the object of the present invention is to provide steering responsiveness and linear steering perception when the steering wheel is restored , even when there is excessive , sudden steering beyond a predetermined tolerance . if a steering angle θ suddenly enters a “ play ” range at the left and right ends of the θ − x n plane , the steering direction of the steering wheel can lead to a localized change in the gear ratio . fig . 3 is a graph showing an example of this type of hysteresis loop . when a driver tries to get out of the “ play ” range by turning the steering wheel in the restoring direction , a positive value can be achieved for the localized gear ratio based on the above hysteresis loop even in the “ play ” range . thus , based on this arrangement , if the steering angle θ exceeds the tolerance range , the localized gear ratio can be prevented from being continuously 0 when the steering wheel is immediately turned in the restoring direction .