ELECTRIC POWER STEERING CONTROL DEVICE AND ITS CONTROLLING METHOD

摘要

PROBLEM TO BE SOLVED: To improve a steering wheel returning characteristic in all the driving states in an electric power steering control device. SOLUTION: First road surface reaction torque is estimated from driver's steering torque detected by means of a steering torque detector 1 while second road surface reaction torque is estimated from a steering angle detected by means of a steering wheel angle sensor, and a steering wheel returning assisting torque signal is computed from the second road surface reaction torque by means of a returning torque compensator 17 so that motor assisting torque is controlled in the direction of returning the steering wheel to its home position according to the computed result. At the same time, by means of the returning torque compensator 17, it is determined that the steering angle sensor is in an abnormal condition when the difference between the first road surface reaction torque and the second road surface reaction torque is larger than a predetermined value.