Showing papers on "Vehicle dynamics published in 1975"

Automobile controllability. driver/vehicle response for steering control. volume i. summary report

Abstract: This report describes an applied research program aimed at identifying those characteristics of the driver/vehicle system which influence the driver's ability to maintain control over the vehicle path in a variety of steering tasks. Program objective include comprehensive measurements of driver and vehicle responses and the quantification of optimum driver/vehicle system characteristics as functions of simplified vehicle dynamic properties and task durations. To accomplish this, a three-pronged approach of analysis, fixed-base simulation, and road test was used for compensatory steering tasks, while road test results were emphasized in discrete and transient maneuvers. The regulation task subjected the car to a random gust disturbance which had to be countered by driver control action. Driver describing functions were estimated (in the analytical treatment) and measured (in the fixed-base simulation and road test environments). A specially-designed variable stability vehicle was used to permit insertion of the simulated gust disturbances and for the driver/vehicle system measurement. Measures of system bandwidth, stability, and time delays were deduced, compared, and rationalized. The experimentally determined driver dynamics correlated well with the driver/vehicle system theory developed in the analytical phase. The full-scale tests were conducted in two phases: an initial phase covering 12 configurations of vehicle dynamics and sterring gain with an expert test driver; and a validation phase which covered six sets of vehicle dynamics and four unmodified production car configurations with 17 subjects. The steering tasks tested included regulation and a complete cross-section of steering maneuvers, such as emergency and double lane changes, which evoked a dual-mode behavior from the driver. Driver evasive action was also studied with the aid of an unexpected obstacle. Key performance measures (including system bandwidth and phase margin for regulation tasks and lane exceedances and driver steering reversals for discrete maneuvers) were shown to be descriptive, selective, and readily applicable to discriminate among the vehicle configurations. These were also correlated with driver ratings of attention and workload in the regulation task and of vehicle responsive in discrete tasks. A six-hour driving duration did not change relative orders among vehicles of driver ratings and response or system performance. Durations as short as one-quarter hour did produce order-of-presentation effects. The key vehicle parameters influencing the driver's response were the vehicle's overall yaw velocity to steering wheel gain and the yaw velocity numerator time constant. Directional undamped natural frequency and damping ratio were also influential but secondary. A tentative optimum range of vehicle dynamics for the directional properties was established, based on the total driver population of 18 and the tests with both laboratory and production vehicles. /Author/

Active Control of the Dynamics of a ,Dual-Spin Spacecraft

Abstract: Active damping of both vehicle nutation and payload flexibility for a dual-spin spacecraft is achieved using the interaction of the vehicle dynamics with the on-board despun payload control system. A closed-form solution to the interaction problem is presented, deriving an analytical expression which is used to establish both the fundamental stability and the strength of the coupling. Analysis of the characteristics of the interaction leads to mass property and control system design criteria which can be used to effectively optimize the interaction and provide substantial active control. Design examples are presented which illustrate the design techniques involved in the optimization. Simulation results are presented which verify the analytical conclusions.

Tire friction models and their effect on simulated vehicle dynamics

Abstract: In this paper, various tire friction models are examined and their similarities and differences are pointed out Emphasis is placed on the tire side force and a numerical comparison is illustrated based on existing experimental data Different uses of the friction ellipse are discussed The sensitivity of vehicle response to different tire models is studied using a nonlinear, simplified vehicle model Three basic maneuvers are simulated: cornering, straight ahead braking and braking in a turn The simulation results are compared with one particular set of simulations in which the tire forces are specified by tables of experimental tire data Accuracies and computing times for each tire model are studied

Comparison of human driver dynamics in simulators with complex and simple visual displays and in an automobile on the road

Abstract: As part of a comprehensive program exploring driver/vehicle system response in lateral steering tasks, driver/vehicle system describing functions and other dynamic data have been gathered in several milieu These include a simple fixed base simulator with an elementary roadway delineation only display; a fixed base statically operating automobile with a terrain model based, wide angle projection system display; and a full scale moving base automobile operating on the road Dynamic data with the two fixed base simulators compared favorably, implying that the impoverished visual scene, lack of engine noise, and simplified steering wheel feel characteristics in the simple simulator did not induce significant driver dynamic behavior variations The fixed base vs moving base comparisons showed substantially greater crossover frequencies and phase margins on the road course

Application of Optimal Estimation Techniques to Acoustic Transponder Navigation Systems

Abstract: In an Acoustic Transponder navigation system the vehicle position is determined in relation to the transponders by the use of ranges to the transponders and the distances between transponders. The vehicle position determined is usually inaccurate due to the timing error and inaccuracy of the sound speed assumed in obtaining the range data. This paper develops computational algorithms for the optimal estimation of vehicle position with given erroneous range data. The development begins with the formulation of a least-squares error criterion. Computational algorithms are then developed to best estimate the vehicle position by minimizing the least-squares error criterion. For the moving vehicles, optimal filtering algorithms are developed which sequentially update the vehicle position based on the knowledge of the vehicle dynamics and the range measurements. Computational results for one illustrative example in the application of optimal filtering algorithms are presented.

Effects of automobile steering characteristics on driver vehicle system dynamics in regulation tasks

Abstract: A regulation task which subjected the automobile to a random gust disturbance which is countered by driver control action is used to study the effects of various automobile steering characteristics on the driver/vehicle system. The experiments used a variable stability automobile specially configured to permit insertion of the simulated gust disturbance and the measurement of the driver/vehicle system characteristics. Driver/vehicle system dynamics were measured and interpreted as an effective open loop system describing function. Objective measures of system bandwidth, stability, and time delays were deduced and compared. These objective measures were supplemented by driver ratings. A tentative optimum range of vehicle dynamics for the directional regulation task was established.

An interactive driving simulation for driver control and decision-making research

Abstract: Display techniques and equations of motion for a relatively simple fixed base car simulation are described. The vehicle dynamics include simplified lateral (steering) and longitudinal (speed) degrees of freedom. Several simulator tasks are described which require a combination of operator control and decision making, including response to wind gust inputs, curved roads, traffic signal lights, and obstacles. Logic circuits are used to detect speeding, running red lights, and crashes. A variety of visual and auditory cues are used to give the driver appropriate performance feedback. The simulated equations of motion are reviewed and the technique for generating the line drawing CRT roadway display is discussed. On-line measurement capabilities and experimenter control features are presented, along with previous and current research results demonstrating simulation capabilities and applications.

Application of Adaptive Filtering Methods to Maneuvering Trajectory Estimation

Abstract: : The purpose of this report is to examine several modifications of extended Kalman filters which can be used to estimate the position, velocity, and other key parameters associated with maneuvering re-entry vehicles. These filters will be described and discussed in terms of the fundamental problems of modeling accuracy, filter sophistication, and the real-time computational requirements. A nine-state, extended Kalman filter based upon the maneuvering vehicle dynamics is compared with several other candidate filters. These candidate filters include a simple filter based upon polynomial dynamics decoupled with respect to the coordinates and a more complex, fully coupled, seven-state, extended Kalman filter based upon a ballistic re-entry vehicle dynamics. Techniques which adaptively increase the process noise to compensate for modeling errors during the maneuvers are examined.

The influence of tire properties on passenger vehicle handling. volume ii - technical report

Abstract: The overall objectives of this research program to identify the properties of tires that affect vehicle dynamic response and to evaluate the degree to which the various tire parameters enter into this response. The main elements of this research study involved: (1) a laboratory tire test program to measure the performance parameters of interest (braking and lateral force coefficients, aligning and overturning moments, etc.) on selected tires with specified construction properties, (2) a vehicle test program in which the effects of tires with different properties and parameters were measured on four cars using nine wet and dry test maneuvers, and (3) a fundamental vehicle simulation study designed to determine the effect of individual tire parameters on various vehicle performance metrics.

Computer mission simulation for parametric design of undersea vehicles

Abstract: The next generation of deep submersible ocean vehicles will require that more effective design approaches be utilized to achieve the full performance potential of this type of vehicle. Possible design shortcomings can be anticipated and corrected for through the exercise of a properly constructed computer program that models the salient features of the vehicle, its subsystems, the environment, and any specific operational mission requirements. A model has been developed by Sperry to assist in the design of deep submersible vehicles and their major subsystems, including sensors, propulsion unit, energy package, and vehicle structures. A variety of vehicle types - manned or unmanned, tethered or independent, small or large - can be modeled, as well as a variety of target and ocean bottom terrain features and mission profiles. The model consists of a 3700-statement Fortran V program having 34 subroutines. The program can provide an evaluation of the sensitivity of the significant vehicle performance measures to variations in design parameters. Computer generated graphs are presented to illustrate the utility of the model in several design problems including parameter determinations of propulsion system rating, weight, and size and navigation sensor accuracy requirements.

Experimental investigation of human steering behavior in a simulated road driving task. part 1

Abstract: The capabilities and limitations of the human controller substantially affect the lateral dynamics of the driver-vehicle system. The steering behavior of the driver is investigated in this paper from a control engineering viewpoint. The experimental data of six subjects who participated in a driving simulator test series are analyzed. The simulated vehicle dynamics approximated an automobile. The driving task was to guide the vehicle as closely as possible along the center line of the road at a verbally requested speed. The driver perceives the critical portion of information for the steering task from his visual field. In the driving simulator the driver's front window scene was simulated with electronically generated quasi-natural road features. The simulated road image consisted of the dotted centerline, the road borders with side posts and a horizontal scene. The information which the driver receives from the complex visual scene may be distinguished into two types which are relevant to two aspects of the driving process: 1. Information on the instantaneous and future course of the forcing function (i.e. road center line) which is contained in the front part of the road. The relevant quantity used in the control engineering concept is the desired path curvature derived from the deterministic run of the road centerline. 2. Information on derivations between the forcing function and the vehicle's actual path. The relevant quantities used are path curvature error, heading angle and lateral deviation from centerline. The derivation of these quantities implied in the visual perception process is discussed in detail on the basis of flowing velocity vector fields and stationary perspective road patterns appearing under certain conditions in these velocity vector fields.

Use of dynamic modeling and analysis to cure ride quality problems

Abstract: A very straightforward procedure for solving ride quality problems is discussed. This procedure utilizes advanced dynamic testing and system modeling techniques in logical three-step sequence. The first step is to define the nature of the problem through measurement of data during operation of the vehicle. The second step involves the measurement of vehicle dynamic characteristics such as resonant frequencies and mode shapes through controlled lab tests. This information is compared with the operating data to identify structural features which contribute to the ride problem. The last step is to assemble a dynamic computer model of the vehicle. /GMRL/

Prediction of braking and directional responses of commercial vehicles

Abstract: This paper provides an overview of the truck and tractor-trailer braking and handling project which the Highway Safety Research Institute (HSRI) has been conducting for the Motor Vehicle Manufacturers Association. The purpose of this research is to establish a digital computer-based mathematical method for predicting the longitudinal and directional responses of trucks and tractor-trailers. In the context of this study, prediction involves the use of computer simulations to obtain numerical results that quantify the braking and steering responses of specific commercial vehicles (or projected vehicles). In addition to providing numerical results, the simulations can aid in developing an understanding of how changes in vehicle components and/or test conditions influence the response of a motor-truck system. A basic understanding of the influence of changes in vehicle parameters and test conditions on vehicle response is fundamental to gaining confidence that the simulations are predicting valid and useful results.

Analysis of Controller/System Dynamics for a Remotely Piloted Vehicle Strike Mission.

Abstract: : The development of an analytical model for the remote human controller/vehicle dynamics during the critical phases of a remotely piloted vehicle (RPV) strike mission is a prerequisite for the quantitative understanding and evaluation of the overall mission effectiveness. The purpose of this report is to develop such a modeling approach and demonstrate its usefulness as an effective tool in the design of a baseline RPV strike mission. Analysis of the controller/vehicle dynamics is used to isolate the principal causes of degradations in the overall weapon system effectiveness. Insight gained from these analyses should prove extremely valuable in selecting a baseline configuration including specific recommentations for the choice of displays, the vehicle augmentation, and the overall RPV strike mission flight profile.

Digital simulation analysis for evaluating earth berm design and vehicle dynamics

Abstract: This study deals with the evaluation and modification of the original North Carolina earth berm based on the generalized vehicle dynamic analysis and computer-aided design using digital simulation techniques. Simulation runs of vehicle-berm interaction were made on both main and transition sections of the original N.C. and the modified berm. The modified berm design RS with energy-dissipating steps would safely redirect a vehicle impacting the berm at 60 mph with an approaching angle up to 20 degrees while the maximum safe approaching angle for the original N.C. earth berm was 11 degrees. Three types of median-curb configurations were investigated to determine the vehicle behavior. The maximum vehicle encroachment angles were evaluated for two maximum steer angles at 45 and 60 mph speeds. The effects of soft soil on vehicle dynamic behavior were studied extensively. The original and modified earth berms with soft earth were capable of redirecting a vehicle approaching at 13 and 24 degree angle respectively with 60 mph speed. Analytical movie techniques were applied to demonstrate the vehicle dynamics and vehicle-berm interactions. Simulation runs on the modified berm without steps showed that the maximum safe approaching angle was 14 degrees on the soft-surfaced and 11 degrees on the hard-surfaced berm. In order to facilitate the interpretation of massive output data from a simulated event, computer graphic displays were used to show the detailed perspective and top views of the vehicle dynamics and designed roadside geometric configuration as seen from a selected viewing position and time intervals. /Author/

Handling dynamics of an intercity bus

Abstract: Recent applied research studies in vehicle handling have emphasized large commercial vehicles. Among the results to date are a set of nonlinear equations to model the lateral and longitudinal handling dynamics of an intercity bus. These equations were implemented as a digital simulation for analysis of vehicle response and performance various steering and braking inputs. Concurrent full-scale tests with an instrumented vehicle served to verify the simulation results for both perturbation and large amplitude motions. This paper describes the bus, the analytical model, and the simulation. Analytical and full-scale results are shown for various maneuvers to demonstrate the fidelity of the simulation, and to illustrate the nature of the limits of performance (spinout, plowout, and rollover).

Tracked levitated research vehicle. final technical report: aeropropelled

Abstract: The results of the 1973 aeropropelled tests of the Tracked Levitated Research Vehicle (TLRV) at the Transportation Test Center (TTC) are presented for the three basic suspension modes (Primary, Body/Chassis and Independent Cushion) at speeds up to 90 mph attained in the 3 mile guideway, which includes straight, transition to curve and superelevated segments. General vehicle and suspension characteristics are reviewed, and the system performance with respect to the air supply system, acoustics, vehicle speed and braking, cushion lift and ride comfort is discussed. Vehicle dynamic responses to perturbations installed in the guideway are compared with the results computed by the TLRV Dynamics Simulation Program.

Coupled Vehicle/Track Dynamics

Abstract: Dynamic coupling occurs between a railway vehicle and the track due to the reaction forces acting between the wheels and the track, and the elasticity of the track and the foundation. It has become apparent that track elasticity can influence the dynamic behaviour of the railway vehicle, yet in most of the research work in the area of railway vehicle dynamics reported so far, the track is regarded simply as a rigid structure, providing the reactions to the loads of passing vehicles. In this paper the models used for the analyses of the vehicle dynamics (on rigid track) and for the coupled vehicle/track dynamics are described. The equations of motion are derived, and the results obtained for the coupled vehicle/track model are presented and compared with those obtained for the case of an infinitely rigid track. Particular empahsis is on the lateral stability and the response to vertical track irregularities.

A Comprehensive Analysis of Methods for Vehicle Dynamics Simulation

Abstract: (1975). A Comprehensive Analysis of Methods for Vehicle Dynamics Simulation∗ ∗. Vehicle System Dynamics: Vol. 4, No. 2-3, pp. 137-141.