Development of a new standing wave type ultrasonic linear motor

This paper presents a new standing wave type linear motor that can move bi-directionally with identical performance in both the forward and backward directions. The motor consists of a metallic stator and two piezoceramic plates bonded to the stator with the spatial phase difference of a half wavelength. With two electric driving signals either in-phase or out-of-phase for the two piezoceramic plates, the piezoceramic plates excite two ultrasonic standing waves with a certain phase difference. They generate a new standing wave when combined. The operation principle of the motor is verified through finite element analyses. For an experimental illustration of the theoretical and numerical results, a sample motor is fabricated and characterized following the numerical design. The experimental results confirm the validity and practical applicability of the new motor structure.