Improvement of low-speed stability in a multilayer piezoelectric linear motor by inertial driving.

Piezoelectric ultrasonic motors (USMs) operating in high-frequency structural vibration resonant modes exhibit rapid motion speeds but typically struggle to maintain stable low-speed operation. To address this limitation, we propose a multilayer piezoelectric ceramic motor that employs a dual-mechanism strategy, combining resonant and off-resonant piezoelectric deformations. When operating in the resonant mode, this linear USM utilizes coupled longitudinal and bending deformations to achieve both high-velocity linear motion (up to 290 mm/s) and a high stall force (4.5 N) under 30 Vpp driving at 47 kHz. In contrast, under off-resonant conditions, the motor functions as an inertial motor via the stick-slip mechanism, producing smooth and steady motion at speeds ranging from 10 μm/s to 10 mm/s without requiring closed-loop control. This dual-mechanism approach offers a promising direction for advancing the design of high-precision USMs, bridging the gap between high-speed and ultra-low-speed performance.