Driving characteristics of an ultrasonic rotary motor consisting of four line contact type stators

Abstract A new type of ultrasonic rotary motor that can replace existing ultrasonic motors for driving camera zoom lenses was proposed and investigated experimentally. The proposed motor composed of four roof-shaped stators. On the upper surfaces of each roof-shaped stator, two rectangular ceramics were attached. When two AC voltages with a 90° phase difference were applied to the ceramics, elliptical displacements occurred at the tip line of the actuator. By combining these elliptical displacements of the four stators, rotational motion of the stator could be achieved. If a circular disk rotor was positioned on the stator, vibrations of the stator were transferred through the four contact lines between the stator and the rotor. Preload of the motor could be controlled by the jointing bolt, which went through the center of the disk rotor and the ball bearings. The finite element analysis (FEA) simulation program ANSYS was used to analyze the elliptical displacement characteristics in relation to changes in the size of the elastic body, piezoelectric ceramics, friction tips, frequency, and applied voltages. A prototype motor was fabricated, and its driving characteristics such as impedances, vibration amplitudes, rotational speed, and torque were measured.