Showing papers on "Vehicle dynamics published in 1994"

Race car vehicle dynamics

Abstract: Written for the engineer as well as the race car enthusiast, Race Car Vehicle Dynamics includes much information that is not available in any other vehicle dynamics text. Truly comprehensive in its coverage of the fundamental concepts of vehicle dynamics and their application in a racing environment, this book has become the definitive reference on this topic. Although the primary focus is on the race car, the engineering fundamentals detailed are also applicable to passenger car design and engineering. Authors Bill and Doug Milliken have developed many of the original vehicle dynamics theories and principles covered in this book, including the Moment Method, "g-g" Diagram, pair analysis, lap time simulation, and tyre data normalization. The book also includes contributions from other experts in the field. Chapters cover: The Problem Imposed by Racing Tire Behavior Aerodynamic Fundamentals Vehicle Axis Systems and more.

Vehicle Handling Dynamics

Abstract: A text which is aimed at tyre and vehicle manufacturers. Topics discussed in the book are the pneumatic tyre, axis systems and equations of motion, the control and stability of basic rigid vehicles, suspension characteristics and control and stability of articulated vehicles.

Analysis on vehicle stability in critical cornering using phase-plane method

Abstract: This paper presents discussions on the vehicle cornering stability in critical cornering, using the "Phase-Plane Method" which takes into account the vehicle side slip angle and its angular velocity as the state variables. In addition, the potential for the enhancement of the vehicle stability in critical cornering with the application for a direct yaw moment control system is also presented.

Development of a rear-end collision avoidance system with automatic brake control

Abstract: We have studied active safety technologies from the standpoint of “collision avoidance”. This paper describes a rear-end collision avoidance system with automatic brake control, which avoids a collision to the vehicle in front caused by inadvertent human errors using automatic emergency braking. The system is comprised of four key technological elements, headway distance measurement using scanning laser radar, path estimation algorithm with vehicle dynamics, collision prediction to the vehicle in front by a safe/danger decision algorithm, and longitudinal automatic brake control.

Learning control for underwater robotic vehicles

Abstract: Underwater robotic vehicles have become an important tool for various underwater tasks because they have greater speed, endurance, and depth capability, as well as a higher factor of safety, than human divers. However, most vehicle control system designs have been based on a simplified vehicle model, which has often resulted in poor performance because the nonlinear and time-varying vehicle dynamics have parameter uncertainty. It was also observed by experiment that the thruster system had nonlinear behavior and its effect on vehicle motion was significant. It is desirable to have an advanced control system with the capability of learning and adapting to changes in the vehicle dynamics and parameters. This article describes a learning control system using neural networks for underwater robotic vehicles. Its effectiveness is investigated by simulation. >

Traffic models for wireless communication networks

Abstract: The authors introduce a deterministic fluid model and two stochastic traffic models for wireless networks. The setting is a highway with multiple entrances and exits. Vehicles are classified as calling or non-calling, depending on whether they have calls in progress. The deterministic model ignores the behavior of individual vehicles and treats them as a continuous fluid, whereas the stochastic traffic models consider the random behavior of each vehicle. However, all three model's use the same two coupled partial (or ordinary) differential equations to describe the system evolution. The call density and call handoff rate (or their expected values in the stochastic models) are readily computable by solving these equations. Numerical examples are presented to illustrate how the models can be used to investigate various aspects of time and space dynamics in wireless networks. These examples also show that the models can serve as useful tools for system engineering and planning. >

Vehicle movement dynamics control system

Abstract: A brake controller is connected downstream of a primary vehicle dynamics computer and has a channel for controlling the yaw velocity at a desired value, and a channel for limiting the sideslip angle. The computer prescribes the desired value and the limit value, and determines which channel is effective on the basis of the driving situation. The two channels generate a control signal which is routed via a control amplifier having a proportional component and a differential component. An actuating signal which is used to input braking pressure at the wheel brakes is formed from the resulting signal components, the instantaneous driving situation being assigned in both cases to one of a plurality of classes, and this assignment being co-used to determine the wheels at which braking pressure is input.

Stability control for a mobile manipulator using a potential method

Abstract: Many future applications of robotic systems will require that manipulators perform operations while being carried by moving vehicles. However, such a vehicle mounted mobile manipulator can be unstable or even tip over. Previous work on stability control hardly considered the dynamics and environmental disturbances. The stability of a mobile manipulator has a close relation with the vehicle motion, manipulator motion and posture, and end-effector force. To evaluate the stability for a mobile manipulator, the concepts about stability, such as the stability degree and the valid stable region based on the zero moment point (ZMP) criterion have already been proposed. In this paper, as a control scheme for maintaining or recovering stability, the method of ZMP path planning by a stability potential field is presented, in which the concepts of the goal state and prohibitive state of stability are outlined. A motion planning algorithm is then formulated, which controls the manipulator in order to maintain the stability of the whole system while the vehicle is moving along a given trajectory. >

Improved GPS Positioning for Motor Vehicles Through Map Matching

Abstract: Absolute positioning systems, especially the Globa l Positioning System (GPS), are playing an increasing role in the tracking of motor vehicles. Such systems, however were net designed to specifically track motor vehicles. Apart from the start and finish of journeys, motor vehicles are restricted to the mad network; a fact not reflected by the position measurements. Techniques exist for carrecting the measurements according to a map of the network but a mathematical framework for this correction process is lacking. The author has develope d such a framework resulting in a map-aided estimation process that takes into account th e measurement noise statistics to optimally translate the raw position measurements onto the road network. The theoratical performance of this estimator is derived and compared with that achieved using GPS measurements. The effect that Selective Availability (SA) has on the map-aided estimator is analysed and a technique for reducing the effect of SA i s demonstrated In addition to the accuracy improvements, th e map-aided positioning framework also provides a means for readily incorporationg other sources of positioning information. Driver bchaviour, mad type, and vehicle dynamics can be used to make further improvements in positioning accuracy and road identitication.’

Singularity-free tracking of unmanned underwater vehicles in 6 DOF

Abstract: Nonlinear tracking control of unmanned underwater vehicles (UUVs) in 6 degrees of freedom (DOF) is discussed. The 4-parameter unit quaternion is used in a singularity-free representation of attitude. Several control laws based on a generalized Lyapunov function for the attitude dynamics are derived, including feedback from the vector quaternion, the Euler rotation vector and the Rodrigues parameter vector. A new feedback gain matrix for translational motion is also proposed. Lyapunov analysis is used in the tracking error convergence analysis. Extensions to adaptive control are made. The control laws are tested in a simulation study. >

A Range Extender Hybrid Electric Vehicle dynamic model

Abstract: This paper describes a dynamic model possessing the key system components of a Range Extender Hybrid Electric Vehicle. The model is suitable for dynamic analysis, control law synthesis, and prototype simulation. The paper contains abbreviated descriptions of a small internal combustion engine, variable field alternator, and a dynamic lead-acid battery model that comprise the primary elements of a highly nonlinear vehicle. The system model is then used for studying the dynamic interaction effects and formulation of a dynamic control system. >

Increased accuracy of motor vehicle position estimation by utilising map data: vehicle dynamics, and other information sources

Abstract: Techniques exist that make use of map information to improve the position estimate of a motor vehicle but the techniques lack a mathematical framework. The authors addresses this problem by developing a map-aided position estimation system whereby the raw position measurements are optimally translated so that they lie on the roads. The accuracy of the map-aided estimates is derived for an arbitrary positioning system with Gaussian measurement noise demonstrating significant improvements over the raw measurements. Further performance improvements are achieved through the use of a 1D Kalman filter developed to utilise the fact that all of the map-aided position estimates lie along known curves. The mathematical framework utilised by the map-aided estimator readily allows other sources of position information such as road type and road rules to be quantified and optimally incorporated into the estimation process. >

FDR: Die Fahrdynamik-regelung von Bosch

Abstract: Vehicle handling at the physical limit of adhesion between the tires and the road is extremely difficult. In such situations the driver may be supported by controlling the longitudinal and lateral forces on the tires. The Vehicle Dynamics Control System of Bosch (VDC) does that by controlled braking of individual wheels which makes the vehicle motion approach the nominal motion intended by the driver. It uses signals to derive the driver's intent (steering wheel angle, brake pressure, engine torque) and signals to derive the actual motion of the vehicle (yaw rate, lateral acceleration). The support of the driver is not limited to coasting conditions

Dynamic modeling of wheeled mobile robots for high load applications

Abstract: This paper examines dynamic modeling of differentially and conventionally steered wheeled mobile robots (WMRs) for high load applications such as highway maintenance and construction. Dynamic models including an accurate tire representation are developed for both types of WMRs. In addition to these dynamic models, both kinematic and simplified dynamic models are also developed for purposes of comparison. The simplified dynamic model utilizes a greatly simplified tire representation. Through the use of simulation, the limits of validity of each of the models is determined thus allowing for the selection of the model most appropriate for a given application. Additionally, the accuracy of the dead reckoning vehicle tracking process is investigated. >

Integrated Controls of Lateral Vehicle Dynamics

Abstract: SUMMARY A study is presented dealing with the synergism coming from the integration of such controlled systems which are designed for improving the dynamic behaviour of road vehicles. A modified 1/4 car model is derived which allows suspension, torque and steering control to be applied to a low order vehicle model. A number of investigations, based either on complex vehicle models or on ground tests, show that important synergistic effects can be obtained from the integration of suspension, torque and steering controls. The straight running on irregular roads may take advantage from the co-operation of active suspension and four-wheel-steering systems. The braking under µ-split conditions can be improved with a proper control of ABS and rear wheel steering. The driveability of a car entering a curve with changing surface conditions could be substantially enhanced thanks to the combined exploitation of ABS and additional four wheel steering.

Effects of model complexity on the performance of automated vehicle steering controllers : controller development and evaluation

Abstract: SUMMARY Due to increased traffic congestion and travel times, research in Advanced Vehicle Control Systems (AVCS) has focused on automated lateral and headway control. Automated vehicles are seen as a way to increase freeway capacity and vehicle speeds while reducing accidents due to human error. Recent research in automated lateral control has focused on vehicle control during low-g maneuvers. To increase safety, automated lateral controllers will need to recognize and react to emergency situations. This paper investigates the effects of vehicle and tire model order on the response of automated vehicles to an emergency step lane change using a controller based on linear vehicle and tire models. From these studies it is concluded that control strategies based solely on linear vehicle and tire models are inadequate for emergency vehicle maneuvers. A strategy is then proposed to automatically control vehicles through emergency maneuvers. Here the response of a nonlinear vehicle model is used with a linear s...

The application of multi-body computer codes to road vehicle dynamics modelling problems

Abstract: Issues involved in the automation of the mathematical modelling of multi-body systems with special reference to road vehicle dynamics problems are discussed and reviewed. Some background and historical informations are provided. Those aspects of road vehicle dynamics problems that are of greatest concern from the point of multi-body modelling and rapid simulation are then considered. Various foundations for the equations of motion of multi-body systems and the treatment of constraints are described and some of the implications of methods chosen are exposed. Significant aspects of the modes of operation of the main relevant numerical and symbolic multi-body modelling codes are addressed. Conclusions are reached on the present state of multi-body modelling as relating to road vehicle dynamics and some thoughts on strategies for effectiveness in the future are offered. A substantial reference list, through which the topic can be pursued in greater detail, is included.

The 4D-approach to dynamic machine vision

Abstract: In this survey paper covering a decade of experience with recursive estimation methods for visual dynamic scene understanding, the common methodical background of the 4D approach exploiting spatio-temporal models of objects and processes observed is discussed. Applications range from 'balancing an inverted pendulum' over 'vehicle docking', 'road vehicle guidance, 'on-board autonomous aircraft landing approaches', 'landmark navigation for land vehicles' to 'grasping of an object freely floating in a satellite orbit with large delay times. Simultaneous recognition of rough 3D shape and motion parameters for moving road vehicles including occlusions has been achieved in well structured Autobahn scenes in real time (5 Hz). Recognition and tracking of moving humans in well structured environments has been advanced to a stage that real-time performance seems possible with the next generation of micro-processors just around the corner. After a brief review of the general method the aspects of exploiting object-oriented, model-based predictions for very efficient intelligent image feature extraction are discussed for some of the tasks considered. >

A new wheel/rail contact model for independent wheels

Abstract: The classical multibody approach in railway vehicle dynamics considers as rolling element a rigid wheelset, for which the geometrical problem associated with the wheel/rail contact and the formulation of the dynamic equations are well known at the present time. New designs of non-conventional bogies led us to develop a new model for independent wheels in which each wheel/rail contact must be treated separately due to the absence of an axle between left and right wheels. This model constitutes an additional feature of the multibody approach for this type of application. The classical multibody formalism is first briefly reviewed and the wheel/rail contact model is then developed in the case of a straight track. The way the model has been extended to curved track is also explained. Finally, numerical results related to classical and non-conventional bogies will be presented before concluding.

Adaptive throttle control for speed tracking

Abstract: SUMMARY Electronic throttle control is an important part of every advanced vehicle control system. In this paper we design an adaptive control scheme for electronic throttle that achieves good tracking of arbitrary constant speed commands in the presence of unknown disturbances. The design is based on a simplified linear vehicle model which is derived from a validated nonlinear one. The designed control scheme is simulated using the validated full order nonlinear vehicle model and tested on an actual vehicle. The simulation and vehicle test results are included in this paper to show the performance of the controller. Due to the learning capability of the adaptive control scheme, changes in the vehicle dynamics do not affect the performance of the controller in any significant manner.

Adaptive Throttle Control for Speed Tracking

Abstract: In this paper, the authors design an adaptive control scheme for electronic throttle that achieves good tracking of arbitrary constant speed commands in the presence of unknown disturbances. The design is based on a simplified linear vehicle model which is derived from a validated nonlinear one. The designed control scheme is simulated using the validated full order nonlinear vehicle model and tested on an actual vehicle. The simulation and vehicle test results are included in this paper to show the performance of the controller. Due to the learning capability of the adaptive control scheme, changes in the vehicle dynamics do not affect the performance of the controller in any significant manner.

An Intelligent Predictive Controller for Autonomous Vehicles

Abstract: : Performance of high speed rough terrain autonomous vehicles is compromised by inadequate real time response characteristics, poor models of vehicle dynamics and terrain following, and suboptimal allocation of limited computational resources. A new approach to high speed rough terrain autonomy is presented which solves these problems through a real-time managed response time strategy, a 3D state space dynamic's and terrain following model, and minimum throughput adaptive perception and planning strategies. The system which has been implemented is called RANGER. This report overviews the implementation of the RANGER code

Drag Measurements On A Platoon Of Vehicles

Abstract: This report details the design and implementation of wind tunnel tests to evaluate the aerodynamic performance of individual members of 2,3, and 4- vehicle platoons The purpose of the tests described here is to quantify the behavior of vehicle drag, or--or more properly--drag coefficient, as a function of vehicle spacing One-eight scale models of the 1991 GM Lumina van are used as the prototype vehicle The design and fabrication of force balances capable of measuring drag, side force and yawing moment is described Models are mounted above a porous ground plane surface designed to control the surface boundary layer thickness

Efficient dynamic simulation of an unmanned underwater vehicle with a manipulator

Abstract: In this paper, an efficient dynamic simulation algorithm is developed for an unmanned underwater vehicle (UUV) with a robotic manipulator It is based on an efficient O(N) algorithm where N is the number of links in the manipulator, and has been extended to include the full effects of a mobile base and various hydrodynamic forces that are exerted on these systems in underwater environments The effects modeled in this paper are added mass, viscous drag, fluid acceleration, and buoyancy forces With efficient implementation of the resulting algorithm, the amount of computation including hydrodynamics almost doubles over the original algorithm for a six degree-of-freedom land-based manipulator with a mobile base Nevertheless, the amount of computation still only grows linearly with the number of links in the manipulator >

Trajectory control of an air cushion vehicle

Abstract: In this report several propulsion systems of air cushion vehicles are introduced, and a state feedback control law for trajectory control of an air cushion vehicle is proposed. We consider that the vehicle should be controlled so that it may not drift sideways for good driving performance. We apply a Lyapunov-like function to develop a nonlinear state feedback control law. Effectiveness of the nonlinear state feedback control law for an ACV model is verified through numerical simulations. >

Vehicle dynamics and control for active safety

Abstract: This paper considers the present status of vehicle dynamics and control technology in ordinary and severe driving conditions. In ordinary driving the driver's feeling of pleasure, the optimisation of design parameters to realise this and confirmation of the driver's reaction are discussed. Open and closed loop system analyses are used. For severe driving conditions, accident avoidance mechanisms discussed include Super Strut suspension, safety guard systems and anti-spin regulators. Possible future systems which could be incorporated into intelligent vehicles are considered and developments already underway around the world are noted. For the covering abstract see IRRD 874974.