2DOF linear rotary type ultrasonic motor

Abstract

A novel linear-rotary type ultrasonic piezoelectric motor was developed for the optical beam luminous flux density control system. The motor has a single stator and consists of a piezoelectric bimorph disc and a carbon fiber cylindrical tube that is glued in the center of the disc perpendicularly to the flat surface of the disc. Quadrilateral shaped waveguides are formed in the inner circumference of the disc so that its orientation coincides with the tan-gential direction of the cylindrical tube outer surface. Such a configuration of the wave-guides is used to transform radial vibrations of the bimorph disc into rotational oscillations of the cylindrical tube. The piezoelectric motor operates in two vibration modes, i.e., the second out-of-plane bending mode of the disc and the first radial mode of the disc. The ring-shaped rotor is located on the carbon tube and can be moved along it or rotated about the tube axis based on the inertial principle. Numerical modeling and experimental study were performed to validate the operating principle of the proposed ultrasonic motor. The prototype motor was made for experimental study, and the electrical as well as mechanical output characteristics, were measured. The average rotation speed of 36.4 rpm and linear velocity of 21.1 mm/s was obtained at the driving voltage of 240 Vp-p.