Analysis of structural dynamics for a circular wedge-wave ultrasonic motor

Abstract

This study analyzes the structural dynamics of an ultrasonic motor driven by a circular wedge acoustic waveguide in order to determine the optimal motor design parameters. The motor stator comprises a metal circular wedge and piezoelectric cylindrical tube. The outer surface of the piezoelectric cylindrical tube is coated with comb-type electrodes, and equispaced electrodes on its surface formed two comb-type transducers. A self-designed high-performance dual-phase driver circuit initiated flexural waves along the wedge peak, changing the driving voltage and phases, which allows for the speed and direction of motor rotation to be controlled accurately. This study uses finite element software to analyze the resonant frequencies and dynamics of the motor. Harmonic analysis and simulation results are then used to derive optimal parameters for motor design. The results indicate that the ultrasonic motor has an operating frequency of 33.8 kHz and operating voltage of ±100V. Two pairs of dual-phase comb-type electrodes generate five flexural waves that transmitted along the wedge peak in a clockwise or counterclockwise direction. The point of contact between the stator and rotor is located approximately 1 mm underneath the wedge peak in order to ensure the motor's optimal performance.