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With the emergence of Driving Automation Systems (SAE levels 1-5), the necessity arises for methods of evaluating these systems. However, these systems are much more challenging to evaluate than traditional safety features (SAE level 0). This is because an understanding of the Driving Automation system’s response in all possible scenarios is desired, but prohibitive to comprehensively test. Hence, this paper attempts to evaluate one such system, by modeling its behavior. The model generated parameters not only allow for objective comparison between vehicles, but also provide a more complete understanding of the system. The model can also be used to extrapolate results by simulating other scenarios without the need for conducting more tests. In this paper, low speed automated driving (also known as Traffic Jam Assist (TJA)) is studied. This study focused on the longitudinal behavior of automated vehicles while following a lead vehicle (LV) in traffic jam scenarios.

The rapid development of driver assistance systems, such as lane-departure warning (LDW) and lane-keeping support (LKS), along with widely publicized reports of automated vehicle testing, have created the expectation for an increasing amount of vehicle automation in the near future. As these systems are being phased in, the coexistence of automated vehicles and human-driven vehicles on roadways will be inevitable and necessary. In order to develop automated vehicles that integrate well with those that are operated in traditional ways, an appropriate understanding of human driver behavior in normal traffic situations would be beneficial. Unlike many research studies that have focused on collision-avoidance maneuvering, this paper analyzes the behavior of human drivers in response to cut-in vehicles moving at similar speeds. Both automated and human-driven vehicles are likely to encounter this scenario in daily highway driving.

When the Hybrid III 10-year old (HIII-10C) anthropomorphic test device (ATD) was adopted into Code of Federal Regulations (CFR) 49 Part 572 as the best available tool for evaluating large belt-positioning booster seats in Federal Motor Vehicle Safety Standard (FMVSS) No. 213, NHTSA stated that research activities would continue to improve the performance of the HIII-10C to address biofidelity concerns. A significant part of this effort has been NHTSA’s in-house development of the Large Omnidirectional Child (LODC) ATD. This prototype ATD is comprised of (1) a head with pediatric mass properties, (2) a neck that produces head lag with Z-axis rotation at the atlanto-occipital joint, (3) a flexible thoracic spine, (4) multi-point thoracic deflection measurement capability, (5) skeletal anthropometry representative of a seated child, and (6) an abdomen that can directly measure belt loading.

On-board Camera/Video Imaging Systems (C/VISs) for heavy vehicles display live images to the driver of selected areas to the sides, and in back of the truck's exterior using displays inside the truck cabin. They provide a countermeasure to blind-spot related crashes by allowing drivers to see objects not ordinarily visible by a typical mirror configuration, and to better judge the clearance between the trailer and an adjacent vehicle when changing lanes. The Virginia Tech Transportation Institute is currently investigating commercial motor vehicle (CMV) driver performance with C/VISs through a technology field demonstration sponsored by the National Highway Traffic Safety Administration (NHTSA) and the Federal Motor Carrier Safety Administration (FMCSA). Data collection, which consists of recording twelve CMV drivers performing their daily employment duties with and without a C/VIS for four months, is currently underway.

In crashes between heavy trucks and light vehicles, most of the fatalities are the occupants of the light vehicle. A reduction in heavy truck stopping distance should lead to a reduction in the number of crashes, the severity of crashes, and consequently the numbers of fatalities and injuries. This study made use of the National Advanced Driving Simulator (NADS). NADS is a full immersion driving simulator used to study driver behavior as well as driver-vehicle reactions and responses. The vehicle dynamics model of the existing heavy truck on NADS had been modified with the creation of two additional brake models. The first was a modified S-cam (larger drums and shoes) and the second was an air-actuated disc brake system. A sample of 108 CDL-licensed drivers was split evenly among the simulations using each of the three braking systems. The drivers were presented with four different emergency stopping situations.

This paper presents the implementation and performance of an electric all-wheel drive system on a series-parallel, through-the-road hybrid electric vehicle. Conventional methods of all-wheel drive do not provide a suitable solution for this type of vehicle as the powertrain lacks a mechanical link between the front and rear axles. Moreover, this unique architecture allows the vehicle to be propelled solely by the front, or the rear, wheels during typical operation. Thus, the algorithm presented here manages wheel slip by either the front, or rear wheels when engaging to provide all-wheel drive capability. necessary testing validates the robustness of this Extensive system.

In 2004, a model of a 6s6m ABS controller was developed in order to support NHTSA's efforts in the study of heavy truck braking performance. This model was developed using Simulink and interfaced with TruckSim, a vehicle dynamics software package, in order to create an accurate braking simulation of a 6×4 Peterbilt straight truck. For this study, the vehicle model braking dynamics were improved and the ABS controller model was refined. Also, the controller was made adaptable to ABS configurations other than 6s6m, such as 4s4m and 4s3m. Controller models were finally validated to experimental data from the Peterbilt truck, gathered at NHTSA's Vehicle Research and Test Center (VRTC).

Tire models used in vehicle dynamics simulation and tire-related research rely basically on curve fitted experimental data and empirical adjustments of theoretical models. The complexity of tire mechanics has limited the development of a complete and reasonable analytical force theory. This paper validates an analytical tire model recently developed by the author. This theoretical model uses physical parameters: lateral and longitudinal stiffnesses, aligning moment pneumatic trail, overturning moment arm, lateral force relaxation length, and friction properties. These are standard mechanical properties that characterize the force generating capacity of tires. The validation procedure compares the theoretical ground forces and moments with experimental data. Tire data measured on a flat track tire testing machine are used in this validation. It covers the full range of longitudinal, lateral, and combined slips.

The paper discusses the development of a model for the 2006 BMW 330i for the National Advanced Driving Simulator's (NADS) vehicle dynamics simulation, NADSdyna. The front and rear suspensions are independent strut and link type suspensions modeled using recursive rigid-body dynamics formulations. The suspension springs and shock absorbers are modeled as force elements. The paper includes parameters for front and rear semi-empirical tire models used with NADSdyna. Longitudinal and lateral tire force plots are also included. The NADSdyna model provides state-of-the-art high-fidelity handling dynamics for real-time hardware-in-the-loop simulation. The realism of a particular model depends heavily on how the parameters are obtained from the actual physical system. Complex models do not guarantee high fidelity if the parameters used were not properly measured. Methodologies for determining the parameters are detailed in this paper.

This paper covers research conducted at the National Highway Traffic Safety Administration's Vehicle Research and Test Center (VRTC) examining the performance of semitrailer anti-lock braking systems (ABS). For this study, a vehicle dynamics model was constructed for the combination of a 4×2 tractor and a 48-foot trailer, using TruckSim. ABS models for the tractor and trailer, as well as brake dynamics and surface friction models, were created in Simulink so that the effect of varying ABS controller parameters and configurations on semitrailer braking performance could be studied under extreme braking maneuvers. The longitudinal and lateral performances of this tractor-trailer model were examined for a variety of different trailer ABS controller models, including the 2s1m, 4s2m, and 4s4m configurations. Also, alternative controllers of the same configuration were studied by varying the parameters of the 2s1m controller.

In support of NHTSA's studies of heavy truck brake types and their effects on vehicle stopping performance and stability, the NHTSA Vehicle Research and Test Center (VRTC) has evaluated four foundation brake types on their Greening Brake Dynamometer. Several sample assemblies of each type of brake were tested to better understand variability. Braking tests were run under the “Laboratory Test Procedure for FMVSS 121D Air Brake Systems - Dynamometer” (TP- 121D-01) procedures. Afterward, the test scope was expanded to include higher speeds and higher severity conditions than those specified Test Procedure. This paper reports on the differences in braking effectiveness between two traditional S-Cam air brake types and two recently introduced Air Disc brake types. Burnish procedure trends are briefly discussed and compared. Responses of the pneumatic brakes to both constant-pressure and dynamic inputs are also compared and discussed.

In an effort to reduce the dry stopping distance required for heavy trucks, it is imperative to increase the effectiveness of the foundation brake systems. Where brakes are torque limited, increasing the brake output can be obtained by increasing brake size, chamber size, slack length, and friction of the braking materials. Looking just at the aspect of foundation brakes, the majority of current tractor and trailer brakes are of the S-Cam and Drum type. Two commercially available alternatives that produce higher output are Air Disc brakes and larger sized S-Cam brakes. Using one type, or a combination of these brakes (discs and drums on different axles) warrants a comparative study. The goal is to improve the effectiveness of the brake system, while maintaining or improving upon vehicle stability during braking. NHTSA's Vehicle Research and Test Center recently completed a brake test study of the effectiveness and stability characteristics of tractor and trailer combinations.

This paper discusses dry stopping performance comparisons of various foundation brake systems on Class-8 truck tractors (having a GVWR greater than 33,000 lbs.). For these studies, four configurations of foundation brakes were fitted to two modern 6x4 conventional truck tractors without modification to the control, application, or ABS systems. Foundation brakes compared include standard S-cam drum brakes on all six positions, high-output S-cam drum and then air disc brakes on the steer axles, and air disc brakes on all six brake positions. Discussions include analyses of stopping distance from 60 mph (96.6 kph) for all test conditions. The truck tractors were tested in two weight configurations, LLVW (i.e., bobtail) and GVWR (50,000 lbs. total axle weight, using an unbraked control semitrailer).

This paper presents the details of the model for the physical steering system used on the National Advanced Driving Simulator. The system is basically a hardware-in-the-loop (steering feedback motor and controls) steering system coupled with the core vehicle dynamics of the simulator. The system's torque control uses cascaded position and velocity feedback and is controlled to provide steering feedback with variable stiffness and dynamic properties. The reference model, which calculates the desired value of the torque, is made of power steering torque, damping function torque, torque from tires, locking limit torque, and driver input torque. The model also provides a unique steering dead-band function that is important for on-center feel. A Simulink model of the hardware/software is presented and analysis of the simulator steering system is provided.

This paper presents a real-time steering system torque feedback model used in the National Advanced Driving Simulator (NADS). The vehicle model is based on real-time recursive multi-body dynamics augmented with vehicle subsystems models including tires, power train, brakes, aerodynamics and steering. The steering system feel is of paramount importance for the fidelity of the simulator. The driver has to feel the appropriate torque as he/she steers the vehicle. This paper presents a detailed mathematical model of the steering physics from low-speed stick-slip to high-speed states. On-center steering weave handling and aggressive lane change inputs are used to validate the basic mathematical predictions. This validation is objective and open loop, and was done using field experiments.

A major focus of the National Highway Traffic Safety Administration's (NHTSA) vehicle compatibility and aggressivity research program is the development of a laboratory test procedure to evaluate compatibility. This paper is written to explain the associated goals, issues, and design considerations and to review the preliminary results from this ongoing research program. One of NHTSA's activities supporting the development of a test procedure involves investigating the use of an mobile deformable barrier (MDB) into vehicle test to evaluate both the self-protection (crashworthiness) and the partner-protection (compatibility) of the subject vehicle. For this development, the MDB is intended to represent the median or expected crash partner. This representiveness includes such vehicle characteristics as weight, size, and frontal stiffness. This paper presents distributions of vehicle measurements based on 1996 fleet registration data.

The National Highway Traffic Safety Administration and the University of Michigan Transportation Institute are investigating truck design countermeasures to provide safety benefits during collisions with light vehicles. The goal is to identify approaches that would best balance costs and benefits. This paper outlines the first phase of this study, an analysis of two-vehicle, truck/light vehicle crashes from 1996 through 1998 using several crash data bases to obtain a current description and determine the scope of the aggressivity problem. Truck fronts account for 60% of light vehicle fatalities in collisions with trucks. Collision with the front of a truck carries the highest probability of fatal (K) or incapacitating (A) injury. Truck sides account for about the same number of K and A-injuries combined as truck fronts, though injury probability is substantially lower than in crashes involving the front of a truck.

The National Highway Safety Administration (NHTSA) is collecting crash data relating to large trucks. Two data collection programs are specified. One is a crash causation study to investigate the cause of fatal and serious large truck crashes over two years. The other study is a continuous effort collecting data on large truck motor carrier crashes in each state, as coded on police accident reports.

This paper describes ongoing research conducted by the National Highway Traffic Safety Administration (NHTSA) to evaluate the potential of safety restraints on large school buses. School bus transportation is one of the safest forms of transportation in the United States. Large school buses provide protection because of their visibility, size, and weight, as compared to other types of motor vehicles. Additionally, they are required to meet minimum Federal Motor Vehicle Safety Standards (FMVSS) mandating compartmentalized seating, emergency exits, roof crush and fuel system integrity, and minimum bus body joint strength.

A research program was initiated to evaluate the performance of prototype dual stage passenger air bags in terms of both restraint system performance and deployment aggressivity for different size occupants. Variations in inflator partitions, vent hole diameter sizes, and deployment timing were examined. High speed unbelted sled tests were conducted with both 50th percentile male and 5th percentile female Hybrid III adult dummies at 48 kmph; and belted sled tests were conducted at 56 kmph. Low risk deployment tests with child dummies were conducted to evaluate air bag aggressivity. Overall, it was concluded that the dual stage air bag systems under evaluation had improved performance over the baseline single stage systems in terms of providing high speed protection while reducing aggressivity to out-of-position occupants; however, some dual stage systems may require additional occupant detection methodologies to suppress or control inflation.