Non-linear control of four-wheel steering cars with actuator constraints

This paper presents a new non-linear steering controller for cars equipped with 4-wheel steer-by-wire that tracks reference sideslip and yaw rate signals describing the desired lateral dynamics. The proposed controller automatically rejects any disturbances in sideslip and yaw-rate, and incorporates an anti-windup scheme to reduce the effects of the saturation of the rear steering actuators. The control design is based on the Individual Channel Analysis and Design (ICAD) methodology. An analysis of the robust stability of the control system is presented. Results from a detailed non-linear simulation model are given to illustrate the controller's performance