A Micro Radial-Torsional Vibration Ultrasonic Motor Driven by Single-Phase Signal

Abstract

Traditional mode conversion ultrasonic motors are typically composed of the superposition of multiple vibration modes, making them more complex than single-mode ultrasonic motors. This complexity makes it difficult to miniaturize. A micro radial-torsional vibration mode ultrasonic motor is proposed and tested in this work. It is excited by a single-phase excitation signal. The proposed motor utilizes the radial in-plane vibration mode of the stator to convert the torsional vibration mode of the inner ring through the beams. The torsional vibration of the inner ring causes the rotor to rotate due to the friction force between the inner ring and the rotor. Based on the designed structure and verified using the finite element method, a prototype motor with a mass of 2.6 g and overall dimensions of Ô20 mm in diameter and 15 mm in height is fabricated and characterized. During the mechanical output performance test, the prototype achieved a maximum no-load speed of 3300 r/min and a stall torque of 0.2 mN $\cdot $ m at the driving voltage of 100 V $_{\mathrm {p-p}}$ .

Keywords

• Ultrasonic motor
• piezoelectric actuator
• radial-torsional vibration
• mode conversion