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Technical Paper

A Biodynamic Model for the Assessment of Human Operator Performance under Vibration Environment

2005-06-14
2005-01-2742
A combined biodynamic and vehicle model is used to assess the vibration and performance of a human operator performing driving and other tasks. The other tasks include reaching, pointing and tracking by the driver and/or passenger. This analysis requires the coordinated use of separate and mature software programs for anthropometrics, vehicle dynamics, biodynamics, and systems analysis. The total package is called AVB-DYN, an acronym for Anthropometrics, Vehicle and Bio-DYNamics. The biodynamic component of AVB-DYN is described, and then compared with an experiment that studied human operator in-vehicle reaching performance using the U.S. Army TACOM Ride Motion Simulator.
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 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 Simulator Solution for the Parachute Canopy Control and Guidance Training Problem

1992-04-01
920984
Maneuverable round and ramair parachutes are flown by professional forestry firefighters, search and rescue personnel, and military combat teams when deployment by fixed or rotary aircraft is inappropriate. Parachute flight training requires the development of perceptual skills in canopy control, guidance, and energy management. These parachutists must learn to accurately sense motion visual cues, and predict and manage their trajectory. Parachute guidance and control can only be acquired through repeated practice. Canopy control training has been traditionally limited to a classroom lecture topic. There was no opportunity for the immediate student/instructor dialogue available during the extensive dual flight training used for conventional aircraft, where instruction can occur during the numerous practice landings available via rapid touch-and-go techniques.
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

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

Combined Terrain, Vehicle, and Digital Human Models Used for Human Operator Performance Analysis

2004-06-15
2004-01-2152
A combined biodynamic and vehicle model is used to assess the vibration and performance of a human operator performing driving and other tasks. The other tasks include reaching, pointing and tracking by the driver and/or passenger. This analysis requires the coordinated use of separate and mature software programs for anthropometrics, vehicle dynamics, biodynamics, and systems analysis. The total package is called AVB-DYN, an acronym for Anthropometrics, Vehicle, and Bio-DYNamics. The objectives and architecture are discussed, and then a preliminary version of this package is demonstrated in an example where a HMMWV (High Mobility Multipurpose Wheeled Vehicle) operator is performing a driving task.
Journal Article

Development of a Vehicle Model/Simulation Evaluation Tool

2008-04-14
2008-01-0778
As part of the evaluation of vehicle simulation models, a vehicle dynamics engineer typically desires to compare simulation results to test data from actual vehicles and/or results from known, or higher fidelity simulations. Depending on the type of model, several types of tests and/or maneuvers may need to be compared. For military vehicles, there is the additional requirement to run specific types of maneuvers for vehicle model evaluations to ensure that the vehicle complies with procurement requirements. A thorough evaluation will run two different categories of tests/maneuvers. The first category consists of laboratory type tests that include weight distribution, kinematics and compliance, steering ratio, and other static measures. The second category consists of dynamic maneuvers that include handling, drive train, braking, ride, and obstacle types. In this paper, a process for proper evaluation of vehicle simulation models is presented.
Technical Paper

Driver Car Following Behavior Under Test Track and Open Road Driving Condition

1997-02-24
970170
This paper describes the results of an experiment concerning driver behavior in car following tasks. The motivation for this experiment was a desire to understand typical driver car following behavior as a guide for setting the automatic control characteristics of an ACC (Adaptive Cruise Control) system. Testing was conducted under both test track and open road driving conditions. The results indicate that car following is carried out under much lower bandwidth conditions than typical steering processes. Dynamic analysis shows driver time delay in response to lead vehicle velocity change on the order of several seconds. Typical longitudinal acceleration distributions show standard deviations of less than 0.05 g (acceleration due to gravity).
Technical Paper

Driver/Vehicle Modeling and Simulation

2002-05-07
2002-01-1568
This paper describes the driver/vehicle modeling aspects of a computer simulation that can respond to highway engineering descriptions of roadways. The driver model interacts with a complete vehicle dynamics model that has been described previously. The roadway path is described in terms of horizontal and vertical curvature and cross slopes of lanes, shoulders, side slopes and ditches. Terrain queries are made by the vehicle dynamics to locate tires on the roadway cross-section, and to define vehicle path and road curvature at some distance down the road. The driver model controls steering to maintain lateral lane position. Speed is maintained at a speed limit on tangents, and decreased as needed to maintain safe lateral acceleration. Because the bandwidth of longitudinal (speed) control is much lower than lateral/directional (steering) control, the driver model looks further ahead for speed control than for steering.
Technical Paper

Effects of Crosswinds on Vehicle Response – Full-Scale Tests and Analytical Predictions

1980-06-01
800848
Full-scale vehicle response tests were conducted on five vehicles using a crosswind disturbance test facility capable of providing a 35 mph wind over a nominal 120 ft test length. The vehicles were a Honda Accord, Chevrolet station wagon, Ford Econoline van, VW Microbus, and Ford pickup/camper. Results showed that passenger cars, station wagons, and most vans have virtually no crosswind sensitivity problems, whereas the VW Microbus, the pickup/camper (in winds higher than 35 mph), and cars pulling trailers do have potential problems. Key vehicle parameters dictating this yaw response sensitivity are the distance between the aerodynamic and tire force centers, tire restoring moment (including understeer gradient), and the basic aerodynamic side forces. A simple analytical relationship in these terms was developed to predict steady-state yaw rate in steady winds.
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

High-Angle-of-Attack Flying Qualities - An Overview of Current Design Considerations

1979-02-01
791085
An overview is given on design considerations for high-angle-of-attack flying qualities by examining the perspectives of three groups. These groups include the airframe manufacturers, the research community, and the aircraft users. The research community is exploring a diversity of high-angle-of-attack-related topics. Airplane manufacturers are restricted by cost and time constraints in their ability to use the design tools either now available or being developed. The user-pilots dwell upon factors which the manufacturers and researchers alike find difficult to address, such as provision of suitable sensory cues or the pilots' uneasiness with flight control computers. Taken together, the three points of perspective suggest ways in which the design practices and standards for high angle of attack flying qualities might be enhanced.
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

Measurement and Interpretation of Driver Steering Behavior and Performance

1973-02-01
730098
Models have been developed to describe the dynamic response and performance of drivers, vehicles, and driver-vehicle systems; and recent experiments have provided some quantification and refinement. This paper summarizes the theory and the data, and attempts to provide part of the transition between properties of the human and the assessment of safety performance in driving. The model and data shown emphasize steering or directional control situations. Simulation experiments with random crosswind gust disturbances were used to measure driver-vehicle describing functions for a number of driver subjects and experimental replications. The results are consistent with previous data and show good repeatability within subjects on successive runs. Interpretation of the data in terms of the driver-vehicle model indicates that the driver's outputs can be explained in simplest terms as functions of lateral position and heading.
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

Physiological and Response Measurements in Driving Tasks

1972-02-01
720139
Driver response and performance can be quantified by observing the stimulus-response environment. Yet the driver's inherent adaptability allows him to have seemingly adequate performance in potentially hazardous driving situations even though he may be operating near the acceptable safety limits. Physiological measures of the driver's internal state can provide further quantification of his performance level and can give a measure of his workload or safety performance margin. Measures of driver physiological and control responses have been made under gust disturbance conditions with the subject's car operating at various speeds. The experimental techniques and data are described, and correlations between the situational parameters and driver stress and control response are shown.
Technical Paper

Relationships Between Optimal and Conventional “Good” Systems - A Simple Case Study

1970-02-01
700339
Conventional system synthesis involves indirect repetitive analysis, while optimal synthesis techniques yield direct solutions, given prescribed criteria. This paper presents some of the relationships between a conventionally derived optimum system and the corresponding optimal system, using a second order example. Methods for specifying optimal cost functions which result in good systems are explored.
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

The Application of Handling Requirements to an RSV-Type Vehicle

1977-02-01
770178
Results of a study to specify, develop, and test the handling characteristics of a prototype research safety vehicle are reported. Handling requirements which were used to evaluate the transient and steady state response and performance are described. These requirements and criteria were based on a review of contemporary results in the area of handling and controllability, and they combine vehicle performance envelopes and driver-centered considerations. The resulting criteria are used as handling objectives in the testing and evaluation of a prototype small sedan.
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