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Torsional stiffness properties were developed for both a 53-foot box trailer and a 28-foot flatbed control trailer based on experimental measurements. In order to study the effect of torsional stiffness on the dynamics of a heavy truck vehicle dynamics computer model, static maneuvers were conducted comparing different torsional stiffness values to the original rigid vehicle model. Stiffness properties were first developed for a truck tractor model. It was found that the incorporation of a torsional stiffness model had only a minor effect on the overall tractor response for steady-state maneuvers up to 0.4 g lateral acceleration. The effect of torsional stiffness was also studied for the trailer portion of the existing model.

This research was to model a 6×4 tractor-trailer rig using TruckSim and simulate severe braking maneuvers with hardware in the loop and software in the loop simulations. For the hardware in the loop simulation (HIL), the tractor model was integrated with a 4s4m anti-lock braking system (ABS) and straight line braking tests were conducted. In developing the model, over 100 vehicle parameters were acquired from a real production tractor and entered into TruckSim. For the HIL simulation, the hardware consisted of a 4s4m ABS braking system with six brake chambers, four modulators, a treadle and an electronic control unit (ECU). A dSPACE simulator was used as the “interface” between the TruckSim computer model and the hardware.

A Computer Accident Simulation (CAS) is the application of dynamics to known physical evidence to yield a best approximation of the interactions of vehicles and other objects during the real world accident scenario. The simulation is based upon the reconstruction after an engineer's examination of the vehicles involved, the roadway (i.e., skid marks and gouges), and any substantiated evidence from witnesses. Examples of various cases are presented to illustrate the engineer's accident reconstruction and how the reconstruction is used to establish the computer simulation. The cases are used to explain the accuracy, features, advantages, and disadvantages of developing a computer accident simulation. During the interaction of the engineer and the graphics specialist, extra information such as witness viewpoint needs to be attained to make the computer simulation.

This paper presents a methodology for validating vehicle stability and control computer simulations. Validation is defined as showing that, within some specified operating range of the vehicle, a simulation's predictions of a vehicle's responses agree with the actual measured vehicle's responses to within some specified level of accuracy. The method uses repeated experimental runs at each test condition to generate sufficient data for statistical analyses. The acquisition and reduction of experimental data, and the processing path for simulation data, are described. The usefulness of time domain validation for steady state and slowly varying transients is discussed. The importance of frequency domain validation for thoroughly validating a simulation is shown. Both qualitative and quantitative methods for the comparison of the simulation predictions with the actual test measurements are developed.

Validation was performed on an existing heavy truck vehicle dynamics computer model with roll stability control (RSC). The first stage in this validation was to compare the response of the simulated tractor to that of the experimental tractor. By looking at the steady-state gains of the tractor, adjustments were made to the model to more closely match the experimental results. These adjustments included suspension and steering compliances, as well as auxiliary roll moment modifications. Once the validation of the truck tractor was completed for the current configuration, the existing 53-foot box trailer model was added to the vehicle model. The next stage in experimental validation for the current tractor-trailer model was to incorporate suspension compliances and modify the auxiliary roll stiffness to more closely model the experimental response of the vehicle. The final validation stage was to implement some minor modifications to the existing RSC model.

During Phase VI of the National Highway Traffic Safety Administration's (NHTSA) Light Vehicle Rollover Research Program, three of the twenty-six light vehicles tested exhibited significant response asymmetries with respect to left versus right steer maneuvers. This paper investigates possible vehicle asymmetric characteristics and unintended inputs that may cause vehicle asymmetric response. An analysis of the field test data, results from suspension and steering parameter measurements, and a summary of a computer simulation study are also given.

Computer simulations are popular for modeling vehicle system dynamics. However, further refinement of the vehicle dynamic model is required for extensive use in the automotive industry. In this paper, the model refining procedure is illustrated by developing reliable kinematic models verified with laboratory test results; instrument test data; and a mathematical optimization method. More specifically, simple kinematic models are developed for reduced computation times using ADAMS. They are tuned by the gradient-based optimization technique using the results from a laboratory testing facility, which includes the compliance effect in order to use the kinematic models in dynamic simulations. Also the Magic Formula tire model is developed using the optimization method and tire property data for the STI (Systems Technology, Incorporated) tire model.

In this research, cervical muscle behavior in rear impact accidents was investigated. Specifically, cervical muscle forces and muscle lengthening velocities were investigated with respect to cervical injuries. Variation of the onset time for muscle activation, variation of muscle activation level and variation of rear impact pulses were considered. The human body simulation computer program, MADYMO and anthropometric numerical human model were used to evaluate the neck. The factors mentioned above were examined with specific data being obtained from several different literature sources. Cervical muscles were separated into three groups, the sternocleidomastoideus, the flexor muscle group and the extensor muscle group. Longuscolli and spleniuscapitis were selected to represent the flexor muscle and extensor muscle groups respectively. The values and trends of the muscle forces and lengthening velocities are investigated in each muscle group.

This paper discusses the development of a 1994 Ford Taurus vehicle model for the National Advanced Driving Simulator's planned vehicle dynamics simulation, NADSdyna. The front and rear suspensions of the Taurus are modeled using recursive rigid body dynamics formulations. To complement vehicle dynamics, subsystems models that include steering, braking, and tire forces are included. These models provide state-of-the-art high fidelity vehicle handling dynamics for real-time simulation. The realism of a particular formulation depend heavily on how the parameters are obtained from the physical system. Therefore, the development of a data set for a particular model is as important as the model itself. The methodology for generating the Taurus data set is presented. The power train model is not yet included, so the simulation is run with the vehicle either at constant speed or decelerating.

This paper describes an adaptive control strategy for improving the steering response of an automated vehicle steering controller. In order to achieve repeatable dynamic test results, precise steering inputs are necessary. This strategy provides the controller tuning parameters optimized for a particular vehicle's steering system. Having the capability to adaptively tune the steering controller for any vehicle installation provides an easy method for obtaining precise steering inputs for a wide range of vehicles, from small off-road utility vehicles to passenger vehicles to heavy trucks. The S.E.A. Ltd. Automated Steering Controller (ASC) is used exclusively in conducting this research. By recording the torque input to the steering system by the steering controller and the resulting steering angle during only a single test, the ASC is able to characterize the steering system of the test vehicle and create a computer model with appropriate parameters.

This paper presents the analytical results of two different computer simulations of the vehicle pedestrian impact; PROMETHEUS 2 and the MacLaughlin/Daniel (MACDAN) models. The results presented illustrate the simularity and differences between the two models and accuracy of both to predict the actual occurrance. Also presented is a discussion relative to the modeling techniques of obtaining data for the pedestrian. This presentation illustrates the scaling techniques and actual data obtained in order to accurately simulate the pedestrian.

This paper presents an interactive computer simulation of the pedestrian/vehicle interface. The simulation presents the results in an easy to analyze format including animation of the whole event. User requests for specific output data is available via a graphic menu. The model employs the use of the MacLaughlin/Daniel Computer Simulation developed by the National Highway Traffic Safety Administration. To illustrate the usefulness of the graphical and pictorial output, the results of a pedestrian/vehicle impact are presented.

Two computer models, ABAG 19 and HSRI-3D, were validated against experimental data to determine and compare their capability for simulating the responses of air bag restrained automobile occupants in severe frontal collisions. Standard sets of model input parameters were developed for both driver and passenger. The primary objective was to determine which model was best suited for determining potential crashworthiness in a large number of production vehicles. Advantages and disadvantages of the models were determined, using criteria such as accuracy, ease of use, quality of documentation and user orientation.

The objective of this paper is to investigate the effect of padding on the human thorax. Different types of padding are used in the computer simulations. Lumped models are developed to perform the simulations. Through the responses of the simulations one can determine what kind of padding is desired. This paper provides the first phase of using a computer-aided tool. Though much attention has been paid to either the investigation of padding or human thorax modelling, how the physical properties of padding affect thoracic protection is not well known. The combination of padding and the thorax needs a lot of effort to unveil their relationship. This paper attempts to provide the guideline of what a good padding material should be. The determination of an optimal padding is one of the goals in this study. Hopefully, the results of this paper can make a contribution to the vehicle safety design, especially the car door.

This paper presents an overview of the evolution of computer simulations in vehicle collision and occupant kinematic reconstructions. The basic principles behind these simulations, the origin of these programs and the evolution of these programs from a basic analytical mathematical model to a sophisticated computer program are discussed. In addition, a brief computer development history is discussed to demonstrate how the evolution of computer assisted vehicle accident reconstruction becomes feasible for a reconstructionist. Possible future research in computer reconstruction is also discussed.

This paper explores the effects of changes in vehicle loading on vehicle inertial properties (center-of-gravity location and moments of inertia values) and handling responses. The motivation for the work is to gain better understanding of the importance vehicle loading has in regard to vehicle safety. A computer simulation is used to predict the understeer changes for three different vehicles under three loading conditions. An extension of this loading study includes the effects of moving occupants, which are modeled for inclusion in the simulation. A two-mass model for occupants/cargo, with lateral translational and rotational degrees of freedom, has been developed and is included in the full vehicle model. Using the simulation, the effects that moving occupants have on vehicle dynamics are studied.

This paper documents the vehicle response of a tractor-semitrailer following a sudden air loss (Blowout) in a steer axle tire while traveling at highway speeds. The study seeks to compare full-scale test data to predicted response from detailed heavy truck computer vehicle dynamics simulation models. Full-scale testing of a tractor-semitrailer experiencing a sudden failure of a steer axle tire was conducted. Vehicle handling parameters were recorded by on-board computers leading up to and immediately following the sudden air loss. Inertial parameters (roll, yaw, pitch, and accelerations) were measured and recorded for the tractor and semitrailer, along with lateral and longitudinal speeds. Steering wheel angle was also recorded. These data are presented and also compared to the results of computer simulation models. The first simulation model, SImulation MOdel Non-linear (SIMON), is a vehicle dynamic simulation model within the Human Vehicle Environment (HVE) software environment.