Nonlinear Control of Active Four Wheel Steer-By-Wire Vehicles

In this paper, a nonlinear triple-step steering controller for four wheel steer-by-wire vehicles has been presented to enhance handling stability. The proposed nonlinear triple-step steering controller commands the front and rear steering angles so as to track both the reference yaw rate and sideslip angle. Thus, it can effectively improve the tracking accuracy even if tyres of vehicles are working in extremely nonlinear region. Considering the influence of the driver on the handling stability, a PID driver model is introduced. Both open-loop and closed-loop simulations are carried out in CarSim.