Study on Mechanical Automation with Optimal Control for Four-Wheel-Active-Steer Vehicle

For improving the vehicle handling at high speed, an optimal controller was introduced for the four-wheel-active-steering vehicle. A closed-loop system was set up by combining vehicle model with driver model. The simulation test in the closed-loop system was carried out to verify control effect of such a optimum controller. Simulation results show that the four-wheel-active-steering vehicle under the optimal control can gain expected control effect such as wiping out sideslip angle and tracking desired yaw rate and so on. In addition, the four-wheel-active-steering vehicle with the optimal control can also track desired trajectory and its following accuracy is better than the traditional front-wheel steering vehicle. So, the steering response characteristic for the four-wheel-active-steering vehicle at high speed is improved.