Study on mixed H∞/h2 control for enhancing the tracking performance of EPS

According to the operating mode of pure electric power bus, the recirculating ball-type EPS (Electric Power Steering System) is designed and its dynamic model is established by the optimum design. Because of the existence of system uncertainty model, disturbance signals, sensor noises and the demand of system dynamic performance, the mixed H_∞/H₂ controller is designed for the EPS. The simulation results show that the EPS with the mixed H_∞/H₂ controller could attenuate the random noises and disturbances and track the boost curve well, so it has improved the system´s robust performance and dynamic performance. At last, the bench test is experimented to verify the simulation results and it shows that the mixed H₂/H_∞ controller for EPS is feasible, and it could improve the steering and handling performance and provide satisfied road feeling for the drivers.