Abstract
The main attention of this paper is to tackle the issue of robust tracking and disturbance estimation for the four wheel steering vehicle by implementing a feedback control design based on the improved-equivalent-input-disturbance technique and the Smith predictor approach. The intention of incorporating the Smith predictor into the controller design is to compensate the effect of input time-delay. In addition, the improved-equivalent-input-disturbance technique is applied for dealing with the nonlinear uncertainty and external disturbances. Based on the proposed controller, both front and rear steering angles of the considered model are controlled to trace the desired position of the vehicle. More precisely, the developed criterion that ensures the desired tracking performance of the vehicle is obtained in the form of linear-matrix-inequalities based on the construction of an appropriate Lyapunov-Krasovskii functional candidate. Numerical simulation results for vehicle dynamics are presented to examine the performance of the proposed control strategy.