抄録
An ultrasonic motor is generally composed of a vibrator and a rotor, and is driven by the frictional force between stator/rotor. Since the contact points on the stator draw elliptic trajectory, relative speed of the point against the rotor varies even when the rotor rotates with a constant speed. This may cause wear and a decrease in efficiency. This research proposes a novel method to reduce the relative speed variation to improve the efficiency of ultrasonic motors by superimposing harmonic vibration with driving vibration. Results of numerical calculation show that the efficiency may be improved by 27 % by the proposed method.
