Development of a novel traveling wave rotary ultrasonic motor by simultaneous planar-cylindrical drive with approach improved output performance

Abstract

In this study proposes an ultrasonic motor to improve output parameters, with a focus on enhancing the torque density and power density. The planar and cylindrical bending modes are combined for a simultaneous drive in the proposed motor. Ultrasonic motors with planar drives often have an unusable space in the axial direction. This study proposed the design of a cylindrical stator with the same frequency as the planar drive to make optimal use of this space and improve the output parameters. The cylindrical stator was designed based on the operating frequency of planar stators in previous studies and was simulated using the finite element method (FEM). Once a prototype model had been constructed and tested, the experimental data and numerical results were compared. The present study designed and used a high-voltage generator rather than a high-voltage amplifier. The speed and torque of the simultaneously driven motor were compared to those of the motor with a planar drive. The results showed that the motor with simultaneous drive increases 2.5 and 3.4 times in speed and torque, respectively. The torque density and power density ratios were also 2 and 5 higher, respectively. At the same time, the proposed motor had a slight increase in weight, dimensions, and volume.