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Technical Paper

Requirements for Vehicle Dynamics Simulation Models

1994-03-01
940175
Computer simulation and real-time, interactive approaches for analysis, interactive driving simulation, and hardware-in-the-loop testing are finding increasing application in the research and development of advanced automotive concepts, highway design, etc. Vehicle dynamics models serve a variety of purposes in simulation. A model must have sufficient complexity for a given application but should not be overly complicated. In interactive driving simulation, vehicle dynamics models must provide appropriate computation for sensory feedback such as visual, motion, auditory, and proprioceptive cuing. In stability and handling simulations, various modes must be properly represented, including lateral/directional and longitudinal degrees of freedom. Limit performance effects of tire saturation that lead to plow out, spin out, and skidding require adequate tire force response models.
Technical Paper

Analysis and Computer Simulation of Driver/Vehicle Interaction

1987-05-01
871086
This paper presents an analysis of driver/vehicle performance over a range of maneuvering conditions including accident avoidance scenarios involving vehicle limit performance handling. Driver behavior is considered in the same dynamic analysis terms as vehicle response in order to give appropriate closed-loop measures of total system maneuvering capability and handling stability. A driver control structure is developed along with closed-loop system stability constraints on model parameters over a wide range of vehicle maneuvering conditions. Example simulation runs are presented for several accident avoidance scenarios.
Technical Paper

Validation of Ground Vehicle Computer Simulations Developed forDynamics Stability Analysis

1992-02-01
920054
This paper describes validation work carried out for two vehicle dynamics computer simulation programs. One program, referred to as VDANL (Vehicle Dynamics Analysis NonLinear), is intended to simulate passenger cars, vans and light trucks. The second program simulates All Terrain Vehicles (ATVs) and is referred to as NLATV (NonLinear ATV). The programs have been checked out and validated for a variety of maneuvering conditions and a broad range of vehicles. The programs run on IBM-PC/MS DOS compatible computers, and numerical methods have been used to give numerically stable solutions with reasonable computational speed over a broad range of maneuvering situations.
Technical Paper

Vehicle Stability Considerations with Automatic and Four Wheel Steering Systems

1993-11-01
931979
Automatic and four wheel steering control laws are often developed from the performance point of view to optimize rapid response. Under linear tire operating conditions (i.e., maneuvering at less than .5g's) both performance and safety conditions can be simultaneously met. Under severe operating conditions, such as might be encountered during crash avoidance maneuvering, tire characteristics can change dramatically and induce directional dynamic instability and spinout. The challenge in automatic and four wheel steering system design is to achieve a compromise between performance and safety. This paper will describe analyses carried out with a validated vehicle dynamics computer simulation that shed some light on the vehicle and control characteristics that influence tradeoffs between performance and safety. The computer simulation has been validated against field test data from twelve vehicles including passenger cars, vans, pickup trucks and utility vehicles.
Technical Paper

Field Testing and Computer Simulation Analysis of Ground Vehicle Dynamic Stability

1990-02-01
900127
This paper considers ground vehicle lateral/directional stability which is of primary concern in traffic safety. Lateral/directional dynamics involve yawing, rolling and lateral acceleration motions, and stability concerns include spinout and rollover. Lateral/directional dynamics are dominated by tire force response which depends on horizontal slip, camber angle and normal load. Vehicle limit maneuvering conditions can lead to tire force responses that result in vehicle spinout and rollover. This paper describes accident analysis, vehicle testing and computer simulation analysis designed to give insight into basic vehicle design variables that contribute to stability problems. Field test procedures and results for three vehicles are described. The field test results are used to validate a simulation model which is then analyzed under severe maneuvering conditions to shed light on dynamic stability issues.
Technical Paper

Computer Simulation Analysis of Light Vehicle Lateral/Directional Dynamic Stability

1999-03-01
1999-01-0124
Dynamic stability is influenced by vehicle and tire characteristics and operating conditions, including speed and control inputs. Under limit performance operating conditions, maneuvering can force a vehicle into oversteer and high sideslip. The high sideslip results in limit cornering conditions, which might proceed to spinout, or result in tip-up and rollover. Oversteer and spinout result from rear axle tire side force saturation. Tip-up and rollover occur when tire side forces are sufficient to induce lateral acceleration that will overcome the stabilizing moment of vehicle weight. With the use of computer simulation and generic vehicle designs, this paper explores the vehicle and tire characteristics and maneuvering conditions that lead to loss of directional control and potential tip-up and rollover.
Technical Paper

Analysis of Potential Road/Terrain Characterization Rating Metrics

2004-10-26
2004-01-2640
The U.S. Army uses the root mean square and power spectral density of elevation to characterize road/terrain (off-road) roughness for durability. This paper describes research aimed toward improving these metrics. The focus is on taking previously developed metrics and applying them to mathematically generated terrains to determine how each metric discerns the relative roughness of the terrains from a vehicle durability perspective. Multiple terrains for each roughness level were evaluated to determine the variability for each terrain rating metric. One method currently under consideration is running a relatively simple, yet vehicle class specific, model over a given terrain and using predicted vehicle response(s) to classify or characterize the terrain.
Technical Paper

Test Methods and Computer Modeling for the Analysis of Ground Vehicle Handling

1986-08-01
861115
This paper presents test methods and modeling procedures for identifying the directional handling characteristics of vehicles over the full maneuvering range from straight running to limit cornering and/or braking. The test procedures are designed to validate steady-state and dynamic response performance. The model parameters are derived from simple static tests of vehicle properties and tire parameters identified from tire machine tests. Current steady-state field test procedures validate the model response under cornering only conditions. Model analysis then extrapolates vehicle response under combined cornering and braking conditions. Some discussion is devoted to potential braking in a turn transient testing for more complete model validation.
Technical Paper

Motion Cueing Evaluation of Off-Road Heavy Vehicle Handling

2016-09-27
2016-01-8041
Motion cueing algorithms can improve the perceived realism of a driving simulator, however, data on the effects on driver performance and simulator sickness remain scarce. Two novel motion cueing algorithms varying in concept and complexity were developed for a limited maneuvering workspace, hexapod/Stuart type motion platform. The RideCue algorithm uses a simple swing motion concept while OverTilt Track algorithm uses optimal pre-positioning to account for maneuver characteristics for coordinating tilt adjustments. An experiment was conducted on the US Army Tank Automotive Research, Development and Engineering Center (TARDEC) Ride Motion Simulator (RMS) platform comparing the two novel motion cueing algorithms to a pre-existing algorithm and a no-motion condition.
Technical Paper

The Use of Simulation in Truck Safety Research, Driver Training and Proficiency Testing

1990-10-01
902271
Real time man-in-the-loop simulation can be used in a variety of research, testing and training roles where safety, efficiency and/or economy are important. Simulation can allow complete control and uniformity over driving conditions and permit analysis of a range of vehicle and driver behavior variables. Simulation complexity and fidelity requirements will vary depending on application requirements. This paper reviews past and current driving simulation development efforts and applications. Simulation requirements are assessed relative to various applications, including vehicle handling, driver behavior, training, licensing and fitness for duty testing.
Technical Paper

Further Analysis of Potential Road/Terrain Characterization Rating Metrics

2005-11-01
2005-01-3562
The U.S. Army uses the root mean square and power spectral density of elevation to characterize road/terrain (off-road) roughness for durability. This paper describes research aimed toward improving these metrics. The focus is on taking previously developed metrics and applying them to mathematically generated terrains to determine how each metric discerns the relative roughness of the terrains from a vehicle durability perspective. Multiple terrains for each roughness level were evaluated to determine the variability for each terrain rating metric. One method currently under consideration is running a relatively simple, yet vehicle class specific, model over a given terrain and using predicted vehicle response(s) to classify or characterize the terrain.
Technical Paper

Real World Experience In Fitness-For-Duty Testing

1992-10-01
921908
This paper considers experience gained from conducting fitness-for-duty testing in the work place, and reviews results obtained with a specific psychomotor task. Performance testing can provide a means for assessing worker fitness-for-duty prior to their admittance to safety critical job functions, but the testing must be reliable and efficient. This paper will discuss the balance between efficacy and efficiency and provide example data from a test that is currently employed in the work place.
Technical Paper

Low Cost Driving Simulation for Research, Training and Screening Applications

1995-02-01
950171
Interactive driving simulation is attractive for a variety of applications, including screening, training and licensing, due to considerations of safety, control and repeatability. However, widespread dissemination of these applications will require modest cost simulator systems. Low cost simulation is possible given the application of PC level technology, which is capable of providing reasonable fidelity in visual, auditory and control feel cuing. This paper describes a PC based simulation with high fidelity vehicle dynamics, which provides an easily programmable visual data base and performance measurement system, and good fidelity auditory and steering torque feel cuing. This simulation has been used in a variety of applications including screening truck drivers for the effects of fatigue, research on real time monitoring for driver drowsiness and measurement of the interference effect of in-vehicle IVHS tasks on driving performance.
Technical Paper

A Low Cost PC Based Driving Simulator for Prototyping and Hardware-In-The-Loop Applications

1998-02-23
980222
This paper describes a low cost, PC based driving simulation that includes a complete vehicle dynamics model (VDM), photo realistic visual display, torque feedback for steering feel and realistic sound generation. The VDM runs in real-time on Intel based PCs. The model, referred to as VDANL (Vehicle Dynamics Analysis, Non-Linear) has been developed and validated for a range of vehicles over the last decade and has been previously used for computer simulation analysis. The model's lateral and longitudinal dynamics have 17 degrees of freedom for a single unit vehicle and 33 degrees of freedom for an articulated vehicle. The model also includes a complete drive train including engine, transmission and front and rear drive differentials, and complete, power assisted braking and steering systems. A comprehensive tire model (STIREMOD) generates lateral and longitudinal forces and aligning torque based on normal load, camber angle and horizontal (lateral and longitudinal) slip.
Technical Paper

A Human Factors Study of Driver Reaction to In-Vehicle Navigation Systems

1991-08-01
911680
This paper describes a laboratory simulation study of driver reaction to in-vehicle navigation systems. The study included a pre-test questionnaire on demographic background and commuting behavior, simulation testing of navigation decision making, and a post-test questionnaire on navigation behavior and reactions to in-vehicle navigation systems and the laboratory simulation. A total of 277 subjects, both male and female, were employed over a wide range of ages. Test subjects were assigned to one of four navigation system groups or a no-system control group for the purpose of comparing system performance. The simulation task required subjects to experience a commuting ‘drive’ on a Southern California freeway route and minimize trip time by diverting off the main route to avoid congestion. Subjects were given orientation and training on the simulation and their navigation system condition, and were motivated by rewards and penalties to minimize trip time.
Technical Paper

Tire Modeling Requirements for Vehicle Dynamics Simulation

1995-02-01
950312
The physical forces applied to vehicle inertial dynamics derive primarily from the tires. These forces have a profound effect on handling. Tire force modeling therefore provides a critical foundation for overall vehicle dynamics simulation. This paper will describe the role tire characteristics play in handling, and will discuss modeling requirements for appropriately simulating these effects. Tire input and output variables will be considered in terms of their relationship to vehicle handling. General computational requirements will be discussed. An example tire model will be described that allows for efficient computational procedures and provides responses over the full range of vehicle maneuvering conditions.
Technical Paper

Meeting Important Cuing Requirements with Modest, Real-Time, Interactive Driving Simulations

1994-03-01
940228
Interactive simulation requires providing appropriate sensory cuing and stimulus/response dynamics to the driver. Sensory feedback can include visual, auditory, motion, and proprioceptive cues. Stimulus/response dynamics involve reactions of the feedback cuing to driver control inputs including steering, throttle and brakes. The stimulus/response dynamics include both simulated vehicle dynamics, and the response dynamics of the simulation hardware including computer processing delays. Typically, simulation realism will increase with sensory fidelity and stimulus/response dynamics that are equivalent to real-world conditions (i.e. without excessive time delay or phase lag). This paper discusses requirements for sensory cuing and stimulus/response dynamics in real-time, interactive driving simulation, and describes a modest fixed-base (i.e. no motion) device designed with these considerations in mind.
Technical Paper

A Computer Simulation Analysis of Safety Critical Maneuvers for Assessing Ground Vehicle Dynamic Stability

1993-03-01
930760
Ground vehicle dynamic stability, including spinout and rollover, is highly dependent on maneuvering conditions and the nonlinear force response characteristics of tires. Depending on vehicle configuration, unstable behavior requires high, sustained lateral acceleration, and some maneuver induced excitation of the roll and yaw mode dynamics. Dynamic instability in some vehicles can be induced by a steering reversal maneuver that involves sustained limit performance lateral acceleration. Using a validated vehicle dynamics simulation, analysis is presented to illustrate what constitutes a critical stability sensitive maneuver. Two example test cases are used to show that a critical stability sensitive maneuver must be more severe than a single lane change. Even reaching tire saturation limits during an aggressive single lane change does not give the sustained lateral acceleration required to provoke instability conditions.
Technical Paper

A Human Factors Simulation Investigation of Driver Route Diversion and Alternate Route Selection Using In-Vehicle Navigation Systems

1991-10-01
912731
This paper describes a human factors simulation study of the decision making behavior of drivers attempting to avoid nonrecurring congestion by diverting to alternate routes with the aid of in-vehicle navigation systems. This study is the first phase of a two part project in which the second phase will apply the driver behavior data to a simulation model analysis of traffic flow. The object of the driver behavior experiment was to compare the effect of various experimental navigation systems on driver route diversion and alternate route selection. The experimental navigation system configurations included three map based systems with varying amounts of situation information and a non map based route guidance system. The overall study results indicated that navigation system characteristics can have a significant effect on driver diversion behavior, with better systems allowing more anticipation of traffic congestion.
Technical Paper

Tire Modeling for Off-Road Vehicle Simulation

2004-05-04
2004-01-2058
A tire/terrain interaction model is presented to support the dynamic simulation of off-road ground vehicle. The model adopts a semi-empirical approach that is based on curve fits of soil data combined with soil mechanics theories to capture soil compaction, soil shear deformation, and soil passive failure that associate with off-road driving. The resulting model allows the computation of the tire forces caused by terrain deformation in longitudinal and lateral direction. This model has been compared with experimental data and shown reasonable prediction of the tire/terrain interaction.
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