Enhancement of robust control law for active front steering control strategy

Abstract

In vehicle lateral dynamic studies, the transient performances of yaw stability control system are essential. Due to uncertainty of cornering stiffness when the road surface is changing, this perturbation may influence the transient performances and affected the handling quality of the vehicle. By designing a yaw rate tracking controller for active front steering control strategy with the enhanced control law using the sliding mode control algorithm, the transient performances are improved. The vehicle lateral dynamic behaviours are described using the linear and nonlinear vehicle models for controller design, simulations and evaluations. To achieve the control objective, the enhanced robust control law is proposed to cater the uncertainty of front wheels cornering stiffness. The proposed control strategy is evaluated using the step steer manoeuvre test for three road surface conditions. The simulation results obtained showed that the transient performances of yaw rate with the enhanced robust control law are better compared to the conventional control law and uncontrolled vehicle especially for wet and snow/icy road surfaces. An enhancement of robust control law that solved the cornering stiffness uncertainty is expected as a knowledge contribution to vehicle lateral dynamic studies.