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Heavy Vehicles Kinematics of Automatic Emergency Braking Test Track Scenarios

NHTSA-Devin Elsasser
Transportation Research Center Inc-M. Kamel Salaani, Christopher Boday
  • Technical Paper
  • 2020-01-0995
To be published on 2020-04-14 by SAE International in United States
This paper presents the test track scenario design and analysis used to estimate the performances of heavy vehicles equipped with forward collision warning and automatic emergency braking systems in rear-end crash scenarios. The first part of this design and analysis study was to develop parameters for brake inputs in test track scenarios simulating a driver that has insufficiently applied the brakes to avoid a rear-end collision. In the second part of this study, the deceleration limits imposed by heavy vehicles mechanics and brake systems are used to estimate automatic emergency braking performance benefits with respect to minimum stopping distance requirements set by Federal Motor Vehicle Safety Standards. The results of this study were used to complete the test track procedures and show that all heavy vehicles meeting regulatory stopping distance requirements have the braking capacity to demonstrate rear-end crash avoidance improvements in the developed tests.
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The Effect of Crash Severity and Structural Intrusion on ATD Responses in Rear-End Crashes

Exponent Inc.-Chantal Parenteau, Jeffrey Croteau, John Zolock
  • Technical Paper
  • 2020-01-1224
To be published on 2020-04-14 by SAE International in United States
This study assesses the vehicle and occupant responses in six high-speed rear impact crash tests. The instrumented vehicle-to-vehicle tests included a lap-shoulder belted Hybrid III ATD. Four tests were with a 50th male in the driver seat, one with a 95th male in the driver seat and one with a 5th female in the left rear seat. Three ATDs had instrumentation which was analyzed and compared to corresponding IARVs (injury assessment reference values). As part of the analysis, the ground based and onboard vehicle videos were synchronized with the vehicle kinematics and ATD measurements. The delta Vs ranged from 48 to 76 km/h in the five tests with the driver ATD. The timing of the crush, intrusion, driver seat back motion and occupant motion was assessed. The results indicated that the rear structures of the struck vehicle were crushed by the striking vehicle rear and over-ride impact. The 2nd row seat intrusion supported and then pushed the driver seat forward, changing the ATD dynamics. The driver ATD neck forces exceeded the IARVs in two tests.…
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The Effect of FMVSS 301R on Vehicle Structure in Rear Impact

Collision Research & Analysis Inc-Gregory Stephens
Exponent Inc.-Chantal Parenteau, Jennifer Yaek, Serge Gregory
  • Technical Paper
  • 2020-01-1226
To be published on 2020-04-14 by SAE International in United States
Vehicle structures are designed to manage impact forces and transfer crash energy. With the introduction of new rear impact requirements, the design of rear structures has evolved and the use of high strength steel has increased. This study objective was to assess the effect of new FMVSS 301 requirements on vehicle responses. NHTSA conducted 33 offset rear crash tests at 80 km/h with vehicles that pre-dated the newer FMVSS 301R requirements and 86 with vehicles that complied with the newer requirements, with a 2009-2015 model year range. The vehicles were grouped by size and the crush was tabulated. Overall, the struck-side maximum crush decreased in the newer model vehicles. Seven matches with pre and post 301R were identified based on make and model. The matched tests were reconstructed using video analysis and crush measurements of both the barrier and vehicle. Generalized vehicle stiffness was determined for each of the matched tests and indicated that vehicles generally became stiffer with new 301R requirements. The average stiffness was about two-times greater in the post-301R models than in…
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Occupant Dynamics During Low, Moderate, and High Speed Rear-End Collisions

Vollmer-Gray Engineering Laboratories-Mohammad Atarod
  • Technical Paper
  • 2020-01-0516
To be published on 2020-04-14 by SAE International in United States
Numerous studies have evaluated occupant kinematics and dynamics in “low-speed” rear-end impacts. Occupant biomechanics during “moderate-to-high” speed rear impacts (delta-V ≥ 15 mph), however, has not been thoroughly examined. This study characterized the motions and forces experienced by the occupant head, neck, torso, hip, and left/right femur during these collisions. The publicly available NHTSA rear-end crash test data were examined. More specifically, the FMVSS 301 Fuel System Integrity tests were used. The test procedure involved a 30 mph moving barrier impacting the rear of the vehicles. Instrumented 50th percentile male Hybrid III ATDs were positioned in the left front driver seat. Occupant data including head accelerations, upper/lower neck shear and axial forces, upper/lower neck moments, lower neck acceleration, torso accelerations, torso deflection, hip accelerations, and left/right femur axial forces were measured and compared to published IARV tolerance data. The vehicle accelerations, vehicle delta-Vs, occupant position data, seat angular velocity, seat rotation and seatbelt forces were also evaluated during these crash tests. The occupant data for the “low-speed” rear-end impacts were extracted from the literature. The…
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Motor Vehicle Seating Systems

Motor Vehicle Council
  • Ground Vehicle Standard
  • J879B_201910
  • Current
Published 2019-10-02 by SAE International in United States
This SAE Recommended Practice establishes uniform test procedures and certain minimum performance requirements for motor vehicle seats and seat adjusters. It is limited to tests that can be conducted on uniform test fixtures and equipment available in commercial laboratory test facilities. This practice includes a minimum requirement for horizontal forward loads encountered in vehicle forward impacts, and horizontal loads obtained by impacting the vehicle from the rear. The requirements and test procedures in this recommended practice reflect current technology and industry experience. It is intended to subject this recommended practice to a continuing review and revision as technology advances and experience is expanded.
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Head and Neck Loading Conditions over a Decade of IIHS Rear Impact Seat Testing

Exponent Inc.-John M. Scanlon, Jessica Isaacs, Christina Garman
Published 2019-04-02 by SAE International in United States
Rear-end impacts are the most common crash scenario in the United States. Although automated vehicle (AV) technologies, such as frontal crash warning (FCW) and automatic emergency braking (AEB), are mitigating and preventing rear-end impacts, the technology is only gradually being introduced and currently has only limited effectiveness. Accordingly, there is a need to evaluate the current state of passive safety technologies, including the performance of seatbacks and head restraints. The objective of this study was to examine trends in head and neck loading during rear impact testing in new vehicle models over the prior decade. Data from 601 simulated rear impact sled tests (model years 2004 to 2018) conducted as a part of the Insurance Institute for Highway Safety (IIHS) Vehicle Seat/Head Restraint Evaluation Protocol were obtained. This dynamic evaluation involves a simulated rear-end crash using a Biofidelic Rear Impact (BioRID IIg) ATD positioned in the seat attached to a crash simulation sled and accelerated to represent a rear crash with a delta-V of approximately 15.6 kph (15.6 ± 0.26 kph). Head and neck injury…
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Low Speed Override of Passenger Vehicles with Heavy Trucks

Kineticorp LLC-David Danaher, William Neale, Sean McDonough, Drew Donaldson
Published 2019-04-02 by SAE International in United States
In low speed collisions (under 15 mph) that involve a heavy truck impacting the rear of a passenger vehicle, it is likely that the front bumper of the heavy truck will override the rear bumper beam of the passenger vehicle, creating an override/underride impact configuration. There is limited data available for study when attempting to quantify vehicle damage and crash dynamics in low-speed override/underride impacts. Low speed impact tests were conducted to provide new data for passenger vehicle dynamics and damage assessment for low speed override/underride rear impacts to passenger vehicles. Three tests were conducted, with a tractor-trailer impacting three different passenger vehicles at 5 mph and 10 mph. This paper presents data from these three tests in order to expand the available data set for low speed override/underride collisions.
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Relating Experimental Drive Distraction and Driving Performance Metrics to Crash Involvement - Definitions of Terms and Concepts

Driver Metrics, Performance, Behaviors and States Committee
  • Ground Vehicle Standard
  • J3151_201810
  • Current
Published 2018-10-18 by SAE International in United States
This Information Report provides functional definitions and discussions of key terms and concepts for relating the experimental evaluation of driver distraction to real-world crash involvement. Examples of driver distraction and driving performance metrics include those related to vehicle control, object and event detection and response (OEDR), physiological indicators, subjective assessments, or combinations thereof. Examples of real-world crash involvement metrics include the epidemiological effect size measures of risk ratio, rate ratio, and odds ratio. The terms and concepts defined in this document are not intended to contribute to methodologies for assessing the individual metrics within a domain; these are covered in other SAE documents (e.g., SAE J2944) and SAE technical reports. For any measure chosen in one domain or the other, the goal is to give general definitions of key terms and concepts that relate metrics in one domain to those in the other. Issues of repeatability and validity are discussed in relation to these methods and metrics for relating the two domains. However, the actual specification of a particular methodology for predicting crash involvement from…
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Driver Risk Perception Model under Critical Cut-In Scenarios

Tongji University-Xuehan Ma, Zhiwei Feng, Xichan Zhu, Zhixiong Ma
Published 2018-08-07 by SAE International in United States
In China Cut-in scenarios are quite common on both highway and urban road with heavy traffic. They have a potential risk of rear-end collision. When facing a cutting in vehicle, driver tends to brake in most case to reduce collision risk. The timing and dynamic characteristics of brake maneuver are indicators of driver subjective risk perception. Time to collision (TTC) and Time Headway (THW) demonstrate objective risk. This paper aims at building a model quantitatively revealing the relationship between drivers’ subjective risk perception and objective risk. A total of 66 valid critical Cut-in cases was extracted from China-FOT, which has a travel distance of about 130 thousand miles. It is found that under Cut-in scenarios, driver tended to brake when the cutting in vehicle right crossing line. This time point was defined as initial brake time. Brake strength and brake speed were taken to describe brake maneuver. Average brake pressure (ABP) and acceleration at initial brake time indicated brake strength. Brake pressure change rate (BPCR) and longitudinal jerk (derivative of acceleration) at initial brake time…
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The Effect of the Head-to-Head Restraint Distance on Occupant Kinematics during Low-Speed Rear-End Crashes

Biodynamic Research Corp.-William R. Scott, Rawson Wood, Lars Reinhart, Herbert Guzman
University of Texas-Alejandra Barraza
Published 2018-04-03 by SAE International in United States
The longitudinal motion of the head, thorax and lumbar spine of two test subjects was measured in low-speed rear-end collisions in order to understand the effect of the head-to-head restraint distance (backset) on the occupant kinematics. The two test subjects were exposed to three rear-end impacts at two crash severities, nominal changes in velocity (ΔV) of 1.11 (low ΔV) and 2.22 m/s (high ΔV). The backset was hypothesized to be an independent variable that would affect the head and neck motion and was set at 0, 5 or 10 cm. The x and z-axis accelerations of the impacted vehicle and the anatomical x and z-axis accelerations of each test subjects’ upper thorax and L5-S1 region were measured and then transformed to an earth-based coordinate system. Head accelerations were measured at the mouth and these accelerations were transformed to an earth-based coordinate system at the head center of gravity (CG). Along the earth x-axis the vehicle accelerations increased first, followed by the accelerations of the lumbar region, the thoracic region, and then the head CG. In the high…
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