Patent ID: 8847533

Claim:
An actuator for driving an object to be driven by transmitting a rotational driving force, generated in an electric motor, to the object to be driven, through the intermediary of a worm gear reduction mechanism, characterized by the fact: that there is provided a drive control section for (a) controlling an output shaft of said electric motor to rotate at a target velocity which is set based on a velocity-command signal, (b) subjecting an angular velocity of the output shaft of said electric motor to a repeated increasing and decreasing fluctuation within a predetermined range with respect to the target velocity while maintaining said rotation of said output shaft in a rotational direction based on the velocity-command signal, and (c) adding a fluctuation signal component having a predetermined frequency and a continuous wave of fine amplitude to the velocity-command signal, said velocity-command signal being a signal in which a fluctuation waveform of the fluctuation signal component is superimposed on a velocity command concerning an operation of said object to be driven; and that the output shaft of said electric motor is directly coupled to a worm of said worm gear reduction mechanism.