An EPS Control Strategy to Reduce Steering Vibration Associated with Disturbance from Road Wheels

This paper presents a new control strategy for Electric Power Steering (EPS) to reduce steering vibration associated with disturbance from road wheels. Disturbance from road wheels may cause undesirable steering vibration if drivers run on an unpaved road or road wheels are not well balanced. For drivers, road information generated by alignment torque is essential to steer a vehicle easily. However drivers are unpleasant for steering vibration associated with disturbance from road wheels. In the steering system, both of them are transmitted to the driver through steering mechanism. We have developed a new EPS control strategy that reduces steering vibration associated with disturbance from road wheels without influencing road information generated by alignment torque considering the difference in frequency. The new EPS controller is constructed based on damping for specified frequency using the motor angular- velocity. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables reduced steering vibration associated with disturbance from an unpaved road without sacrificing road information generated by alignment torque.