Development of a 3-DOF Cylindrical Ultrasonic Motor Based on Non-Standard Modes

Abstract

Cylindrical multi-degree-of-freedom (multi-DOF) ultrasonic motors have the potential to significantly reduce motor size compared to other ultrasonic motors. They find applications in various systems, including micro-robot joints and space probes. This paper proposes a 3-DOF cylindrical ultrasonic motor with hybrid vibration modes. Hybrid vibration modes encompass non-standard longitudinal and bending vibrations. The structure and operating principle of the motor are described first. COMSOL Multiphysics models the stator’s vibration modes, frequency response, and 3-DOF motion. A motor prototype is manufactured and characterized to demonstrate the output characteristics of the motor. The results indicate that the motor has a no-load speed of 37 rpm along the x- and y-axes and up to 77 rpm along the z-axis. The maximum output torque of the motor is 25 Nm. The motor is low in height and compact, providing a method for further reducing the stator length of motors of the same type.