Robust Quasi-Sliding Mode Control for Four Wheel Steering Vehicle Based on Side Slip Angle Tracking

This paper has proposed robust quasi-sliding mode control for four wheel steering (4WS) vehicle based on vehicle side slip angle tracking with consideration of the variation of the center of vehicle gravity and disturbance of lateral wind, which are both in bounded ranges. By replacing ideal switching function with saturation function and setting a proper thickness of boundary layer, the controller is able to depress or avoid the chattering of control signal, effectively track zero sideslip angle at steady-state, and is insensitive to the variation of vehicle parameters and external disturbance. Compared with conventional two wheel steering (2WS) vehicle, the simulation results indicate that the 4WS vehicle with robust quasi-sliding mode controller can be designed to achieve the desirable robust stability, and reduces the vehicle steady-state sideslip angle to zero rapidly.