Patent ID: 7221116

Claim:
A motor control apparatus comprising: an encoder for producing a pulse output signal in synchronism with rotation of a rotor of a motor that rotates a control object; and control means for rotating the rotor to a target position by detecting a rotation position of the rotor on the basis of a count of the output signal of the encoder and sequentially switching a current supply phase of the motor, wherein the control means includes means for learning a play amount of a rotation transmission system for converting a rotation amount of the motor into a manipulated variable for the control object, and wherein the control means learns a play amount of the rotation transmission system by performing a first-direction butting control for rotating the rotor until butting occurs at one limit position of a movable range of the control object and a second-direction butting control for rotating the rotor until butting occurs at a second limit position of the movable range, determining, as an actual measurement value of the movable range of the control object, an increase or decrease of the count of the output signal of the encoder from the one limit position to the second limit position, and learning, as a play amount of the rotation transmission system, a difference between the actual measurement value of the movable range and a design value of the movable range, and in rotating thereafter the rotor to the target position, the control means sets the target position by taking the learned play amount of the rotation transmission system into consideration.