specified in FMVSS No. 208 for
use in frontal crash compliance tests.
DATES: You should submit your comments early enough to be received not
later than November 6, 2023.
Proposed Effective Date: Since this rulemaking action would not
impose requirements on anyone, we are proposing that the final rule
would be effective on publication in the Federal Register.
ADDRESSES: You may submit comments electronically to the docket
identified in the heading of this document by visiting the Federal
eRulemaking Portal at http://www.regulations.gov. Follow the online
instructions for submitting comments.
Alternatively, you can file comments using the following methods:
Mail: Docket Management Facility: U.S. Department of
Transportation, 1200 New Jersey Avenue SE, West Building Ground Floor,
Room W12-140, Washington, DC 20590-0001.
Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m. ET,
Monday through Friday, except Federal holidays. To be sure someone is
there to help you, please call (202) 366-9826 before coming.
Fax: (202) 493-2251.
Instructions: All submissions must include the agency name and
docket number or Regulatory Information Number (RIN) for this
rulemaking. For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to http://www.regulations.gov, including any personal information
provided. Please see the Privacy Act heading below.
Docket: For access to the docket to read background documents or
comments received, go to http://www.regulations.gov. You may also
access the docket at 1200 New Jersey Avenue SE, West Building, Room
W12-140, Washington, DC 20590, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal Holidays. Telephone: 202-366-9826.
Confidential Business Information: If you claim that any of the
information in your comment (including any additional documents or
attachments) constitutes confidential business information within the
meaning of 5 U.S.C. 552(b)(4) or is protected from disclosure pursuant
to 18 U.S.C. 1905, please see the detailed instructions given under the
Public Participation heading of the Supplementary Information section
of this document.
Privacy Act: Please see the Privacy Act heading under the
Regulatory Analyses section of this document.
FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may contact
Mr. Garry Brock, Office of Crashworthiness Standards, Telephone: (202)
366-1740; Email: [email protected]; Facsimile: (202) 493-2739. For
legal issues, you may contact Mr. John Piazza, Office of Chief Counsel,
Telephone: (202) 366-2992; Email: [email protected]; Facsimile: (202)
366-3820. The address of these officials is: the National Highway
Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington,
DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
III. Design, Construction, and Instrumentation
A. Anthropometry
B. Technical Data Package
C. Head and Face
D. Neck
E. Chest
1. Design
2. Instrumentation
F. Shoulder
1. Alternate Shoulder Specification
2. Shoulder Slip
G. Hands
H. Spine
I. Abdomen
J. Pelvis
K. Upper Leg
L. Knee
M. Lower Leg
N. Data Acquisition System
IV. Biofidelity
V. Qualification Tests
A. Head Impact
B. Face Impact
C. Neck
D. Upper Thorax
E. Lower Thorax
F. Abdomen
G. Upper Leg
H. Knee and Lower Leg
VI. Repeatability and Reproducibility
A. Qualification Tests
B. Sled Tests
1. Methodology
2. Thoracic Injury Criteria Development Sled Tests
3. Low-Speed Belted Sled Tests
4. Low-Speed Unbelted Sled Tests
VII. Overall Usability and Performance
A. Assembly and Qualification
B. Durability and Maintenance
1. Elevated Energy Qualification Test Series
2. Oblique OMDB Test Series
3. FMVSS No. 208 Unbelted Vehicle Crash Tests
C. Sensitivity to Restraint System Performance
VIII. Intellectual Property
IX. Consideration of Alternatives
X. Lead Time
XI. Incorporation by Reference
XII. Regulatory Analyses
XIII. Public Participation
Proposed Regulatory Text
I. Executive Summary
This document proposes to amend NHTSA's regulation on
anthropomorphic test devices--or, more colloquially, crash test
dummies--to include an advanced crash test dummy, the Test Device for
Human Occupant Restraint (THOR) 50th percentile adult male (THOR-50M).
The dummy represents an adult male of roughly average height and weight
and is designed for use in frontal crash tests.
Crash test dummies are complex instruments that simulate the
response of a human occupant in a crash. Each type of test dummy is
designed for use in specific types of crashes (for instance, frontal or
side) and is instrumented with sensors to measure the forces that would
have been experienced by a human occupant in a similar crash in the
real world. These measurements are then used to assess the potential
for injury.
Crash test dummies are used by NHTSA and by the broader vehicle
safety community in a variety of ways.
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NHTSA uses crash test dummies to test vehicles for compliance with
Federal Motor Vehicle Safety Standards (FMVSSs) and to determine
vehicle crashworthiness ratings for the New Car Assessment Program's
(NCAP) 5-Star Safety Ratings, as well as to conduct vehicle safety
research. Crash test dummies are also used by regulatory authorities in
other countries and regions, third-party vehicle rating programs, motor
vehicle and equipment manufacturers, and others to evaluate vehicle
safety and design safer vehicles and equipment.
The dummies NHTSA currently uses in FMVSS compliance testing and
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices.
Part 572 sets out detailed design information, including engineering
drawings and procedures for assembly and inspection. These are intended
to describe the dummy with sufficient detail so that it is an objective
measuring tool that produces consistent responses. NHTSA has codified
numerous dummies that range in sex, size, age, and measurement
capability. This includes dummies representing midsize adult males,
small-stature adult females, infants, toddlers, and older children.\1\
These dummies are meant to provide a range of body types in order to
maximize data and test results that can assess injury and fatality
risks in a range of crash outcomes. The 50th percentile male dummy
currently defined in Part 572 for frontal impacts is the Hybrid III-
50M, which NHTSA uses to test for compliance with the frontal crash
test requirements in FMVSS No. 208, ``Occupant crash protection'' and
to rate vehicles for NCAP. NHTSA added the HIII-50M to Part 572 in
1986.
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\1\ This reflects a ``bookend'' approach to testing vehicles for
crashworthiness, in which a range of occupant types, bookended by an
average male and a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible benefits of
developing new crash test dummies, such as a 50th percentile female
crash test dummy.
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NHTSA is continually researching and improving its test dummies and
has been researching advanced test dummies since the implementation of
the HIII-50M. An initial THOR-50M design was published in 2001. There
are currently two different THOR dummies, the THOR-50M, and one under
development that represents a small-statured adult female, the THOR 5th
percentile adult female (THOR-05F). Although this proposal is limited
to the THOR-50M, we anticipate publishing a rulemaking proposal in the
near future to add the THOR-05F to Part 572.
The THOR-50M improves on the HIII-50M in a number of ways. It
responds more like a human occupant in a crash and its advanced
instrumentation enables it to more accurately measure the forces acting
on the dummy. As a result, it is better able to predict the risk of
injury to a human occupant. This should help vehicle designers develop
and test improved occupant restraint systems (e.g., advanced seat belts
and air bags) as well as the types of novel vehicle seating
configurations likely to be used in highly automated vehicles.
NHTSA has tentatively concluded that the THOR-50M is sufficiently
biofidelic, exhibits repeatable and reproducible performance, and is
sufficiently durable. As such, we believe that it would be suitable for
use in regulatory compliance testing and is therefore suitable for
incorporation into Part 572. NHTSA and others have already taken
advantage of the THOR-50M's advanced capabilities. NHTSA, vehicle and
restraint manufacturers, and vehicle safety researchers have used the
THOR-50M to evaluate vehicle crashworthiness and develop occupant
protection countermeasures for frontal and oblique crashes. The
European New Car Assessment Programme (Euro NCAP) has officially
adopted the THOR-50M and is currently rating vehicles using the dummy.
Moreover, the Economic Commission for Europe is considering adopting
the THOR-50M for use in frontal crash testing under its vehicle safety
regulations.
NHTSA expects a variety of benefits from incorporating the THOR-50M
into Part 572. The definition of the THOR-50M in Part 572 will enable
its use in regulatory and consumer information programs, both within
NHTSA and externally. NHTSA believes that the THOR-50M's enhancements
will lead to more effective restraint system designs and more
informative comparisons of the safety of different vehicles. Because of
this--as well as the fact that manufacturers are already using the
dummy--we believe vehicle manufacturers would choose to certify
vehicles to FMVSS No. 208 using the THOR-50M if given the option. This
would enable manufacturers to streamline testing by using the same
dummy for research and development and to verify compliance. NHTSA
anticipates issuing a proposal in the near future to amend FMVSS No.
208 to specify the THOR-50M as an alternative (at the vehicle
manufacturer's option) to the HIII-50M test dummy for use in frontal
crash compliance tests. There would be other benefits as well. For
instance, NHTSA's test dummies are used in a range of applications
beyond FMVSS compliance testing--such as NCAP testing, standards and
regulations in other transportation modes, and research. Including the
dummy design in Part 572 will help provide a suitable, standardized,
and objective test tool for the safety community.
II. Background
This document proposes to amend 49 CFR part 572, Anthropomorphic
Test Devices, to include an advanced test dummy representing a 50th
percentile adult male, the Test Device for Human Occupant Restraint
(THOR-50M).\2\ The THOR-50M is a test dummy designed for use in frontal
crash tests. It has several advanced capabilities and advantages over
the Hybrid III 50th percentile male test dummy (HIII-50M) that is
currently specified in Part 572 and used in frontal crash testing under
FMVSS No. 208, ``Occupant crash protection,'' and the U.S. New Car
Assessment Program (NCAP).\3\ NHTSA plans to issue a proposal in the
near future to amend FMVSS No. 208 to specify the THOR-50M as an
alternative to the HIII-50M for use in frontal crash tests.\4\
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\2\ NHTSA has registered the term ``THOR'' as a trademark (U.S.
Registration No. 5,104,395).
\3\ The HIII-50M is also specified for use in FMVSS No. 202a,
Head Restraints, in an optional rear impact dynamic test.
\4\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
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This document proposes incorporating by reference in Part 572 a
parts list, design drawings, qualification procedures, and procedures
for assembly, disassembly, and inspection, to ensure that THOR-50M
dummies are uniform in design, construction, and response. This section
provides background on NHTSA's crash test dummies, the development of
the THOR-50M, and its use in other jurisdictions, among other topics.
Overview of Use of Vehicle Crash Test Dummies
Anthropomorphic Test Devices (ATDs)--or crash test dummies--are
complex instruments that serve as human surrogates in vehicle crash
tests (among other types of tests \5\). Test dummies simulate the
response of a human occupant in a crash and measure
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the effects of the crash forces on the occupant. They are used to
estimate the severity of the injuries that would have been experienced
by a human occupant in a similar crash in the real world. Each type of
test dummy is designed for use in specific types of crashes (frontal,
side, etc.), and is instrumented with a wide array of sensors to
measure the forces that would be relevant in the type of crash for
which it is designed and to assess the potential for injury. The more
closely a dummy represents how an actual human would respond, the more
biofidelic the dummy is considered to be.
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\5\ NHTSA also uses ATDs in sled tests (which simulate a vehicle
crash by using a simplified test buck to represent a vehicle), and
out-of-position air bag tests. ATDs are also used outside the
vehicle safety context to measure human responses in a variety of
other areas, such as aviation and aeronautics.
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NHTSA and the vehicle safety community use crash test dummies in a
variety of ways. NHTSA uses crash test dummies for vehicle compliance
testing, safety ratings, and safety research. NHTSA's Federal Motor
Vehicle Safety Standards establish mandatory minimum safety performance
requirements for motor vehicles and motor vehicle equipment. Vehicles
and equipment manufactured for sale in the United States must be
certified to comply with all applicable FMVSSs. A number of the FMVSSs
specify crash tests, using specified dummies, that the vehicle must be
certified as passing.\6\ NHTSA's vehicle safety compliance program
selects vehicles (and equipment) for compliance testing every year;
this includes crash testing vehicles to ensure that they comply with
the performance requirements that are evaluated by means of crash
tests. NHTSA's NCAP also evaluates vehicle performance in crash tests
using dummies as part of its 5-Star Safety Ratings. Finally, NHTSA's
vehicle safety research program uses crash test dummies to evaluate new
vehicle safety countermeasures and develop new vehicle crash testing
protocols. Dummies are also used outside of NHTSA by regulatory
authorities in other countries and regions, for third-party ratings
(such as Insurance Institute for Highway Safety ratings), and by
industry and the vehicle safety community to measure performance and
design safer vehicles.
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\6\ The FMVSS specify the procedures NHTSA will use in
compliance testing, including what dummies it will use for testing.
Part 572 specifies the dummies. While manufacturers must exercise
reasonable care in certifying that their products meet applicable
standards, they are not required to follow the compliance test
procedures set forth in a standard or use the dummy specified in
Part 572. See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(``Manufacturers should understand that they are not required to
test their products in any particular manner, as long as they
exercise due care that their products will meet the requirements
when tested by the NHTSA under the procedures specified in the
standard.'').
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The dummies NHTSA currently uses in FMVSS compliance testing and in
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices.
Part 572 sets out detailed design information, including engineering
drawings and procedures for assembly and inspection. These are all
intended to describe the dummy with sufficient detail so that it
produces consistent responses when it is tested under similar
conditions in repeated tests at the same laboratory (repeatability) or
between multiple dummies manufactured to the same specification used at
different test laboratories (reproducibility).
FMVSS No. 208 Frontal Crash Tests Using a 50th Percentile Male Dummy
FMVSS No. 208, ``Occupant crash protection,'' specifies a variety
of different requirements using crash test dummies. This includes
frontal crash tests in which the vehicle is moving and tests that are
performed with a stationary vehicle and are intended to help ensure
that air bags do not harm small-stature occupants and children. The
test dummies used in FMVSS No. 208 were designed to evaluate vehicle
performance in frontal crashes and are fitted with a variety of
instruments to measure the forces typically experienced by an occupant
in a frontal crash.\7\ The 50th percentile male dummy that is currently
specified for use in FMVSS No. 208 is the Hybrid III-50M.\8\ The HIII-
50M has been specified in FMVSS No. 208 since 1986,\9\ and replaced an
even earlier dummy, the Hybrid II. FMVSS No. 208 also specifies tests
using dummies representing a 5th percentile female, a 6-year-old, a 3-
year-old, and an infant.\10\
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\7\ Other FMVSS specify different types of crash or sled tests
that use different dummies. For example, FMVSS No. 214, Side Impact
Protection, specifies two crash tests (simulating a side impact with
a vehicle and a pole impact). This test uses two different side
impact dummies.
\8\ Part 572, Subpart E.
\9\ 51 FR 26688 (July 25, 1986) (final rule adding HIII-50M).
The Hybrid III-50M was developed by General Motors and added to Part
572 and for use in FMVSS No. 208 in response to a petition for
rulemaking from GM.
\10\ This reflects a ``bookend'' approach to testing vehicles
for crashworthiness, in which a range of occupant types, bookended
by an average male and a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible benefits of
developing new crash test dummies, such as a 50th percentile female
crash test dummy.
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FMVSS No. 208 specifies two tests (both of which are crash tests)
using the HIII-50M: a crash test in which the dummy is belted and the
test vehicle, traveling up to 35 mph, impacts a rigid barrier at a
ninety-degree angle or perpendicular; \11\ and a crash test in which
the dummy is unbelted and the test vehicle, traveling 20-25 mph,
impacts a rigid barrier at an angle ranging from 30
degrees oblique from perpendicular.\12\ NCAP also evaluates vehicle
performance in a frontal crash test at 35 mph using a belted HIII-50M
dummy.
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\11\ S5.1.1(b)(2), S14.5.1(b).
\12\ S5.1.2(b), S14.5.2.
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FMVSS No. 208 regulates vehicle performance in these crash tests by
specifying injury criteria and associated injury assessment reference
values (IARVs). Injury criteria and their respective risk functions
relate instrumentation measurements to a predicted risk of human
injury. Each IARV is a maximum value or threshold for a specific injury
criterion that may not be exceeded when the vehicle is tested with the
specified dummy under the specified test conditions and procedures. For
example, FMVSS No. 208 specifies a head injury criterion,
HIC15, with an IARV of 700. Thus, if NHTSA runs a compliance
frontal crash test and the calculated HIC15 value exceeds
700, this would be considered an apparent noncompliance. FMVSS No. 208
specifies the following injury criteria for the HIII-50M: a head injury
criterion (HIC15); \13\ a thoracic acceleration criterion;
\14\ a chest deflection criterion; \15\ a criterion based on the
maximum force transmitted axially through the upper leg (femur); \16\
and three neck injury criteria.\17\
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\13\ S6.2(b).
\14\ S6.3.
\15\ S6.4.
\16\ S6.5.
\17\ S6.6.
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Development of the THOR ATDs
NHTSA has continually conducted research into advancements in crash
safety, including the development of advanced dummies.\18\ The goal of
this research has been to create ATDs that represent the responses of
human occupants in modern vehicle environments with advanced restraint
systems. This research has led to the development of the two Test
Device for Human Occupant Restraint (THOR) ATDs, designed primarily for
use in frontal and frontal oblique motor vehicle crash environments.
There are currently two main implementations of the THOR design, both
representing seated motor vehicle occupants: one representing a 50th
percentile male and
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one representing a 5th percentile female.
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\18\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA
THOR Alpha ATD Design,'' The 17th International Technical Conference
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
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Development of THOR-50M
The initial design version of the THOR-50M, introduced in 2001, was
the THOR Alpha.\19\ The THOR Alpha, which integrated some components
from the earlier prototype demonstrator known as the Trauma Assessment
Device, introduced some of the features that exist in the current
version of THOR-50M, including the multi-direction neck, human-like
ribcage geometry and impact response, multi-point thorax and abdomen
deflection measurement system, and instrumented lower extremities.
NHTSA refined the THOR Alpha design and reintroduced it in 2005 as the
THOR-NT,\20\ which included updates to anthropometry, durability,
usability, biofidelity, and fit and finish. In 2011, NHTSA, in
coordination with the SAE International (SAE) THOR Evaluation Task
Group, introduced a modification package (Mod Kit) intended to enhance
the biofidelity, repeatability, durability, and usability of the THOR-
NT.\21\ After the introduction of the THOR Mod Kit, an upgrade to the
Chalmers shoulder assembly that was developed through the European
Union's THORAX project was integrated into the THOR-50M design.\22\ The
THOR-50M drawing package was then converted from the traditional
measurement system to the metric system through soft conversion (where
any non-metric measurements are mathematically converted to metric
equivalents without changes to the physical dimensions). All fasteners
were also replaced with the nearest metric equivalents. NHTSA made this
integrated drawing package (with incremental improvements and
corrections) publicly available online in 2015,\23\ 2016,\24\ 2020,\25\
and 2023.\26\ The version published in 2023 is referred to as the 2023
drawing package, which consists of two-dimensional drawings and a Parts
list; this, together with the Procedures for Assembly, Disassembly, and
Inspection (PADI), and qualification procedures, is referred to as the
2023 technical data package. (The version published in 2020 is referred
to as the ``2018 drawing package'' or the ``2018 technical data
package.'') The version of THOR that is being proposed is the version
defined in the 2023 technical data package. In 2019, NHTSA began
publishing THOR-50M documentation in a new docket titled, ``NHTSA
Crashworthiness Research--THOR-50M Documentation.'' \27\ In addition to
the documents that make up the 2018 and 2023 technical data packages,
the docket folder includes the following: durability report; seating
procedure; injury criteria; biofidelity report; Oblique Moving
Deformable Barrier (OMDB) Repeatability and Reproducibility (R&R); and
Qualification test R&R. This documentation is discussed further in
Section III.B and in the relevant sections of this preamble.\28\ NHTSA
has tentatively concluded that the THOR-50M is sufficiently biofidelic,
exhibits repeatable and reproducible performance, and is sufficiently
durable. As such, we believe that it would be suitable for use in
regulatory compliance testing and is therefore suitable for
incorporation into Part 572. A more detailed discussion of the
technical data package is provided in Section III.B.
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\19\ Id.
\20\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y., Platten,
G., Spade, C., Pope, P., Haffner, M., ``Development of THOR NT:
Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,'' The
19th International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 05-0455, 2005.
\21\ Ridella, S., Parent, D., ``Modifications to Improve the
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The
22nd International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011.
\22\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson, J.,
Song, E., Lecuyer, E., ``Development of an advanced frontal dummy
thorax demonstrator,'' Proceedings of the 2012 IRCOBI Conference,
2012.
\23\ National Highway Traffic Safety Administration (2015).
Parts List and Drawings, THOR-M Advanced Frontal Crash Test Dummy,
September 2015. Regulations.gov Docket ID NHTSA-2015-0119-0005,
available at: https://www.regulations.gov/document/NHTSA-2015-0119-0005 (NCAP docket).
\24\ National Highway Traffic Safety Administration (2016).
Parts List and Drawings, THOR-50M Advanced Frontal Crash Test Dummy,
August 2016, available at: https://www.nhtsa.gov/es/document/thor-50m-drawing-package-august-2016.pdf.
\25\ National Highway Traffic Safety Administration. Parts List
and Drawings, THOR-50M Advanced Frontal Crash Test Dummy, August
2018. Regulations.gov Docket ID NHTSA-2019-0106-0002, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0002.
\26\ National Highway Traffic Safety Administration. THOR 50th
Percentile Male with Alternate Shoulders Frontal Crash Test Dummy
Drawings, External Dimensions, and Mass Properties, THOR-50M
Advanced Frontal Crash Test Dummy, August 2018. Regulations.gov
Docket ID NHTSA-2019-0106-0013, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0013.
\27\ Docket NHTSA-2019-0106.
\28\ These documents are located in the research docket, Docket
No. NHTSA-2019-0106. NHTSA is not placing copies of these documents
in the docket for this rulemaking action in order to avoid potential
confusion from having identical documents docketed at different
times in different dockets. Nevertheless, NHTSA intends these to be
included as part of the rulemaking record for this rulemaking
action. A memorandum explaining this is also being placed in the
docket for this rulemaking.
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Development of THOR-05F
NHTSA understands that the risk of injury in a crash can depend on
the occupant's physical characteristics (e.g., height, weight, bone
density) and how they interact with the restraint system and vehicle
environment. To that end, NHTSA has developed comprehensive research
plans to address differences in crashworthiness safety testing and
outcomes, including differences in injury risk. Human body modeling
research efforts are underway to consider female and male occupants and
vulnerable road users of various ages, shapes, and sizes. This includes
continuing and accelerating research efforts to address differences in
motor vehicle safety based on physical characteristics, including sex,
and making data-driven decisions supported by the research outcomes. A
series of efforts is specifically focused on female occupant crash
safety, spanning field data analysis, tool development, demonstration,
and application.\29\
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\29\ See National Highway Traffic Safety Administration (2022).
NHTSA Female Crash Safety Research Plan, November 2022.
Regulations.gov Docket ID NHTSA-2022-0091-0002, available at:
https://www.regulations.gov/document/NHTSA-2022-0091-0002.
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As part of these efforts, NHTSA has been developing the THOR 5th
percentile adult female frontal crash test dummy (THOR-05F). The THOR-
05F represents a small adult female and has a seated height of 81.3 cm
(32.0 in), approximate standing height of 151 cm (59.4 in), and weight
of 49 kg (108.0 lbs). The THOR-05F has improved measurement
capabilities over the Hybrid III-5F, which is specified in FMVSS No.
208 and documented in Part 572. The THOR-05F's instrumentation is
similar to that of the THOR-50M. Improved designs resulting from the
development of the THOR-50M related to the head, neck, thorax, and
lower extremities have also been incorporated into the design of the
THOR-05F. Currently, NHTSA is evaluating the THOR-05F's biofidelity and
durability, developing design updates, injury criteria, and
documentation, and assessing its utility in full-scale crash testing.
NHTSA anticipates completing the research and testing necessary to
support a rulemaking for the THOR-05F
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in 2023.\30\ Possible test modes in which THOR-05F may be used include
FMVSS No. 208 testing and NCAP frontal crash tests. NHTSA has placed
documentation and research for the THOR-05F in an online docket and
will continue adding additional research and information to this docket
as it becomes available.\31\
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\30\ Part 572 THOR 5th Female Crash Test Dummy (RIN 2127-AM56),
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM56. This
rulemaking would amend 49 CFR part 572 by adding design and
performance specifications for a new test dummy known as the THOR-
05F.
\31\ See Docket No. NHTSA-2019-0107, available at
regulations.gov.
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Innovative Features of the THOR-50M
Frontal crashes are the leading cause of injuries and fatalities in
occupants of motor vehicle crashes on U.S. public roadways. The vehicle
front is the initial point of impact in a majority of crashes in the
U.S. In 2021, 15,570 occupants of passenger cars or light trucks died,
and 1,144,169 were injured, in frontal crashes.\32\ This suggests that
even though occupant protection systems have improved over the years
and saved many lives,\33\ improvements to occupant protection in
frontal crashes still need to be made.
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\32\ Data Sources: Fatality Analysis Reporting System (FARS):
2017-2020 Final File and 2021 Annual Report File (ARF); Report
Generated: Wednesday, June 28, 2023 (12:48:52 p.m.); VERSION 5.6,
RELEASED MAY 19, 2023
\33\ Charles J. Kahane, Lives Saved by Vehicle Safety
Technologies and Associated Federal Motor Vehicle Safety Standards,
1960 to 2012--Passenger Cars and LTVs--With Reviews of 26 FMVSS and
the Effectiveness of Their Associated Safety Technologies in
Reducing Fatalities, Injuries, and Crashes. 89 DOT HS 812 069 at 89,
Department of Transportation, National Highway Traffic Safety
Administration (2015).
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The THOR-50M is designed to better evaluate the effectiveness of
modern vehicle restraint systems and address the types of injuries that
continue to occur. These improvements include the following:
Improved biofidelity. Biofidelity is a measure of how well a dummy
replicates the response of a human. The THOR-50M was designed with
advanced features that enable it to have improved biofidelity compared
to the HIII-50M. The dummy's head includes a deformable facial insert
that emulates human response to impact. The components in the neck
representing bone and ligament structure are separate from those
representing muscular structure, improving both kinematic response and
injury prediction. The thorax simulates the shape and impact response
of the human rib cage. The spine incorporates flexible joints in the
thoracic and lumbar spine, allowing dynamic spine flexion as well as
static adjustment in the neck and lumbar spine to accommodate seating
in various postures. The upper leg has a compressive element in the
femur and the lower leg has a compressive element in the tibia and an
Achilles tendon load path to achieve human-like impact response. The
biofidelity of the THOR-50M has been assessed in a wide array of both
component and full-body test conditions for which human response is
known and was found to be both qualitatively and quantitatively
congruent with human response corridors.
Improved instrumentation. The THOR-50M has both improved and
additional instrumentation compared to the HIII-50M. The thorax
instrumentation measures the three-dimensional deformation of the rib
cage at four locations. The abdomen is also designed with a multi-point
measurement system that monitors three-dimensional deformation of the
abdomen at two locations. The upper leg includes an acetabulum load
cell in the pelvis to measure load transfer from the femur to the hip.
The lower leg has extensive instrumentation to support injury risk
calculation.
Improved injury prediction. The biofidelity of the THOR-50M,
combined with its extensive instrumentation, provides an enhanced
capability to measure expected human response and predict injury.
Injury criteria and injury risk functions, which relate instrumentation
measurements to a predicted risk of human injury, have been developed
for the head, neck, chest, abdomen, pelvis, upper leg, and lower leg of
the THOR-50M.\34\ These include injury criteria analogous to those
currently specified for the HIII-50M in FMVSS No. 208 as well as injury
criteria that are not currently specified for the HIII-50M in FMVSS No.
208. We believe this enhanced injury prediction capability will
translate into restraint system designs that have the potential to
enhance occupant protection. NHTSA and others, including vehicle
manufacturers, have already taken advantage of these capabilities in
the research arena.
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\34\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
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Improved evaluation of vehicle performance. These enhancements
allow the THOR-50M to better differentiate the performance of different
vehicles and restraint systems. The more sophisticated measurement
capabilities of an advanced ATD are better suited to develop and test
more sophisticated and highly tunable contemporary restraint systems
with features such as multi-stage air bags and force-limiting/
pretensioning seat belts. Motor vehicle manufacturers and restraint
suppliers have already used the THOR-50M to evaluate vehicle
crashworthiness and develop occupant protection countermeasures.
Numerous conference and journal articles describing the use of the
THOR-50M have been published. For example, in a study examining the
performance of different restraint systems in frontal impact sled tests
using both the THOR-50M and HIII-50M, the THOR-50M was found to be more
sensitive to the restraint conditions, as it was able to differentiate
between both crash severity and restraint performance.\35\ Another
study investigated a novel air bag system with three inflated chambers
with a connected sail panel to promote earlier engagement with the
occupant and prevent lateral motion and head rotation; sled testing
using the THOR-50M demonstrated a reduction in brain injury risk due to
head angular velocity, as quantified using the Brain Injury Criterion
(BrIC).\36\ Other studies have also implemented the THOR-50M to assess
and develop restraint systems.\37\
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\35\ Sunnev[aring]ng, C., Hynd, D., Carroll, J., Dahlgren, M.,
``Comparison of the THORAX Demonstrator and HIII Sensitivity to
Crash Severity and Occupant Restraint Variation,'' Proceedings of
the 2014 IRCOBI Conference, Paper No. IRC-14-42, 2014.
\36\ Hardesty, J. (2021). Next-Generation Passenger Airbag. SAE
Government-Industry Digital Summit (oral only).
\37\ See also, e.g., Hu, J., Reed, M. P., Rupp, J. D., Fischer,
K., Lange, P., & Adler, A. (2017). Optimizing seat belt and airbag
designs for rear seat occupant protection in frontal crashes (No.
2017-22-0004). SAE Technical Paper; Eggers, A., Eickhoff, B.,
Dobberstein, J., Zellmer, H., Adolph, T. (2014). Effects of
Variations in Belt Geometry, Double Pretensioning and Adaptive Load
Limiting on Advanced Chest Measurements of THOR and Hybrid III.
Proceedings of the 2014 IRCOBI Conference, Paper No. IRC-14-40; Hu,
J., Fischer, K., Schroeder, A., Boyle, K., Adler, A., & Reed, M.
(2019, October). Development of oblique restraint countermeasures
(Report No. DOT HS 812 814). Washington, DC: National Highway
Traffic Safety Administration. Available at: https://rosap.ntl.bts.gov/view/dot/44143.
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Adoption of the THOR-50M in Europe
In 2013, the European Commission (EC) issued a final report
detailing the need for a new crash test dummy as a means to implement
regulatory requirements for new vehicle safety technologies,
particularly those technologies that reduce thorax injuries in frontal
crashes.\38\ At the time, the
[[Page 61901]]
THOR-50M was envisioned as the best evaluation tool for this purpose.
In 2015, United Nations Economic Commission for Europe (UNECE)
Regulation No. 137 (R137) went into effect. R137 specifies a 50 km/h,
full-width rigid barrier frontal impact test with driver and passenger
HIII-50M and HIII-5F dummies respectively. One objective of the
regulation was to encourage better restraint systems across a wider
range of collision severities.\39\
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\38\ European Commission, Seventh Framework Programme, THORAX
Project Final Report, Thoracic injury assessment for improved
vehicle safety, 1/7/2013.
\39\ Seidl, M., Edwards, M., Barrow, A., Hynd, D., & Broertjes,
P. (2017). The Expected Impact of UN Regulation No. 137 Tests on
European Cars and Suggested Test Protocol Modifications to Maximise
Benefits. In 25th International Technical Conference on the Enhanced
Safety of Vehicles (ESV).
---------------------------------------------------------------------------
In 2017, an ECE-funded study found that the R137 condition and
dummy diversity were not sufficiently different to existing UN
Regulation No. 94 (R94) to force improvements in restraint systems. R94
involves a 56 km/h frontal offset test which also prescribes the HIII-
50M in the driver and right front seat. To deliver the expected
benefits, the 2017 final report recommended implementation of the THOR-
50M in R137 as a replacement for the HIII-50M.\40\ The THOR-50M was
recognized as being more biofidelic in its representation of thoracic
response and prediction of thorax injuries, which are the key serious
and fatal injury types in full-width collisions targeted by R137.
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\40\ Seidl M, Hynd D, McCarthy M, Martin P, Hunt R, Mohan S,
Krishnamurthy V and O'Connell S: TRL Ltd. (2017). In depth cost-
effectiveness analysis of the identified measures and features
regarding the way forward for EU vehicle safety, Final Report, ISBN
978-92-79-68704-4, European Commission, 08-31-2017.
---------------------------------------------------------------------------
In 2018, the EC published a report on the cost-effectiveness and
the number of future injuries and fatalities that could be prevented at
a European level for different sets of vehicle safety measures.\41\
Several new sets of safety measures were considered for mandatory
implementation in new vehicles starting from 2022. This included the
introduction of the THOR-50M into R137. The THOR-50M was considered for
inclusion in a program titled ``Full-width Frontal Occupant Protection
with THOR (FFW-THO),'' which would lower injury criteria thresholds to
encourage implementation of adaptive restraints. It was envisioned that
the implementation of the THOR-50M would result in an initial cost of
16 Euros per vehicle, for vehicles that currently comply with UN
Regulation No. 137 with Hybrid III ATDs but not with THOR-50M ATDs. It
was estimated that vehicles that comply with FFW-THO would provide a 6%
increase in effectiveness in protecting against serious injuries
compared to vehicles that comply with R137 alone.
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\41\ Seidl, M., Khatry, R., Carroll, J., Hynd, D., Wallbank, C.,
Kent, J. (2018) Cost-effectiveness analysis of Policy Options for
the mandatory implementation of different sets of vehicle safety
measures--Review of the General Safety and Pedestrian Safety
Regulations, Technical Annex to GSR2 report SI2.733025.
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In 2019, the EC presented work priorities to WP.29 \42\ for 2019-
2021 for UNECE activities. An amendment to introduce the THOR-50M into
R137 was included. The target date for a WP.29 vote was listed as Q4/
2021.\43\ In 2020, Japan and the EC jointly initiated discussions
within WP.29 to establish a priority for the new task. In preparation
for an eventual adoption into R137, the E.C. commissioned TRL
(Transport Research Laboratory, UK) \44\ to conduct a survey of various
stakeholders on the readiness of the THOR-50M. ATD manufacturers, crash
test laboratories, and crash safety research laboratories were
consulted. The results of the survey are contained within Annex 7 of a
broader report on general safety regulations, published by the E.C. in
2021.\45\ In the E.C. report, there are a number of recommendations
based on stakeholder feedback. They include revisions to the dummy
design and qualification procedures that may be needed prior to
adopting THOR-50M into M.R. 1 \46\ and R137. Most stakeholders
recommended the formation of either an Informal Working Group or a
Technical Evaluation Group under the umbrella of UNECE WP.29 to co-
ordinate this activity. As of May 2023, a WP.29 working group has yet
to be established and timelines for amendments to R137 and M.R. 1 are
undetermined. The areas for further investigation identified in Annex 7
are discussed in this NPRM.
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\42\ This was a thrice-annual briefing on the regulatory status
within the various working parties under WP.29's World Forum for
Harmonization of Vehicle Regulations, including the status of R137
under the Working Party for Passive Safety (GRSP).
\43\ WP.29-177-18, 177th WP.29, 12-15 March 2019, EU Work
priorities for 2019-2021 for UNECE activities.
\44\ TRL serves as an independent advisory to the E.C. TRL's
report was performed under contract with the European Commission
(E.C.), who sought to update the General Safety Regulation for
Europe to include new and developing technologies with the aim of
reducing Europe's annual road fatalities. The report reflects TRL's
recommendations for consideration by the E.C.
\45\ General Safety Regulation: Technical study to assess and
develop performance requirements and test protocols for various
measures implementing the new General Safety Regulation, for
accident avoidance and vehicle occupant, pedestrian and cyclist
protection in case of collisions, Final Report, March 2021,
Publications Office of the EU (europa.eu)), ISBN 978-92-76-08556-0,
DOI 10.2873/499942, Catalogue number, ET-04-19-467-EN-N. https://op.europa.eu/en/publication-detail/-/publication/6987b729-a313-11eb-9585-01aa75ed71a1/language-en/format-PDF/source-217672351 (last
accessed 5/25/2023).
\46\ Mutual Resolution No. 1 (M.R.1) of the 1958 and the 1998
Agreements. Concerning the description and performance of test tools
and devices necessary for the assessment of compliance of wheeled
vehicles, equipment and parts according to the technical
prescriptions specified in Regulations and global technical
regulations, ECE/TRANS/WP.29/1101, 10 January 2013.
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Although the ECE has not yet officially adopted the THOR-50M, the
European New Car Assessment Programme (Euro NCAP) has been rating
vehicles using the dummy. Euro NCAP has implemented a moving
progressive deformable barrier (MPDB) frontal impact testing protocol
with a THOR-50M in the driver's seat.\47\ The THOR-50M used by Euro
NCAP is specified in Technical Bulletin 026 (TB026) \48\ ``THOR
Specification and Certification.''TB026 explicitly adopts--with some
variations--NHTSA's 2018 technical data package (i.e., the 2018 drawing
package,\49\ qualification procedures,\50\ and PADI \51\). The
variations to the 2018 technical data package are relatively limited.
For example, TB026 specifies an onboard (in-dummy) data acquisition
system and a variation to the adjustable spine to facilitate data
acquisition system (DAS) installation; minor deviations in the shoulder
assembly; and the use of the HIII-50M lower legs. These modifications
are discussed in more detail in the relevant sections of the preamble
and are summarized in Section IX, Consideration of alternatives.
NHTSA's understanding is that no regulatory authorities or third-party
vehicle rating programs other than Euro NCAP currently specify the
THOR-50M for use in vehicle crash tests.
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\47\ European New Car Assessment Programme (2022). MPDB Frontal
Impact Testing Protocol, Version 1.1.3, available at: https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
\48\ European New Car Assessment Programme (2023). THOR
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\49\ Sec. 1.1.
\50\ Sec. 2.1.
\51\ Sec. 3.1.
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Motor vehicle and equipment manufacturers' interest in the design
and operation of the THOR-50M has been heightened since the dummy was
introduced into Euro NCAP and plans for R137 were announced.
Discussions are taking place within International Standards
Organization (ISO) Technical Committee 22 (Road Vehicles), Sub-
Committee 36 (Safety and impact testing), Working Group 5
(Anthropomorphic test devices) for
[[Page 61902]]
modifications suggested by manufacturers. With no defined European
entity to maintain configuration control, ISO has enlisted Humanetics
Innovative Solutions, Inc. (Humanetics) to investigate its change
recommendations directly. In particular, discussions have taken place
regarding modifications to the shoulder pad and rib guide. These
modifications are discussed in the relevant sections of the NPRM.
Need for This Rulemaking
NHTSA expects a variety of benefits from incorporating the THOR-50M
in Part 572. The THOR-50M is an advanced dummy with many advantages
over existing dummies with respect to biofidelity, instrumentation, and
injury prediction. NHTSA believes that the THOR-50M's enhancements will
lead to more effective restraint system designs and more informative
comparisons of the safety of different vehicles. Euro NCAP has adopted
it, the ECE is considering it for use in R137, and it is likely being
used by vehicle and restraint manufacturers for testing, research, and
development. Therefore, we believe vehicle manufacturers would choose
to certify new vehicles using the THOR-50M if given the option, because
this would enable manufacturers to streamline testing by using the same
dummy for research and development and to verify compliance and vehicle
ratings. NHTSA is therefore also considering a proposal to amend FMVSS
No. 208 to give vehicle manufacturers the option of selecting the THOR-
50M for use in belted and unbelted crash testing instead of the HIII-
50M.\52\
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\52\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21. This
rulemaking would propose injury assessment reference values for the
THOR-50M comparable to the IARVs currently specified for the HIII-
50M.
---------------------------------------------------------------------------
There would be other benefits as well. For instance, the THOR-50M
is well-suited for the types of new seating configurations brought on
by vehicles with Automated Driving Systems (ADS). NHTSA is developing
an adaptation of the THOR-50M that is better suited for reclined
postures which may be prevalent among ADS occupants.\53\ NHTSA's test
dummies are also used in a range of applications beyond FMVSS
compliance testing--such as NCAP testing, standards and regulations in
other transportation modes, and research. While the purpose of Part 572
is to describe the anthropomorphic test devices that are to be used for
compliance testing of motor vehicles and motor vehicle equipment with
motor vehicle safety standards,\54\ it also serves as a definition of
the ATD for other purposes, such as consumer information crash testing,
standards and regulations in other transportation modes, and research.
As such, it would be to the benefit of government, academia, and the
multi-modal transportation industry to include a definition of the
THOR-50M ATD in Part 572.\55\
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\53\ Forman, J., Caudillo-Huerta, A., McMahon, J., Panzer, M.,
Marshall, W., Winter, D., Dyer, M., Lemmen, P. (2021). Modifications
to the THOR-50M for Improved Usability in Reclined Postures--Update
and Preliminary Findings. 2021 SAE Government-Industry Digital
Summit, available at: https://www.nhtsa.gov/node/103691. The
adaptation to the THOR-50M design for use in reclined seating
environments is outside of the scope of this Part 572 NPRM.
\54\ 49 CFR 572.1.
\55\ For example, American Public Transportation Association
standard APTA PR-CS-S-018-13 Rev. 1 describes the use of a THOR ATD
in the testing of fixed workstation tables in passenger rail cars.
American Public Transportation Association. (2015, October). Fixed
Workstation Tables in Passenger Rail Cars. PR-CS-S-018-13, Rev. 1.
Washington, DC, available at: https://www.apta.com/wp-content/uploads/Standards_Documents/APTA-PR-CS-S-018-13-Rev-1.pdf.
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III. Design, Construction, and Instrumentation
In this section we discuss the anthropometry, design, construction,
and instrumentation of the THOR-50M.
A. Anthropometry
The THOR-50M is a physical model of a 50th percentile male motor
vehicle occupant. It is intended for use in the development and
evaluation of vehicle safety countermeasures and vehicle safety
performance in frontal crash tests. To ensure that the dummy responds
in a human-like manner in a vehicle crash environment, it is necessary
that the size and shape of the dummy, referred to as anthropometry,
provide an accurate representation of a mid-sized male. The
anthropometry of the THOR-50M is based on a study by the University of
Michigan Transportation Research Institute that documented the
anthropometry of a mid-sized (50th percentile in stature and weight)
male occupant in an automotive seating posture (AMVO
study).56 57 This study defines an average male as 76.57 kg
(168.8 lb) in weight with a standing height of 175.1 cm (68.9 in). The
AMVO study is currently internationally accepted as the standard
anthropometry for the 50th percentile male ATD. The THOR-50M has a mass
of 77.37 kg (170.6 lb) and a seated height of 101.8 cm (40.2 in). The
standing height of the ATD cannot be measured since the pelvis does not
allow a full standing posture; however, since it was developed using
the AMVO body segment geometry and seated anthropometry, it is assumed
that the stature of the THOR-50M is also 175.1 cm.
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\56\ Schneider, L.W., Robbins, D.H., Pflug, M.A., Snyder, R. G.,
``Development of Anthropometrically Based Design Specifications for
an Advanced Adult Anthropomorphic Dummy Family; Volume 1-Procedures,
Summary Findings and Appendices,'' U.S. Department of
Transportation, DOT-HS-806-715, 1985.
\57\ Robbins, D.H., ``Development of Anthropometrically Based
Design Specifications for an Advanced Adult Anthropomorphic Dummy
Family; Volume 2-Anthropometric Specifications for mid-Sized Male
Dummy; Volume 3- Anthropometric Specifications for Small Female and
Large Male Dummies,'' U.S. Department of Transportation, DOT-HS-806-
716 & 717, 1985.
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The THOR-50M is consistent with the AMVO anthropometry. NHTSA
compared the dimensions of a representative dummy (S/N 9798) with the
AMVO target dimensions (Table 1).\58\ The AMVO procedure originally
used to collect measurements from volunteers was adapted to collect the
same or similar measurements on the THOR-50M.\59\ Most of these
measurements were taken with the THOR-50M seated on the AMVO bench,
which has an angled seat and backrest. One adaptation was necessary to
collect leg measurements on the AMVO bench: the THOR-50M has an
integrated molded shoe that cannot be separated from its foot, while
the AMVO data were collected on barefoot volunteers. To remedy this
situation, the THOR-50M measurements were recorded after removing the
entire molded shoe assembly and positioning the center of the ankle
joint at the same location as the AMVO ankle landmark. Another
adaptation was that four of the measurements were collected with the
THOR-50M seated on a 90-degree bench, as specified on drawing 472-0000,
Sheet 4. NHTSA also compared
[[Page 61903]]
the body segment masses specified in the proposed THOR drawing package
(472-0000, Sheet 5) with the AMVO body segment masses (Table 2), and
the masses were also consistent.
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\58\ A THOR-50M unit is a collection of serialized parts that
can be swapped out with other dummies, so is not considered a
``serialized'' dummy. Indeed, many of the subassemblies that were
part of S/N 9798 when NHTSA took these measurements were
subsequently swapped out of the dummy. See Section VII.A.
\59\ These AMVO measurements were collected as an assessment of
anthropometry; it is understood that there is variation in initial
position and measurement methodology that prevents the use of such
measurements as a repeatable dimensional assessment. In practice, a
simplified set of dimensional requirements are put in place as a
check for overall part fit, tolerance stack, and to ensure that the
dummy is assembled correctly. These requirements are specified on
drawing 472-0000, Sheet 4, and are collected following the
``Procedures for Measuring External Dimensions'' section of the
PADI.
Table 1--THOR-50M Anthropometry Compared to AMVO
------------------------------------------------------------------------
AMVO target
Dimensions (all measurements in (Robbins et al THOR-50M S/N
centimeters) 1983) 9798
------------------------------------------------------------------------
Height of top of head to floor.......... 100.3 101.8
Height of shoulder to floor............. 72.1 74.2
H-point to knee joint distance (note 1). 43.2 42.3
Buttock to knee end distance (note 2)... 59.3 62.0
Height of knee from floor............... 45.3 47.0
Head circumference...................... 57.1 58.7
Head top-chin distance.................. 19.7 22.9
Head breadth............................ 15.8 15.3
Chest circumference..................... 101.1 95.5
Chest breadth........................... 34.9 30.9
Chest depth (note 3).................... 22.7 22.4
Abdomen circumference................... 91.3 99.0
Abdomen breadth......................... 32.5 32.5
Abdomen depth (note 2).................. 26.9 29.8
Pelvis breadth.......................... 38.5 38.8
Thigh max circumference................. 57.9 56.8
Thigh max breadth....................... 19.4 17.1
Mid thigh circumference................. 50.4 56.0
Mid thigh breadth....................... 15.5 17.8
Calf circumference...................... 37.3 37.5
Calf breadth............................ 11.0 9.1
Calf depth.............................. 11.8 11.9
------------------------------------------------------------------------
\1\ THOR-50M specified on 472-0000, Sh. 4, measurement F (Knee Pivot to
Hip Pivot) as seated upright on a 90-degree bench.
\2\ THOR-50M and AMVO measured as seated upright on a 90-degree bench.
\3\ THOR-50M specified on 472-0000, Sh. 4, measurement I (Rib #3 depth)
as seated upright on a 90-degree bench without jacket installed.
Table 2--THOR-50M Body Segment Masses Compared to AMVO
------------------------------------------------------------------------
AMVO target THOR-50M
Body segment masses (all measurements in (Robbins et al specification
kilograms) 1983) *
------------------------------------------------------------------------
Head.................................... 4.137 4.501
** (4.55)
Neck.................................... 0.965 2.363
Thorax.................................. 23.763 23.517
Lower Abdomen........................... 2.365 2.664
Pelvis.................................. 11.414 15.229
Upper Arm, Left or Right................ 1.769 1.701
Lower Arm with Hand, Left or Right...... 2.022 2.227
Upper Leg, Left or Right................ 8.614 5.618
Lower Legs, Left or Right............... 3.587 3.396
Feet, Left or Right including shoe...... *** 1.551 1.604
-------------------------------
Total Weight........................ 76.562 77.366
------------------------------------------------------------------------
* Listed on Drawing No. 472-0000, Sh. 5.
** Mass reported in Melvin JW, Weber, K. ``Task B Final Report: Review
of Biomechanical Impact Response and Injury in the Automotive
Environment,'' U.S. Department of Transportation, DOT-HS-807-042,
1985. The AMVO target is believed to be too low.
*** This adds the mass of a size 11 Oxford shoe (0.57 kg) specified for
use in FMVSS No. 208 for the HIII-50M) to the AMVO specification of
0.981 kg so as to be comparable to the THOR's foot-within-a-molded-
shoe mass.
B. Technical Data Package
The construction of the THOR-50M is similar to other ATDs currently
defined in Part 572, with a metallic frame largely covered in urethane
and/or vinyl representing flesh; body segments connected by
translational and rotational joints; and deformable rubber or foam
elements to prevent hard contact between metallic surfaces and to
provide human-like impact response. The kinematic and dynamic
biomechanical performance requirements of the THOR-50M were developed
based on post-mortem human subject (PMHS) and volunteer response data,
described in Section IV, Biofidelity.
The THOR-50M that we are proposing in this NPRM is the version
defined in the 2023 technical data package (consisting of two-
dimensional engineering drawings and a Parts list; procedures for
assembly, disassembly, and inspection (PADI); and qualification
procedures). The 2023 technical data package also includes an addendum
with the drawings and drawing/parts list for an alternate configuration
with an in-dummy data acquisition system, as discussed in Section
III.N, Data Acquisition System. It is anticipated that, upon
finalization of this proposal,
[[Page 61904]]
the in-dummy DAS drawings will be fully integrated within the relevant
technical data package components. The technical data package is
summarized in Table 3. For these documents, the NPRM cites to the
document location in the research docket. NHTSA is not placing copies
of these documents in the rulemaking docket, in order to avoid
potential confusion from having identical documents docketed at
different times in different dockets. However, NHTSA intends these to
be included as part of the rulemaking record. A memo explaining this is
also being included in the rulemaking docket. In addition, as noted in
the background section, NHTSA began publishing the technical data
package to its website starting in 2015. The 2023 technical data
package updates the 2018 technical data package. These updates were
made to address typographical errors, improve clarity, and add
alternative design elements. Table 4 summarizes these updates.
Table 3--THOR-50M Technical Data Package
------------------------------------------------------------------------
Title Link
------------------------------------------------------------------------
THOR 50th Percentile Male with https://www.regulations.gov/
Alternate Shoulders Frontal Crash Test document/NHTSA-2019-0106-0013.
Dummy Drawings, External Dimensions,
and Mass Properties.
*THOR-50M DAS Integration Kit Drawings, https://www.regulations.gov/
April 2023. document/NHTSA-2019-0106-0019.
*Parts List, THOR-50M DAS Integration https://www.regulations.gov/
Kit, April 2023. document/NHTSA-2019-0106-0018.
Parts List, THOR 50th Percentile Male https://www.regulations.gov/
Frontal Crash Test Dummy with document/NHTSA-2019-0106-0015.
Alternate Shoulders.
THOR 50th Percentile Male (THOR-50M): https://www.regulations.gov/
Procedures for Assembly, Disassembly, document/NHTSA-2019-0106-0017.
and Inspection (PADI): June 2023.
THOR 50th Percentile Male (THOR-50M) https://www.regulations.gov/
Qualification Procedures and document/NHTSA-2019-0106-0010.
Requirements, April 2023.
------------------------------------------------------------------------
* The DAS Integration Kit drawings and drawing/parts list would not
themselves be incorporated by reference into Part 572. It is
anticipated that, upon finalization of this proposal, these documents
will be fully integrated within the relevant technical data package
components.
Table 4--Summary of Updates Made in the 2023 THOR-50M Technical Data
Package
------------------------------------------------------------------------
Technical Data Package
Element Revisions in 2023 Version
------------------------------------------------------------------------
Drawing Package.............. Includes drawings for alternate shoulder,
removal of notes suggesting that
qualification specifications supersede
drawing specifications, and changes to
correct typographical drawing errors.
Complete change log found in ``THOR-50th
Percentile Male with Alternate Shoulders
(THOR-50M w/ALT. SHOULDERS) Drawing
Revisions''.\60\
PADI......................... Minor typographical changes; complete
change log found in Section 20 of ``THOR
50th Percentile Male (THOR-50M)
Procedures for Assembly, Disassembly,
and Inspection (PADI)''.
Qualification Procedures..... Revised upper leg qualification test
mode, adjusted language to be more
prescriptive, removed unit conversions,
and corrected typographical errors.
Complete change log found in Appendix B
of ``THOR 50th Percentile Male (THOR-
50M) Qualification Procedures and
Requirements, April 2023''.
------------------------------------------------------------------------
Below we briefly discuss several aspects of the technical data
package in more detail.
---------------------------------------------------------------------------
\60\ See Table 5.
---------------------------------------------------------------------------
Engineering Drawings and Parts List
The engineering drawings and parts list specify the configuration
of the THOR-50M. Included in the drawings are the required dimensions
and tolerances, material properties, and component or material testing
requirements and associated specifications. In a few instances, the
drawings specify quasi-static tests and/or performance requirements for
individual parts (such as a compression or flexion test for a molded
part or subassembly); however, passing a specified performance (or
qualification) test is not an alternate criterion for accepting a part
that deviates from the drawing specifications.\61\ All instruments are
specified by corresponding SA572-xxx drawings.\62\ SA drawings are
included for associated mounts and hardware that are not otherwise
needed when the dummy is configured with a corresponding structural
replacement. Brand name call-outs are only used for parts and materials
that have widespread availability and are used for a wide variety of
non-ATD applications. It includes materials widely identified by their
tradenames, such as Teflon, Acetal, Lexan, and Nitinol. Call-outs are
also used for bonding agents, fasteners, and other items that are also
widely available for non-ATD applications.
---------------------------------------------------------------------------
\61\ In the drawings which were part of the August 2018
technical data package, several notes state that ``qualification
takes precedence over design.'' These notes were unintentionally
carried over from earlier drawing versions used during THOR-50M
development, and have since been removed. These are reflected in the
proposed 2023 technical data package. In cases where some
flexibility is allowed in order to meet the qualification
specification, a ``REF.'' prefix is added to specific dimensions or
material specifications.
\62\ This convention is used for all instruments on all Part 572
dummies. SA572 simply indicates that it is an instrument, and Sxx is
the next-in-line number assigned by NHTSA to the instrument. Some
load cells (and part numbers) are used on different Part 572 subpart
dummies. For THOR, this applies to SA572-S4 (accelerometer) which is
used on many other dummies.
---------------------------------------------------------------------------
In some instances, the drawing package permits two different part
or instrumentation configurations that are both fully specified. For
example, the head accelerometer mounting plate assembly drawing (472-
1200) calls out three different angular rate sensors (SA572-S56, SA572-
S57, or SA572-S58) which may be desired by the end user depending on
the implementation of the ATD.\63\ In the sections below on specific
body regions we discuss the proposed as well as alternate designs and
instrumentations that are not included in the proposed specifications
but which we are considering specifying in the final rule and on which
we are seeking comment. If NHTSA were to use the dummy for FMVSS
compliance testing, NHTSA could test with any alternative
configurations at its own discretion. Thus, the IARVs would have
[[Page 61905]]
to be met using a dummy with any permissible configuration.
Manufacturers are not required to test their products in any particular
manner, as long as they exercise due care that their products will meet
the requirements when tested by NHTSA under the procedures specified in
the standard, including the relevant dummy specified in Part 572.\64\
However, a manufacturer would not be able to claim that a vehicle fully
complies with a standard if it meets the standard's requirements in
only one of the dummy's configurations, but not the other.
---------------------------------------------------------------------------
\63\ Similar situations exist with currently federalized ATDs,
such as the HIII-10C, where either a chest slider pot or an IR-TRACC
is permissible.
\64\ See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(``Manufacturers should understand that they are not required to
test their products in any particular manner, as long as they
exercise due care that their products will meet the requirements
when tested by the NHTSA under the procedures specified in the
standard.'').
---------------------------------------------------------------------------
In addition to the engineering drawings that would be incorporated
by reference, we are also providing supplemental documentation on the
form and function of the THOR-50M. These reference materials are
summarized in Table 5. These files would not be incorporated by
reference in Part 572 and would therefore not be part of the THOR-50M
specification. Instead, they are intended only for reference purposes
(e.g., to facilitate fabrication and inspection of parts with intricate
geometries).
Table 5--THOR-50M Design Reference Documentation
------------------------------------------------------------------------
Title Link
------------------------------------------------------------------------
THOR-50M Drawing Package--2D AutoCAD https://static.nhtsa.gov/nhtsa/
Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20with%20Alternate%20Shoul
ders%20Jan%202023-
AutoCAD%20DWG%20Files.zip.
THOR-50M Drawing Package--3D Inventor https://static.nhtsa.gov/nhtsa/
Format Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20with%20Alternate%20Shoul
ders%20Jan%202023-
Inventor%20Files.zip.
THOR-50M Drawing Package--3D STEP https://static.nhtsa.gov/nhtsa/
Format Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
3D%20STEP%20Files_April%202023
.zip.
THOR 50th Percentile Male with https://www.regulations.gov/
Alternate Shoulders Drawing Revisions, document/NHTSA-2019-0106-0014.
Jan 2023.
THOR-50M DAS Integration Kit--2D https://static.nhtsa.gov/nhtsa/
AutoCAD, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
AutoCAD%20DWG%20Files_April%20
2023.zip.
THOR-50M DAS Integration Kit--3D STEP https://static.nhtsa.gov/nhtsa/
Format, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
3D%20STEP%20Files_April%202023
.zip.
THOR-50M DAS Integration Kit--Inventor https://static.nhtsa.gov/nhtsa/
Format, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
Inventor%20Files_April%202023.
zip.
------------------------------------------------------------------------
The THOR-50M used by Euro NCAP is specified in Technical Bulletin
026, ``THOR Specification and Certification.'' \65\ TB026 explicitly
adopts--with some deviations--the 2018 drawing package.\66\ These
deviations in TB026 include specification of an onboard (in-dummy) data
acquisition system and a variation to the adjustable spine to
facilitate DAS installation; minor deviations in the shoulder assembly;
and the use of the HIII-50M lower legs. These modifications are
discussed in more detail in the relevant sections of the preamble, and
are summarized in Section IX, Consideration of alternatives. Euro NCAP
TB026 specifies the 2018 drawing package, while this proposal specifies
the 2023 drawing package. However, given the differences described in
Table 4 above, this deviation is likely to be inconsequential. The
deviations TB026 makes to the 2018 drawing package are not accompanied
by engineering drawings, which may tend to lessen the dummy's overall
objectivity. Objectivity is a statutory necessity for ATDs in Part 572.
While the lack of accompanying drawings for these deviations may be
adequate for the Euro NCAP rating program, it could lead to a future
population of THOR-50M units that are sufficiently non-uniform as to
render them unsuited for FMVSS applications.
---------------------------------------------------------------------------
\65\ European New Car Assessment Programme (2023). THOR
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\66\ Sec. 1.1.
---------------------------------------------------------------------------
PADI
The PADI provides step-by-step procedures on how to properly
assemble the dummy. This includes instructions on part alignment,
torque settings, wire routings, and other adjustments that are not
otherwise described in the engineering drawings. The PADI provides
explicit installation instructions for all instruments. Euro NCAP TB026
specifies the 2018 PADI,\67\ while this proposal specifies the 2023
PADI. However, the differences between the 2018 PADI and 2023 PADI are
primarily corrections to typographic errors, so this deviation is
likely to be inconsequential. In some instances, the drawing package
permits two different part or instrumentation configurations that are
(or will be in the final rule) both fully specified (for example, the
IR-TRACC and the S-Track for the chest instrumentation). The proposed
PADI does not currently contain installation instructions for the
optional parts (e.g. alternate shoulder) or instrumentation (e.g., the
S-Track). However, where multiple optional configurations are permitted
and installation differences are non-trivial, NHTSA anticipates
supplementing the PADI with such instructions in the final rule.
---------------------------------------------------------------------------
\67\ Sec. 3.1.
---------------------------------------------------------------------------
Qualification Procedures
The qualification procedures describe a series of impact tests
performed on a fully assembled dummy or sub-assembly. NHTSA has
established numeric bounds or acceptance intervals for the ATD
responses in these tests. The qualification procedures are discussed in
Section V.
[[Page 61906]]
Summary
NHTSA believes that the technical data package adequately describes
and would ensure the uniformity of the dummy. Upon finalization of this
proposal, a new subpart for the THOR-50M would be added to Part 572,
and the technical data package documents would be incorporated by
reference.
NHTSA seeks comment on whether the dummy is sufficiently specified
to ensure that dummies are uniform such that they will provide
repeatable and reproducible measurements. We also seek comment on
whether it would be useful to end-users of the dummy if NHTSA created a
list of suppliers used by NHTSA to obtain various parts and
instrumentation, and/or general specifications or operating
characteristics of a part (as provided by a manufacturer's
specification sheet). Such documentation would not be incorporated into
Part 572 but would be provided as a reference aid for users and could
be periodically updated by NHTSA.
C. Head and Face
The head of the THOR-50M is primarily constructed of a cast
aluminum skull covered in a urethane head skin. It includes two
features not seen on the HIII-50M: spring towers and a featureless
face. The spring towers are integral to the response of the head/neck
system, as they are the mounting location of the cables that represent
the musculature of the neck (described further in the following
section). The head is equipped with three uniaxial accelerometers and
three angular rate sensors at the head center of gravity (CG) to
measure translational acceleration and angular velocity, respectively.
The head also includes a biaxial tilt sensor which measures the quasi-
static orientation of the head for pre-test positioning purposes.
The face is constructed of an open-cell urethane foam sandwiched
between the head skin and the face load distribution plates. The
featureless face allows for more repeatable and reproducible
interactions with potential contact surfaces and meets enhanced
biomechanical response requirements which have not been implemented on
any existing ATDs. Additionally, the face can be configured with five
uniaxial load cells: left and right eye, left and right cheek, and
chin.\68\
---------------------------------------------------------------------------
\68\ These load cells have not been used in any tests currently
available in NHTSA's Vehicle or Biomechanics databases, and are
typically replaced with structural replacements during testing.
While the THOR-50M Qualification Procedure does include a face
impact test which would exercise the face load cells if installed,
there are currently no qualification specifications on face load
cell forces.
---------------------------------------------------------------------------
D. Neck
The neck of the THOR-50M is visibly and functionally different than
the ATDs currently defined in Part 572. While typical ATD designs use
only a pin joint between the base of the head and the upper neck load
cell, the THOR-50M neck is connected to the head via three separate
load paths: two cables (one anterior and one posterior) and a pin joint
between the base of the head and the upper neck load cell. These load
paths are independently instrumented, allowing the isolation of forces
and moments on the components representing bone and ligament from the
components representing muscles. This is expected to allow for improved
injury prediction for the cervical spine because the abbreviated injury
scale (AIS) 2+ injuries \69\ to the cervical spine in motor vehicle
crashes are most commonly fractures, so the ability to measure forces
and moments acting on the bones and ligaments separately from the
forces acting through the musculature allows a more accurate prediction
of these fractures.\70\
---------------------------------------------------------------------------
\69\ The Abbreviated Injury Scale (AIS) ranks individual
injuries by body region on a scale of 1 to 6: 1=minor,
2=moderate, 3=serious, 4=severe, 5=critical, and 6=maximum
(untreatable).
\70\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
The biomechanical basis of the THOR-50M neck design is well-
established.71 72 The construction of the THOR-50M neck
allows the head to initially rotate relatively freely in the fore and
aft directions. This allows the head/neck assembly to demonstrate the
phenomenon known as head lag demonstrated by human volunteers in
restrained frontal loading conditions, where the rotation of the head
is delayed relative to the rotation of the neck.\73\ This phenomenon
results from the head initially translating forward with respect to the
base of the neck, which is attached to the restrained torso. The change
in angle of the head initially lags the change in angle of the line
between the head and the neck but catches up by the time of peak
excursion.
---------------------------------------------------------------------------
\71\ White RP., Zhoa Y., Rangarajan N., Haffner M., Eppinger R.,
Kleinberger M., ``Development of an Instrumented Biofidelic Neck for
the NHTSA Advanced Frontal Test Dummy,'' The 15th International
Technical Conference on the Enhanced Safety of Vehicles, Paper No.
96-210-W-19, 1996.
\72\ Hoofman, M., van Ratingen, M., and Wismans, J.,
``Evaluation of the Dynamic and Kinematic Performance of the THOR
Dummy: Neck Performance,'' Proceeding of the International
Conference on the Biomechanics of Injury (IRCOBI) Conference, pp.
497-512, 1998.
\73\ Thunnissen, J., Wismans, J., Ewing, C.L., Thomas, D.J.
(1995) Human Volunteer Head-Neck Response in Frontal Flexion: A New
Analysis. 39th Stapp Car Crash Conference, SAE Paper # 952721.
---------------------------------------------------------------------------
The instrumentation in the neck assembly includes spring load cells
which measure the compression at the anterior and posterior spring
locations, six-axis load cells at the top and base of the neck to
measure the forces and moments developed at these locations, and a
rotary potentiometer at the occipital condyle pin to measure the
relative rotation between the head and top of the neck. Due to the
multiple load paths of the neck, comparing THOR-50M neck forces and
moments to traditional single-load-path ATD designs is not
straightforward; the THOR-50M instrumentation would require post-
processing \74\ to represent the total neck forces and moments in order
to compare to the upper neck load cell measurements of a HIII-50M ATD.
However, as described in the THOR-50M Injury Criteria Report,\75\ post-
processing of the neck for calculation of neck injury risk is not
necessary.
---------------------------------------------------------------------------
\74\ GESAC, Inc (2005). Users Manual: THOR Instrumentation Data
Processing Program, Version 2.3; Appendix C: Procedure for
Calculating Head Loads at the Occipital Condyle from Neck Load Cell
Measurements. National Highway Traffic Safety Administration.
Available at: https://one.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/THORTEST.zip.
\75\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
E. Chest
Throughout the development of the THOR-50M ATD, specific attention
was given to the human-like response and injury prediction capability
of the chest. Below we discuss the design and instrumentation of the
THOR-50M chest.
1. Design
The THOR-50M's rib cage geometry is more realistic than the HIII-
50M because the individual ribs are angled downward to better match the
human rib orientation.\76\ Biomechanical response requirements were
selected to ensure human-like behavior in response to central chest
impacts, oblique chest impacts, and steering rim impacts to the
[[Page 61907]]
rib cage and upper abdomen.\77\ Better chest anthropometry means that
the dummy's interaction with the restraint system is more
representative of the interaction a human would experience.
---------------------------------------------------------------------------
\76\ Kent, R., Shaw, C.G., Lessley, D.J., Crandall, J.R. and
Svensson, M.Y, ``Comparison of Belted Hybrid III, THOR, and Cadaver
Thoracic Responses in Oblique Frontal and Full Frontal Sled Tests,''
Proc. SAE 2003 World Congress. Paper No. 2003-01-0160, 2003.
\77\ National Highway Traffic Safety Administration,
``Biomechanical Response Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S.
Department of Transportation, Washington, DC, March 2005. [http://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf.
---------------------------------------------------------------------------
The design of the THOR-50M includes a part known as a rib guide
(472-3310) which is intended to prevent excessive downward motion of
the anterior thorax during an impact. The rib guide is attached to the
shoulder, and when there is downward motion of the ribs, the bottom of
the rib damping material on rib #1 (the superior-most rib in the torso,
472-3310) can contact the top of the rib guide. Over time, this can
result in an indent in the rib damping material. This indent has been
observed on NHTSA-owned THOR-50M ATDs, but it has not been a concern as
this is a sign of the rib guide performing its intended function. While
this indent is not included on the drawing package, it is understood
that an indent is acceptable as long as the qualification
specifications (specifically, those of the upper thorax and lower
thorax) are met, and it is not so deep that it allows metal-to-metal
contact between the rib guide and the steel of the rib.
While Euro NCAP TB026 adopts the chest specified in the 2018
drawing package without any modifications, NHTSA is aware of two
potential changes that have been discussed. Both of these changes
appear to be intended to help ensure that the dummy is able to meet the
upper thorax qualification response requirements. (The TB026 upper
thorax qualification response requirements differ in a few ways from
the proposed qualification requirements. This is discussed in more
detail in Section V, Qualification Tests.)
The first change that has been discussed is a shorter rib guide.
Humanetics Innovative Solutions, Inc. (Humanetics) reported to ISO WG5
(in June 2020) that while the indent on the damping material has been a
known issue since the THOR-NT, it has led to concerns because it leads
to issues meeting the Euro NCAP upper thorax qualification response
requirements (specifically, the Z-axis upper rib deflection
requirement) on a consistent basis. Humanetics has therefore suggested
the use of a new, shorter rib guide which would allow more Z-axis
deflection--primarily in the upper thorax qualification test, but
presumably in other impact scenarios as well.
The second change is an additional rib performance specification.
NHTSA is aware of a presentation made by the Japanese Automobile
Manufacturers Association (in June 2020) to ISO WG5 describing an
additional rib performance specification (i.e., that would be specified
in the drawing package) geared towards more consistently meeting the
TB026 upper thorax qualification response requirements. The
presentation included a procedure for an individual rib test using the
same apparatus as the rib drop test for the ES-2re 50th percentile
adult male side impact test dummy.\78\ It noted data showing that the
stiffness of the individual rib in the drop test was correlated with
the thoracic impact response in the upper thorax qualification test
condition.
---------------------------------------------------------------------------
\78\ 49 CFR 572.185(b) Individual rib drop test.
---------------------------------------------------------------------------
NHTSA has tentatively decided not to implement either change.
NHTSA's qualification testing of the dummy did not reveal any issues
with meeting the proposed upper thorax qualification requirements, so
we do not believe such changes are necessary. Moreover, before
implementing the rib guide modification, it could be necessary to
evaluate whether it would influence the dummy's response in biofidelity
or thorax injury criteria test conditions. We do note, however, that
the additional rib performance specification could be a useful way for
ATD manufacturers to ensure that the fabricated ribs will result in an
upper thorax qualification response consistent with upper thorax
qualification specifications.
We seek comment on these issues. In particular, NHTSA requests
comment from THOR-50M users who have evaluated alternative rib guide
designs and have data to support equivalence of durability,
repeatability and reproducibility, and equivalence of response in
qualification, biofidelity, injury criteria, and vehicle crash test
conditions.
2. Instrumentation
The THOR-50M is capable of measuring detailed information about how
the chest responds in a crash. While the HIII-50M can measure chest
deflection at only a single point (the sternum), the THOR-50M measures
chest deflections at four points. This is useful because thoracic
trauma imparted to restrained occupants does not always occur at the
same location on the rib cage for all occupants in all frontal
crashes.\79\ Measuring deflection from multiple locations has been
found to improve injury prediction,\80\ and can improve the assessment
of thoracic loading in a vehicle environment with advanced occupant
restraint technologies.\81\ While the HIII-50M measures the one-
dimensional deflection at a single point, the THOR-50M can measure the
three-dimensional position time-history for four points on the anterior
rib cage relative to the local spine segment of rib origination, with
two points on the upper chest, and two points on the lower chest.
Between the upper and lower thorax instrumentation attachment points is
a flexible joint (the Upper Thoracic Spine Flex Joint), so the
reference coordinate system for the upper and lower thorax 3D motion
measurements can change dynamically during a loading event. This
instrumentation, coupled with its thoracic biofidelity,\82\ provides
the THOR-50M ATD with the ability to better predict thoracic injuries
and to potentially drive more appropriate restraint system
countermeasures.\83\
---------------------------------------------------------------------------
\79\ Morgan, R.M., Eppinger, R.H., Haffner, M.P., Yoganandan,
N., Pintar, F.A., Sances, A., Crandall, J.R., Pilkey, W.D., Klopp,
G.S., Kallieris, D., Miltner, E., Mattern, R., Kuppa, S.M., and
Sharpless, C.L., ``Thoracic Trauma Assessment Formulations for
Restrained Drivers in Simulated Frontal Impacts,'' Proc. 38th Stapp
Car Crash Conference, pp. 15-34. Society of Automotive Engineers,
Warrendale, PA., 1994.
\80\ Kuppa, S., Eppinger, R., ``Development of an Improved
Thoracic Injury Criterion,'' Proceedings of the 42nd Stapp Car Crash
Conference, SAE No. 983153, 1998 (data set consisting of 71 human
subjects in various restraint systems and crash severities).
\81\ Yoganandan, N., Pintar, F., Rinaldi, J., ``Evaluation of
the RibEye Deflection Measurement System in the 50th Percentile
Hybrid III Dummy.'' National Highway Traffic Safety Administration,
DOT HS 811 102, March 2009.
\82\ Parent, D., Craig, M., Ridella, S., McFadden, J.,
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327,
2013.
\83\ In addition to the deflection measurement system, the THOR-
50M can also be instrumented with a uniaxial sternum accelerometer,
triaxial accelerometers installed along the spine at the level of
T1, T6, and T12, and a five-axis (three forces, two moments) load
cell installed between the lumbar spine pitch change mechanism and
the lumbar spine flex joint at the approximate anatomical level of
T12. Clavicle loads cells can also be installed, but are not
included in the THOR-50M described in the 2023 drawing package.
---------------------------------------------------------------------------
NHTSA is proposing to specify two deflection measurement devices,
either of which NHTSA could choose, at its option, for use in the THOR-
50M: the IR-TRACC and the S-Track.
IR-TRACC
The 2023 drawing package specifies a specific deflection
measurement device, the Infrared Telescoping Rod for Assessment of
Chest Compression (IR-
[[Page 61908]]
TRACC).\84\ The IR-TRACC improved on the previous deflection
measurement systems (CRUX--Compact Rotary Unit; DGSP--Double Gimbaled
String Potentiometer) in many ways. The 2023 drawing package specifies
six IR-TRACCs: four in the thorax and two in the abdomen.\85\ Each IR-
TRACC measures the absolute point-to-point distance along its length;
this is used in the calculation of thorax and abdomen compression. The
IR-TRACC is attached to two rotational potentiometers; this enables
measurement of the three-dimensional position of the anterior
attachment point at the rib or front of the abdomen relative to the
attachment point at the spine.
---------------------------------------------------------------------------
\84\ Rouhana, S.W., Elhagediab, A.M., Chapp, J.J. ``A high-speed
sensor for measuring chest deflection in crash test dummies.''
Proceedings: International Technical Conference on the Enhanced
Safety of Vehicles. Vol. 1998, Paper No. 98-S9-O-15. National
Highway Traffic Safety Administration, 1998.
\85\ See SA572-S117 and SA572-S121.
---------------------------------------------------------------------------
While NHTSA has generally been satisfied with the performance of
the IR-TRACC, the experience of NHTSA and other users with IR-TRACC-
equipped THOR-50Ms has revealed a few potential issues. Vehicle
manufacturers have raised several concerns about the performance and
durability of the IR-TRACC, such as having to frequently repair or
replace IR-TRACCs, and problems with the abdomen IR-TRACCs.\86\ And
during NHTSA-sponsored testing (particularly in the frontal oblique
crash test mode), NHTSA observed abrupt decreases in the IR-TRACC
voltage time-history.\87\ We believe this is noise (and not a signal)
because it occurs in all IR-TRACC voltage channels of a single ATD at
the same points in time. As explained later in this document (Section
VII.B.2) and in Appendix F to the preamble,\88\ NHTSA testing has shown
that once the IR-TRACC voltage signal is linearized, scaled, filtered,
and converted to three-dimensional deflection, this noise is no longer
evident. Nonetheless, this presents a risk of perceived or actual
inaccuracies in thoracic and abdominal injury prediction during crash
tests.
---------------------------------------------------------------------------
\86\ Alliance of Automobile Manufacturers, Inc. (2016).
Technical Considerations Concerning NHTSA's Proposal to Rework the
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
\87\ See Figure 1 in Hagedorn, A., Murach, M., Millis, W.,
McFadden, J., Parent, D., (2019). Comparison of the THOR-50M IR-
TRACC Measurement Device to an Alternative S-Track Measurement
Device. Proceedings of the Forty-Seventh International Workshop on
Human Subjects for Biomechanical Research.
\88\ NHTSA is placing a separate document, ``Supplemental
Technical Appendices to Preamble,'' in the docket for this
rulemaking.
---------------------------------------------------------------------------
S-Track
In 2016 NHTSA issued a request for proposals for commercially-
available devices capable of measuring the same or greater deflection
range (roughly 90 millimeters of deflection for the thorax and 120
millimeters of deflection for the abdomen) within the same packaging
space as the existing IR-TRACC devices.\89\ Only one device--the S-
Track--was identified. The S-Track, which is patented,\90\ is produced
by ATD-LabTech GmbH. (In 2022, Humanetics acquired ATD-LabTech.)
Subsequent to the request for proposal, NHTSA also became aware of two
additional deflection measurement devices: the KIR-TRACC, sold by
Kistler Group, and the Spiral Track, sold by JASTI. NHTSA does not know
whether these devices are congruent with the current THOR-50M parts and
SA-drawings that describe the configuration and installation of IR-
TRACCs. Because NHTSA became aware of these devices late in the
development process (and neither was identified in NHTSA's request for
proposals), they have not been considered for inclusion in the
proposal, although NHTSA is considering evaluating whether they would
be suitable instrumentation for the THOR-50M. Euro NCAP allows for
installation of the IR-TRACC, the S-Track, and the KIR-TRACC.\91\
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\89\ National Highway Traffic Safety Administration (2016). IR-
TRACC Direct Replacement Sensor. Solicitation Number DTNH2216Q00014,
available at https://sam.gov/opp/d505f6119f9a31bcdfa36607ed669e6b/view.
\90\ Pheifer, G. (2020). U.S. Patent No. 10,713,974. Washington,
DC: U.S. Patent and Trademark Office.
\91\ European New Car Assessment Program (2022). Euro NCAP
Supplier List, Appendices I & II, October 2022, TB 029, available
at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
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The S-Track is similar to the IR-TRACC in that it is in-dummy
instrumentation that attaches to the same points in the dummy as the
IR-TRACC. Both measure linear displacement, and when coupled with the
gimballed potentiometers, their signals can be post-processed to
calculate three-dimensional motion. It differs in that the S-Track uses
a mechanical scissor mechanism coupled to a linear potentiometer to
measure linear motion along its axis, while the IR-TRACC uses a
measurement of light transmittance, which requires a linearization
calculation to estimate linear motion.
NHTSA has conducted a range of testing to evaluate the performance
and equivalence of the S-Track. The testing, which included a partial
qualification test series and sled tests, is briefly summarized
below.\92\ A more detailed discussion of this material is available in
a previously published paper (except, as noted below, the second set of
sled tests, for which a report is forthcoming).\93\
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\92\ This evaluation of alternate thorax and abdomen
instrumentation only considered replacement of the displacement
transducer component of the 3D IR-TRACC measurement system. Though
it was not available at the time of purchase, a double gimbal kit to
allow 3D measurement is now available from the S-Track manufacturer.
ATD-Labtech GmbH (2017). 3D Adaption THOR-50th upper Thorax left
20_303. Available at: https://www.atd-labtech.com/files/atd/uploads/produkte/s-track/produkte/4%20TH-3D-Adapter-Upper-Thorax-left/data_sheet-3D-Adaption_Thor-50th_upper_Thorax_left%20Rev%2001.PDF.
To evaluate whether the S-Track 3D adaption kit would result in
equivalent measurement capabilities as the 3D IR-TRACC measurement
system, the testing described here would be repeated, starting with
the 3D static measurement assessment.
\93\ Hagedorn, A., Murach, M., Millis, W., McFadden, J., Parent,
D., (2019). Comparison of the THOR-50M IR-TRACC Measurement Device
to an Alternative S-Track Measurement Device. Proceedings of the
Forty-Seventh International Workshop on Human Subjects for
Biomechanical Research. Available at: https://www-nrd.nhtsa.dot.gov/pdf/bio/proceedings/2019/Hagdeorn_S-Track_Biomechanics%20Workshop%202019_FINAL.pdf.
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The range and linearity of the S-Track and IR-TRACC
sensors are comparable. The range of measurement of the S-Track is
consistent with or larger than the range of measurement of the IR-
TRACC, and all sensors were within the manufacturer's specification for
the maximum allowable linear error as a percentage of full scale. This
specification (0.5%) is tighter compared to the corresponding IR-TRACC
specification (2%), though only one of the IR-TRACCs (right abdomen)
showed a linearity error greater than 0.5%.
Calibration and 3D static measurement assessments
demonstrated similar or better accuracy compared to the IR-TRACC in the
double-gimbal configuration for the upper left thorax, lower left
thorax, and left abdomen. In the upper and lower thorax configurations,
the S-Track showed less error than the IR-TRACC, and in the abdomen
configuration, showed errors similar to the IR-TRACC.
The form, fit, and function is comparable to the IR-TRACC.
A full set of six S-Tracks was installed in a THOR-50M ATD. It did not
present any connectivity or interference issues and appeared to be a
plug-and-play replacement to the IR-TRACCs. One possible durability
issue was identified
[[Page 61909]]
(damage to the cable at the base of the S-Track). This issue is
mitigated if cable routing documentation is followed or the S-Track-
specific double-gimbal assembly is used.
The S-Track performed equivalently in qualification tests.
NHTSA carried out the qualification tests for the body regions expected
to be sensitive to a difference in thorax and abdomen instrumentation
(upper thorax, lower thorax, and abdomen) on a THOR-50M in two
different configurations: a baseline configuration with IR-TRACCs in
all locations, and an alternate configuration with S-Tracks in all
locations. Both configurations met the qualification targets for all of
the test modes specified for those body regions, which demonstrates
that the difference in measured deflections between the S-Track and IR-
TRACC were well within expected test-to-test variation. In addition,
the deflection time-history was qualitatively similar to the IR-TRACC.
The S-Track performed equivalently to the IR-TRACC in most
respects in a series of sled tests. NHTSA conducted sled tests in
several conditions with the THOR-50M in two configurations: one with
the IR-TRACC in all locations, and one with the S-Track in all
locations:
[cir] The first series used a reinforced buck representative of the
front half of a mid-sized passenger vehicle (including seat belt,
frontal air bag, and side curtain air bag) and simulated a near-side
frontal oblique (20 degrees) crash. The crash pulse was based on a
frontal oblique crash test of the same vehicle. The S-Track proved to
be durable and did not demonstrate the same noise artifacts as the IR-
TRACC. The S-Tracks in the thorax showed similar measurements as the
IR-TRACCs, particularly in the upper right thorax, the closest
measurement location to the shoulder belt. There were some potential
differences between the abdomen measurements, but abdominal deflection
is not currently included as an injury criterion in FMVSS No. 208 and
is not currently included in the rating calculation for frontal
NCAP.\94\
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\94\ Additional evaluation would be desirable in cases where
abdominal deflection is a critical measurement, such as a rear seat
environment where submarining may be more likely to occur.
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[cir] The second series of sled tests were conducted in the Gold
Standard 1 (40 km/h, 12g peak pulse, standard lap and shoulder belt)
and Gold Standard 2 (30km/h, 9g peak pulse, 3kN load limited shoulder
belt) test conditions, which were used both in biofidelity assessment
and in the development of thoracic injury criteria.\95\ The goal of
this testing was to determine if any differences occurred between the
IR-TRACC and S-Track measurement devices, and if so, whether the
magnitude of these differences would affect the biofidelity and injury
criteria development analyses. NHTSA is preparing a report on this
second series of sled tests, which will be placed in the research
docket when it is complete.
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\95\ The Gold Standard 1 test uses a flat rigid seat, standard
lap and shoulder belts, knees restrained, and right front passenger
restraint geometry. The Gold Standard 2 test uses a flat rigid seat,
a force-limited shoulder belt and standard lap belt, knees
restrained, and right front passenger restraint geometry.
---------------------------------------------------------------------------
Based on this testing and analysis, NHTSA believes that the S-Track
is equivalent to the IR-TRACC (with the potential exception of the
abdomen deflection in a sled test environment).
Proposal
NHTSA proposes to specify both the IR-TRACC and the S-track as
permissible instrumentation for the THOR-50M. A THOR-50M configured
with all IR-TRACCs or all S-tracks would conform to Part 572 and NHTSA
could perform compliance testing with either device installed in the
THOR-50M. The dummy has not been tested in a mixed configuration, with
both devices installed (e.g., IR-TRACCS in the chest and S-Tracks the
abdomen, or with one IR-TRACC and three S-Tracks in the chest). The
overall effects of such configurations are unknown. NHTSA seeks comment
on whether the final specifications should allow such configurations.
The IR-TRACC is specified in the 2023 drawing package (in SA572-S117
and SA572-S121). NHTSA has not yet published engineering drawings and
parts packages to specify how the S-Track is installed in the dummy,
but intends to integrate such documentation into the associated
technical data package components upon finalization of this proposal.
NHTSA seeks comment on this proposal.
F. Shoulder
The THOR-50M shoulder was developed to allow a human-like range of
motion and includes a clavicle linkage intended to better represent the
human shoulder interaction with shoulder belt restraints.\96\ Clavicle
load cells that can be installed in the proximal and distal ends of the
clavicles are commercially available, but these load cells are not
currently defined in the drawing package and NHTSA has not evaluated
them.
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\96\ T[ouml]rnvall, F.V., Holmqvist, K., Davidsson, J.,
Svensson, M.Y., H[aring]land, Y., [Ouml]hrn, H., ``A New THOR
Shoulder Design: A Comparison with Volunteers, the Hybrid III, and
THOR NT,'' Traffic Injury Prevention, 8:2, 205-215, 2007.
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Below we discuss shoulder components for which NHTSA is proposing
alternative permissible specifications (the alternate shoulder) or for
which design modifications have been developed by external THOR-50M
users but which NHTSA has tentatively decided not to incorporate in the
drawing package (shoulder slip and coracoid process).
1. Alternate Shoulder Specification
Portions of the shoulder assembly specified in the 2018 drawing
package (referred to as the SD-3 shoulder) are covered by a patent
issued to Humanetics. However, for the reasons discussed in more detail
in Section VIII, NHTSA has generally avoided specifying in Part 572
patented components or copyrighted designs without either securing
agreement from the rights-holder for the free use of the item or to
license it on reasonable terms or developing an alternative
unencumbered by any rights claims. NHTSA has therefore designed, built,
and tested an alternative design for a part of the shoulder assembly
referred to as the shoulder pivot assembly that is not subject to any
intellectual property claims. Accordingly, the proposed drawing package
(the 2023 drawing package) includes specifications for the SD-3
shoulder pivot assembly as well as the alternate shoulder pivot
assembly, so that either may be used. We explain this in more detail
below.
SD-3 Shoulder
The SD-3 shoulder is notably different from the shoulder specified
for the THOR-NT. The THOR-NT design includes a clavicle linkage
attached by ball joints at the sternum and acromion, a linkage between
the acromion and the scapula to which the upper arm attaches, and a
linkage representing the scapula that attaches to the acromion linkage
and the spine with unconstrained revolute joints. While there were some
benefits of the THOR-NT design compared to existing ATDs at the time,
the range of motion of the THOR-NT shoulder was found to be lacking
compared to the human shoulder.\97\
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\97\ Shaw, G., Parent, D., Purtsezov, S., Lessley, D., Crandall,
J., Tornvall, F., ``Torso Deformation in Frontal Sled Tests:
Comparison Between THOR-NT, THOR-NT with the Chalmers SD-1 Shoulder,
and PMHS,'' Proceedings of the International IRCOBI Conference,
2010.
---------------------------------------------------------------------------
An improved shoulder design was independently initiated by the
Chalmers University of Technology (Chalmers), in
[[Page 61910]]
a project sponsored by Volvo and Autoliv, that sought to improve the
prediction of occupant response in offset and oblique frontal crashes.
Several prototype shoulder assemblies were constructed and evaluated,
the most promising being labeled the Shoulder Design 1 (SD-1).\98\ The
SD-1 shoulder design includes a clavicle linkage with human-like
geometry, connected by cardan joints to the sternum and acromion; a
linkage representing the scapula that includes attachment to the upper
arm; and a two-part linkage connecting the scapula to the spine which
allows both upward and anterior motion of the shoulder assembly. The
anterior rotation of the scapula linkage about a vertical shaft is
governed by a coil spring within an assembly mounted to the spine box.
Several rotation stops are installed throughout the assembly to prevent
metal-to-metal contact at the extents of the range-of-motion.
---------------------------------------------------------------------------
\98\ T[ouml]rnvall et al. (2007), 205-215.
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After evaluation of the SD-1 in dynamic sled testing in comparison
to the standard THOR-NT shoulder and to PMHS,\99\ several improvements
were proposed, including durability improvements to the humerus joint,
decreasing the range of motion in the anterior and superior directions,
and increasing the range of motion in the posterior and medial
directions. The improved design, labelled as the SD-2 shoulder, was
fabricated by GESAC to Chalmers' specifications, installed on a THOR-
50M ATD, and evaluated in sled tests in the Gold Standard 1 and Gold
Standard 2 conditions at the University of Virginia.\100\ Several
additional durability and usability concerns were raised upon post-test
inspection, including deformation of the joint between the clavicle and
the acromion and hard contact to the humerus joint.
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\99\ Shaw et al (2010).
\100\ Crandall, J. (2013). ATD Thoracic Response: Effect of
Shoulder Configuration on Thoracic Deflection. NHTSA Biomechanics
Database, Report b11017R001, available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11017&index=1&database=B&type=R.
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Subsequently, an updated version of the SD-2 shoulder, known as the
SD-3, was designed and fabricated as part of the European Union's
Thoracic Injury Assessment for Improved Vehicle Safety (THORAX)
project.\101\ Changes introduced in the SD-3 design included redesigned
sterno-clavicular joint anthropometry, an updated shoulder cover, and
improvements intended to address the durability and usability concerns
raised by the University of Virginia testing. These latter improvements
consisted of replacing the clavicle U-joint with a spherical joint;
replacing the humerus joint with a metric version of the HIII-50M upper
arm joint; and introducing a series of washers and bushings to the
bottom of the vertical shaft to enable the resistance of the assembly
to be adjusted to allow a more reproducible initial position.
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\101\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson,
J., Song, E., and Lecuyer, E. (2012). Development of an advanced
frontal dummy thorax demonstrator. Proceedings of the 2012 IRCOBI
Conference, Paper No. IRC-12-87, September 2012.
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The SD-3 shoulder was installed on a THOR-50M ATD and sled testing
was again carried out at the University of Virginia in the Gold
Standard 1 and Gold Standard 2 conditions, as well as a variation of
Gold Standard 1 with a force-limited belt.\102\ The SD-3 shoulder
assembly was inspected in detail throughout this testing, and no
evidence of damage was identified. The chest deflection and torso
motion was similar to the SD-1 and SD-2 shoulders, while durability was
improved. NHTSA also conducted an evaluation of blunt thoracic impact
response of several configurations of THOR-50M ATDs and found the
iteration with the SD-3 shoulder assembly installed to have the highest
qualitative and quantitative biofidelity.\103\ Given these findings,
NHTSA modified the drawing package to include the SD-3 shoulder. The
first iteration of the drawing package to include the SD-3 shoulder was
published as the September 2014 version.\104\
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\102\ Crandall, J. (2013). ATD Thoracic Response: SD3 Shoulder
Evaluation. NHTSA Biomechanics Database, Report b11470R001,
available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11470&index=1&database=B&type=R.
\103\ Parent, D., Craig, M., Ridella, S., McFadden, J.,
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327,
2013.
\104\ National Highway Traffic Safety Administration (2014).
THOR 50th Percentile Male Drawing Package, September 2014. available
at: https://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR%20Advanced%20Crash%20Test%20Dummy/thoradv/THOR-M_PDF_2014-09-29.pdf.
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After the publication of the September 2014 drawing package,
Humanetics filed an application for a patent describing a shoulder
assembly as well as an upper arm with an integrated load cell.\105\
Similar to the SD-3 shoulder, the design patent describes a shoulder
pivot assembly which includes, among other things, a coil spring and an
adjustable resistance element. After discussions between NHTSA and
Humanetics, a disclaimer stating that portions of the THOR-50M drawings
were covered by a Humanetics patent was added first to the NHTSA
website where the drawings were available for download, and later to
the drawings for the shoulder and upper arm assemblies in the drawing
package itself.
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\105\ Been, B., & Burleigh, M. (2017). U.S. Patent No.
9,799,234. Washington, DC: U.S. Patent and Trademark Office.
---------------------------------------------------------------------------
NHTSA has generally avoided specifying such parts, consistent with
the legislative history of the Safety Act. (See Section VIII,
Intellectual Property.) For this reason, as explained below we are also
proposing, in addition to the SD-3 shoulder, an alternative shoulder
pivot assembly design.
Alternate Shoulder Pivot Assembly Design
To address the potential issues with specifying only a proprietary
shoulder design, NHTSA has designed, built, and tested an alternate
shoulder pivot assembly that is not subject to any intellectual
property claims. The alternate shoulder pivot assembly does not include
any components to adjust the resistance of the assembly, and does not
use a coil, clock, or watch-spring mechanism. Instead, the alternate
shoulder pivot assembly design uses a molded rubber cylinder acting as
a torsion bar. The top of the cylinder is attached to the shoulder
support assembly and the bottom is attached to the spring housing, so
rotation of the shoulder about the local Z-axis of the ATD results in
torsion of the rubber cylinder. In order to adjust the resistance of
the assembly, the springs must be removed and replaced.
NHTSA has evaluated the alternate shoulder in a variety of tests
and tentatively concludes that its performance is similar to the SD-3
shoulder based on testing carried out to date. This testing, which
included a partial qualification test series and sled tests, is briefly
summarized below. A more detailed discussion of this material is
available in a testing report that NHTSA is preparing, and which will
be placed in the research docket when it is completed. NHTSA is also
preparing another report that describes additional sled testing that
was conducted; this report will be placed in the research docket when
it is complete.
First, the alternate shoulder was installed in a THOR-50M without
any issues regarding the form, fit, or function. Second, in a quasi-
static rotation test, the alternate shoulder showed a similar moment-
rotation loading slope to the SD-3 shoulder in both the forward and
rearward rotation directions. Third, the SD-3 and alternate shoulder
showed nearly identical longitudinal motion in all three loading
directions in a quasi-static biofidelity evaluation comparing each
[[Page 61911]]
shoulder's range of motion to that of human volunteers; the responses
of both were generally similar to the human volunteer response
corridors. Fourth, the qualification tests most likely to be affected
by shoulder response (upper thorax and chest) were carried out; the
THOR-50M with the alternate shoulder met all qualification
specifications for the upper thorax, and the force-deflection
characteristic of the chest was nearly identical to that of a THOR-50M
with the SD-3 shoulder. Finally, sled tests conducted in both a full
frontal and a far-side oblique condition did not reveal any durability
or usability issues, and the response of the THOR-50M with the
alternate shoulder was within the test-to-test variation of the THOR-
50M with the SD-3 shoulder.
NHTSA is therefore proposing the alternative shoulder as an
acceptable optional subassembly. The shoulder assemblies are specified
on drawings 472-3810 (left) and 472-3840 (right). Each shoulder
assembly drawing specifies that either the SD-3 shoulder pivot assembly
or the alternate shoulder pivot assembly may be used. The proposed
specifications for the SD-3 shoulder pivot assembly are provided in
drawings 472-3811 and 472-3841, and the proposed specifications for the
alternate shoulder pivot assembly are provided in drawings 472-6810-1
and 472-6810-2. The drawing package currently indicates that the
selection of which shoulder pivot assembly to use is made separately
for the left and right shoulder assemblies, so that the dummy could be
fitted with the SD-3 shoulder pivot assembly on one side, and the
alternate shoulder pivot assembly on the other side. The dummy has not
been tested in such a mixed configuration, and the overall effects of
such configurations are unknown. NHTSA seeks comment on whether the
final specifications should allow such mixed configurations.
NHTSA seeks comment on whether the final drawing package should
include the SD3 shoulder, the alternate shoulder, or both. NHTSA also
seeks comment from THOR-50M users who have evaluated the proposed
alternate shoulder design, or other alternate shoulder designs, and
have data related to equivalence with respect to durability,
repeatability and reproducibility, and response in qualification,
biofidelity, injury and vehicle crash test conditions.
2. Shoulder Slip
NHTSA is aware that some researchers and regulatory authorities
have identified what they view as a possible design flaw in the
shoulder--that the shoulder belt may slip towards the neck in a crash--
and have developed potential modifications to the shoulder design to
prevent this from happening.
This concern was first raised in a 2018 conference paper describing
research conducted by Transport Canada. Transport Canada conducted a
series of vehicle crash tests with the THOR-50M in the driver seat in
two conditions: 40% offset and full frontal rigid barrier.\106\ It was
reported that the upper portion of the shoulder belt could translate
towards the neck and become entrapped in the gap between the neck and
the shoulder. This occurred in 33 of the 45 offset tests and in 2 of
the 13 full frontal rigid barrier tests. Compared to tests without
shoulder belt slip, tests with shoulder belt slip showed higher
measurements for lower neck shear (X-axis and Y-axis force), higher
chest deflections in the upper left and lower right quadrants, and
lower clavicle axial forces.
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\106\ Tylko, S., Tang, K., Giguere, F., Bussieres, A. (2018).
Effects of Shoulder-belt Slip on the Kinetics and Kinematics of
THOR. Proceedings of the 2018 IRCOBI Conference.
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Following that research, a 2019 Humanetics study identified and
evaluated three prototype alternative modifications to the shoulder
specified in the 2018 drawing package to prevent the shoulder belt from
entering the gap between the neck and the shoulder.\107\ The study
concluded that all three prototype modifications prevented belt
entrapment and identified the preferred design alternative (referred to
as a profiled split design). While the shoulder specified by NHTSA uses
the same material for the entire shoulder pad, the profiled split
design replaces the material closest to the neck with a higher-
stiffness plastic material. This is intended to prevent the collar (the
portion of the shoulder pad closest to the neck) from deforming and
allowing the shoulder belt to slip towards the neck.
---------------------------------------------------------------------------
\107\ Wang, Z.J., Fu, S., McInnis, J., Arthur, J. (2019).
Evaluation of Novel Designs to Address the Shoulder-belt Entrapment
for THOR-50M ATD. Proceedings of the 2019 IRCOBI Conference.
---------------------------------------------------------------------------
In addition, in recent discussions with NHTSA, Euro NCAP has noted
that several instances of shoulder belt slippage were observed in Euro
NCAP testing as well as research tests with the mobile progressive
deformable barrier. Euro NCAP reported that it was evaluating two
potential shoulder design modifications, and expected these to be
presented for approval in 2023.
While NHTSA has witnessed the shoulder belt moving towards the neck
in vehicle crash tests, this phenomenon does not appear to influence
dummy measurements related to injury criteria. NHTSA seeks comment on
the desirability of and specifications for a modification to prevent
belt slippage, including data on testing with the proposed shoulder
design showing that it is leading to belt slippage that has a
meaningful effect on test results. NHTSA also requests comment from
THOR-50M users who have evaluated the split shoulder pad (or any
available alternatives) and have data to support equivalence of
durability, repeatability and reproducibility, and response in
qualification, biofidelity, injury criteria, and vehicle crash test
conditions.
G. Hands
The THOR-50M specified in the 2023 drawing package includes the
same hand design as the HIII-50M. The drawing defining the hand
assembly of the THOR-50M \108\ includes material formulation (Solid
Vinyl, Formulation Portland Plastics, PM-7003) along with two two-
dimensional images and one three-dimensional image of the hand.
Additionally, the three-dimensional geometry of the hand assembly is
included in the computer-aided design (CAD) files available through the
NHTSA website in both Autodesk Inventor and generic STEP formats.
However, the vinyl call-out does not sufficiently specify the hardness
or the stiffness of the material formulation and may be insufficient to
define the part. NHTSA therefore seeks comment on whether there is a
need for a material test (e.g., hardness measurement or a quasi-static
compression test of a coupon of the material) or performance test
(e.g., quasi-static or dynamic impact to the as-fabricated hand) to
further define the hand assembly of the THOR-50M, and if so, what the
test might be.
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\108\ Drawing 472-6900-1/2.
---------------------------------------------------------------------------
H. Spine
The spine of the THOR-50M ATD is primarily constructed of steel.
There are two flexible elements (one in the thoracic spine and one in
the lumbar spine) that are intended to allow human-like spinal
kinematics in both frontal and oblique loading conditions.\109\ Between
the two flexible elements is a posture adjustment joint known as the
lumbar spine pitch change mechanism, which allows the posture of the
THOR-50M to be adjusted into various seating configurations in three-
[[Page 61912]]
degree increments, including, but not limited to, four designated
positions (erect, neutral, slouched, and super slouched).\110\ The
spine is instrumented with a five-axis thoracic spine load cell mounted
below the lumbar spine pitch change mechanism and above the lumbar
spine flex joint (a flexible joint that allows the dummy to go into
flexion/extension in the lumbar region). Triaxial accelerometers can be
installed in the nominal locations of the first, sixth, and twelfth
thoracic vertebra.
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\109\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T. (2001). Foundations and Elements of the
NHTSA THOR Alpha ATD Design. The 17th International Technical
Conference for the Enhanced Safety of Vehicles, Paper No. 458.
\110\ See Fig. 5-32 in the PADI.
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The proposed spine design differs from the THOR-50M used by Euro
NCAP. Whereas the 2023 drawing package specifies a lumbar spine pitch
change mechanism, TB026 specifies a four-position lumbar spine box or
an ``alternative spine box'' if ``data has been provided to show
equivalence between the NHTSA spine assembly and modified spine
assembly.'' \111\ Humanetics holds a patent on the four-position spine.
The four-position lumbar spine is not specified further, but it does
differ from the spine specified by the NHTSA drawings. The spine pitch
change mechanism specified in the 2023 drawing package allows the spine
to be set at a multitude of flexion or extension settings, not just
four. NHTSA understands that the Euro NCAP design is intended to
accommodate the in-dummy installation of some DAS brands by providing a
mounting surface for data loggers. THOR-50M units built for Euro NCAP
are configured with in-dummy DAS systems have the four-position spine.
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\111\ Sec. 1.4.3.
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NHTSA has tentatively decided not to specify a lumbar spine pitch
change mechanism limited to four positions for a few reasons. First,
NHTSA has not inspected, nor has it performed any testing with, the
four-position spine. Second, NHTSA generally avoids specifying patented
components in Part 572 (see Section VIII, Intellectual Property).
Third, the proposed spine specifications provide more adjustability
than the four-position spine so the dummy may be used in a wider range
of applications. NHTSA seeks comment on user experience with the four-
position spine, including any data on equivalence with the THOR-50M as
specified in the 2023 drawing package or biofidelity.
It is also NHTSA's understanding that members of Working Group 5
have observed variations in the ATD responses in the upper thorax
qualification tests that have led to difficulties in meeting the Euro
NCAP qualification specifications. Some manufacturers have suggested
that this variation in response is due to variation in the spine flex
joint (specifically, the vertical displacement (Z-axis) of the ribs is
too high). One potential cause that has been identified (by Porsche in
November 2019) is that that the hardness of the material comprising the
spine flex joint was lower than the specification called for.
NHTSA's qualification testing did not reveal any issues with
meeting the upper thorax qualification specifications (See Section
V.D). In any case, in light of the potential concerns raised within
Working Group 5 of possible excessive variation in the performance of
the spine flex joint, potentially traceable to out-of-specification
materials, NHTSA conducted a limited modeling exercise using the THOR-
50M Finite Element (FE) model to investigate this. This analysis
suggested that while variation in the lumbar and thoracic spine flex
joints does influence the thoracic response in both qualification and
sled test conditions, this variation is smaller than the expected test-
to-test and ATD-to-ATD variation; specifically, a decrease in stiffness
of the spine flex joints can influence the upper thorax qualification
response, but by a much smaller magnitude than the width of the
qualification specifications and test-to-test and ATD-to-ATD
variations. For more information on this issue and NHTSA's FE
modelling, please see Appendix B.
Nonetheless, a research effort is currently underway to assess the
influence of the lumbar and thoracic spine flex joints in physical
qualification tests (which would provide additional validation data to
the computational analysis) and develop isolated dynamic tests of the
lumbar and thoracic spine flex joints. Based on these results, NHTSA
could potentially consider adding such a test(s) in the drawing
package, qualification procedures, or laboratory test procedures. NHTSA
requests comment from THOR-50M ATD users who have data to demonstrate
variation in THOR-50M response that is believed to result from spine
flex joint variation, specifically when the parts evaluated met the
specifications of the THOR-50M drawing package. Additionally, NHTSA
requests comment on the need for a thoracic spine and/or lumbar spine
flex joint specification beyond the geometry and material properties
defined in the drawing package.
I. Abdomen
The abdomen of the THOR-50M consists of two components, the upper
abdomen and the lower abdomen. The lower abdomen is the region between
the lower thoracic rib cage and the pelvis. The upper abdomen is the
region on the dummy that represents the lower thoracic cavity, which
fills the volume that exists between the lowest three ribs, above the
lower abdomen and in front of the spine. The upper and lower abdomen
components of THOR-50M are represented by structural fabric bags
containing foam inserts which define the compression stiffness. Both
abdomen inserts are anchored posteriorly to the spine, while the upper
abdomen insert is additionally anchored to the lower rib cage. When the
lumbar spine pitch change joint is set to the ``slouched'' position,
the abdomen inserts are in contact with one another; when in the
``erect'' and ``neutral'' positions, the gap between the abdominal
inserts is filled with the lower abdomen neutral/erect position foam.
This gap is also spanned by two steel stiffeners on each side that are
installed into the torso jacket. The bottom surface of the lower
abdomen insert is coincident with the pelvis.
J. Pelvis
The THOR-50M pelvis is designed to represent human pelvis bone
structure to better represent lap belt interaction,112 113
and the pelvis flesh is designed to represent uncompressed geometry to
allow human-like interaction of the pelvis flesh with the vehicle
seat.\114\ The pelvis assembly is constructed of a steel and aluminum
structure representing bone surrounded by a molded foam-filled vinyl
covering representing flesh. The flesh is not physically connected to
the pelvis bone but is held in place due to the tight fit of
protrusions of the pelvis bone into recesses in the pelvis flesh, as
well as circular bosses in the pelvis flesh into recesses in the pelvis
bone. The pelvis flesh includes a portion of the upper thigh flesh, the
interior surface of which includes gaps around the femur bone to allow
articulation of the leg about the hip joint.
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\112\ Reynolds, H., Snow, C., Young, J., ``Spatial Geometry of
the Human Pelvis,'' U.S. Department of Transportation, Technical
Report No. FAA-AM-82-9, 1982.
\113\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA
THOR Alpha ATD Design,'' The 17th International Technical Conference
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
\114\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y.,
Platten, G., Spade, C., Pope, P., Haffner, M., ``Development of THOR
NT: Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,''
The 19th International Technical Conference for the Enhanced Safety
of Vehicles, Paper No. 05-0455, 2005.
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The THOR-50M pelvis flesh is a molded component, with a vinyl outer
[[Page 61913]]
layer filled with expandable polyurethane foam. The two-dimensional
drawing includes top, side, front, and isometric views of the molded
pelvis flesh, while its three-dimensional geometry is included in the
CAD files available through the NHTSA website in both Autodesk Inventor
and generic STEP formats. The drawing package specifies part weight and
foam density \115\ but not a material response or performance
requirement for the pelvis flesh.
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\115\ Drawing 472-4100.
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NHTSA is considering adding a performance specification for the
pelvis flesh similar to that defined in the HIII-50M PADI. Such a
performance specification would dictate the amount of allowable
compression of the pelvis flesh under a defined load. A similar test
was conducted on the pelvis flesh during the THOR Alpha design
development.\116\ One such possible requirement would be the
compression at a force of 500 N. Alternatively, Porsche has suggested a
dynamic impact test using an impactor similar to that used in the upper
thorax qualification test to impact the bottom of the pelvis flesh at a
velocity of 2 m/s. NHTSA seeks comment on the need and specifications
for a pelvis compression test, including whether it should be a
qualification requirement, a drawing specification, or otherwise.
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\116\ White Jr, R.P., Rangarajan, N., Haffner, M., ``Development
of the THOR Advanced Frontal Crash Test Dummy'', 34th Annual SAFE
Symposium, Conference paper, 1996.
---------------------------------------------------------------------------
The pelvis is instrumented with bi-lateral triaxial load cells
attached to the acetabulum (in order to measure the reaction force
between the femur and the pelvis) and a triaxial accelerometer array at
its center of gravity. The pelvis is also instrumented with bi-lateral
anterior-superior iliac spine (ASIS) load cells that measure contact
force in a nominally longitudinal axis and moment about a nominally
lateral axis. The ASIS load cell is primarily used to measure the force
transferred to the pelvis through the lap belt, in which case the
moments can be used to determine the vertical level or center of
pressure of the lap belt force.
K. Upper Leg
The upper leg assembly is constructed of steel and aluminum and
includes a rubber compressive element at the middle of the femur shaft.
This compressive element consists of a steel plunger that can translate
axially along the femur shaft through a guide system. When the femur is
loaded in axial compression (e.g., pushing the knee towards the pelvis
parallel to the femur), the motion of the plunger is resisted by a
rubber element, which allows a human-like compression response.\117\ At
the proximal end, the femur is connected to the pelvis through a ball
joint in a socket attached to the acetabulum load cell. At the distal
end, there is a six-axis load cell attaching the femur to the knee
assembly.
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\117\ Ridella, S., Parent, D., ``Modifications to Improve the
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The
22nd International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011. See Figure 17.
---------------------------------------------------------------------------
L. Knee
The THOR-50M knee is similar in construction to that of the HIII-
50M, with a few differences. The primary structure of the knee cap is
fabricated from aluminum, attached proximally to the femur load cell.
Inside of the kneecap assembly, a slider mechanism is installed to
allow translational motion of the tibia with respect to the knee. The
knee slider includes a stop assembly to prevent metal-to-metal contact
and to define the force-deflection characteristic of the tibia
translation. Attached to the slider is a string potentiometer to
measure the magnitude of tibia translation relative to the knee. The
sides of the kneecap are enclosed by urethane covers to protect the
slider mechanism, and the knee assembly is wrapped in a foam-filled
vinyl cover representing knee flesh.
The design of the knee slider modifies the HIII-50M design by
changing the geometry and material properties of the molded slider
assemblies (472-5320 and 472-5330) and stop assemblies (472-5358).\118\
This change was made because at levels of knee displacement below the
10.2-millimeter (mm) biofidelity response requirement, the HIII-50M has
been found to be stiffer than PMHS response corridors. Thus, during the
THOR-50M Mod Kit project, biomechanical response requirements were
specified with an additional measurement point at 5 mm of knee
displacement with a force between 100 and 500 N. The Mod Kit also
relegated the measurement point at 10.2 mm of deflection to a secondary
requirement, as it was shown to be at the high end of the underlying
PMHS corridors. While the 5 mm and 17.8 mm response requirements were
met by the revised THOR-50M knee slider,\119\ the force-deflection
response was below the human response corridor between 8 mm and 15 mm
of deflection, but above the corridor after 18 mm of deflection.\120\
As such, when the biofidelity was evaluated using BioRank, the external
biofidelity score of 2.282 indicated that the THOR-50M response was
more than two standard deviations from the PMHS mean response. This
BioRank score was lower than the corresponding HIII-50M score (1.070).
This should be taken into consideration when using the THOR-50M to
evaluate the risk of ligamentous knee injury.
---------------------------------------------------------------------------
\118\ Id. at Figure 16.
\119\ Id.
\120\ See Biofidelity Report, p. 254 (Fig. 45).
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M. Lower Leg
The mechanical design of the THOR-50M lower extremity includes a
compressive rubber section in the tibia shaft, similar to the compliant
femur section, which provides more biofidelic force transmission from
the heel to the knee. The spring damper Achilles tendon system aids in
producing biofidelic ankle motion and torque characteristics. The ankle
design allows rotation about three axes, representing inversion/
eversion, dorsi/plantar-flexion, and axial rotation, and includes
molded rubber elements to define the moment/rotation response and limit
metal-to-metal contact at the extents of the range of motion. Different
from existing ATDs, the THOR-50M includes a molded shoe design which
integrates the foot and shoe into a single part. This feature, added in
the 2016 update to the THOR-50M drawing package,\121\ is intended to
reduce potential variability in the response of commercially available
shoes.
---------------------------------------------------------------------------
\121\ National Highway Traffic Safety Administration (2016).
Parts List and Drawings THOR-50M Advanced Frontal Crash Test Dummy
THOR-50M Male August 2016. Docket ID NHTSA-2015-0119-0376.
---------------------------------------------------------------------------
Euro NCAP TB026 deviates from the proposed drawing package in that
it specifies the HIII-50M lower legs, including the military
specification \122\ shoes, knee slider sensor, and roller ball-bearing
knees. We believe the THOR-50M specifications are preferable, for the
reasons given above (e.g., biofidelity).
---------------------------------------------------------------------------
\122\ Specification is not stated in Euro NCAP TB026, but
believed to be MIL-S-13192P as specified in 49 CFR 571.208 S8.1.8.2.
---------------------------------------------------------------------------
Each lower leg can be instrumented with five-channel load cells in
the upper and lower tibia, a uniaxial load cell to measure the Achilles
cable force, and three rotary potentiometers to measure the rotation of
the individual ankle joints. Two uniaxial accelerometers can be mounted
to the tibia and a tri-pack accelerometer assembly can be mounted to
each foot plate.
N. Data Acquisition System
Testing with THOR-50M requires (as does testing with any dummy) a
data
[[Page 61914]]
acquisition system (DAS). The data acquisition system performs signal
conditioning, triggering, and data collection to store measurements
from instrumentation installed in the dummy during a test into
nonvolatile memory. As it relates to ATDs, there are effectively two
types of DAS: external and internal (or in-dummy). As we explain below,
while the 2018 drawing package does not specify a DAS (because it
assumes the use of an external DAS), NHTSA is proposing to specify an
optional in-dummy DAS.\123\
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\123\ We note that the 2023 drawing package itself does not
contain specifications for an in-dummy DAS. Instead, the proposed
in-dummy DAS specifications are set out in an addendum that is being
docketed along with the 2023 drawing package.
---------------------------------------------------------------------------
An external DAS is, as the name indicates, external to the dummy.
The instrumentation in the dummy is connected to the external DAS via
wires, sometimes referred to as an umbilical cable. The 2018 drawing
package does not explicitly specify a DAS or related equipment, but the
drawings assume an external DAS: they assume that the instrumentation
wires are long enough to be bundled into an umbilical cable and
connected to a DAS located in the lab or mounted to the vehicle in
which the ATD is seated.
An internal DAS is installed within the dummy itself. An internal
DAS has some advantages to an external DAS. The primary advantage is
related to the mass properties of the dummy. With an internal DAS
system, there are no external cables that may possibly affect body
segment masses; segment masses are always the same no matter how the
dummy is used. While upfront cost is higher, an internal DAS would
reduce per-test costs, eliminate the need for interface cables to lab-
specific DAS systems (which have been a frequent sources of
instrumentation failures in research testing), and reduce the
adjustments needed to arrive at the target test vehicle weight.
Feedback from industry \124\ as well as Euro NCAP indicates that users
prefer an in-dummy DAS for its many usability advantages. Euro NCAP
TB026 requires an in-dummy DAS.\125\ While Euro NCAP TB029 currently
does not specify an approved in-dummy DAS,\126\ earlier versions of
TB029 did specify a few different approved in-dummy DAS systems.\127\
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\124\ Alliance of Automobile Manufacturers, Inc. (2016).
Technical Considerations Concerning NHTSA's Proposal to Rework the
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
\125\ TB026 Sec. 1.2.
\126\ European New Car Assessment Programme (2022). Euro NCAP
Supplier List, Version 4.0, October 2022, TB 029, available at:
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\127\ European New Car Assessment Programme (2022). Euro NCAP
Supplier List, Version 3.1, April 2021, TB 029, available at:
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/. The DTS TDAS G5, SLICE Nano, and SLICE6; the
Kistler DTI, microDAU, and NXT32; and the Messring M=BUS.
---------------------------------------------------------------------------
In light of these potential advantages and user preferences, NHTSA
sponsored development and testing of an in-dummy DAS. NHTSA published a
request for solicitation for an in-dummy DAS.\128\ This was before Euro
NCAP began testing with the THOR-50M. The solicitation favored a
minimal redesign of existing THOR-50M parts, in order to facilitate
interchangeability of parts between THOR-50Ms with and without in-dummy
DASs. NHTSA contracted Diversified Technical Systems (DTS) to implement
its SLICE6 data acquisition system in a NHTSA-owned THOR-50M. This
included delivery of DAS components, replacement instrumentation
compatible with the DAS, and replacement ATD parts to allow attachment
of DAS components and preservation of inertial properties. The
resulting implementation distributes a series of small 6[hyphen]channel
data acquisition modules throughout the ATD, mounted directly on load
cells or sensors where possible, or close to the sensor with short
cables to the sensor. The DAS modules are chain[hyphen]networked with
four wiring harnesses which connect to the SLICE6 Distributor, with a
single ATD exit cable connecting the DAS to the full test system.
---------------------------------------------------------------------------
\128\ National Highway Traffic Safety Administration (2017).
Implement and Install THOR 50M In Dummy Data Acquisition System.
Solicitation Number DTNH2217Q00033, available at https://sam.gov/opp/068c7821de797ebe7f9e78a0f2b68dc4/view.
---------------------------------------------------------------------------
NHTSA evaluated the overall performance and equivalence of the
THOR-50M with the in-dummy SLICE6 DAS in a full suite of qualification
testing and a variety of sled and vehicle crash testing. This research
and analysis is described briefly below. The vehicle crash testing is
described in more detail in the cited report. NHTSA is preparing a
report on the installation, qualification testing, and sled testing of
the SLICE6 in-dummy DAS, which will be placed in the research docket
when it is complete. Additional information on the durability of the
THOR-50M with the in-dummy DAS system is included in Section VII.B,
Durability and Maintenance.
It was possible to install the SLICE6 into the dummy with
negligible changes to the mass, moment of inertia, and center of
gravity of the ATD and its individual body segments. This did require
modifications to several THOR-50M parts (e.g., the lower thoracic spine
assembly) in order to allow attachment of the DAS hardware to the rigid
components of the ATD.
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\129\ Saunders, J., Parent, D. (2023). Update on NHTSA's OMDB's
half barrier analysis. Proceedings of the 27th Enhanced Safety of
Vehicle Conference, Yokohama, Japan.
\130\ The OVSC Laboratory Test Procedures for FMVSS No. 208
specify an ambient temperature measured within 36 inches of the ATD
to be between 69 and 72 degrees Fahrenheit. National Highway Traffic
Safety Administration (2008). Laboratory Test Procedure for FMVSS
208, Occupant Crash Protection, TP208-14, available at: https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/tp-208-14_tag.pdf.
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NHTSA has been able to fully qualify THOR-50M ATDs with
the in-dummy DAS installed. Since the SLICE system has been installed,
we have used the dummy in many tests and have qualified it with no
issues. The THOR-50M with the in-dummy DAS was tested in simplified
sled tests. Sled tests were conducted in the Gold Standard 1 (40 km/h,
12g peak pulse, standard lap and shoulder belt) and Gold Standard 2
(30km/h, 9g peak pulse, 3kN load limited shoulder belt) test
conditions, which were used both in biofidelity assessment and in the
development of thoracic injury criteria. The goal of this testing was
to determine if any differences occurred between the external and
internal DAS configurations, and if so, whether the magnitude of these
differences would affect the biofidelity and injury criteria
development analyses.
NHTSA also tested the THOR-50M with an in-dummy DAS in a
series of vehicle crash tests in the OMDB test condition with three
different deformable barrier faces. While some of the OMDB tests
appeared to show differences between the in-dummy DAS and umbilical
configurations, it was not clear whether this was due to variation in
the dummy response or variation in dummy positioning, vehicle response,
and/or restraint system response.\129\
Importantly, this testing did not reveal any potential durability
or usability issues associated with the in-dummy DAS, with one possible
exception: The temperature inside the thoracic cavity of the ATD can
increase beyond the ambient temperature typically prescribed for
regulatory and consumer information crash tests.\130\ In a more recent
set of vehicle crash tests, NHTSA closely monitored the rib temperature
of the THOR-50M with the
[[Page 61915]]
in-dummy DAS.\131\ By routinely limiting the ``ON'' time of the DAS,
NHTSA has been able to maintain the temperature range. Additionally,
NHTSA has used a portable fume extractor device to aid in maintaining
the temperature of the WorldSID-50M side impact dummy, which also has
internal DAS system.132 133 This device may also be employed
in tests with the THOR-50M.
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\131\ Saunders, J., Parent, D., Martin, P. (2023). THOR-50M
fitness assessment in FMVSS No. 208 unbelted crash tests.
Proceedings of the 27th Enhanced Safety of Vehicle Conference,
Yokohama, Japan.
\132\ Tatem, W., Louden, A. (2023). WorldSID-50M Fitness
Assessment in FMVSS No. 214 Moving Deformable Barrier and Oblique
Pole Crash Tests. Proceedings of the 27th Enhanced Safety of Vehicle
Conference, Yokohama, Japan.
\133\ This device is used to dissipate heat from the dummy in
the pre-test setup (for example, while seating and positioning the
dummy). Typically, a tube is inserted into the dummy jacket and in
conjunction with the fan is used to vent heat from the dummy to
maintain an in-spec internal temperature. The apparatus is detached
from the dummy immediately prior to the vehicle or sled test. Use of
such a fan may be specified in the OVSC laboratory test procedure.
---------------------------------------------------------------------------
Based on this testing, NHTSA has tentatively concluded that the
THOR-50M with the in-dummy DAS is equivalent to one with the external
DAS. NHTSA is therefore proposing an internal DAS as permitted optional
instrumentation that it could use in its testing. This necessitates
changes to the dummy to accommodate the DAS while ensuring that there
are no changes to the mass, moment of inertia, and center of gravity of
the ATD and its individual body segments. These changes may differ from
the Euro NCAP approach specified in TB026, which permits the four-
position spine box (discussed in Section III.H above) to accommodate
the installation of some DAS brands by providing a mounting surface for
data loggers. Euro NCAP does not provide part-by-part engineering
drawings of the various DAS packages, which is necessary for THOR-50M
to be sufficiently objective.
NHTSA has therefore provided, in an addendum to the 2023 drawing
package, further specifications for the dummy to accommodate an
internal DAS. It is anticipated that, upon finalization of this
proposal, the in-dummy DAS drawings will be fully integrated within the
relevant technical data package components. These specifications
consist of descriptions of the instrumentation and new drawings for the
dummy parts that require modifications to accommodate the DAS. The
changes are specified such that the dummy with the in-dummy DAS will
have the same inertial properties as the dummy using the external DAS.
The drawings show DAS mass blanks in lieu of the actual DAS components
(battery, data logger, etc.) with the exterior dimensions of the blank
matching those of the corresponding SLICE6 component.
If an in-dummy DAS component is not installed (for example, if
lower leg instrumentation is not needed for a given test mode), the
blank would be filled with a material of a specified density. The
material of the blank is not specified (although a reference
specification is provided) but would be selected to provide an
appropriate density and may also have internal flashing holes needed to
attain the desired mass, which is chosen to match the mass of the
actual DAS component. It is anticipated that, upon finalization of this
proposal, the PADI will show two sets of installation steps: one with
the ``blank'' component, and one with the actual DAS parts. (This two-
set convention is also followed with load cells and their structural
replacements). The proposed specifications are based on, but not
necessarily limited to, the SLICE6 (the SLICE6 is not explicitly
specified or called-out by name), so that another system fitting within
the defined specifications could also be utilized.\134\
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\134\ While we are aware of in-dummy DASs produced by other
manufacturers, we have not evaluated whether these systems would be
compatible with the in-dummy DAS addendum to the 2023 drawing
package.
---------------------------------------------------------------------------
NHTSA seeks comment from users who have experience with both
umbilical and in-dummy DAS configurations of the THOR-50M, as to
whether they have seen any quantifiable differences between the two.
NHTSA also seeks comment on whether any additional changes should be
made to the proposed drawings specifying the in-dummy DAS to make it
more amenable to additional DAS systems that are already in the field.
IV. Biofidelity
Biofidelity is a measure of how well the dummy replicates a human,
and includes anthropometry, mass properties, range of motion, and
impact response. The impact biofidelity is evaluated by comparing the
response of the dummy to the response of a post-mortem human surrogate
(PMHS or cadaver) or human volunteer in a variety of different test
conditions (also referred to as test modes). Some of these tests focus
on individual dummy components (head, neck, chest, abdomen, upper leg,
knee, lower leg) and some evaluate the entire dummy as a complete
assembly.
To evaluate the biofidelity of THOR-50M, NHTSA selected test
conditions based on relevance to frontal and frontal oblique crash test
applications and the availability of data. For example, a neck frontal
flexion test was conducted by attaching the base of the THOR-50M neck
to a sled and applying a certain acceleration pulse. This was then
compared to the response measured on human volunteers who were
subjected to a similar pulse. Specifically, the impact biofidelity of
the THOR-50M was assessed in twenty-one test conditions. The test
conditions are summarized in Table 6. Each test produces a series of
data points (e.g., force vs. time).
The test conditions have been developed over the years by various
researchers to evaluate biofidelity and have been published in peer-
reviewed journals. The PMHS and human volunteer response data generally
comes from this published research. The THOR-50M response data comes
from testing that NHTSA has been conducting on the THOR-50M throughout
its development, all of which is available in NHTSA's Biomechanics Test
Database.\135\ NHTSA also compared THOR-50M's biofidelity to that of
the HIII-50M; many of the tests conducted with THOR-50M were paired
with the same test conducted on the HIII-50M. In our testing we
attempted to match the test conditions as closely as possible to the
test conditions in the original PMHS or volunteer tests.\136\
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\135\ Available at https://www.nhtsa.gov/research-data/research-testing-databases#/biomechanics.
\136\ Overall, while some assumptions were necessary in the
reproduction of the PMHS or volunteer test conditions, we believe
that these assumptions should not affect the overall biofidelity
assessment of the THOR-50M. For instance, NHTSA simplified some of
the original tests in order to facilitate ease of testing when we
expected the simplification to have a negligible influence on the
result, such evaluating neck flexion using only the ATD's head and
neck, and not the entire dummy. These assumptions and
simplifications, as well as any limitations to our analyses, are
discussed in detail in the docketed biofidelity report. Parent, D.,
Craig, M., Moorhouse, K. 2017. Biofidelity Evaluation of the THOR
and Hybrid III 50th Percentile Male Frontal Impact Anthropomorphic
Test Devices. Stapp Car Crash Journal, 61, 227-276, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0004.
[[Page 61916]]
Table 6--Biofidelity Conditions Considered in the Design of the HIII
Frontal Dummies and THOR-50M ATDs
------------------------------------------------------------------------
Subpart
Body region Test condition E, O, W THOR-50M
------------------------------------------------------------------------
Head......................... Isolated Head Drop...
Whole-body Head ........
Impact.
Face Rigid Bar....... ........
Face Rigid Disk...... ........
Neck......................... Neck Flexion, ........
Pendulum.
Neck Extension, ........
Pendulum.
Neck Frontal Flexion, ........
Sled.
Neck Lateral Flexion, ........
Sled.
Neck Torsion......... ........
Thorax....................... Sternal Impact, 6.7 m/ ........
s.
Sternal Impact, 4.3 m/ ........
s.
Lower Ribcage Oblique ........
Abdomen...................... Upper Abdomen ........
Steering Rim.
Lower Abdomen Rigid ........
Bar.
Abdomen Belt Loading. ........
KTH.......................... Femur Compression....
Knee Shear...........
Lower Extremity.............. Dynamic Heel Impact.. ........
Tibia Axial ........
Compression.
Dynamic Dorsiflexion. ........
Whole-body................... Gold Standard 1...... ........
Gold Standard 2...... ........
Gold Standard 3...... ........
Far Side Oblique..... ........
------------------------------------------------------------------------
The test conditions used to evaluate the THOR-50M represent an
accumulation of biomechanics research. All conditions are accompanied
by a well-specified, objective test procedure and a well-founded set of
human response targets. The set of test conditions has grown
substantially over the span of Part 572 rule makings. For example, in
NHTSA's original 1998 proposal for the Subpart O HIII-5F dummy,\137\
only six biofidelity conditions were assessed.\138\ Since then, the
list has grown substantially; new conditions have been developed for
all body regions, and whole-body sled test conditions have been
developed.\139\
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\137\ 63 FR 46981.
\138\ Mertz, H.J., Irwin, A.L., Melvin, J.W., Stanaker, R.L., &
Beebe, M. (1989). Size, weight and biomechanical impact response
requirements for adult size small female and large male dummies (No.
890756). SAE Technical Paper.
\139\ See National Highway Traffic Safety Administration,
``Biomechanical Response Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S.
Department of Transportation, Washington, DC, March 2005 (available
at http://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf) and
Ridella, S., Parent, D., ``Modifications to Improve the Durability,
Usability, and Biofidelity of the THOR-NT Dummy,'' The 22nd
International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011.
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NHTSA quantified how closely the response of the THOR-50M matched
the response of the PMHS or human volunteers using the Biofidelity
Ranking system (BioRank).\140\ BioRank has been applied in other
instances cited in the literature \141\ and in other NHTSA Part 572
rulemakings.\142\ This methodology statistically compares the dummy
response to the average PMHS/volunteer response (typically a time-
series but sometimes a point estimate). A BioRank value of 0.0
indicates an ATD response identical to the average PMHS/volunteer
response; a value of 1.0 indicates an ATD response that is on average
one standard deviation \143\ away from the average PMHS/volunteer
response; a value of 2.0 indicates an ATD that is on average two
standard deviations away from the average PMHS/volunteer response; and
so on. Therefore, the lower the BioRank value, the better the
biofidelity. We computed BioRank scores for both the THOR-50M and the
HIII-50M.
---------------------------------------------------------------------------
\140\ Rhule, H., Maltese, M., Donnelly, B., Eppinger, R.,
Brunner, J., Bolte, J. (2002) Development of a New Biofidelity
Ranking System for Anthropomorphic Test Devices. Stapp Car Crash
Journal 46: 477-512.
\141\ Rhule, H., Moorhouse, K., Donnelly, B., Stricklin, J.
(2009) Comparison of WorldSID and ES-2RE Biofidelity Using Updated
Biofidelity Ranking System. 21st ESV Conference, Paper No.09-0563.
\142\ The analysis using Biorank described here mirrors (with
some exceptions) the approach used in the assessment of the WorldSID
50th ATD. See, e.g., 80 FR 78522, 78538 (Dec. 16, 2015) (New Car
Assessment Program Request for Comments); 71 FR 75304 (Dec. 14,
2006) (final rule for ES-2re Side Impact Crash Test Dummy 50th
Percentile Adult Male); 71 FR 7534 (Dec. 14, 2006) (final rule for
SID-IIs Side Impact Crash Test Dummy 5th Percentile Adult Female).
\143\ The standard deviation is a statistic that measures the
dispersion of a dataset relative to its mean.
---------------------------------------------------------------------------
For each body region, we calculated two BioRank scores: one for
external biofidelity (the extent to which the ATD represents a human
surrogate to the vehicle or restraint system); and one for internal
biofidelity (the ability of the ATD to represent the human responses
that relate to prediction of injury). External biofidelity measures are
generally those recorded at the test fixture level, such as pendulum
force or belt force; internal biofidelity measures are generally those
recorded by the internal instrumentation of the ATD or test equipment
such as motion tracking that records subject excursion.
NHTSA considered two other methods of quantifying biofidelity. One
is the International Standards Organization (ISO) 9790 Biofidelity
Classification System. ISO 9790 defines the analysis process, response
corridors, and weighting factors for the quantitative assessment of
biofidelity of side impact ATDs. Because the ISO 9790 response
corridors and weighting factors are specific to side-impact ATDs, it
could not be directly applied to a frontal impact ATD such as the THOR-
50M, and we are not aware of a corollary ISO standard for assessment of
frontal impact ATD biofidelity. While a method similar to that
described in ISO 9790 could be developed to assess frontal impact ATD
biofidelity, we believe such a method may introduce subjective bias
because it contains many subjective features, including weighting
[[Page 61917]]
of test conditions and body regions.\144\ The BioRank system was
developed to minimize subjectivity in the areas of corridor
development, weighting, and scoring. Another method NHTSA considered is
correlation and analysis (CORA), which may be a useful tool to carry
out quantitative analysis.\145\ However, the vast array of tunable
parameters in the software can result in unintentional subjectivity and
poor reproducibility. Further, there are no known and accepted
relationships between CORA scores and biofidelity classifications.
Accordingly, we evaluated biofidelity using BioRank.
---------------------------------------------------------------------------
\144\ Rhule, D., Rhule, H., Donnelly, B. (2005) The Process of
Evaluation and Documentation of Crash Test Dummies for Part 572 of
the Code of Federal Regulations. 19th ESV Conference, Paper No. 05-
0284, pp. 9-10.
\145\ Gehre C, Gades H, Wernicke P (2009) Objective rating of
signals using test and simulation responses, The 21st International
Technical Conference for the Enhanced Safety of Vehicles, Paper No.
09-0407, 2009.
---------------------------------------------------------------------------
We note that because many of the biofidelity test conditions
utilize specialized instrumentation or test equipment, they are not
intended to be carried out as certification or qualification tests
conducted between crash tests or sets of crash tests to confirm that
specified ATD response requirements are met. Instead, due to its
relative complexity, biofidelity testing is carried out at the ATD
design stage to assess the biofidelity of the design. Simplified and
standardized versions of the biofidelity test conditions have been
developed as qualification procedures for some body regions. Because
the qualification response requirements are based on the expected
variation in response of the ATD, not the underlying human response,
the qualification requirements specify a much smaller allowable range
in response than the biomechanical design targets. Therefore, it is
expected that all THOR-50M units that meet the specifications of the
qualification procedures would demonstrate similar biofidelity. The
proposed qualification response requirements are discussed in Section
V.
A full description of NHTSA's biofidelity testing and analysis can
be found in the docketed biofidelity report.\146\ We note that there
are no separate discussions in the report for the shoulder, spine, or
pelvis. Impact biofidelity of the spine and pelvis, as well as the
dynamic biofidelity of the shoulder, are intrinsically evaluated as
part of the whole-body biofidelity sled test series.\147\ Shoulder
biofidelity has also been assessed quasi-statically and found to be
more similar to the human volunteer corridors than existing ATDs. NHTSA
is finalizing a report on the alternate shoulder design, which includes
the biofidelity evaluation described here; once complete, this report
will be published to the research docket.
---------------------------------------------------------------------------
\146\ Parent, D., Craig, M., Moorhouse, K. 2017. Biofidelity
Evaluation of the THOR and Hybrid III 50th Percentile Male Frontal
Impact Anthropomorphic Test Devices. Stapp Car Crash Journal, 61,
227-276, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0004.
\147\ The qualitative biofidelity of the shoulder is also
discussed in the Biofidelity Report, where the role of the shoulder
in belt retention (or lack thereof) is discussed qualitatively. See
p. 272-273.
---------------------------------------------------------------------------
NHTSA believes that the THOR-50M is sufficiently biofidelic for
incorporation into Part 572. The biofidelity report shows that the
THOR-50M exhibits overall internal and external BioRank scores of below
2.0. See Table 7. Both internal and external BioRank scores are lower
than those of the HIII-50M, which is defined in Part 572 (Subpart E)
and used in regulatory and consumer information frontal impact crash
testing. At the body region level, the internal and external BioRank
scores for THOR-50M are all below 2.0 except for neck internal
biofidelity and abdomen external biofidelity. The THOR-50M BioRank
score for the neck and abdomen external biofidelity are, however, lower
(better) than those for the HIII-50M. Overall, the internal BioRank
scores for the THOR-50M were lower than those of HIII-50M in 5 of the 7
body regions evaluated, and THOR-50M external BioRank scores were lower
than those of HIII-50M in 6 of the 7 body regions evaluated. Thus, the
THOR-50M has generally improved biofidelity in the individual body
region tests, which improves the accuracy of injury predictions. The
THOR-50M and the HIII-50M have comparable quantitative biofidelity in
the whole-body sled test conditions.\148\
---------------------------------------------------------------------------
\148\ This finding has been confirmed by independent research; a
2018 study showed that the HIII-50M and THOR-50M demonstrated
similar biofidelity scores in a sled test environment representing a
production vehicle. See Albert, Devon L., Stephanie M. Beeman, and
Andrew R. Kemper. ``Occupant kinematics of the Hybrid III, THOR-M,
and postmortem human surrogates under various restraint conditions
in full-scale frontal sled tests.'' Traffic Injury Prevention
19.sup1 (2018): S50-S58.
Table 7--Body Region Internal and External BioRank Summary
----------------------------------------------------------------------------------------------------------------
THOR-50M HIII-50M
Body region ---------------------------------------------------------------
Internal External Internal External
----------------------------------------------------------------------------------------------------------------
Head............................................ 0.155 1.143 0.013 6.640
Neck............................................ 2.155 1.677 2.185 4.318
Thorax.......................................... 0.917 0.948 1.603 2.070
Abdomen......................................... 1.470 2.803 1.629 3.474
KTH............................................. 1.400 1.731 3.875 6.667
Lower Extremity................................. 1.349 0.871 0.832 1.108
Whole-body...................................... 1.472 1.989 1.576 1.780
---------------------------------------------------------------
Overall..................................... 1.274 1.594 1.673 3.722
----------------------------------------------------------------------------------------------------------------
Since a majority of the test conditions involved pure frontal
loading, and several involved oblique and lateral loading (neck lateral
flexion, neck torsion, lower thorax oblique, Gold Standard 3, and Far
Side Oblique test conditions), these findings are expected to extend to
frontal and frontal oblique crash test conditions. The findings may
not, however, extend to other loading conditions (such as pure lateral
or rear impacts) without further research.
V. Qualification Tests
This NPRM proposes qualification tests (also referred to as
qualification procedures) for THOR-50M. The qualification procedures
describe a series of impact tests performed on a fully-assembled dummy
or dummy sub-assembly. The tests assess the components that play a key
role in the dummy's performance in the intended application of frontal
and frontal oblique crashes. We propose
[[Page 61918]]
qualification tests for the head, face, neck, upper thorax, lower
thorax, abdomen, upper leg, knee, and lower leg. For some body regions
(such as the face) we propose a single test condition (also referred to
as a test mode), while for other body regions (for example, the neck)
we propose a series of different test conditions.
Each qualification test condition consists of test procedures, test
parameters, and acceptance intervals. The test procedures describe a
detailed series of steps that must be carried out to perform the test.
Test parameters describe specific aspects of the dummy's response.
Acceptance intervals (or qualification targets) are specified for each
test parameter. Acceptance intervals are a typically pair of numeric
values (a minimum value and maximum value) within which the dummy
response must fall in order to pass, but can also represent a minimum
or maximum value of the response. For instance, one of the tests
involves striking the head with an impactor and measuring the head's
acceleration, which must be within the acceptance interval 117 11.7 Gs.
The qualification tests mirror the dummy loading patterns observed
in frontal crash tests, including full frontal, oblique, and offset
modes. For the neck assembly, we have specified separate requirements
in flexion, extension, and lateral flexion. These bending modes have
all been observed in crash testing. Additionally, a torsion test is
prescribed for the neck since it also twists along its long axis to
some degree. For the feet and ankles, tests in inversion, eversion,
dorsiflexion, and axial loading through the tibia are specified to
account for the various injurious loads that have been observed in
crash tests. For the head, face, upper and lower thorax, abdomen, upper
legs, and knees, we have only prescribed impact tests to anterior
aspects since injurious loads pass primarily through those aspects
during crash testing. The impact speeds and probe masses have been
selected to demonstrate that the various body segments work properly at
energy levels at or near those associated with high injury risks. For
measurements not associated with an injury criterion, energy levels are
chosen to exercise the dummy approaching its functionality limits, but
without causing damage.
The qualification tests ensure that the dummy is functioning
properly. There are a few inter-related aspects to this. One is that
qualification tests ensure that dummy components and sensors are
properly assembled and functioning. Qualification tests monitor the
response of components that may have become loosened or misaligned
since initial assembly. For each test, certain dummy sensors and signal
characteristics (such as the magnitude and timing) have been specified
as qualification targets. Loose or misaligned parts may become evident
when a signal does not conform to the prescribed signal
characteristics. By monitoring these sensors, the qualification tests
ensure that the dummy is functioning properly. The tests also ensure
that the sensors themselves are working properly. Another aspect is
that qualification tests help identify components that have
deteriorated over time, preventing the dummy from meeting the
qualification targets; such parts need to be replaced or refurbished.
Many of the qualification test protocols are very similar to the
dynamic tests used to assess biofidelity. This helps to ensure that a
qualified dummy is also a biofidelic dummy. Finally, they ensure that
the dummy or particular sub-assembly is responding in a uniform and
expected manner; if it is not, certain dummy components might need to
be tuned or adjusted to obtain a response within the qualification
targets.
NHTSA's experience has shown that the impact tests on body segments
are needed to ensure uniformity of dummy responses in a subsequent
vehicle crash test. In other words, full conformance to part and
assembly specifications (in accordance with the drawings and PADI) is
not enough to guarantee a uniform dummy response in a crash test.\149\
Qualification tests have proven reliable and sound in qualifying
NHTSA's other test dummies. Moreover, some of the proposed
qualification tests use the same test equipment as other ATDs, thus
minimizing the amount of new qualification equipment needed by test
laboratories that may already have such equipment in place for
qualifying other ATDs. Meeting the qualification tests helps ensure
that the dummy is capable of responding properly in a compliance or
research test. This in turn helps to ensure that the dummy is an
objective test device suitable for the assessment of occupant safety in
compliance tests specified in Federal Motor Vehicle Safety Standards,
and for other testing purposes.
---------------------------------------------------------------------------
\149\ At the same time, conformance to a qualification
requirement is not a substitute for parts that do not conform to
drawing specifications.
---------------------------------------------------------------------------
NHTSA proposes setting the qualification targets at
10% of the mean response for each qualification parameter as reported
in the qualification test R&R study (discussed in Section VI). In that
study we subjected multiple dummies to repeated tests in each test
condition at multiple test laboratories. The repeatability testing and
analysis for the qualification tests is described in more detail in
Section VI.A. We believe that 10% is wide enough to account for normal
variations in ATD and laboratory differences, and narrow enough to
ensure consistent and repeatable measurements in standardized testing
with the ATD. This is also consistent with the qualification limits for
the other Part 572 ATDs. For example, for the Hybrid III 10-year-old
child dummy, the acceptance intervals are, on average, set at 9.9% from the nominal midpoint, with a low of 8.4% (neck rotation
in the neck extension test) and a high of 10.8% (in the neck moment in
the extension test and chest deflection in the thorax impact
test).\150\ For all Part 572 ATDs, the average acceptance interval is
11%.
---------------------------------------------------------------------------
\150\ HIII-10C, Subpart T.
---------------------------------------------------------------------------
We also considered setting the qualification targets at plus or
minus two standard deviations from the mean response observed in the
testing reported in the repeatability and reproducibility study. This
would have narrowed the acceptance interval for almost all responses,
some of which would have been unreasonably narrow. For instance, the
head impact test results in the repeatability and reproducibility study
were very uniform, with a CV for peak force of 0.9%. If the acceptance
interval for peak force were set to plus or minus two standard
deviations (1.8%), 24 of the 26 trials would have resulted
in a pass; if it were set to 2.5%, all 26 trials would have
resulted in a pass. This result may have been a function of using only
three THOR-50M units in the test series, all of which were brand new
when we tested them. Therefore, we propose a greater allowance of
10% for all qualification requirements to account for
slight variations that may arise from equipment and testing variations
at different test labs as well as a future population of THOR-50M units
from dummy manufacturers in which lot-to-lot differences in the
fabrication of parts from the same manufacturer may exist. It also
allows for slight changes to individual THOR-50M units over time,
either due to aging of polymeric components or wear and tear under
normal use. Table 8 summarizes the proposed THOR-50M qualification
requirements.
[[Page 61919]]
Table 8--Proposed THOR-50M Qualification Requirements
----------------------------------------------------------------------------------------------------------------
Acceptance
Test Measurement Units Nominal target interval
----------------------------------------------------------------------------------------------------------------
1. Head Impact.................. Peak Probe Force....... N................. 5580 5022-6138
Peak Head CG Resultant G................. 117.0 105.3-128.7
Acceleration.
2. Face Impact.................. Peak Probe Force....... N................. 7098 6378-7796
Peak Head CG Resultant G................. 138 124-152
Acceleration.
3. Neck Flexion................. Peak Upper Neck My..... N-m............... 31.0 27.9-34.1
Upper Neck Fz Most N................. 860 774-946
Positive Value Prior
to 40 ms.
Peak Head Angular deg/sec........... 1975 1777-2172
Velocity vy (relative
to earth).
Peak Head Rotation deg............... 64.5 58.1-71.0
(relative to pendulum).
4. Neck Extension............... Peak Upper Neck My..... N-m............... 23.0 20.7-25.3
Peak Upper Neck Fz..... N................. 2918 2626-3210
Peak Head Angular deg/sec........... 2061 1855-2267
Velocity vy (relative
to earth).
Peak Head Rotation deg............... 65.0 58.5-71.5
(relative to pendulum).
5. Neck Lateral................. Upper Neck Mx first N-m............... 49.7 44.8-54.7
peak after 40.0 ms.
First Peak Head Angular deg/sec........... 1362 1226-1498
Velocity vx (relative
to earth).
Peak Head Rotation deg............... 41.7 37.6-45.9
(relative to pendulum).
6. Neck Torsion................. Peak Upper Neck Mz..... N-m............... 41.4 37.3-45.6
First Peak Upper Neck deg/sec........... 1390 1251-1529
Angular Velocity vz
(relative to earth).
Peak Neck Fixture deg............... 47.9 43.1-52.7
Rotation.
7. Upper Thorax................. Peak Probe Force....... N................. 3039 0-3039
Peak Upper Resultant mm................ 53.6 48.3-59.0
Deflection.
Difference Between Peak mm................ 0 -5 to 5
Left & Right Resultant
Deflections.
Force at Peak Resultant N................. 2677 2409-2944
Deflection.
8. Lower Thorax................. Peak Probe Force....... N................. 3484 3136-3832
Resultant Deflection at mm................ 50.9 45.8-56.0
Peak Force.
9. Lower Abdomen................ Peak Probe Force....... N................. 2918 2626-3210
Lower Abdomen X-axis N................. 83.0 74.7-91.3
Deflection at Time of
Peak Force.
Difference Between Peak mm................ 0 -8 to 8
Left & Right X-axis
Deflections.
10. Upper Leg................... Peak Probe Force....... N................. 8333 7500-9166
Peak Femur Force, Fz... N................. 4920 4428-5412
Peak Resultant N................. 2738 2464-3012
Acetabulum Force.
11. Knee........................ Peak Femur Z-axis Force N................. 6506 5855-7156
Knee Deflection at Peak mm................ 20.2 18.2-22.2
Femur Force.
12. Ankle Inversion............. Peak Lower Tibia Fz.... N................. 505 454-555
Peak Ankle Resistive N-m............... 39.1 35.2-43.0
Moment.
Peak Ankle X-axis deg............... 34.5 31.0-37.9
Rotation.
13. Ankle Eversion.............. Peak Lower Tibia Fz.... N................. 571 514-629
Peak Ankle Resistive N-m............... 43.0 38.7-47.3
Moment.
Peak Ankle X-axis deg............... 29.6 26.6-32.5
Rotation.
14. Ball of Foot................ Peak Lower Tibia Fz.... N................. 3170 2853-3487
Peak Ankle Resistive N-m............... 55.3 49.8-60.8
Moment.
Peak Ankle Y-axis deg............... 33.8 30.4-37.2
Rotation (in
dorsiflexion).
15. Heel........................ Peak Lower Tibia Fz.... N................. 3162 2846-3478
----------------------------------------------------------------------------------------------------------------
Note: For comparison purposes, unless otherwise noted, only positive values are shown for the Nominal Target and
Acceptance Range. Some targets, such as Neck Flexion Angular Velocity ([omega]y = -1362 deg/sec), are defined
by negative values.
The proposed qualification requirements are the same as the 2018
version except for the upper leg; this is discussed in the section
below for the upper leg.
Euro NCAP TB026 explicitly adopts NHTSA's 2018 qualification
procedures \151\ with a couple of differences. First, there are a few
differences between the proposal and TB026 with respect to the tests or
test parameters. TB026 specifies somewhat different qualification
metrics for the upper thorax test and does not include a face impact
test. TB026 prescribes the upper leg test described in NHTSA's 2018
qualification procedures, which we are proposing to update. And,
because TB026 specifies the HIII-50M lower extremities, the
corresponding qualification tests are not the same as those proposed.
Second, although TB026 adopts the rest of the 2018 qualification test
procedures and test parameters, it specifies acceptance intervals that
differ from the proposed acceptance intervals with respect to both the
width and midpoint of the interval. While the proposed acceptance
intervals are 10% around the mean (as calculated from our
R&R testing), the width of the acceptance intervals specified in TB026
range from 1% to 10%, with many of them less than 10%. In addition, the
midpoint of these intervals differs from the means NHTSA calculated
based on its R&R testing. For nine of the parameters, the TB026
specifications are fully contained within the proposed acceptance
intervals. Of the remaining parameters, there is a minimum of 82%
overlap between the Euro NCAP specifications and the proposed
acceptance intervals. Therefore, it is feasible, but not guaranteed,
for a THOR-50M which meets the Euro NCAP acceptance intervals to also
meet the proposed acceptance intervals. NHTSA has tentatively decided
not to adopt narrower acceptance intervals, such as those specified in
TB026, for the reasons given above. Moreover, NHTSA is unaware of the
data on which the Euro NCAP specifications are based, whereas the
proposed specifications are based on NHTSA's carefully-controlled
study. The differences between the proposed
[[Page 61920]]
qualification tests and those specified in TB026 are discussed in more
detail in the relevant sub-sections below. In addition, the proposed
qualification test parameters and acceptance intervals and the
corresponding TB026 values are summarized in Appendix G.
---------------------------------------------------------------------------
\151\ Sec. 2.1.
---------------------------------------------------------------------------
We propose to set out the qualification procedures in a separate
document that would be incorporated by reference into Part 572. See
Section XI, Incorporation by reference. This would be a departure from
the other ATDs currently specified in Part 572, for which the
qualification tests are set out in full in the regulatory text in each
of the relevant paragraphs (corresponding to that ATD) in part 572. We
are proposing a separate qualification procedures document for THOR-50M
because the THOR-50M qualification procedures contain many photographs
and diagrams that are not amenable to publication in the CFR; we
believe this extra level of detail will be helpful for end users who
are attempting to qualify the ATD.
NHTSA seeks comment on the proposed qualification tests. NHTSA also
seeks any qualification data commenters are able to provide, as long as
the data are from THOR-50M ATDs conforming to the 2023 drawing package
and were collected following the April 2023 Qualification Procedures
Based on any comments and data received, NHTSA might consider changing
the qualification targets to reflect the larger population of THOR-50M
units in the field. However, before doing so we would assess the effect
that any change could have on the biofidelity of the dummy and the
applicability of injury risk functions. We also seek comment on whether
we should incorporate the qualification procedures by reference, or
whether it would be preferable to locate a much-simplified set of
qualification procedures directly in Part 572 and put additional detail
and documentation in the Office of Vehicle Safety Compliance (OVSC)
laboratory test manual or similar document that would not be
incorporated by reference but instead provided as guidance to DOT
contractors and other ATD end users.
A. Head Impact
The head qualification test is identical to the whole-body head
impact biofidelity assessment, where a fully-assembled THOR-50M is
seated on a table and impacted on the forehead with a 23.36 kg rigid
impactor at 2.00 0.05 m/s. This test serves as a surrogate
for the isolated head drop test used by other ATDs; due to the
construction of the head and neck of the THOR-50M ATD (specifically,
the integration of the neck spring cables into the skull), separation
of the head from the neck is not feasible. The test assesses the
performance of the head skin and CG accelerometers, which are used to
calculate HIC15.\152\ The probe force and the head CG
resultant acceleration are measured and would have to be within the
proposed acceptance intervals.
---------------------------------------------------------------------------
\152\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
B. Face Impact
The face qualification test is identical to the face rigid disk
impact biofidelity assessment, where a fully-assembled THOR-50M is
seated on a table and impacted on the face with a 13 kg rigid impactor
with a 152.4 mm diameter flat disk impact surface at 6.73
0.05 m/s. This test assesses the impact response of the face, which is
driven primarily by the face foam insert (Part No. 472-1401).
Additionally, as this test is more severe than the head impact test, it
assesses the head CG accelerometers (which are used to calculate
HIC15) at a level of severity closer to that expected from
vehicle crash tests. FMVSS No. 208 specifies a maximum calculated
HIC15 value of 700 for the HIII-50M, and the average
HIC15 measurement from a set of 29 vehicle crash tests in
either the full frontal rigid barrier or OMDB crash test modes was
285.\153\ The head impact test, however, results in an average
HIC15 of 157 (probability of AIS 3+ injury of 0.05%), while
the face impact is more severe, with an average HIC15 of
around 450 (probability of AIS 3+ injury of 3.5%). Therefore, compared
to the head impact test, the face impact test is a better assessment of
the head response at a severity level expected from vehicle crash
tests, as it results in a HIC15 that is closer to the
current FMVSS No. 208 injury assessment reference value. During these
tests, the probe force and the head center of gravity (CG) resultant
acceleration are measured and would have to be within the proposed
response corridors.
---------------------------------------------------------------------------
\153\ The range was 104-1262 and the standard deviation was 210.
---------------------------------------------------------------------------
C. Neck
The proposed neck qualification test series, in which the entire
head-neck assembly is removed from the ATD and affixed to the
conventional Part 572 swinging pendulum to apply a prescribed impulse
to the neck, includes six tests: flexion, extension, left lateral
flexion, right lateral flexion, left torsion, and right torsion. The
swinging pendulum apparatus serves as a surrogate for the more complex
neck biofidelity assessment, which is carried out in a sled test
configuration. The neck qualification tests assess the collective
performance of the molded neck column, the occipital condyle cam and
associated bump stops, and the neck spring towers. In the process, the
neck qualification tests assess the performance of the upper neck load
cell, from which the Z-axis force and Y-axis moment are used to
calculate Nij.\154\ The neck axial force, neck moment about the
relevant axis, and neck rotation about the relevant axis are measured
and would have to be within the proposed acceptance intervals. The neck
flexion and extension qualification tests are similar to those
specified for the HIII-50M \155\ in that they use the same pendulum and
similar deceleration specifications.
---------------------------------------------------------------------------
\154\ Craig et al (2020), Injury Criteria for the THOR 50th Male
ATD.
\155\ 49 CFR 572.33 Neck.
---------------------------------------------------------------------------
D. Upper Thorax
This test involves impacting the chest of a fully-assembled THOR-
50M seated on a table with a rigid impactor. The upper thorax
qualification test is configured similarly to that carried out on the
HIII-50M,\156\ using the same pendulum (23.36 kg, 152.40 mm diameter)
to impact the mid-sternum, but at a lower impact velocity of 4.3 meters
per second. This test assesses the dynamic thoracic response to sternal
impact as well as the functionality of the upper left and upper right
thoracic deflection instrumentation. This test condition is identical
to the associated biofidelity assessment, though the qualification test
uses only internal deflection measurements so that motion tracking or
other external instrumentation is not required. Several measurements
must be within the proposed acceptance intervals: the peak overall
probe force, the peak upper left and upper right resultant deflections,
the difference between the peak left and right resultant deflections,
and the probe force at the peak left and right resultant deflections.
---------------------------------------------------------------------------
\156\ 49 CFR 572.34 Thorax.
---------------------------------------------------------------------------
In the 2016 qualification procedures, the upper thorax
qualification required individual X-axis and Z-axis deflection
specifications for both the upper left and upper right thorax. This was
revised in the 2018 qualification procedures by specifying the peak
resultant deflection instead, which better aligns with the peak
resultant deflection measure used to evaluate thoracic injury
risk.\157\
[[Page 61921]]
Applying specifications on the resultant deflection instead of two
individual components allows for a reduction in the overall number of
required measurements, while still capturing the physical response of
the dummy since the X-axis and Z-axis deflections are the primary
components of the resultant deflection in this test condition.
---------------------------------------------------------------------------
\157\ Craig et al (2020), Injury Criteria for the THOR 50th Male
ATD.
---------------------------------------------------------------------------
The Euro NCAP qualification response requirements differ from the
proposal in three ways. First, they include an additional parameter:
the ratio of Z-axis to X-axis deflection. Second, they do not require a
maximum difference between left and right peak resultant deflection,
whereas the proposed qualification targets limit the left-to-right
difference to 5 millimeters. Using the Euro NCAP targets, the
difference between the left and right peak resultant deflections could
be as high as 7.2 millimeters. Third, as noted above, the qualification
targets are narrower than the proposed qualification targets.
NHTSA has tentatively decided not to specify the ratio of Z-axis to
X-axis deflection because doing so would effectively revert to the 2016
approach of individual X-axis and Z-axis deflection requirements, which
would increase the difficulty in meeting the qualification
specification without a direct link to injury prediction, as the peak
resultant deflection specification is of primary importance because it
is the metric used in the calculation of thoracic injury risk.
NHTSA is aware that the upper thorax qualification specification
has been a topic of frequent discussion within the International
Standards Organization (ISO) working groups (particularly ISO/TC 22/SC
36, Safety and impact testing, Working Groups 5, Anthropomorphic Test
Devices, and 6, Performance criteria expressed in biomechanical terms).
NHTSA understands that those discussions have focused on potential
modifications to the drawing package to meet the upper thorax
qualification response requirements (in the context of testing related
to Euro NCAP). Those modifications--specifically, the shorter rib
guide, the individual rib performance test, and changes in the area of
the coracoid process--have been discussed as describe in Section III,
Design, Construction, and Instrumentation.\158\ NHTSA does not believe
the modifications are necessary to meet the proposed upper thorax
qualification requirements because NHTSA's repeatability and
reproducibility testing showed that those requirements were achieved by
three different THOR-50M units at three different test labs. See
Section VI, Repeatability and Reproducibility. Moreover, it is not
clear whether these changes would preclude a THOR-50M from meeting the
proposed qualification requirements, though since the Euro NCAP
specifications are narrower, any variation caused by these changes may
be within the NHTSA's proposed acceptance intervals. Before
implementing any of these design changes, the performance of the
prototype parts would need to be evaluated.
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\158\ In addition, some members of Working Group 5 have observed
variations in the ATD responses in the upper thorax qualification
tests that have led to difficulties in meeting the Euro NCAP
qualification specifications, and have suggested that this may
result from variation in the spine flex joint, potentially due to
material that was not as hard as the specification called for.
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In an effort to further investigate these contemplated changes to
THOR-50M, NHTSA analyzed its upper thorax qualification test data.
NHTSA's limited analysis suggests that the difficulty meeting the Euro
NCAP upper thorax qualification requirements might stem not from the
dummy design, but from the smaller allowable range of peak resultant
deflection and the addition of the deflection ratio corridor specified
in TB026. However, it would be necessary to know how the Euro NCAP
upper thorax qualification requirements were determined to carry out a
complete analysis. This preliminary analysis is discussed in more
detail in Appendix A.
E. Lower Thorax
The lower thorax qualification test is unique to the THOR-50M. This
test involves impacting the lower thorax of a fully-assembled THOR-50M
seated on a table with a rigid impactor. It is similar to the upper
thorax qualification test, as it uses the same pendulum (23.36 kg,
152.40 mm diameter) at the same impact velocity (4.3 meters per
second). The test assesses the dynamic impact response of the lower
torso, to which the rib cage and the upper and lower abdomen assemblies
contribute, while at the same time assessing the functionality of the
lower left and upper right thoracic deflection instrumentation. The
lower thorax qualification test is a simplification of the lower
ribcage oblique impact biofidelity condition. In the biofidelity
condition, the torso is rotated by 15 degrees and a chestband is used
to measure external deflection. In the qualification condition, the
torso is not rotated, but instead offset relative to the line of travel
of the pendulum such that the pendulum is centered on the lower left or
lower right anterior attachment point of the thoracic deflection
instrumentation. As in the upper thorax condition, the lower thorax
qualification mode uses internal deflection measurements so that motion
tracking or other external instrumentation is not required. During this
test, the peak overall probe force and the peak resultant thoracic
deflection at the time of peak probe force are measured and would have
to be within the proposed acceptance intervals.
F. Abdomen
This test (which is unique to the THOR-50M) impacts the lower
abdomen of a fully-assembled THOR-50M with a 177.8 mm by 50.8 mm rigid
rectangular face impactor, weighing 32.00 kg, at 3.30 m/s. It was
originally based on the lower abdomen rigid bar biofidelity condition,
though several modifications were made over time to increase its
objectivity and improve its utility as a qualification test. This test
assesses the dynamic response of the lower abdomen, including the
jacket, lower abdomen foam inserts, and lower abdomen bag, as well as
the functionality of the abdominal deflection instrumentation. The peak
overall probe force, the peak left and right X-axis abdomen deflection
at the time of peak probe force, and the difference between the left
and right X-axis deflection at the time of peak probe force are
measured and would have to be within the proposed acceptance intervals.
G. Upper Leg
The upper leg qualification test assesses the dynamic impact
performance of the knee flesh, knee flesh insert, and femur compression
element, while evaluating the functionality of the femur and acetabulum
load cells. The full THOR-50M is seated on a table with a posterior
restraint adjacent to the pelvis flesh and impacted at the knee by a
12.00 kg impactor with a 76.2 mm diameter rigid disk impact surface at
3.3 0.05 m/s parallel to the femur. The peak probe force,
peak femur Z-axis force, and peak resultant acetabulum force would have
to be within the proposed acceptance intervals.
This differs from the test procedure in the 2018 Qualification
Procedures Manual in the THOR-50M research docket. The 2018 draft
qualification test procedures for impacting the knee specifies the use
of a 5.0 kg impactor at 2.6 m/s. NHTSA's repeatability and
reproducibility testing of the qualification procedures, however--which
used the 2018 draft procedures--resulted in coefficients of variation
[[Page 61922]]
(CVs) \159\ above 10%, particularly for the peak resultant acetabulum
force. NHTSA therefore conducted a detailed review of the qualification
test procedure.\160\ This review led NHTSA to conclude that the impact
energy was unrealistically low, leading to two problems. First, the low
test energy did not load the acetabulum at a magnitude similar to that
produced in vehicle crash tests or associated with a meaningful injury
risk. This is particularly important because the upper leg test mode is
the only qualification test that assesses the acetabulum load cells,
and peak resultant acetabulum force is used in calculating the
acetabulum injury risk. Second, and relatedly, the measurement values
were so low, it was difficult to distinguish the signal from the noise.
---------------------------------------------------------------------------
\159\ See infra Section VI.A.
\160\ Millis, W. (2021). An Improvement to the THOR-50M Upper
Leg Qualification Test Methodology. 2021 SAE Government-Industry
Digital Summit, available at: https://www.nhtsa.gov/node/103666.
---------------------------------------------------------------------------
Accordingly, NHTSA revised the test parameters by increasing the
impactor mass and velocity and installing a backer plate behind the
pelvis to prevent any rearward motion during the test. These are the
parameters that we are proposing and for which data is presented (and
acceptance intervals calculated) in the qualification repeatability and
reproducibility study. As we explain in Section VI.A, the revised test
procedures resulted in repeatability and reproducibility CVs of 5% or
lower for all test measurements including peak resultant acetabulum
force. Additionally, the average acetabulum force recorded in the
improved upper leg qualification is more representative of the forces
recorded in frontal rigid barrier and OMDB vehicle crash tests, and
represents a non-negligible injury risk.
H. Knee and Lower Leg
NHTSA is also proposing qualification tests for the knee and lower
leg (ankle, ball of foot, and heel).
The knee qualification test is a simplification of the knee shear
biofidelity condition. The test assesses the response of the anterior-
posterior translation of the tibia with respect to the femur at the
knee joint, the translational resistance of the knee slider and the
stiffness of the stop assembly, and the functionality of the knee
slider string potentiometer. To conduct the knee impact test, the left
or right knee assembly (detached at the base of the femur load cell) is
removed from the ATD and mounted to a rigid surface, and a load
distribution bracket is attached to the knee slider assembly. The load
distribution bracket is impacted with a 12.00 kg impactor with a 76.2
mm diameter rigid disk impact surface at 2.20 0.05 m/s.
Unlike the HIII-50M knee slider test, no foam pad is used on the impact
surface for this test. During these tests, the femur Z-axis force and
knee slider deflection at peak femur force are measured and would have
to be within the proposed acceptance intervals.
We propose four different qualification tests to assess the lower
leg responses: ankle inversion, ankle eversion, ball of foot impact,
and heel impact. All four test setups are similar. In each, the lower
legs are removed from the dummy and each leg is tested separately. The
leg is affixed to a rigid fixture and struck by a pendulum parallel to
the tibia. The alignment of the pendulum differs for each test: for the
heel impact, it is in-line with the tibia; for the ball of foot impact,
it produces dorsiflexion of the foot; for the inversion impact; it is
offset medially from the tibia; for the eversion impact, it is offset
laterally from the tibia. For the inversion and eversion impacts, the
shoe is removed and replaced with a special striker plate that
interfaces with the pendulum.
Euro NCAP TB026 specifies different qualification requirements for
the knee and lower leg because TB026 specifies that the THOR-50M be
fitted with the HIII-50M knee and lower leg.
VI. Repeatability and Reproducibility
Any ATD that is to be used for Federal regulatory testing must have
an acceptable level of repeatability and reproducibility to ensure
confidence in the responses provided by the dummy. In the context of
dummy evaluation, repeatability refers to the similarity of responses
from a single dummy when repeatedly subjected to a particular test
condition. Reproducibility refers to the similarity of the responses
from multiple dummies repeatedly subjected to a particular test
condition. NHTSA also evaluated the repeatability and reproducibility
of the qualification tests themselves, in addition to the dummy. To
evaluate whether the THOR-50M ATD yields consistent results, NHTSA
undertook an extensive series of testing.
NHTSA systematically investigated the repeatability and
reproducibility (R&R) of the THOR-50M by conducting an extensive series
of qualification and sled tests. Qualification test measurements are
especially useful for evaluating dummy R&R because they are relatively
simple tests on individual dummy components that can be tightly
controlled so that variability in the test measurements is more likely
to come from the dummy than from other potential sources of
variability, such as the test procedures or vehicle structures and
materials. Sled testing is useful because it offers insight into the
dummy's performance as a complete system in an environment similar to
that of an actual vehicle--e.g., the consistency of its kinematics, its
impact response as an assembly, and the integrity of the dummy's
structure. Sled tests are therefore more challenging for the dummy,
while at the same time much more tightly controlled than a vehicle
test, which does not provide a desirable environment for R&R testing
due to the uncontrollable variation in vehicle structural materials and
manufacturing variability. Qualification and sled tests together
provide a basis for assessing whether the dummy will yield consistent
results when it is ultimately used in full-scale vehicle tests. NHTSA's
R&R testing also served several other important functions, such as
developing the qualification corridors and further validating the
usability and durability of the dummy.
NHTSA's R&R analysis of qualification and sled testing is briefly
summarized in the next two sections. For more detailed information, the
reader is referred to the docketed report ``THOR-50M Repeatability and
Reproducibility of Qualification Tests'' (R&R Report).\161\
---------------------------------------------------------------------------
\161\ National Highway Traffic Safety Administration (2022).
THOR-50M Repeatability and Reproducibility of Qualification Tests,
May 2021, available at https://downloads.regulations.gov/NHTSA-2019-0106-0009/attachment_2.pdf. We note that for the sled test R&R
analysis, there are no previously-published reports that provide
this analysis. However, this analysis is provided in the paragraphs
below on sled testing (and in the relevant appendices) and the
underlying data is available in the NHTSA crash test database in
either the biomechanics or vehicle paragraphs (the specific location
is provided in the relevant discussion below).
---------------------------------------------------------------------------
A note about dummy reproducibility: At the time NHTSA conducted
this R&R testing (both qualification tests and sled tests) it only
owned--and tested--THOR-50M units manufactured by Humanetics.
Therefore, the reproducibility analyses reported here concerned dummy
reproducibility (same lab, different dummies) and test reproducibility
(same dummy, different labs).\162\ However, another aspect of
reproducibility is whether dummies fabricated by different
manufacturers perform in a uniform manner. To this end, NHTSA has
purchased THOR-50M units from JASTI, Cellbond, and Kistler,
[[Page 61923]]
and may test with these units prior to the final rule.
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\162\ NHTSA did not examine lab-to-lab reproducibility of the
sled tests.
---------------------------------------------------------------------------
A. Qualification Tests
NHTSA has completed an R&R study of the qualification tests. This
study has three main purposes. One is to assess the repeatability and
reproducibility of the dummy. Another is to determine the acceptance
intervals for the qualification tests. Third, is to assess the R&R of
the qualification tests themselves. Assessing the R&R of the
qualification tests is important for at least two reasons: it aids in
determining whether the variation in measurements are attributable to
the dummy, the test procedures, or the testing practices of different
laboratories, and it helps ensure that the qualification test
procedures themselves are as consistent and replicable as possible so
that, ultimately, the test measurements obtained in a compliance test
are uniform across dummies and test laboratories. In addition to these
main purposes, the qualification R&R testing also helped NHTSA to
identify and resolve potential issues with the qualification
procedures; reveal and resolve potential issues with, and functional
limitations of, the dummy.
Below, we first summarize our methodology for the qualification R&R
analysis, and then proceed to briefly summarize the results of the R&R
assessment for each THOR-50M body region.
Methodology
The proposed qualification tests were carried out on three THOR-50M
ATDs manufactured by Humanetics. The ATDs conformed to the proposed
drawing package. Every ATD was subjected to five repeat tests in each
qualification test condition at NHTSA's Vehicle Research and Test
Center (VRTC) and one of the three dummies was tested at two other
labs, Humanetics and Calspan (with some exceptions as described in the
following paragraphs). All tests were used in development of the
proposed qualification acceptance intervals, with some exceptions as
explained below where the input velocity did not meet the
specification. For qualification test conditions where one ATD
component is tested in both the left and the right direction, only the
left direction is included in the analysis, as the dummy design is
symmetric and not expected to differ between the two sides. For
qualification test conditions in which multiple ATD components are
tested, data from the left and right tests or measurements are
combined.
We evaluated R&R of both the dummy and the qualification tests
using a statistical analysis of variance referred to as the coefficient
of variation (CV). The CV approach was first introduced by NHTSA as a
means for evaluating dummy repeatability when the original subpart B
Hybrid II 50th percentile male ATD was proposed.\163\ Since then, the
agency has used this approach for other Part 572 rulemakings.\164\ The
CV is a measure of variability expressed as a percentage of the mean.
It is defined as the percentage of the sample standard deviation
divided by the mean of the data set:
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\163\ 40 FR 33466 (Aug. 8, 1975).
\164\ See, e.g., 85 FR 69898, 69904-69905 (Nov. 3, 2020) (final
rule for Q3s ATD).
[GRAPHIC] [TIFF OMITTED] TP07SE23.019
In the qualification test series, the data points of each trial are
considered on their own and not as being representative of a large
population. Thus, the sample-based standard deviation is applied in
which s is an estimate of the standard deviation based on a
sample.\165\ It is computed using the following formula, where x is the
average value of the trials (sample mean) and n is the number of trials
(sample size).
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\165\ The population-based standard deviation, which is always
lower than the sample-based standard deviation, is not appropriate
because only a limited number of NHTSA-owned THOR-50M units were
tested, and the tests were carried out at a limited number of test
facilities.
[GRAPHIC] [TIFF OMITTED] TP07SE23.020
For each qualification test parameter (e.g., head impact peak probe
force) specified for each test condition (e.g., head impact), we
computed the mean, standard deviation, and coefficient of variation.
More specifically, to investigate dummy repeatability and test
repeatability, we calculated these summary statistics for the five
tests of each test condition performed on each of the three dummies at
VRTC. To investigate dummy reproducibility, we pooled the data for the
three dummies tested at VRTC. Finally, to investigate test
reproducibility, we pooled the data for the dummy that was tested at
VRTC, Calspan, and Humanetics.
We used the following approach to assess R&R:
CV <5%: No further investigation. We believe that a set of
responses with a CV below 5% indicates a highly repeatable and
reproducible condition.
5% >= CV <= 10%: sources of variability investigated.
CV >10%: Test procedure thoroughly reviewed and dummy(ies)
inspected.
When the CV was greater than or equal to 5%, we investigated the
source of the variability. In all cases, we were able to determine the
source of the variation with reasonable confidence. Once NHTSA had
refined the qualification test procedures it only obtained a CV greater
than 10% in two instances--repeatability of the face foam, and test
reproducibility in one measurement in the neck extension mode. Prior to
refining the test procedures, NHTSA obtained a CV greater than 10% for
the upper leg test. A full investigation led to a new and improved test
procedure. That new test procedure is reflected in the R&R report, and
the resulting CVs all less than 10%. Table 9 and Table 10 summarize the
CVs that we calculated for each test parameter for each qualification
test condition. Table 11 summarizes the variability sources and
resolutions seen in the qualification R&R test series.
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Table 11--Summary of Qualification Test Variability Sources and
Resolutions
------------------------------------------------------------------------
Test mode Source of varibility; control solution
------------------------------------------------------------------------
Head......................... None.
Face......................... Face foam degradation occurs cumulatively
with successive impacts; monitor and
swap out foam as needed.
Neck Extension............... The inverse relationship between My and
Fz may be balanced by adjusting the
input pulse through the selection of the
pendulum's honeycomb cell configuraton.
Neck Flexion................. For a new molded neck, My and Fz may be
elevated in initial test only. Also, the
pendulum's honeycomb cell configuration
may need attention to control input
pulse.
Neck Lateral................. None.
Neck Torsion................. None.
Upper Thorax................. None.
Lower Thorax................. The asymmetric test setup requires a high
level of diligence from operator in
aligning the dummy with the probe.
Abdomen...................... Operator diligence is needed to ensure a
symmetric test setup. Otherwise, right
vs. left discrepancies in force and
deflection measurements will occur.
Upper Leg.................... If a high femur Fz occurs, a test lab may
need to experiment with set-ups and
dummy positioning (within allowable
tolerances).
Knee......................... Low femur Fz measurements may be resolved
at the test labs by experimenting with
setups and dummy positioning.
Ankle Inversion.............. Ankle inversion and eversion tests are
Ankle Eversion............... run on the same apparatus and are nearly
identical. The ankle moment, tibia Fz,
and ankle rotation may be slightly low
in an initial qualification test if
there has been an extended period of non-
use of the Ensolite pad on the test
fixture. This is only a concern if the
tibia force and moment are just below
the upper qualification limits, since
subsequent tests may be expected to
produce slightly higher moments and
forces (which might be out of the
qualification range). Labs can simply
perform an additional test to confirm
that the response of the ankle is within
the requirements.
Ball of Foot................. Test labs may need to adjust their set-
ups and fixtures (within allowable
tolerances) to attain a reponse within
10% of the target for ankle moment.
Heel......................... In cases where passing qualification
results cannot be achieved, a test lab
may need to replace the molded shoe
assembly (472-7800-1 (left) or -
2(right)) and/or the upper tibia
complaint bushing assembly (472-7315) in
order to attain a peak lower tibia Fz
within 10% of the target.
------------------------------------------------------------------------
Our investigation of the sources of variability also gives us
additional confidence that the proposed acceptance intervals ( 10% of the mean response reported in the R&R study) are both
achievable and sufficient to ensure that the dummy is providing uniform
responses. In NHTSA's testing, when the CV was below 5%, the responses
in all the tests were always within the proposed acceptance intervals.
When the CV exceeded 5%, however, we observed a response outside the
proposed acceptance interval in at least one test. When the CV exceeded
10%, several tests were outside the qualification corridor.
NHTSA seeks comment on this methodology. Although the qualification
R&R study utilizes only NHTSA's test data, NHTSA is open to considering
qualification data provided by commenters in the finalization of the
qualification specifications, provided that the data are from THOR-50M
ATDs conforming to the 2023 drawing package and collected following the
proposed Qualification Procedures.
Head Impact
In the head impact qualification test mode, all CVs for
repeatability and reproducibility were below 5%, and the responses in
all the tests were within the proposed qualification acceptance
intervals.
Face Impact
We used a slightly different approach to evaluating the R&R of the
face than we did for the other qualification tests. Our approach was
motivated by two characteristics of the THOR-50M face.
First was the response of the face foam. The impact response of the
face is driven primarily by the face foam insert, which is constructed
of a memory foam that necessitates an extensive recovery period after a
dynamic impact; the THOR-50M Qualification Procedures specifies at
least 24 hours of recovery between tests. Even with this extended
recovery period, however, the foam progressively degrades after each
impact so that the peak probe force and peak head resultant
acceleration increases with each test. We were able to conduct eight to
nine tests with a new face foam insert before the face fell outside the
upper bound of the face rigid disc impact biofidelity corridor (4,400 N
to 8,200 N).
Second, because the face foam degrades, any variations in the dummy
response are likely to be masked by the significant variations caused
by the foam. That is, most of the observed variation in the face
qualification test is essentially due to the face foam response; any
contributions of other components or lab-to-lab differences were
negligible.\166\
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\166\ This is seen in the head impact test series, in which the
headskins were found to be repeatable and reproducible, with
repeated impacts to the head yielding nearly identical responses.
---------------------------------------------------------------------------
In light of these characteristics, we modified the R&R test
methodology for the face impact tests. Our testing consisted of
evaluating one dummy (DO9799) at VRTC, using three different new,
unused, face foams (as opposed to testing three different ATDs); we
deemed it unnecessary to test multiple ATDs because the variation in
response was predominantly due to the face foam, not the ATD. We also
did not test lab-to-lab variability (test reproducibility), because
this would require testing the same face foam successively at multiple
laboratories, which the degradation of the face foam prevented us from
doing. We allowed 24 hours between tests as specified in the
Qualifications Procedures. We tested each dummy until the peak probe
force
[[Page 61930]]
fell out of the biofidelity corridor (until the peak probe force
exceeded 8,200 N). Only those tests which fell within the peak probe
force biofidelity corridor were then included in the repeatability
analysis and used to set the qualification targets. This gave us eight-
to-nine tests for each of the three face foams we tested.
For two of the face foam inserts tested, repeatability CVs were
below 10%. The third face foam insert resulted in CVs for peak probe
force and peak head CG resultant acceleration of 10.1% and 12.1%.
Though not reported in the R&R paper, CVs for the HIC15
values associated with the head resultant accelerations recorded in the
face impact test are within 1% of the CVs for peak resultant head CG
acceleration. However, in practice, we would likely not observe this
level of variability because in several of the tests used to calculate
CV, the peak probe force was outside of the qualification targets
(either too high or too low) and so the dummy would have been further
adjusted before being used in a compliance (or research) test. We
observed that when the response of a new face foam insert is too low,
it likely indicates the need for an additional ``break in'' test, in
which case the face impact test would be repeated. If the response is
too high, it likely indicates that the face foam needs to be replaced,
in which case a new face foam insert will be installed and the face
impact test repeated. Therefore, we believe that the face impact test
is sufficiently repeatable. Moreover, although we did not test at
multiple labs to evaluate reproducibility due to face foam degradation,
we also believe that the face impact test is reproducible. The head
impact test uses essentially the same test apparatus and a similar
impact condition as the face impact test. Because the test
reproducibility was very good in the head impact test, we expect that
there will be acceptable levels of lab-to-lab variability for the face
impact test as well.
Neck
For the neck qualification tests, the entire head-neck assembly is
removed from the THOR-50M, so the serial numbers listed in Table 9 are
those of the individual head-neck assemblies and not the ATD itself.
With respect to repeatability, across all four neck test modes
(flexion, extension, lateral flexion, and torsion), CVs for
repeatability were below 10% for all qualification test parameters and
for all necks, and were below 5% except in the neck flexion test mode
for two of the necks: peak upper neck Y-axis moment (5.8%) and peak
upper neck Z-axis force (6.0%) for neck EB6007, and peak upper neck Y-
axis moment for neck EB6006 (5.1%). For both of these necks, the first
test resulted in a peak upper neck Y-axis moment higher than the
resulting qualification targets; thus this first test would have been
re-run in practice. If this first test were discarded, the resulting
repeatability CVs would be at or below 5% for all necks. Labs may find
that while the first neck flexion test performed on a new neck produces
a Y-axis moment greater than the qualification targets, subsequent
tests result in lower values within the acceptance interval. Also, labs
may need to adjust the input pulse by experimenting with honeycomb cell
configurations to achieve the target response.
Reproducibility CVs were below 5%, except in four instances, two
for the neck flexion test mode, and two for the neck extension test
mode.
In the neck flexion test mode, the dummy reproducibility CV for
peak upper neck Y-axis moment was 5.4%. This likely results from the
same break-in issue described above. Also in the neck flexion test
mode, the test reproducibility CV for peak upper neck Z-axis force was
7.5%. In this case, there were two tests each at Calspan and Humanetics
that would not have met the resulting qualification
specifications,\167\ though discarding these tests would still result
in a reproducibility CV of 6.4% for peak upper neck Z-axis force.
However, we believe that this variance is not likely to lead to
inconsistent compliance test outcomes because the average peak upper
neck Z-axis force (860 N) represents a very low probability of injury
(0.7% risk of AIS 3+ injury). Although NHTSA has not yet established
injury assessment reference values (IARVs) for the THOR, when it does
(NHTSA anticipates rulemaking in the near future to add the THOR-50M to
FMVSS No. 208 as an optional test device) an IARV for neck flexion
would almost certainly be specified to correspond to a risk of AIS 3+
injury much higher than 0.7%, i.e., corresponding to a much higher Z-
axis force than 860 N.\168\
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\167\ R&R Report, Table 6-14.
\168\ Upper neck Fz is currently specified in FMVSS
NO. 208 as an injury criterion for the HIII-50M and is also a
component of THOR-specific Nij criterion.
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In the neck extension test mode, two test reproducibility CVs were
above 5%: peak upper neck Y-axis moment (5.6%) and peak upper neck Z-
axis force (12.2%). These elevated CVs result from the tests on neck
EB6007 at Calspan, for which the first four tests resulted in peak
upper neck Z-axis forces lower in magnitude than the resulting
qualification targets, while the last test resulted in a peak upper
neck Y-axis moment higher in magnitude than the resulting qualification
targets, and at Humanetics, for which four of the five tests resulted
in peak upper neck Z-axis forces higher in magnitude than the
qualification targets, though by not more than 32 N.\169\ However,
since all of the remaining tests on neck EB6007 at VRTC (15 tests)
would have met the qualification targets, and the associated test
reproducibility CVs would be below 3% for all test parameters except
for the Calspan observations, this finding likely results from either
an issue with test execution at Calspan, or an issue specific to neck
EB6007, such as damage or unintended adjustment of the neck spring
cables after it was tested at both VRTC and Humanetics.
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\169\ R&R Report, Table 7-16.
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While the input parameters for the tests conducted on EB6007 were
all within the qualification specifications, the pendulum velocity at
20 and 30 milliseconds after T-zero was notably higher at Calspan
compared to VRTC and Humanetics, which may explain the differences in
results. As such, it may be worth considering narrower specifications
on the pendulum velocity input parameters. On the other hand, if the
differing results at Calspan resulted from issues with the neck itself,
then the fact that the qualification specifications were not met
indicates that the qualification tests successfully identified a
damaged or improperly configured neck.
Upper Thorax
In the upper thorax qualification test mode, all CVs for
repeatability and reproducibility were below 5%, which indicates that
the qualification specifications were achievable by three different
THOR-50M ATDs and at three different test labs. Further, as all CVs
were below 3.7%, this indicates that all tests were within the 10% target.
Lower Thorax
In the lower thorax qualification test mode, all but one of the CVs
for repeatability were below 5%. One repeatability assessment, peak
resultant deflection at peak probe force for ATD DO9798, had a CV of
5.2%. For this ATD, peak resultant deflections on the right side were
closer to the upper end of the corridor, while those on the left side
were closer to the lower end of the corridor. CVs for dummy
reproducibility were below 5%. Test
[[Page 61931]]
reproducibility CVs were slightly above 5%. Here, one of the tests at
Humanetics would not have met the resulting peak probe force
qualification specifications, while four of the tests at Calspan would
not have met the resultant deflection at peak force specification.\170\
If the tests that would not fall within the qualification
specifications were excluded, as would be done in practice,
reproducibility CVs would be below 5%. Overall, the lower thorax
qualification specifications were achievable by three different THOR-
50M ATDs and at three different test labs.
---------------------------------------------------------------------------
\170\ R&R Report, Table 11-9.
---------------------------------------------------------------------------
Abdomen
When the abdomen qualification repeatability and reproducibility
testing was conducted, all three THOR-50M ATDs were not available.
As an alternative, three different abdomen assemblies were tested
on the same ATD. We believe this modification is acceptable because the
abdomen foam inserts and the structure of the abdomen bag are
responsible for a majority of the variation in the lower abdomen
qualification test, whereas the remainder of the THOR-50M is
essentially a ballast.
All of the CVs for repeatability and reproducibility of peak probe
force were below 5%. All of the CVs for repeatability and
reproducibility of the peak left and right X-axis deflection at the
time of peak force were between 5% and 6%. Of these tests, three at
Calspan resulted in right abdomen X-axis deflections lower in magnitude
than the qualification specifications. While not included in the CV
calculation, the difference between left and right X-axis deflection
measurement highlighted the fact that all tests at VRTC had a positive
difference of at least 6.8 millimeters, indicating that the magnitude
of right X-axis deflection was greater than the magnitude of left X-
axis deflection in all tests. The opposite was true at Calspan, where
three of the tests showed notably higher magnitude deflections on the
left side. In total, six of the abdomen qualification tests (five at
VRTC and one at Calspan) were beyond the 8 millimeter difference
specified by the qualification specifications. Further examination of
the test setup at VRTC showed that the ATD was consistently rotated
slightly about the Z-axis, resulting in the right side of the abdomen
being closer to the probe than the left side, and subsequently
recording more deflection. The test configuration at VRTC has since
been corrected. This issue is not expected to introduce variability in
test results in the future because such tests outside the qualification
targets would necessitate dummy adjustment and re-running the test. If
only tests that were within the maximum difference in left-to-right
deflection specification were included, both the dummy and test
reproducibility CVs would be 5.0% or below.
Upper Leg
As we explained earlier (Section VI, Qualification Tests), the
proposed upper leg qualification test procedure reflects revisions to
the 2018 Qualification Test Procedures that we made in light of our R&R
testing. The CVs for repeatability and reproducibility for the revised
test procedure for all three measurements were at or below 5%,
demonstrating that the upper leg qualification specifications can be
met by three different THOR-50M ATDs at three different test labs.
Knee
For the knee qualification test, all CVs for repeatability were
below 5%. For dummy reproducibility, CVs were 5.0% and below for both
measures. For test reproducibility, the CV for knee deflection at peak
femur Z-axis force was below 5%, while the CV for peak femur Z-axis
force was 5.9%. This elevated CV appears to result from the tests at
Calspan, which were all generally lower in magnitude than at VRTC and
Humanetics, and three of the tests resulted in peak femur Z-axis force
lower than the qualification specification. As the three tests that
were outside of the qualification specifications were the first or
second tests in the series, it is possible that the lower forces
resulted from misalignment of the load distribution plate or other
slack in the system that was corrected in the remaining tests. In light
of this, we believe that the knee qualification repeatability and
reproducibility test series demonstrated that the qualification
specifications could be achieved by six different THOR-50M knees at
three different test labs.
Lower Leg
As used by VRTC, the lower legs are considered modular, and are
typically assigned to a THOR-50M on deployment and not necessarily tied
to a specific THOR-50Ms serial number. As such, the repeatability and
reproducibility qualification study was carried out by testing three
different lower legs at VRTC, followed by testing two of those legs at
both Humanetics and Calspan. This resulted in a total of 15 tests for
the dummy reproducibility assessment, and 30 tests for the
reproducibility assessment (although several of the tests at Calspan
were not included because they did not meet the test velocity input
specifications).
For all the lower leg test modes, repeatability CVs were all below
5%, indicating that the qualification specifications are achievable by
three different THOR-50M ATDs. There were, however, a few test mode/
parameters for which reproducibility CVs were above 5%.
In the ankle inversion test mode, test reproducibility for the peak
lower tibia Z-axis force measurement was 5.3%. The source of this
elevated CV appears to be the first test of leg DL5405 at VRTC, where
the peak lower tibia Z-axis force was -451 N, which was just outside
the acceptance interval (-454 to -555 N). In practice, this test would
have been re-run, and all the remaining tests on this leg would have
met the qualification targets. Removing this test from the CV
calculation would result in a test reproducibility CV of 4.9%.
In the ankle eversion test mode, dummy reproducibility was above 5%
for the peak lower tibia Z-axis force (5.7%), and test reproducibility
was above 5% for lower tibia Z-axis force (6.0%) and peak ankle
resistive moment (5.1%). These elevated CVs appear to result from the
first tests on DL0202 at VRTC, where the peak lower tibia Z-axis force
(-512 N) was just outside the acceptance interval (-514 N to -629 N),
and at Calspan, where the peak lower tibia Z-axis force (-454 N) and
the peak angle resistive moment (35.6 Nm) were both below the lower end
of the associated qualification specifications (-514 N and 38.7 Nm,
respectively). In practice, these tests would have been re-run, and all
the remaining tests on this leg at both labs would have met the
qualification specification. Removing these two tests from the CV
calculation would result in reproducibility CVs all below 5%, which
demonstrates that the ankle eversion qualification specifications can
be met by six different legs at three different test labs.
In the ball-of-foot test mode, which assesses both the impact
response of the ball-of-foot portion of the molded shoe and the
dorsiflexion response of the ankle, the only CV above 5% was the test
reproducibility of the peak ankle resistive moment (6.9%). In the tests
at Calspan, only two of the five tests on the left leg (DL0202) met the
qualification specification for input velocity. The three tests that
did not meet the qualification specification were considered invalid
tests and therefore were not included in the test
[[Page 61932]]
reproducibility assessment, so only seven tests from Calspan were
included as opposed to 10 tests from each of the other labs. Of the
tests run by Calspan on the right leg (DL5404), four of the five
resulted in peak ankle resistive moments of 61.3 to 61.8 Nm, just above
the upper end of the qualification specification (60.8 Nm). As the
tests at Calspan were consistently higher in peak ankle resistive
moment than those at VRTC and Humanetics, it is possible that this
finding results from either an issue with test execution at Calspan, or
an issue specific to leg DL5404, such as damage or unintended
adjustment of the Achilles spring cables after it was tested at both
VRTC and Humanetics. Reviewing the time-history data for ankle
resistive moment from exemplar tests from Calspan, VRTC, and Humanetics
(Figure 1), there are some differences early in the event (note the
large positive moment before 10 milliseconds in the Calspan test) that
suggest differences in test setup and/or impactor hardware.
[GRAPHIC] [TIFF OMITTED] TP07SE23.028
In the heel impact test, which assesses both the impact response of
the heel portion of the molded shoe and the tibia compliant element,
the repeatability CVs were all under 5%, but both the dummy (6.4%) and
test (5.9%) reproducibility CVs were over 5%. If the test CVs are
calculated independently for the left and right legs, the resulting CVs
are much lower (2.1% and 3.0%, respectively). This suggests that the
test itself is repeatable (as all repeatability CVs were 1.6% or below)
and reproducible, but that there is some ATD-to-ATD (in this case, leg-
to-leg) variation. Nonetheless, the qualification specifications for
the heel impact test can be met using three different legs in at least
two different test labs.
Additional Qualification Test Lab
We performed a variety of vehicle tests (discussed in Section VIII,
Overall Usability and Performance) where multiple dummies were
qualified at two different labs, including a lab (Applus+ IDIADA KARCO
Engineering LLC) that was not one of the laboratories used to develop
the qualification specifications, and it was possible to qualify the
dummies. This qualitative information gives us further confidence that
the qualification tests are reproducible. Therefore, NHTSA tentatively
concludes that there is a sufficiently high degree of uniformity in the
construction of the dummy components being tested and in the procedures
followed by the labs for that test requirement for the THOR-50M to be
incorporated into Part 572.
B. Sled Tests
THOR-50M repeatability was also assessed through sled tests
representing several different vehicle crash environments, including
unbelted, standard, and load-limited three-point belt configurations at
different speeds for both the driver and right front passenger seating
positions, as well as several restraint configurations in the rear
seat. NHTSA's sled test repeatability analysis is based on data from
three different sled test series that NHTSA ran in the course of
developing THOR-50M. One is a sled test series conducted to develop
thoracic injury criteria for the THOR-50M. Another is a sled test
series conducted to assess the performance of THOR-50M in low-speed
belted crashes. The third is a sled test series conducted to assess
THOR-50M's performance in low-speed unbelted crashes.
In summary, while there were several cases where the variation from
test to test of the same THOR-50M ATD was greater than 10%, these cases
can be explained by either differences in physical interactions (e.g.,
contact of the head with the arm in the rear seat sled test), which can
be addressed by careful pre-test positioning of the ATD, or by the low
magnitude of the measurements, as demonstrated through the use of
normalized CV to identify cases where the variation occurs at a much
lower level than would be associated with a risk of injury.
This is discussed in more detail in the sections that follow. We
begin by explaining our methodology, and then proceed to discuss the
three different test series.
1. Methodology
As with the qualification R&R analysis, we assessed repeatability
using the coefficient of variation. The CVs were calculated for each of
the injury criteria described in the THOR-50M injury criteria report,
as well as for peak
[[Page 61933]]
values from a few other key data channels: \171\ lap belt, upper
shoulder belt, and lower shoulder belt.
---------------------------------------------------------------------------
\171\ The low-speed sled tests have fewer metrics than the
thoracic injury criteria set (11 vs. 12) because lower shoulder belt
loads were not recorded in the low-speed sled tests.
---------------------------------------------------------------------------
The CV analysis was the same as in the qualification test R&R
study, with two modifications. As with the qualification test R&R
study, CVs below 5% were considered to require no further
investigation; for CVs between 5% and 10% we reviewed the results for
outliers; and for CVs greater than 10% we thoroughly investigated the
sources of variability in the test procedure and the ATD. However, our
assessment differed in two ways from the CV assessment in the
qualification R&R study.
First, we used the population standard deviation instead of the
sample standard deviation to calculate the CV because these test series
are the only sled test series that have been run.\172\ Accordingly,
---------------------------------------------------------------------------
\172\ This differs from the qualification tests, for which it is
known that the data set is a sample of a larger population (because
NHTSA and other test labs have run the qualification tests on other
THOR-50M ATDs).
[GRAPHIC] [TIFF OMITTED] TP07SE23.029
Second, in addition to the CVs we also considered the normalized
CVs. A potential limitation of the CV calculation is that when the
magnitude of a given measurement is relatively low, as is the case with
off-axis sensor channels, the standard deviation can be high relative
to the mean, leading to CVs over 10%. However, this result is not
necessarily meaningful: although the amount of variation might be high
relative to the mean, it might not be high with respect to say, a
critical value of the measurement being evaluated (e.g., in the context
of a compliance test involving an ATD, it might not be high with
respect to the IARV). This was generally not an issue in the
qualification test R&R analysis because the qualification modes, test
parameters, and targets were all selected because they are meaningful
to the test mode and/or are in the primary load path, so that the
resulting measurements were generally of sufficient magnitude for a
reliable CV calculation. In sled and vehicle crash tests, on the other
hand, it is not known in advance which sensor channels will be of
sufficient magnitude for a reliable CV assessment. For this reason,
researchers often disregard high CV values when the magnitude of the
measurement is relatively low. However, determining the level of the
measurement below which CV is not reliable is inherently subjective.
Accordingly, for CVs above 10% we also considered normalized CVs.
To calculate normalized CV, the mean ([mu]) in the CV calculation (Eqn.
1) is replaced with a meaningful, pre-determined reference value. Such
a reference value could be an IARV or a measurement value that
corresponds to an injury risk similar to the risk that would correspond
to an IARV. Because IARVs for the THOR-50M have not yet been finalized,
in most cases we calculated the normalized CV using the value
associated with a 50% risk of AIS 3+ (above the pelvis) or AIS 2+
(below the pelvis) injury as the reference value.\173\ However, there
is not a known risk function that relates belt forces to risk of
injury, so for this metric we normalized using the average shoulder
belt force from the thoracic injury criteria development data set, for
which just over 50% of the subjects sustained AIS 3+ thoracic injuries
(a denominator of 5,000 N).\174\ The normalization denominators used
for each of the measurements are shown in Table 12.
---------------------------------------------------------------------------
\173\ Fifty percent risk of a given injury severity is a widely-
used tolerance level in ATD research. IARVs specified in the FMVSS
may or may not correspond to a 50% risk.
\174\ We used the shoulder belt force to normalize the lap belt
force because there was not meaningful lap belt force data in some
of the thoracic injury criteria development test conditions.
Table 12--Normalization Denominators for Calculation of Normalized CV
----------------------------------------------------------------------------------------------------------------
Metric Normalization factor Normalization rationale
----------------------------------------------------------------------------------------------------------------
HIC15................................... 1724................................ 50% risk of AIS 3+ injury.
BrIC.................................... 0.96................................
Neck Tension............................ 4,662 N............................. 50% risk of AIS 3+ injury when
used in Nij risk function.
Neck Compression........................ -5,017 N............................
Nij..................................... 1.11................................ 50% risk of AIS 3+ injury.
Chest Peak Res. Defl.................... 51.4 mm.............................
Left Femur Axial Force.................. 10,577 N............................ 50% risk of AIS 2+ injury.
Right Femur Axial Force................. 10,577 N............................
Peak Femur Axial Force.................. 10,577 N............................
Lap Belt Force.......................... 5,000 N............................. Average from thoracic injury
criteria development data set.
Upper Shoulder Belt Force............... 5,000 N.............................
Lower Shoulder Belt Force............... 5,000 N.............................
----------------------------------------------------------------------------------------------------------------
As an example, consider a repeated test with peak femur forces of
500 N, 1,000 N, and 1,500 N. For these tests, the calculated CV would
be 41% (standard deviation of 408 N divided by average of 1000 N),
which would require a thorough investigation of the test procedure and
ATD. However, these femur forces are all well below 10,577 N, the force
at which 50% risk of AIS 2+ injury occurs. Thus, calculating a
normalized CV may provide a more meaningful assessment. In this case,
the normalized CV would be 4% (standard deviation of 408 N divided by
50% risk of AIS 2+ injury of 10,577 N), which would require no further
investigation.
2. Thoracic Injury Criteria Development Sled Tests
One source of data NHTSA looked at to further assess repeatability
is a sled test series conducted to develop thoracic injury criteria for
the THOR-50M. This involved conducting matched-pair tests of PMHS and a
THOR-50M ATD in a variety of sled
[[Page 61934]]
test conditions.\175\ This series tested the same THOR-50M unit in
three to four repeat tests in each of six different test conditions:
Gold Standard 1, 2, and 3; Rear Standard; Rear Load-limited (Rear LL);
and Rear Inflatable (Table 13).\176\
---------------------------------------------------------------------------
\175\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
\176\ Our testing included a seventh test condition: Far-Side
Oblique (representing the right front passenger in an oblique moving
deformable barrier crash test). The THOR-50M setup and positioning,
however, differed in each of these tests. These tests were not valid
for the purposes of the repeatability analysis, because the
differences in setup and positioning is expected to--and in fact
did--lead to a wider variation in results. Specifically, the CVs for
8 of the 15 measurements exceeded 10%, with most of these over 20%,
and some as high as 72%.
Table 13--THOR-50M Thoracic Injury Criteria Development Test Matrix
----------------------------------------------------------------------------------------------------------------
Nominal test
TSTNO TSTREF speed (km/h) Test condition name, description
----------------------------------------------------------------------------------------------------------------
11117...................................... S0156 40 Gold Standard 1: flat rigid seat,
11118...................................... S0157 standard lap and shoulder belts,
11119...................................... S0158 knees restrained, right front
passenger restraint geometry.
11120...................................... S0159 30 Gold Standard 2: flat rigid seat,
11121...................................... S0160 force-limited shoulder belt and
11122...................................... S0161 standard lap belt, knees
restrained, right front passenger
restraint geometry..
11514...................................... UVAS0309 30 Gold Standard 3: flat rigid seat
11515...................................... UVAS0310 angled 30 degrees
11516...................................... UVAS0311 counterclockwise, force-limited
11517...................................... UVAS0312 shoulder belt and standard lap
belt, knees restrained, right
front passenger restraint
geometry.
11143...................................... S0199 48 Rear Standard: rear passenger in
11144...................................... S0200 2004 Ford Taurus buck; 3-point
11145...................................... S0201 standard belt.
11140...................................... S0196 48 Rear LL: rear passenger in 2004
11141...................................... S0197 Ford Taurus buck; 3-point load-
11142...................................... S0198 limited belt with pretensioner.
11137...................................... S0193 48 Rear Inflatable: rear passenger in
11138...................................... S0194 2004 Ford Taurus buck; 3-point
11139...................................... S0195 inflatable force-limited belt with
pretensioner.
----------------------------------------------------------------------------------------------------------------
Notes: All tests were on THOR-50M S/N 9207. These tests are available in the NHTSA biomechanics database.
We calculated CVs and normalized CVs for each of the injury
criteria described in the THOR-50M injury criteria report, as well as a
few other key data channels, for a total of 12 metrics for each of the
six test conditions. See Table 14 (CVs) and Table 12 (normalization
denominators). Sixty-five of the seventy-two CVs calculated were below
10%, while seven CVs were 10% or above.
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We believe that this data supports our tentative conclusion that
the THOR-50M is sufficiently objective for inclusion in Part 572.
Almost all the CVs were below 10%, and many were at or below 5%. For
the seven CVs at or above 10%, we believe that these do not indicate
that the dummy does not yield repeatable results. These seven
measurements with CVs above 10% were: Gold Standard 1 condition for
neck compression, Nij, and lap belt load; rear-seat standard belt
condition neck tension; rear-seat load-limited condition for BrIC and
neck compression; and rear-seat inflatable belt condition for
HIC15). When normalized, however, none of these CVs were
above 10%. This suggests that the variability in these measurements
would not likely lead to variability in actual testing outcomes. The
variability in these measurements is much lower than the magnitudes of
these measurements that would be used as an IARV specified in FMVSS No.
208.
For instance, the individual measurements for neck compression in
the Gold Standard 1 tests were -394 N, -427 N, and -328 N. These have
an average of -383 N and a standard deviation of 41 N, resulting in an
unadjusted CV of 11%. While this is greater than 10%--potentially
suggesting that the source of this variability needs investigation--
these measurements are all much lower in
[[Page 61936]]
magnitude than the compression force that would result in a 50% risk of
AIS 3+ injury (-5017 N). When the standard deviation is compared to
this compression force instead of the average neck compression, we
obtain a normalized CV of 0.8%. This suggests that the magnitudes of
the neck compression measurements are low compared to the magnitude of
compression that corresponds to a meaningful injury risk.
There was one measurement for which the unadjusted CV was below 10%
but the normalized CV was above 10%: the peak lap belt force in the
rear-seat inflatable belt condition, which had a normalized CV of
11.7%. In this instance, the average lap belt load (6,701 N) was higher
than the normalizing denominator (5,000 N), resulting in an inflated
normalized CV. As stated earlier, there is not a known risk function
that relates belt forces to risk of injury, so this elevated normalized
CV is not of particular concern.
Otherwise, the highest normalized CV occurred in the BrIC
measurement in the rear seat load-limited and pretensioned condition
(9.6%). This appears to result from inconsistent initial positioning of
the left arm, which is more of a test procedure concern than a THOR-50M
concern.
3. Low-Speed Belted Sled Tests
Another source of data NHTSA looked at to assess repeatability is a
sled test series conducted to assess the performance of THOR-50M in
low-speed belted conditions. These tests were based on the rigid
barrier, perpendicular impact belted crash test specified in FMVSS No.
208 for the HIII-50M. Sled tests were conducted at crash pulses
representing three frontal rigid barrier impact velocities (24, 32, and
40 km/h) (15, 20, and 25 mph). This range of speeds was selected
because FMVSS No. 208 specifies a speed of up to 56 km/h (35 mph) for
this crash test, and air bag deployment thresholds are typically around
24 km/h (15 mph); we spanned the 24-40 km/h (15-25 mph) range and
selected a mid-point of 32 km/h (20 mph) to conduct a crash test and
get a crash pulse. In each test, the THOR-50M was seated in either the
driver or right front passenger seating locations of a buck
representing a mid-sized passenger car.\177\ Three tests were conducted
at each impact velocity, for a total of 9 tests. The test buck was
created from an actual vehicle, and included seat belts, front air
bags, knee-bolsters, and pretensioners. The test matrix and additional
information about the test setup is provided in Appendix D.
---------------------------------------------------------------------------
\177\ A HIII-50M was seated in the other front outboard seat.
---------------------------------------------------------------------------
As with the thoracic injury criteria development test series, both
CVs and normalized CVs (Table 15) were calculated for each of the
relevant injury metrics described in the THOR-50M Injury Criteria
Report, as well as femur and seat belt loads, for 11 metrics for each
of the six test conditions. Of these 66 CVs, 31 were under 5%, 17 were
between 5% and 10%, and 18 were above 10%.
We believe that this data supports our tentative conclusion that
THOR-50M is sufficiently objective to include in Part 572. Most of the
CVs were under 10% and many were under 5%. None of the 18 measurements
for which the CV was above 10% had a normalized CV over 10%, and only
five were above 5%. This is not surprising, as the low-speed belted
test condition presents a low likelihood of injury. Thus, while there
may be variations in the injury metrics, these variations are small
relative to the values that would represent a meaningful injury risk.
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4. Low-Speed Unbelted Sled Tests
Another source of data NHTSA looked at to assess repeatability is a
sled test series conducted to assess the performance of THOR-50M in a
low-speed unbelted condition. Sled tests were conducted at crash pulses
representing two frontal rigid barrier impact velocities, 32 km/h (20
mph) and 40 km/h (25 mph), with the THOR-50M in both the driver and
right front passenger seating locations of a test buck. Three tests
were conducted at each impact velocity. The test buck was identical to
that used in the low-speed belted tests except for some minor
modifications. The test matrix and additional information about the
test setup is provided in Appendix E.
[[Page 61938]]
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As with the thoracic injury criteria development and belted test
series, CVs and normalized CVs were calculated for each of the relevant
injury metrics described in the THOR-50M Injury Criteria Report, as
well as femur loads, for nine metrics for each of the two crash pulses.
Of these 36 CVs, 12 were less than 5%, 20 were between 5% and 10%, and
four were above 10% (Table 16).
We believe this supports our tentative conclusion that the THOR-50M
is objective. Almost all the CVs were under 10%, and many were under
5%. Three of the four measurements with a CV over 10% had a normalized
CV under 10% (neck tension for driver 32 km/h and RFP 40km/h, and
HIC15 for RFP 40 km/h), suggesting that the variation is
small relative to the values that would represent a meaningful injury
risk. The low magnitudes of neck tension occur because there is no
torso restraint in these unbelted tests, so that the tension force
acting on the neck due to the deceleration of the torso is minimal
(below 500 N). The HIC15 measurements were relatively low
because the frontal air bags minimized the contact of the head with
hard surfaces or at least decelerated the head before contact. The
highest average HIC15 (360) occurred in the right front
passenger 40 km/h condition, where individual measurements of 309, 349,
and 423 resulted in a standard deviation of 47.3 and a CV of 13.1.
Only one of those four measurements that had a CV over 10% also had
a normalized CV over 10% (BrIC in the Driver 40 km/h condition, 14%).
NHTSA's analysis of the test procedure and ATD revealed that the
variation in this case appears to result from a difference in head
interaction with the sun visor and underlying roof structure, brought
about by small differences in the timing and/or position of the head at
the time of contact. This variation could be brought on by initial
position differences, differences in interaction of the pelvis and
thighs with the seat cushion during initial forward translation, or
differences in knee interaction with the knee bolster and/or knee
bolster air bag. For additional information on this analysis, see
Appendix E.
There was one measurement with a relatively low CV, but an
associated normalized CV above 10%. This occurred for the Nij
measurement in the
[[Page 61939]]
driver 40 km/h condition, where the CV was 4.7% and the normalized CV
was 10.7%. Because we normalized by the value of Nij associated with a
50% injury risk, this indicates that the average value of Nij from the
three tests in the driver 40 km/h condition were above an Nij
associated with 50% risk of injury. Closer inspection of the data
revealed several peaks that cannot be explained by the interaction of
the dummy with the restraint system and vehicle interior. This suggests
possible damage to a load cell or cabling. For additional information
on this analysis, see Appendix E.
VII. Overall Usability and Performance
NHTSA's extensive testing with the THOR-50M has also enabled it to
assess THOR-50M's overall usability and performance. This includes
durability, ease and frequency of maintenance, and how the ATD fits and
responds in the vehicle environment. We discuss these issues in the
sections that follow.
A. Assembly and Qualification
Based on NHTSA's experience with the dummy at VRTC, assembling the
THOR-50M following the instructions in the PADI takes roughly 80 hours,
as detailed in Table 17.
We note that NHTSA treats its THOR-50M units not so much as a
serialized dummy, but as a set of serialized parts and sub-assemblies.
NHTSA's THOR-50M units typically undergo a routine breakdown and
inspection after each application; when the dummy is reassembled,
different parts may be introduced (for example, if a part needed to be
refurbished before it could be used again). In addition, parts or sub-
assemblies may be taken out of service at regular intervals and set
aside to await preventative maintenance. For example, a head and neck
sub-assembly (both of which are serialized) may be taken out of service
at regular intervals and set aside to await preventative maintenance;
once clear, the head and neck sub-assembly may end up in another
serialized dummy. Therefore, a serialized dummy does not typically
define the dummy well because different parts are constantly being
interchanged. The parts and assemblies which are serialized, either by
the manufacturer or by NHTSA upon delivery of a new ATD or part, are
listed in Appendix C.
Table 17--Estimated Time To Carry Out Assembly and Associated Procedures
Described in the THOR-50M PADI
------------------------------------------------------------------------
PADI assembly time
-------------------------------------------------------------------------
Time
Body region or procedure (hrs)
------------------------------------------------------------------------
Head......................................................... 4
Neck......................................................... 8
Spine........................................................ 4
Thorax....................................................... 8
Shoulder..................................................... 4
Upper Abdomen................................................ 4
Lower Abdomen................................................ 4
Pelvis....................................................... 8
Upper Leg.................................................... 4
Lower Extremity.............................................. 8
Arm.......................................................... 4
Jacket and Clothing.......................................... 4
Bundling Cables.............................................. 4
Polarity Check............................................... 4
Documentation................................................ 8
----------
Total.................................................... 80
------------------------------------------------------------------------
Based on NHTSA's experience at VRTC, a complete qualification test
series of 24 tests takes roughly 80 hours, assuming that the
qualification specifications are met (Table 18). If the qualification
specifications are not met, it may take additional time to inspect,
replace parts where necessary, and re-test. Table 19 describes the
equipment required to carry out the THOR-50M qualification tests, along
with the associated setup procedures. Some of this equipment is the
same or similar to the equipment required for qualification of ATDs
currently defined in Part 572. For example, the THOR-50M qualification
procedures for the neck and the upper thorax use the same equipment as
used in qualification of the HIII-50M. For equipment not currently
defined in Part 572, the necessary drawings are included in the THOR-
50M drawing package with two exceptions: the impactors for the face
qualification test and upper leg and knee qualification tests. We
believe that existing impactors (such as the knee impact probe for the
HIII-5F \178\) can be modified or ballasted to achieve the required
mass.
---------------------------------------------------------------------------
\178\ 49 CFR 572.137(b).
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BILLING CODE 4910-59-P
[[Page 61940]]
[GRAPHIC] [TIFF OMITTED] TP07SE23.033
BILLING CODE 4910-59-C
[[Page 61941]]
Table 19--Equipment Required for Qualification Tests
----------------------------------------------------------------------------------------------------------------
Test fixture description [0.02 kg, 0.25 mm] Reference Section(s) Title
----------------------------------------------------------------------------------------------------------------
Rigid disk impactor 23.36 kg, 152.4 mm CFR Title 49, Sec. 4, 7, 8 Head, Upper Thorax, Lower
diameter disk. 572.36(a); DL500-325. Thorax.
Rigid disk impactor 13.0 kg, 152.4 mm THOR-50M Qualification 5 Face.
diameter disk. Procedures, Section 5.2.
Neck pendulum.......................... Figure A-2; CFR Title 49, 6.6, 6.7, 6.8, Neck Torsion, Neck
Sec. 572.33(c)3. 6.9 Frontal Flexion, Neck
Extension, Neck Lateral
Flexion.
THOR neck twist fixture................ DL472-1000............... 6.6 Neck Torsion.
Lower abdomen probe face assembly...... DL472-3000............... 9 Abdomen.
Rigid disk impactor 12.0 kg, 76.2 mm THOR-50M Qualification 11 Upper Leg, Knee.
diameter disk. Procedures, Section 11.2.
Dynamic impactor....................... TLX-9000-013............. 12, 13, 14 Ankle Inversion and
Eversion, Ball of Foot,
Heel.
External positioning bracket........... TLX-9000-016M............ 12, 14 Ankle Inversion and
Eversion, Heel.
Dynamic inversion/eversion bracket..... TLX-9000-015............. 12 Ankle Inversion and
Eversion.
Lower leg mounting bracket assembly.... DL472-4100............... 12, 13 Ankle Inversion and
Eversion, Ball of Foot
Lower leg zero bracket................. DL472-3500............... 3.4 Ankle Rotary
Potentiometer Zeroing
Procedure.
Achilles fixture complete assembly..... DL472-4000............... 3.5 Achilles Cable Adjustment
Procedure.
Load cell mounting assembly............ DL472-4200............... 3.5 Achilles Cable Adjustment
Procedure.
Knee slider load distribution bracket DL472-5000............... 11 Knee.
assembly.
Tibia adaptor.......................... DL472-4300............... 14 Heel.
----------------------------------------------------------------------------------------------------------------
B. Durability and Maintenance
In previous sections of the NPRM, we have discussed NHTSA's
biofidelity testing, qualification testing, and sled tests. In this
testing, we generally observed that THOR-50M stood up well during
testing and required maintenance consistent with existing Part 572
ATDs. In addition to that testing, NHTSA has conducted a variety of
other tests over the last several years as development of THOR-50M has
progressed. With respect to evaluating THOR's durability and
maintenance needs, three series of tests are especially useful because
they subject the THOR-50M to more severe or challenging crashes:
elevated energy qualification tests; OMDB testing; and unbelted FMVSS
No. 208 tests. We discuss this testing in the sections that follow.
1. Elevated Energy Qualification Test Series
In order to assess THOR-50M's durability, NHTSA conducted an
additional series of qualification tests at elevated energy levels (for
example, impactor velocities that exceeded the levels specified in the
qualification test procedures).\179\ A series of five tests was
conducted for each of the qualification test modes (except, as
explained below, the abdomen). The first test in each set was a
baseline test performed according to the qualification, except that if
the response measurement did not either represent at least a 50% risk
of injury or have a magnitude greater than the mean plus one standard
deviation of the same measurement in a set of 18 oblique vehicle crash
tests,\180\ the test speed was increased until either of those targets
were met; this was then considered the baseline speed. There were two
test modes where the test speed specified in the qualification
procedures did not reach either of these targets: upper leg impact and
heel impact.\181\ The next three tests were at speeds corresponding to
energy level increases of 10 percent, 20 percent, and 30 percent. A
final baseline test was then performed at the prescribed qualification
test velocity. The results were considered to show acceptable
durability if the final baseline test demonstrated a response similar
to the initial baseline test and within the qualification targets, and
visual inspection revealed no damage to any of the dummy components.
For a majority of the qualification test modes, durability was found to
be acceptable. No visible damage was observed in any of the tested
components after the series of five tests. Two exceptions to these
findings occurred in the face and the abdomen qualification test modes.
---------------------------------------------------------------------------
\179\ National Highway Traffic Safety Administration (2020).
THOR-50M Durability Report. Regulations.gov Docket ID NHTSA-2019-
0106-0003, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0003.
\180\ Saunders, J., Parent, D., Ames, E., 2015. NHTSA oblique
crash test results: vehicle performance and occupant injury risk
assessment in vehicles with small overlap countermeasures. In:
Proceedings of the 24th International Technical Conference for the
Enhanced Safety of Vehicles (No. 15-0108). Available at https://downloads.regulations.gov/NHTSA-2019-0106-0008/attachment_1.pdf.
\181\ The increase in energy of the upper leg impact test was
later implemented in the revised qualification procedure.
---------------------------------------------------------------------------
In the face impact test, the final baseline peak probe force and
peak head CG resultant acceleration were higher than the qualification
specifications. This is consistent with the results of the
qualification R&R study (Section VI.A). While not ideal, we believe
that, because this is now a known issue, it can be managed with the
replacement of a face foam insert when the face qualification test
results are higher in magnitude than the qualification specification.
Moreover, the deterioration in the face foam insert probably would not
meaningfully affect crash test results because, in a vehicle test, more
energy will likely be absorbed by a vehicle interior component and/or
restraint system compared to the rigid qualification impact probe.
However, NHTSA would consider specifying a different face foam material
or design that had improved durability, as long as the material or
design does not introduce unintended consequences such as negatively
impacting biofidelity, changes to the inertial properties of the head,
degradation of repeatability and reproducibility, overall usability, or
other concerns.
We did not conduct elevated-energy tests for the abdomen because
the qualification test already demonstrates a higher energy condition
than a vehicle crash test. Accordingly, impacts at a
[[Page 61942]]
higher energy level could cause damage due to exhausting the stroke of
the abdomen instrumentation. Moreover, this would not be meaningful as
it would represent a loading condition not representative of the front
seat vehicle crash test environment. However, we do recognize that our
testing has shown that damage to the abdomen deflection instrumentation
can occur in vehicle crash test environments where submarining is
possible, such as reclined rear seats. For example, several rear seat
sled tests were conducted at VRTC in 2015 in which the IR-TRACCs
installed in the abdomen experienced dislodged internal retaining rings
and damage including pinched cables. These issues are believed to have
resulted from interaction of the IR-TRACC tubes with the foam inserts
inside of the lower abdomen bag. To address this, the lower abdomen
sewing assembly (472-4763) was redesigned in late 2015, and an
inspection procedure was added to the drawing package (472-8320) to
ensure that the lower abdomen foam inserts remain aligned once
installed in the assembled lower abdomen bag.
We seek comment on these issues, especially on alternative
equivalent face foams.
2. Oblique OMDB Test Series
In developing THOR-50M, NHTSA ran a series of full-vehicle oblique
tests with a moving deformable test barrier (OMDB).\182\ Three crash
tests were conducted on the same make/model vehicle (a 2016 Mazda CX-5)
at three different test facilities. ATDs were seated in both front
outboard seats and were fully qualified. Two THOR-50M ATDs were
successfully implemented in a total of nine vehicle crash tests, with
qualification tests before and after each set of three tests. In this
test condition, there were no signs of damage beyond normal wear and
tear, and there were no sensor failures that were critical to the
calculation of injury risk. The dummies were inspected after each test.
---------------------------------------------------------------------------
\182\ Saunders, J., & Parent, D. (2018). Repeatability and
reproducibility of oblique moving deformable barrier test procedure
(No. 2018-01-1055). SAE Technical Paper, available at https://www.regulations.gov/document/NHTSA-2019-0106-0005. The discussion
here briefly summarizes some of the relevant results from this
report. This testing is not being considered as an evaluation of the
ATD's repeatability and reproducibility because in order to provide
a meaningful ATD R&R analysis, control of the test conditions must
be exercised. Component tests, such as the qualification tests, are
more readily controlled and thus may be expected to provide the best
estimates of a dummy's R&R. Sled testing provides an efficient
alternative to vehicle crash testing and offers insight into the
dummy's performance as a complete system. In full-vehicle crash
testing, however, the variation contributed by the vehicle (e.g.,
variation in structural materials) and the overall test procedure
make it difficult to identify the variability attributable to the
dummy itself. Additionally, the severity of the test conditions
utilized for R&R assessment must also be considered. For example, if
the test conditions are so severe that the responses are near or
beyond the dummy's mechanical limits or electronic capacity, then
the corresponding R&R analysis may not be meaningful. See generally
Rhule et al (2005).
---------------------------------------------------------------------------
There were no signs of damage beyond normal wear and tear, and no
part replacements were necessary. We did observe some sensor anomalies
or failures to sensors, but almost all the sensors that failed were
non-critical--for example off-axis channels (e.g., right femur X-axis
force) or sensors not used in the calculation of injury criteria (e.g.,
lower neck load cell, foot accelerometers). See Appendix F. Such sensor
anomalies can also occur in other Part 572 ATDs, such as the HIII-50M
and HIII-05F used in Frontal NCAP testing. In the past six years of
Frontal NCAP testing, there was an average of one failed ATD sensor
channel per crash test (0.68 1.08), with five of those
instances occurring in a critical channel.
Many of these anomalies were the results of loose Amphenol pins.
These are the electrical contacts inside of the connectors used to
interface the THOR-50M umbilical cables with the specific data
acquisition system of the test facility. These connectors are used to
prevent the need for cutting wires and attaching lab-specific
connectors each time an ATD is sent to a new facility with a different
data acquisition system. In practice, ATDs sent to test facilities for
the execution of regulation or consumer information testing will often
remain on-site for an extended period of time, which makes laboratory-
specific connectors more feasible. Such issues would not exist for
THOR-50M ATDs with in-dummy data acquisition systems. Many of the
sensor failures that occurred were in non-critical instrumentation, for
example off-axis channels or sensors not used in the calculation of
injury criteria. For research tests, a larger number of sensors are
recorded for the sake of completeness and post-test investigation; in a
regulatory or consumer information testing environment, these channels
may not be recorded. If the user does want to record such sensors, they
would need to be repaired or replaced before pre-test qualification for
the next vehicle crash test.
The only sensor anomalies related to the calculation of injury
criteria were in the chest and abdomen, but, once linearized, scaled,
filtered, and converted to three-dimensional resultant deflection local
spine coordinate system, these ``blips'' were no longer evident; thus
they would not influence the calculation of injury risk for this
occupant. These voltage drops are characteristic of the abrupt
decreases in the IR-TRACC voltage time-history described in Section
III.E.2. See Appendix F.
3. FMVSS No. 208 Unbelted Vehicle Crash Tests
NHTSA performed a series of unbelted vehicle crash tests required
in FMVSS No. 208. The results are briefly summarized in this section
and are discussed in more detail in the referenced paper.\183\ FMVSS
No. 208 specifies a frontal crash test into a rigid barrier with the
barrier angle at 0 degrees to 30 degrees at between 20 mph
(32 km/h) and 25 mph (40 km/h), inclusive, with an unbelted 50th
percentile male dummy seated at either front outboard seat.\184\
---------------------------------------------------------------------------
\183\ Saunders, J., Parent, D., Martin, P., 2023. THOR-50M
Fitness Assessment In FMVSS No. 208 Unbelted Crash Tests. In:
Proceedings of the 24th International Technical Conference for the
Enhanced Safety of Vehicles (No. 23-0339). Available at: https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000339.pdf.
\184\ S14.5.2; S5.1.2(b).
---------------------------------------------------------------------------
NHTSA ran two sets of tests. First, we ran this test at the highest
regulatory speed of 40 km/h (25 mph) for crash geometries of 30 degrees
to the left, 30 degrees to the right, and perpendicular (12 tests).
Second, we ran a modified version of this test, with an elevated speed
of 48 km/h (30 mph) for crash geometries of 30 degrees to the left and
right (six tests). We tested with two different THOR-50M ATDs, both
manufactured by Humanetics and built to the 2018 drawing package
(except that one ATD (EG2595) was fitted with the proposed optional in-
dummy DAS). For these tests, the laboratory test procedures for FMVSS
No. 208 \185\ were followed, with the exception of the seating
procedure, for which the Revised THOR 50th Percentile Male Dummy
Seating Procedure \186\ was followed. The ATD was instrumented so that
all injury criteria defined for the HIII-50M in FMVSS No. 208 and in
the THOR-50M Injury Criteria Report could be calculated. A total of 19
tests were run on four different vehicle models
[[Page 61943]]
(the Honda Accord, Mazda CX-5, Chevrolet Equinox, and Ford Escape).
---------------------------------------------------------------------------
\185\ National Highway Traffic Safety Administration (2008).
Laboratory Test Procedure for FMVSS 208, Occupant Crash Protection,
TP208-14.
\186\ National Highway Traffic Safety Administration (2020).
Revised THOR 50th Percentile Male Dummy Seating Procedure, June
2019. Regulations.gov Docket ID NHTSA-2019-0106-0006, available at
https://www.regulations.gov/document/NHTSA-2019-0106-0006.
---------------------------------------------------------------------------
This study showed that the THOR-50M, when exercised in unbelted
frontal rigid barrier testing, experienced only minor issues. We
performed a full set of qualification tests before the test series, a
partial qualification test series \187\ after each test, and a full
qualification test series halfway through the test series. In all
cases, the THOR-50Ms met the qualification specifications without need
for part replacement or other refurbishment. In addition, each ATD was
inspected after each test for damage and to investigate sensor
anomalies. While no parts were found to be in need of replacement,
there were some sensor anomalies and damage. One of the ATDs did not
experience any sensor anomalies or damage during testing, while the
other ATD experienced some sensor anomalies that were repairable, while
others were not. The sensors that were not repaired were non-critical
channels (for example, the left tibia mid-shaft X-axis accelerometer),
thus a decision was made to continue testing instead of repairing or
replacing the sensors, which would have caused delays in the test
schedule. The quantity and severity of sensor anomalies were similar to
those experienced in testing with the HIII-50M, especially considering
increased sensor count and level of complexity of the THOR-50M. Aside
from minor wear and tear (e.g., scrapes on the top of the head skin of
one ATD were noted after one test) there was no damage to either ATD
and both met all qualification specifications.
---------------------------------------------------------------------------
\187\ To maximize efficiency, the partial qualification test
series only included the tests that did not require any disassembly
of dummy components: head, upper thorax, lower thorax, lower
abdomen, and left/right upper leg. The face impact test was not
included because direct impact to the face was not expected during
this test series.
---------------------------------------------------------------------------
Based on these observations, NHTSA tentatively concludes that THOR-
50M is sufficiently durable for use in FMVSS No. 208 unbelted testing,
even at an elevated closing speed. Overall, this unbelted test series
provides additional assurance that the THOR-50M units are durable and
stand up well under testing, with the amount of wear and tear normal
for our test dummies, and that NHTSA's THOR-50M design specifications
have resulted in highly uniform and durable units.
C. Sensitivity to Restraint System Performance
NHTSA's testing with the THOR-50M has also highlighted its ability
to detect differences in restraint system performance. One example of
this occurred in the Oblique OMDB testing described above in Section
VII.B.2.\188\ This testing involved vehicles of the same model and
model year with a THOR-50M seated in each front outboard seat. In one
series of tests which included three Oblique OMDB crash tests of the
same vehicle make and model, the THOR-50Ms seated in the right front
passenger seat showed a much wider variation in injury assessment
values related to head injury risk than the THOR-50Ms seated in the
driver's seat. A thorough investigation of the test data, including
inspection of the high-speed video, revealed that the right front
passenger air bag did not function consistently to manage the ride-down
of the occupant: the high-speed images revealed differences in air bag
deployment, interaction between the head and the air bag, and contact
between the head and the instrument panel. Inspection of the air bag
revealed tears in the air bags in two of the three tests, with the
largest tears associated with the highest injury assessment
values.\189\ This is one example of how the innovative features of the
THOR-50M can help lead to improved vehicle safety.
---------------------------------------------------------------------------
\188\ Saunders, J., & Parent, D. (2018). Repeatability and
reproducibility of oblique moving deformable barrier test procedure
(No. 2018-01-1055).
\189\ These results were shared with the vehicle manufacturer,
which instituted a series of modifications. In a later test of the
vehicle, there were no passenger air bag tears evident, and the head
injury criteria were similar to those measured in the previous tests
that did not appear to result in air bag tears.
---------------------------------------------------------------------------
VIII. Intellectual Property
While there is no specific prohibition on specifying a patented
component, copyrighted design, or name-brand product in Part 572, NHTSA
has been mindful of the legislative history of the Safety Act and its
own responsibility under statute to make all information, patents, and
developments related to a research and development activity available
to the public where it makes more than a minimal contribution to the
activity.\190\ This understanding has guided dummy development at NHTSA
for many years and explains why NHTSA has not incorporated into final
rules materials owned by third parties except in rare cases (discussed
below). The legislative history of the Safety Act shows that while
Congress explicitly declined to include a provision preventing use of
patents by the agency in standards, Congress did ``assume[ ] that the
Secretary is not likely to adopt a standard which can be met only by
using a single patented device, and that the Secretary would, before
doing so, take steps to obtain an understanding from the patent holder
that he would supply the item or grant licenses on reasonable terms.''
\191\ In addition, NHTSA itself plays a significant role in the
testing, evaluation and performance verification of dummies and
provides a substantial amount of information to the public to identify
the basis for improvement in testing devices to ensure the
repeatability and reproducibility of results. The outcome of the
agency's involvement has been an interest in making sure the test
device is available for use without restriction to the public.
---------------------------------------------------------------------------
\190\ 49 U.S.C. 30182(f).
\191\ S. Rep. No. 89-1301, at 15, reprinted in U.S.C.C.A.N.
2709, 2723.
---------------------------------------------------------------------------
To be clear, there are also several potential concerns with
specifying proprietary components. They may be modified by the
proprietary source such that original is no longer available, and the
new part no longer fits. The proprietary source may alter the part in
ways that change the response of the dummy, such that dummies with the
newer part do not provide the same response as dummies with the older
part. Components produced by only one manufacturer are not subject to
competitive sales pressures. And the manufacturer of a sole-source part
may simply cease manufacturing the part.
For these reasons, NHTSA has generally avoided specifying in Part
572 patented components or copyrighted designs without either securing
agreement from the rights-holder for the free use of the item or to
license it on reasonable terms \192\ or developing an alternative
unencumbered by any rights claims.\193\
---------------------------------------------------------------------------
\192\ See, e.g., 38 FR 8455 (Apr. 2, 1973) (NPRM for the initial
50th percentile male dummy) (``To the knowledge of this agency, the
only patent on a component of the specified dummy is one on the knee
held by Alderson, and that company has stated to the NHTSA that it
will license production under its patent for a reasonable
royalty.'')
\193\ See, e.g., 65 FR 17180, 17187 (Mar. 31, 2000) (final rule
for twelve-month-old child dummy) (declining to incorporate a
copyrighted PADI developed by an ATD manufacturer and instead
incorporating a NHTSA-authored PADI).
---------------------------------------------------------------------------
As noted earlier in the preamble (Section III), we are specifying
some patented parts but not without specifying suitable alternates
where no intellectual property claims apply. We briefly discuss these
below.
Shoulder
As explained earlier, we are proposing to include two alternative
shoulder specifications: the SD-3 shoulder and the alternate shoulder.
Humanetics has two patents on the SD-3 shoulder: one describes a
mechanical shoulder joint assembly and the other describes an upper arm
[[Page 61944]]
assembly with a load cell.\194\ The shoulder joint is formed using a
pivot connected to a spring element inside of a housing, which has an
adjustable element to control the friction of the joint. Humanetics is
currently the sole manufacturer of the SD-3 shoulder in the United
States.
---------------------------------------------------------------------------
\194\ U.S. Patent Nos. 9,514,659 (upper arm assembly) and
9,799,234 (shoulder joint assembly).
---------------------------------------------------------------------------
In order to avoid potential concerns with specifying a patented
part as the sole specification, NHTSA has developed an alternative to
the SD-3 shoulder. The alternate shoulder does not include the
adjustable friction element, and does not use a coil, clock, or watch
spring mechanism. Instead, the alternate shoulder design uses a molded
rubber cylinder acting as a torsion bar. The response of the rubber
cylinder can be tuned by both changes in material and changes in
geometry, such as removal of material to create voids of different
sizes and shapes. This lack of a friction adjustment in the alternate
shoulder is a change in the functional aspect of the design.
Accordingly, with the significant differences noted, we are proposing
to specify the use of either the alternate shoulder or the SD-3
shoulder.
Chest Instrumentation
NHTSA is proposing the IR-TRACC and the S-Track as permissible
alternate instrumentation. While NHTSA is not aware of any patent
protection on the IR-TRACC, it is manufactured only by Humanetics.
There is a patent on the S-Track, and NHTSA's understanding is that the
S-Track is currently manufactured only by ATD-LabTech, which was
recently acquired by Humanetics.
We believe that specifying the design such that either the IR-TRACC
or the S-Track could be used would be sufficient to ensure
instrumentation availability to dummy users. We seek comment on this.
IX. Consideration of Alternatives
NHTSA is not aware of a 50th percentile male ATD intended for use
in frontal or frontal oblique crash tests and more advanced than the
HIII-50M, other than the THOR-50M. Throughout this document we have
discussed various alternative configurations, specifications, and tests
that we have considered in developing the proposal and on which we are
seeking comment.
As discussed in more detail in the rulemaking analyses section,
Executive Order 13609 provides that international regulatory
cooperation can reduce, eliminate, or prevent unnecessary differences
in regulatory requirements. Similarly, Sec. 24211 of the
Infrastructure, Investment, and Jobs Act \195\ instructs DOT to
harmonize the FMVSS with global regulations to the maximum extent
practicable (for example, to the extent that harmonization would be
consistent with the Safety Act).
---------------------------------------------------------------------------
\195\ H.R. 3684 (117th Congress) (2021).
---------------------------------------------------------------------------
The only regulatory authority or consumer ratings program we are
aware of that currently uses the THOR-50M is Euro NCAP. Euro NCAP TB026
references the August 2018 drawing package,\196\ the September 2018
Qualification Procedures,\197\ and the August 2018 PADI.\198\ Although
TB026 largely follows these documents, it does depart from them in
several ways. Those differences have been identified and discussed in
the relevant sections of the preamble and are summarized in Table 20.
The tentative reasons for those differences are explained in detail in
the relevant section of the preamble. In general, we believe that those
differences are justified given NHTSA's experience testing with the
THOR-50M in frontal rigid barrier and frontal oblique vehicle crash
test modes, and the necessity of ensuring that a dummy specified for
use in regulatory compliance testing be objectively specified.
---------------------------------------------------------------------------
\196\ Sec. 1.1.
\197\ Sec. 2.1.
\198\ Sec. 3.1.
Table 20--Summary of Differences Between the THOR-50M as Proposed and as
Specified for Use in Euro NCAP
------------------------------------------------------------------------
Issue Proposal Euro NCAP
------------------------------------------------------------------------
Design & Construction:
Split shoulder pad.......... Not proposed...... Under
consideration.
Spine....................... Spine Pitch Change Four-Position
Joint. Spine Box.
Lower Leg................... THOR-specific HIII-50M lower
lower leg. leg.
Instrumentation:
S-Track/IR-TRACC............ IR-TRACC or S- IR-TRACC, S-Track,
Track. or KIR-TRACC
Does not specify
the systems part-
by-part with
engineering
drawings.
In-dummy DAS................ Permitted as TB026 requires an
optional in-dummy DAS.
configuration TB029 currently
with part-by-part does not specify
engineering any specific in-
drawings dummy DAS,
compatible with although earlier
the SLICE6 and versions of TB029
any other did specify a few
similarly- different
configured system. approved in-dummy
DAS systems.
Does not specify
the systems part-
by-part with
engineering
drawings.
Qualification Tests:
Acceptance interval midpoint Based on R&R test Basis not
data. identified in
TB026.
Acceptance interval width... 10% Varies from 1% to 10%.
Upper thorax................ Ratio of Z-axis to Specifies ratio of
X-axis deflection Z-axis to X-axis
not specified as deflection as
test parameter. test parameter.
Face impact test............ Specified......... Not specified.
Knee slider................. Specified......... Certified to SAE
J2876.
Lower legs...................... Ankle inversion/ Certified to Annex
eversion; Ball of 10 of ECE
foot; heel. Regulation No.
94.
------------------------------------------------------------------------
[[Page 61945]]
X. Lead Time
Since this rulemaking action itself would not impose requirements
on anyone, we are proposing that the final rule would be effective on
publication in the Federal Register.
XI. Incorporation by Reference
Under regulations issued by the Office of the Federal Register (1
CFR 51.5(a)), an agency, as part of a final rule that includes material
incorporated by reference, must summarize in the preamble of the final
rule the material it incorporates by reference and discuss the ways the
material is reasonably available to interested parties or how the
agency worked to make materials available to interested parties.
In this proposed rule, NHTSA incorporates by reference a technical
data package for the THOR-50M. The technical data package consists of
two-dimensional engineering drawings and a parts list; procedures for
assembly, disassembly, and inspection (PADI); and qualification
procedures. Copies of these documents are available in the research
docket identified earlier in this document. Interested persons can
download a copy of the materials or view the materials online by
accessing www.Regulations.gov. The material is also available for
inspection at the Department of Transportation, Docket Operations, Room
W12-140, 1200 New Jersey Avenue SE, Washington, DC Telephone: 202-366-
9826. If the proposed rule is finalized, final versions of these
documents would be placed in a docket that would be readily available
to the public online (via regulations.gov) and in-person at DOT
headquarters.
Although agency-created documents are presumptively ineligible for
incorporation by reference, they may be approved for incorporation by
the Office of the Federal Register if they (among other things) consist
of criteria, specifications, or illustrations; are reasonably available
to the class of persons affected; are easy to handle; and possesses
other unique or highly unusual qualities.\199\
---------------------------------------------------------------------------
\199\ See 1 CFR 51.7(b) (``The Director will assume that a
publication produced by the same agency that is seeking its approval
is inappropriate for incorporation by reference. A publication
produced by the agency may be approved, if, in the judgment of the
Director, it meets the requirements of paragraph (a) and possesses
other unique or highly unusual qualities. A publication may be
approved if it cannot be printed using the Federal Register/Code of
Federal Regulations printing system.''); (a)(2)(i)(``published data,
criteria, standards, specifications, techniques, illustrations, or
similar material''); (a)(3)(``reasonably available to and usable by
the class of persons affected''); (a)(3)(i)(``The completeness and
ease of handling of the publication'').
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We believe these documents (which were created by NHTSA) meet these
criteria. Except for the qualification procedures, NHTSA typically
incorporates these elements of the technical data package by reference.
NHTSA has not typically incorporated the qualification procedures by
reference. Doing so is a departure from the other ATDs currently
specified in Part 572, for which the qualification tests are set out in
full in the regulatory text in each of the relevant paragraphs
(corresponding to that ATD) in part 572. We are proposing a separate
qualification procedures document for the THOR-50M because the THOR-50M
qualification procedures involve procedures that are made clearer by
photographs and diagrams that are not amenable to publication in the
CFR.\200\ We believe this extra level of detail will be helpful for end
users who are attempting to qualify the ATD. We seek comment on this.
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\200\ The qualification procedures document states that the
photographs are provided for reference only.
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XII. Regulatory Analyses
Executive Order (E.O.) 12866, E.O. 13563, E.O. 14094, and DOT
Regulatory Policies and Procedures
NHTSA has considered the impacts of this regulatory action under
Executive Orders 12866, 13563, 14094, and the Department of
Transportation's regulatory policies and procedures.\201\ This
rulemaking action was not reviewed by the Office of Management and
Budget under E.O. 12866. It is also not considered ``of special note to
the Department'' under DOT Order 2100.6A. We have considered the
qualitative costs and benefits of the proposed rule under the
principles of E.O. 12866.
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\201\ 49 CFR, Part 5, Subpart B; Department of Transportation
Order 2100.6A, Rulemaking and Guidance Procedures, June 7, 2021.
---------------------------------------------------------------------------
This document would amend 49 CFR part 572 by adding design and
performance specifications for an advanced test dummy representative of
a 50th percentile adult male that the agency would possibly use in
FMVSS No. 208 front crash tests and for research purposes. This Part
572 proposed rule would not impose any requirements on anyone.
Businesses are affected only if they choose to manufacture or test with
the dummy.
There are benefits associated with this rulemaking but they are not
readily quantifiable. The THOR-50M is an advanced dummy with advantages
over existing dummies with respect to biofidelity, instrumentation,
injury prediction, and evaluation of vehicle performance. The dummy is
currently used for testing by Euro NCAP, and may be incorporated in ECE
R137. It is also likely being used by vehicle and restraint
manufacturers for testing, research, and development.
Accordingly, NHTSA is considering a proposal to incorporate the
THOR-50M into FMVSS No. 208, ``Occupant crash protection,'' for use in
frontal crash compliance testing at the manufacturers' option.\202\
This contemplated rulemaking action would permit manufacturers to
direct NHTSA to use the THOR-50M in belted and unbelted barrier crash
testing of the vehicles they produce instead of the HIII-50M ATD in
NHTSA's compliance tests. Incorporating the dummy in Part 572 will
enable manufacturers and others to streamline testing, choosing to use
THOR-50M in place of the HIII-50M, potentially reducing the number of
tests they run, and leveraging the value of the tests they do run.
---------------------------------------------------------------------------
\202\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
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Incorporating the THOR-50M into Part 572 would also have other
benefits beyond use in NHTSA's compliance testing. The ability of the
THOR-50M to potentially monitor additional injury modes and its
improved biofidelity may facilitate the development and introduction of
innovative occupant crash protection features. While the purpose of
Part 572 is to ``describe the anthropomorphic test devices that are to
be used for compliance testing of motor vehicles and motor vehicle
equipment with motor vehicle safety standards,'' it also serves as a
definition of the ATD for other purposes as well, such as consumer
information crash testing, standards and regulations in other
transportation modes, and research. As such, it would be to the benefit
of government, academia, and the multi-modal transportation industry to
include a definition of the THOR-50M ATD in Part 572. In addition, the
availability of this dummy in a regulated format would be beneficial by
providing a suitable, stabilized, and objective test tool to the safety
community for use in better protecting occupants in frontal impacts.
The costs associated with the THOR-50M only affect those who choose
to use the THOR-50M. This rule would not impose any requirements on
anyone. If incorporated into FMVSS No. 208, NHTSA would use the dummy
in its compliance testing of the requirements
[[Page 61946]]
at the option of a regulated entity, but regulated entities are not
required to use the dummy or assess the performance of their products
in the manner specified in the FMVSSs.
NHTSA has found that the cost of a THOR-50M corresponding to the
2023 drawing package has been approximately $550,000 to $750,000
depending on whether an in-dummy DAS is installed and the level of
instrumentation. The minimum set of instrumentation needed for
qualification testing includes 66 channels. If the S-Track were used
instead of the IR-TRACC, the total cost would be roughly the same.
In addition to these costs, as with any ATD, dummy refurbishments
and part replacements are an inherent part of ATD testing. Various
parts will likely have to be refurbished or replaced, but we generally
do not know which parts are likely to be worked on the most. As we note
in the NPRM, however, the face foam appears to need more frequent
replacement but this should not add appreciably to the overall cost.
Because the dummies are designed to be reusable, costs of the dummies
and of parts can be amortized over a number of tests. While the
expected maintenance costs for the THOR-50M are expected to be higher
than those for less complex dummies such as the HIII-50M, these costs
are expected to be similar to advanced dummies such as the WorldSID.
There are minor costs associated with conducting the qualification
tests. Most of the qualification fixtures are common with those used to
qualify other Part 572 dummies (including the neck pendulum and the
probes used in the head, upper thorax and lower thorax tests). Some
additional equipment unique to the THOR-50M may be fabricated from
drawings within the technical data package, for an estimated cost of
about $50,000. This includes the cost to fabricate the torsion fixture
for the neck torsion test, the lower abdomen probe face assembly,
impact probes not used for other Part 572 dummies (or weighted collars
to achieve the specified mass), and test apparatus for the lower leg
tests (including the dynamic impactor, external positioning bracket,
dynamic inversion/eversion bracket, lower leg mounting bracket, lower
leg zero bracket, Achilles fixture, load cell mounting assembly, knee
slider load distribution bracket, and tibia adapter). The costs of the
instrumentation equipment needed to perform the qualification tests
amounts to about an additional $4,400 (two angular rate sensors, $850
apiece; two test probe accelerometers, $800 apiece; one rotary
potentiometer, $1,100).
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq.,
as amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA) of 1996), whenever an agency is required to publish a proposed
or final rule, it must prepare and make available for public comment a
regulatory flexibility analysis that describes the effect of the rule
on small entities (i.e., small businesses, small organizations, and
small governmental jurisdictions), unless the head of the agency
certifies the rule will not have a significant economic impact on a
substantial number of small entities. The Small Business
Administration's regulations at 13 CFR part 121 define a small
business, in part, as a business entity ``which operates primarily
within the United States.'' (13 CFR 121.105(a)).
We have considered the effects of this rulemaking under the
Regulatory Flexibility Act. I hereby certify that this rulemaking
action would not have a significant economic impact on a substantial
number of small entities. This action would not have a significant
economic impact on a substantial number of small entities because the
addition of the test dummy to Part 572 would not impose any
requirements on anyone. This NPRM only proposes to include the dummy in
NHTSA's regulation for crash test dummies; it does not propose NHTSA's
use of the ATD in agency testing or require anyone to manufacture the
dummy or to test motor vehicles or motor vehicle equipment with it.
National Environmental Policy Act
NHTSA has analyzed this proposed rule for the purposes of the
National Environmental Policy Act and determined that it would not have
any significant impact on the quality of the human environment.
Executive Order 13045 and 13132 (Federalism)
Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any
rule that: (1) is determined to be ``economically significant'' as
defined under E.O. 12866, and (2) concerns an environmental, health, or
safety risk that NHTSA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, we must evaluate the environmental health or safety
effects of the planned rule on children and explain why the planned
regulation is preferable to other potentially effective and reasonably
feasible alternatives considered by us.
This proposed rule is not subject to the Executive Order because it
is not economically significant as defined in E.O. 12866.
NHTSA has examined this proposed rule pursuant to Executive Order
13132 (64 FR 43255, August 10, 1999) and concluded that no additional
consultation with States, local governments or their representatives is
mandated beyond the rulemaking process. The agency has concluded that
the proposed rule would not have federalism implications because the
proposed rule would not have ``substantial direct effects on the
States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government.'' This proposed rule would not impose any
requirements on anyone. Businesses will be affected only if they choose
to manufacture or test with the dummy.
Further, no consultation is needed to discuss the preemptive effect
of this proposed rule. While NHTSA's safety standards can have
preemptive effect, the proposed rule would amend 49 CFR part 572 and is
not a safety standard. This Part 572 proposed rule would not impose any
requirements on anyone.
Civil Justice Reform
With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729, February 7, 1996) requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses other important issues affecting
clarity and general draftsmanship under any guidelines issued by the
Attorney General. This document is consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows.
The issue of preemption is discussed above in connection with E.O.
13132. NHTSA notes further that there is no requirement that
individuals submit a petition for reconsideration or pursue other
administrative proceeding before they may file suit in court.
[[Page 61947]]
Paperwork Reduction Act
Under the Paperwork Reduction Act of 1995, a person is not required
to respond to a collection of information by a Federal agency unless
the collection displays a valid control number from the Office of
Management and Budget (OMB). This proposed rule would not have any
requirements that are considered to be information collection
requirements as defined by the OMB in 5 CFR part 1320.
National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272)
directs NHTSA to use voluntary consensus standards in its regulatory
activities unless doing so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. The NTTAA directs NHTSA to
provide Congress, through OMB, explanations when the agency decides not
to use available and applicable voluntary consensus standards.
The following voluntary consensus standards have been used in
developing the THOR-50M:
SAE J211-1, Instrumentation for impact test--Part 1:
Electronic Instrumentation, Version 2014-03-31
SAE J1733, Sign Convention for Vehicle Crash Testing,
Version 2007-11-02.
SAE J2570, Performance specifications for anthropomorphic
test device transducers, Version 2009-08-12.
SAE J2876, Low Speed Knee Slider Test Procedure for the
Hybrid III 50th Male Dummy, Version 2015-05-07.
ISO-MME Task Force, 2015-04-15 proposed mnemonic codes for
the THOR-50M.
Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) (UMRA)
requires agencies to prepare a written assessment of the costs,
benefits, and other effects of proposed or final rules that include a
Federal mandate likely to result in the expenditures by States, local
or tribal governments, in the aggregate, or by the private sector, of
$100 million or more (adjusted annually for inflation with base year of
1995) in any one year. Adjusting this amount by the implicit gross
domestic product price deflator for 2022 results in $177 million
(111.416/75.324 = 1.48). The assessment may be included in conjunction
with other assessments, as it is here. UMRA requires the agency to
select the ``least costly, most cost-effective or least burdensome
alternative that achieves the objectives of the rule.''
This proposed rule would not impose any unfunded mandates under the
UMRA. This proposed rule does not meet the definition of a Federal
mandate because it does not impose requirements on anyone. It amends 49
CFR part 572 by adding design and performance specifications for a 50th
percentile adult male frontal crash test dummy that the agency could
use in FMVSS No. 208 and for research purposes. This proposed rule
would affect only those businesses that choose to manufacture or test
with the dummy. It would not result in costs of $100 million or more
(adjusted for inflation) to either State, local, or tribal governments,
in the aggregate, or to the private sector.
Plain Language
Executive Order 12866 and E.O. 13563 require each agency to write
all rules in plain language. Application of the principles of plain
language includes consideration of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please include them
in your comments on this proposal.
Regulation Identifier Number
The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified Agenda in April and October of each year. You may
use the RIN contained in the heading at the beginning of this document
to find this action in the Unified Agenda.
Privacy Act
In accordance with 5 U.S.C. 553(c), DOT solicits comments from the
public to better inform its rulemaking process. DOT posts these
comments, without edit, to www.regulations.gov, as described in the
system of records notice, DOT/ALL-14 FDMS, accessible through
www.dot.gov/privacy. In order to facilitate comment tracking and
response, we encourage commenters to provide their name, or the name of
their organization; however, submission of names is completely
optional. Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, if submitted on behalf
of an association, business, labor union, etc.). You may review DOT's
complete Privacy Act Statement in the Federal Register published on
April 11, 2000 (Volume 65, Number 70; Pages 19477-78).
XIII. Public Participation
How do I prepare and submit comments?
Your comments must be written and in English. To ensure that your
comments are correctly filed in the Docket, please include the agency
name and the docket number or Regulatory Identification Number (RIN) in
your comments.
Your comments must not be more than 15 pages long. (49 CFR 553.21).
We established this limit to encourage you to write your primary
comments in a concise fashion. However, you may attach necessary
additional documents to your comments. There is no limit on the length
of the attachments.
If you are submitting comments electronically as a PDF (Adobe)
file, NHTSA asks that the documents be submitted using the Optical
Character Recognition (OCR) process, thus allowing NHTSA to search and
copy certain portions of your submissions.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at https://www.transportation.gov/regulations/dot-information-dissemination-quality-guidelines.
[[Page 61948]]
How can I be sure that my comments were received?
If you wish the Docket to notify you upon its receipt of your
comments, enclose a self-addressed, stamped postcard in the envelope
containing your comments. Upon receiving your comments, the Docket will
return the postcard by mail.
How do I submit confidential business information?
You should submit a redacted ``public version'' of your comment
(including redacted versions of any additional documents or
attachments) to the docket using any of the methods identified under
ADDRESSES. This ``public version'' of your comment should contain only
the portions for which no claim of confidential treatment is made and
from which those portions for which confidential treatment is claimed
has been redacted. See below for further instructions on how to do
this.
You also need to submit a request for confidential treatment
directly to the Office of Chief Counsel. Requests for confidential
treatment are governed by 49 CFR part 512. Your request must set forth
the information specified in Part 512. This includes the materials for
which confidentiality is being requested (as explained in more detail
below); supporting information, pursuant to Part 512.8; and a
certificate, pursuant to Part 512.4(b) and Part 512, Appendix A.
You are required to submit to the Office of Chief Counsel one
unredacted ``confidential version'' of the information for which you
are seeking confidential treatment. Pursuant to Part 512.6, the words
``ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION'' or ``CONFIDENTIAL
BUSINESS INFORMATION CONTAINED WITHIN BRACKETS'' (as applicable) must
appear at the top of each page containing information claimed to be
confidential. In the latter situation, where not all information on the
page is claimed to be confidential, identify each item of information
for which confidentiality is requested within brackets: ``[ ].''
You are also required to submit to the Office of Chief Counsel one
redacted ``public version'' of the information for which you are
seeking confidential treatment. Pursuant to Part 512.5(a)(2), the
redacted ``public version'' should include redactions of any
information for which you are seeking confidential treatment (i.e., the
only information that should be unredacted is information for which you
are not seeking confidential treatment).
NHTSA is currently treating electronic submission as an acceptable
method for submitting confidential business information to the agency
under Part 512. Please do not send a hardcopy of a request for
confidential treatment to NHTSA's headquarters. The request should be
sent to Dan Rabinovitz in the Office of the Chief Counsel at
[email protected]. You may either submit your request via email
or request a secure file transfer link. If you are submitting the
request via email, please also email a courtesy copy of the request to
John Piazza at [email protected].
Will the agency consider late comments?
We will consider all comments received before the close of business
on the comment closing date indicated above under DATES. To the extent
possible, we will also consider comments that the docket receives after
that date. If the docket receives a comment too late for us to consider
in developing a final rule (assuming that one is issued), we will
consider that comment as an informal suggestion for future rulemaking
action.
How can I read the comments submitted by other people?
You may read the comments received by the docket at the address
given above under ADDRESSES. The hours of the docket are indicated
above in the same location. You may also see the comments on the
internet. To read the comments on the internet, go to http://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that even after the comment closing date, we will
continue to file relevant information in the docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.
You can arrange with the docket to be notified when others file
comments in the docket. See www.regulations.gov for more information.
List of Subjects in 49 CFR Part 572
Motor vehicle safety, Incorporation by reference.
Proposed Regulatory Text
In consideration of the foregoing, NHTSA proposes to amend 49 CFR
part 572 as follows:
PART 572--ANTHROPOMORPHIC TEST DEVICES
0
1. The authority citation for part 572 continues to read as follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.
0
2. Add Subpart X, consisting of Sec. Sec. 572.220 through 572.221, to
read as follows:
Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy
Secs.
572.220 Incorporation by reference.
572.221 General description.
Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy
Sec. 572.220 Incorporation by reference.
Certain material is incorporated by reference (IBR) into this part
with the approval of the Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, NHTSA must publish a document in the Federal
Register and the material must be available to the public. This
material is available for inspection at the Department of
Transportation, the National Archives and Records Administration
(NARA), and in electronic format through regulations.gov. Contact DOT
at: Department of Transportation, Docket Operations, Room W12-140, 1200
New Jersey Avenue SE, Washington DC 20590, telephone 202-366-9826. For
information on the availability of this material at NARA, email
[email protected] or go to www.archives.gov/federal-register/cfr/ibr-locations. To locate the material on regulations.gov, search for
Docket No. NHTSA-202X-XXXX. The material may be obtained from the
source:
(a) NHTSA Technical Information Services, 1200 New Jersey Ave. SE,
Washington, DC 20590, telephone 202-366-5965.
(1) A drawing package entitled, ``THOR-50th Percentile Male with
Alternate Shoulders Frontal Crash Test Dummy (THOR-50M Male w/Alt.
Shoulders) Drawings, External Dimensions, and Mass Properties,'' dated
(and revised) January 2023 (Drawings and Specifications); IBR approved
for Sec. 572.221.
(2) A parts list entitled, ``Parts List, THOR-50th Percentile Male
Frontal Crash Test Dummy with Alternate Shoulders (THOR-50M w/Alt.
Shoulders)'' dated (and revised) January 2023 (Parts List); IBR
approved for Sec. 572.221.
(3) A procedures document entitled ``THOR 50th Percentile Male
(THOR-50M) Procedures for Assembly, Disassembly, and Inspection
(PADI)'' dated (and revised) June 2023 (PADI); IBR approved for Sec.
572.221.
[[Page 61949]]
(4) A procedures document entitled ``THOR 50th Percentile Male
(THOR-50M) Qualification Procedures and Requirements'' dated (and
revised) April 2023 (Qualification Procedures); IBR approved for Sec.
572.221.
Sec. 572.221 General description.
(a) The THOR-50M 50th percentile male test dummy is defined by the
following materials:
(1) The Drawings and Specifications (incorporated by reference, see
Sec. 572.220);
(2) The Parts List (incorporated by reference, see Sec. 572.220);
(3) The PADI (incorporated by reference, see Sec. 572.220);
(4) The Qualification Procedures (incorporated by reference, see
Sec. 572.220).
Issued under authority delegated in 49 CFR 1.95, 501.4, and 501.
Ann Carlson,
Acting Administrator.
[FR Doc. 2023-19008 Filed 9-6-23; 8:45 am]
BILLING CODE 4910-59-P