Title: Investigation into the stability of four wheel steering vehicles

Authors: A.G. Nalecz, A.C. Bindemann

Addresses: Associate Professor, Department of Mechanical and Aerospace Engineering, University of Missouri-Columbia, Columbia, Missouri 65211, USA. ' Research Associate, Department of Mechanical and Aerospace Engineering, University of Missouri-Columbia, Columbia, Missouri 65211, USA

Abstract: Automotive manufacturers have recently been developing four wheel steering systems as part of an effort to enhance the dynamic response characteristics of passenger vehicles. The systems being developed by the various manufacturers differ in the control methods used to steer the rear wheels. These systems enhance the response of the vehicles at high speed by steering the rear wheels in the same direction as the front wheels in order to reduce vehicle sideslip and reduce the time required by the vehicle to achieve steady state. This paper investigates the stability properties of four different steering control methods in pure cornering manoeuvres at moderate and high speeds, as well as stability properties in combined cornering and braking manoeuvres. A three degree of freedom, non-linear, time domain vehicle model was used to simulate the dynamic behaviour of a vehicle using each steering control method. Stability is based on the comparison of generated tyre forces with the tyre limits of adhesion. The tyre model used in the simulation is based on the friction ellipse concept and uses Calspan tyre data to compute peak lateral and longitudinal friction coefficients and tyre cornering stiffnesses as non-linear functions of tyre normal load. Three dimensional suspension kinematics are utilized to determine the vehicle roll axis as well as the steer and camber angles of each wheel.

Keywords: vehicle dynamics; vehicle design; vehicle modelling; vehicle steering; four wheel steering; digital simulation; transport; vehicle stability.

DOI: 10.1504/IJVD.1988.061479

International Journal of Vehicle Design, 1988 Vol.9 No.2, pp.159 - 178

Published online: 26 May 2014 *

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