Optimal model following control of four-wheel active steering vehicle

In this paper, four-wheel active steering (4WAS), which can control the front wheel steering angle and rear wheel steering angle independently, has been investigated based on the analysis of deficiency of conventional four wheel steering (4WS). A model following control structure is adopted to follow the desired yaw rate and vehicle sideslip angle, which consists of feedforward and feedback controller. The feedback controller is designed based on the optimal control theory, minimizing the tracking errors between the outputs of actual vehicle model and that of linear reference model. Finally, computer simulations are performed to evaluate the proposed control system via the co-simulation of Matlab/Simulink and CarSim. Simulation results show that the designed 4WAS controller can achieve the good response performance and improve the vehicle handling and stability.