Patent ID: 7567051

Claim:
A position shift control apparatus comprising: a motor joined to an object through an output shaft and a torque transmission mechanism to move the object to a target position; a detent mechanism working to produce elastic pressure to hold the object at the target position; an output shaft position sensor which measures an angular position of the output shaft to produce an output indicative thereof; a motor position sensor which measures an angular position of the motor to produce an output indicative thereof; and a controller which controls an operation of said motor to move the object, said controller determining a value of the angular position of said motor, as sampled upon a change in the output from the output shaft position sensor, as a reference angular position of said motor when torque, which is created by the elastic pressure produced by said detent mechanism and acts on the output shaft during rotation of said motor, is opposite in orientation to that outputted by said motor, said controller monitoring the output of the motor position sensor and shifting the angular position of said motor into agreement with a position which corresponds to the target position of the object and is determined based on the reference angular position to move the object to the target position thereof.