An Electric Power Steering System Controller based on Disturbance Observer

Driver´s steering feel for back force of road is an important characteristic performance for electric power steering (EPS) system, except for the characteristic of convenient of steer wheel rotating and safety of driving. In this paper, a model of EPS system is set up, and a new low-pass filter is introduced. A controller is designed by using disturbance observer method for the EPS system. An analysis method of road information is proposed. Information regarding varying road surface conditions includes both road´s back force information and disturbance information, which can be separated by frequency. The performance of the proposed controller is simulated by MATLAB and the results show that the EPS system with robust controller has good robustness and road pertinent information can pass through but the ineffective information was regulated. So it can maintain a safe and comfortable driving experience for driver.