Title: Closed-loop design for decoupling control of a four-wheel steering vehicle

Authors: E.C. Yeh, R.-H. Wu

Addresses: Associate Professor, Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, 30043, Taiwan. ' Graduate Student, Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, 30043, Taiwan

Abstract: In this paper, a closed-loop four-wheel steering (4WS) control system with multiple inputs is introduced for both stable and unstable plants. With this 4WS system, the driver can control the sideslip motion and yaw motion of the vehicle simultaneously and independently. The decoupling control is accomplished by a closed-loop steering controller which translates the error signals between the desired and the output signals into the steer angles of the front and the rear wheels. For the feedback loop, a method for measuring the output signals is presented. In designing the steering controllers, two steering controllers with different orders are designed by a method similar to the Q parametrization method. For the unstable vehicle plant, an output feedback inner loop is used to stabilize the plant. This stabilizing inner loop is shown to be effective at all speeds for any vehicle with steerable front wheels. System performance under the variations of vehicle parameters is also examined.

Keywords: four-wheel-steering; 4WS; multiple-input multiple-output system; MIMO; decoupling control; steering control; controller design; closed-loop control.

DOI: 10.1504/IJVD.1989.061558

International Journal of Vehicle Design, 1989 Vol.10 No.6, pp.703 - 727

Published online: 26 May 2014 *

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