Showing papers on "Vehicle dynamics published in 1997"

Propulsion system design of electric and hybrid vehicles

Abstract: There is a growing interest in electric and hybrid-electric vehicles due to environmental concerns. Efforts are directed toward developing an improved propulsion system for electric and hybrid-electric vehicles applications. This paper is aimed at developing the system design philosophies of electric and hybrid vehicle propulsion systems. The vehicles' dynamics are studied in an attempt to find an optimal torque-speed profile for the electric propulsion system. This study reveals that the vehicles' operational constraints, such as initial acceleration and grade, can be met with minimum power rating if the power train can be operated mostly in the constant power region. Several examples are presented to demonstrate the importance of the constant power operation. Operation of several candidate motors in the constant power region are also examined. Their behaviors are compared and conclusions are made.

Motor Vehicle Dynamics: Modeling and Simulation

Abstract: This book begins with an historical overview of road vehicles. The first part deals with the forces exchanged between the vehicle and the road and the vehicle and the air with the aim of supplying the physical facts and the relevant mathematical models about the forces which dominate the dynamics of the vehicle. The second part deals with the dynamic behaviour of the vehicle in normal driving conditions with some extensions towards conditions encountered in high-speed racing driving. This book is based on lectures given at the Technical University of Torino, Italy.

Design and analysis of gain-scheduled control using local controller networks

Abstract: This paper describes a nonlinear control structure known as a local controller network. The structure consists of a weighted combination of a number of individual controllers, each of which is valid locally in the state space of the plant. Local controller designs are based upon local models valid in operating regimes which do not necessarily contain any physical equilibria. Consequently, the transient performance can be improved. Some 'scheduling' variables determine the current operating regime, and a validity function is assigned to each local controller. A 'feedforward' component may be used in each local controller in order to compensate directly for the operating-point-dependent model offsets. The application of the local controller network approach to a nonlinear control problem, that of longitudinal vehicle dynamics control, is described. A stability analysis for the discrete-time local controller network is given in this paper and the results are compared with known theoretical guidelines for rel...

Unified Theory for Aircraft Handling Qualities and Adverse Aircraft-Pilot Coupling

Abstract: A unified theory for aircraft handling qualities and adverse aircraft-pilot coupling or pilot-induced oscillations is introduced. The theory is based on a structural model of the human pilot. A methodology is presented for the prediction of (1) handling qualities levels; (2) pilot-induced oscillation rating levels; and (3) a frequency range in which pilot-induced oscillations are likely to occur. Although the dynamics of the force-feel system of the cockpit inceptor is included, the methodology will not account for effects attributable to control sensitivity and is limited to single-axis tasks and, at present, to linear vehicle models. The theory is derived from the feedback topology of the structural model and an examination of flight test results for 32 aircraft configurations simulated by the U.S. Air Force/CALSPAN NT-33A and Total In-Flight Simulator variable stability aircraft. An extension to nonlinear vehicle dynamics such as that encountered with actuator saturation is discussed.

Prediction of Wheel/Rail Profile Wear

Abstract: SUMMARY The alteration in wheel and rail profiles due to wear involves considerable vehicle and track-maintenance costs, and influences the loading capacity of the rails, as well as the operation safety and riding comfort of the vehicles. In the past twenty years a vehicle dynamics, contact mechanics and tribology based research work has emerged which is also recently continuous in an international scale, and this research is more and more intensive. Parallel to the growing possibilities of computer based analyses, several algorithms and numerical procedures have been elaborated, as well as measurement based experiments have been carried out to establish the reliable prediction of wear-caused wheel and rail profile alterations and to maximise the mileage performance by selecting the optimum vehicle system parameters for running gears operating on a selected railway line or a whole network under specified -in general inherently stochastic - traffic conditions. This paper takes an attempt to introduce the e...

Estimation of track-soil interactions for autonomous tracked vehicles

Abstract: Real time estimation of soil parameters is essential in achieving precise, robust autonomous guidance and control of a tracked vehicle. The paper shows that the slip of the tracks over the terrain can be identified from trajectory data using an extended Kalman filter. The use of a suitable soil model can then allow key soil parameters to be estimated as the vehicle passes over the soil. Knowledge of the soil parameters may in turn be used to allow reference trajectories and control algorithms to be adjusted to suit the soil conditions.

Advanced chassis control systems for vehicle handling and active safety

Abstract: SUMMARY In this paper chassis controls for vehicle handling and active safety have been reviewed. In particular, we have observed the effectiveness and limit of 4WS and DYC. It is pointed out that DYC is more effective in vehicle motion with larger side-slip and/or higher lateral acceleration and taking the nonlinearity of tire and vehicle dynamics into consideration is essential for introducing the control law for the chassis controls and their integration/coordination. We wish to emphasize that there is a need to further propose control laws based on deeper observation and understanding on the tire and vehicle dynamics.

Improved vehicle performance using combined suspension and braking forces

Abstract: SUMMARY This work presents a preliminary investigation into the integration of particular subsystems of an automobile's chassis. The specific focus of this research is the integration of Active Suspension components with Anti-Lock braking (ABS) mechanisms. The performance objective for the integrated approach is defined as a reduction in braking distance over just anti-lock brakes. Several models, of varying degrees of complexity, are presented to determine the effect of modeling accuracy on the potential performance improvement. In the most detailed model, a four degree of freedom Half Car vehicle model is developed along with models for a hydraulic Active Suspension and an ABS system. For both subsystems, actuator dynamics are included. The tire-road interface is modeled using the Magic Formula tire model. Individual controllers are developed for the subsystems and a governing algorithm is constructed to coordinate the two controllers. Simulations of the integrated controller and an ABS system, for each...

Vision-based lateral control of vehicles

Abstract: We describe the problem of automated steering using computer vision, focusing the analysis and design on appropriate lateral controllers. We investigate various static feedback strategies where the measurements obtained from vision, namely offset from the center line at some lookahead distance and the angle between the road tangent and the orientation of the vehicle at some lookahead distance, are directly used for control. Within this setting we explore the role of lookahead, its relation to the vision processing delay, the longitudinal velocity and road geometry. Results from ongoing experiments with our autonomous vehicle system are presented along with simulation results.

Active suspension control to improve vehicle ride and handling

Abstract: SUMMARY In practice most active vehicle suspension work can be traced to two sources, Lotus' modal control and Karnopp's skyhook damper. A model is developed which allows comparison of different active suspension control algorithms. The Lotus modal control algorithm is reviewed, and compared with Karnopp's skyhook damper. It is shown that a tight inner closed loop allows the Lotus algorithm to achieve the inertial damping described by Kamopp for a single comer or quarter car. It is suggested that to achieve simultaneously high inertial damping and good disturbance rejection an inner force loop is desirable. A vehicle control scheme is presented which combines the Lotus modal decomposition with Karnopp's skyhook damper, allowing nearly optimal ride and simultaneously permitting modification of vehicle handling properties.

A Comparison of Alternative Intervention Strategies for Unintended Roadway Departure (URD) Control

Abstract: SUMMARY This paper investigates the use of several different inputs for the control of a vehicle, in the context of URD. In this investigation, the goal of the URD controller is to provide an intervention in the event of the vehicle leaving the road. The types of inputs that will be considered are (i) Four Wheel Steering, (ii) Front Wheel Steering, (iii) Four Wheel Brake Steering, (iv) Front Wheel Brake Steering, and (v) Rear Wheel Brake Steering. The controller design is an LQ controller based on the simplified dynamics of a 2 degree of freedom bicycle model. However, the analysis of the different strategies are performed on a 7 degree-of-freedom nonlinear vehicle model. The key contribution of this paper is the quantitative evaluation of the relative efficiencies of each of these input strategies being examined. Unlike most control schemes, the performance measure to be used will not be the output tracking error of the system. Instead, the metric of performance is the ratio of peak tire force used versu...

Traction control of electric vehicle based on the estimation of road surface condition-basic experimental results using the test EV "UOT Electric March"

Abstract: The most distinct advantage of an electric vehicle is in its quick and precise torque generation. The authors propose two novel traction control techniques of electric vehicles: model-following control; and optimal slip ratio control. Their effectiveness is demonstrated by using the "UOT Electric March" test vehicle.

Modelling and control of an automated vehicle

Abstract: SUMMARY We present a vehicle model that includes the vehicle dynamics and a vehicle tire model. The model developed is then used for conducting steering analysis of an automated vehicle. We test the developed model on a step lane change maneuver and propose a model-reference based controller for remote control of a vehicle. Stability analysis of the closed-loop system using die Lyapunov approach is included.

Active Dual Mode Tilt Control for Narrow Ground Vehicles

Abstract: SUMMARY Small, narrow commuter vehicles have attracted considerable interest in recent years as a means to increase the utilization of existing freeways and parking facilities. However, conventional narrow track vehicles are likely to have reduced stability against overturning during hard cornering. A possible solution to this problem lies in vehicles which tilt toward the inside of a turn. Two different ways to achieve this tilt will be analyzed. For direct tilt control (DTC) an actuator forces the upper part of the vehicle to tilt. Steering tilt control (STC) uses steering to control the tilt as is done by motorcycle or bicycle riders. At low speeds, only the DTC system is effective while at high speeds the STC offers less lateral acceleration for the passenger during transient cornering and may seem more natural. The two methods of control will be studied separately and it will be shown that even though the same steady state tilt can be achieved with either system, the transient behavior of the systems...

Vehicle merging control design for an automated highway system

Abstract: The merging process in an automated highway system (AHS) is divided into a speed adjustment stage and a lane merging stage. Three important parameters, namely acceptability, availability and pursuability, are analyzed to characterize the AHS lane gap features for the ideal, smooth and safe merging of the ramp vehicles. Three control guidance laws, namely linear, optimal and parabolic speed profiles, are developed to describe the desired behaviors of the merging vehicle based on the merging quality and safety. The desired states of the merging vehicle are generated through the outer loop by specified control guidance law. The tracking errors compared with desired states are eliminated by the proper design of controllers in the inner loop. Both longitudinal and lateral controllers are designed using sliding mode control theory that can handle the nonlinear and model uncertainties of the vehicle dynamics. The simulation results show encouraging results.

Robust control of an underactuated surface vessel with thruster dynamics

Abstract: A continuous periodic time-varying feedback law is proposed that exponentially stabilizes both the position and orientation of a surface vessel having only two actuators. To this end, a stability result for a class of homogeneous time-periodic systems is presented. The exponential stability provided by the proposed feedback law does not depend on exact knowledge of the model parameters, and is thus robust to model parameter uncertainty. The surface vessel model considered is nonlinear and describes both the dynamics and the kinematics of the surface vessel. Furthermore the actuator dynamics is included in the control design. Simulation results are presented.

Parcel manipulation and dynamics with a distributed actuator array: the virtual vehicle

Abstract: We are developing a materials handling system where many small simple actuators cooperate to transport and to manipulate large objects in the plane. A discrete set of cells, each comprising two actuators, are fixed in a planar array. By coordinating the actuators in the cells on which an object rests, an object can be transported and manipulated. In essence, this system is an improvement over traditional conveyor systems in that objects can be re-oriented, as well as conveyed. Such an array provides flexible materials handling in which many objects independently can be manipulated and transported at the same time. The array is coordinated in a distributed manner where each cell has its own controller and each controller communicates with its neighbors. Towards the goal of motion planning, in this paper we consider the dynamics of parcel transport and manipulation. The parcel dynamics are based on an exact discrete representation of the system, unlike other methods where a continuity assumption is made. Two types of contact models are considered.

A comparison of moment of inertia estimation techniques for vehicle dynamics simulation

Abstract: The moments of inertia, in yaw, pitch, and roll, as well as the center of gravity height are necessary to successfully model the three-dimensional (3D) dynamic behaviour of vehicles before, during and after collision A number of vehicle parameter estimation techniques have been developed and are currently in use in North America and Europe Many parameters have been measured by the National Highway Traffic Safety Administration (NHTSA) and others The estimation techniques are compared to the available measured values, and recommendations are made for best estimating the parameters when measured values are not available The sensitivity of 3D vehicle collision dynamics and trajectory simulation to variance in the moment of inertia is demonstrated (A) For the covering abstract of the conference see IRRD 899758

A sliding mode controller for wheel slip ratio control system

Abstract: SUMMARY A sliding mode controller has been developed for a wheel slip ratio control system for commercial vehicles with sluggish braking actuators to replace conventional if-then rule-like ABS control laws. New techniques overcome the tendency of sliding mode controllers to chatter. Computer simulation (hardware-in-the-loop simulation) and actual vehicle tests verified the effectiveness of this method to suppress chattering and keep the wheel slip ratio in a desirable range during braking on low-friction road surfaces.

Vehicle dynamics control system

Abstract: A vehicle dynamics control system for an automotive vehicle with a parallel split layout of brake circuits comprises a tandem master cylinder, a hydraulic pump fluidly disposed in one brake circuit, a selector valve for selecting a brake-fluid pressure to be fed to a first brake line from between the fluid pressure generated from the pump and the master-cylinder pressure, a plurality of pressure control valves for regulating a fluid pressure in each individual wheel-brake cylinder, vehicle sensors for detecting a vehicle's cornering behavior, and a control unit being responsive to the sensor's input information for controlling the respective control valves associated with the front wheel-brake cylinders. The control unit operates to supply the fluid pressure generated from the pump to an inner front wheel-brake cylinder in the vehicle understeer on turns. The control unit also operates to supply the fluid pressure generated from the pump to an outer front wheel-brake cylinder in the vehicle oversteer on turns.

Dynamic Characteristics of Magnetically-Levitated Vehicle Systems

Abstract: The dynamic response of magnetically levitated (maglev) ground transportation systems has important consequences for safety and ride quality, guideway design, and system costs. Ride quality is determined by vehicle response and by environmental factors such as humidity and noise. The dynamic response of the vehicles is the key element in determining ride quality, while vehicle stability is an important safety related element. To design a guideway that provides acceptable ride quality in the stable region, vehicle dynamics must be understood. Furthermore, the trade off between guideway smoothness and levitation and control systems must be considered if maglev systems are to be economically feasible. The link between the guideway and the other maglev components is vehicle dynamics. For a commercial maglev system, vehicle dynamics must be analyzed and tested in detail. This report, which reviews various aspects of the dynamic characteristics, experiments and analysis, and design guidelines for maglev systems, discusses vehicle stability, motion dependent magnetic force components, guideway characteristics, vehicle/ guideway interaction, ride quality, suspension control laws, aerodynamic loads and other excitations, and research needs.

A Semi-Analytical Tyre Model for Steady- and Transient-State Simulations

Abstract: On the basis of previous research papers, an enhanced tyre model is presented which could be useful both for vehicle dynamics analysis and for tyre design. The physical phenomena involved in tyre-ground force generation are described mathematically in a semi-analytical form. Given the main mechanical parameters of the tyre, the friction coefficients and the running conditions, the model returns the values of the forces generated at the tyre-ground interface either at steady- or at transient-state condition. Comparisons between experimental and computed data have been performed with satisfactory results.

Dynamics of Tracked Vehicles

Abstract: SUMMARY This paper provides a brief review of the state-of-the-art of tracked vehicle dynamics, including mobility over soft terrain, ride dynamics over rough surfaces and manoeuvrability. It is fo...

Fault Detection and Diagnosis of Components of the Vehicle Vertical Dynamics

Abstract: In this paper, model and signal-based methods for supervision ofsuspension elements of a car are presented. A model-based approach usingparameter estimation is used to determine the current parameters of avehicle suspension. Exploiting the analytical redundancy, different faults,like weak dampers or sensor faults, can be distinguished. For faultdetection the use of parity equations is shown. In addition, a signal-basedapproach is presented which makes a detection of tire pressure losspossible. All presented results were drawn from a test rig or from a drivingcar.

Development of Robust Active Rear Steering Control for Automobile

Abstract: A new concept for a robust active rear steering(ARS)system is presented. The system exhibits good control performance even if the vehicle parameters and / or road surface conditions are changed. This system makes the vehicle follow the desired dynamic model by state feedback of both yaw rate and side slip angle. For utilization of a noisy yaw rate sensor and maintenance of high robust control performance, a controller with frequency-dependent gain characteristics was designed by μ synthesis. For estimatation of the side slip angle using a noisy sensor, a new time-variant observer employing a frequency filter was introduced. The results of the simulation and the experimental tests prove the great effect of the new ARS system.