A miniature piezoelectric ultrasonic motor based on circular bending vibration mode

A rod-type miniature piezoelectric ultrasonic motor based on free-free bending vibration mode with improved construction was developed for application of precise positioner. The design methodology, construction, and operation principle of the motor are presented. By using the finite element method, the motor´s vibration modes and driving mechanism were modeled. The characteristics of the prototype were investigated experimentally. The experimental results first reveal that both a corrugated tube type of horn and “soft-type” piezoelectric ceramic in the piezoelectric transducer (stator) can widen the band of operational frequency of the motors notably. The developed prototypes, 15 mm in diameter and 25 mm in length, have shown some advantages such as low speed (70 r/min) with large torque (0.055 N·M), very high resolution (0.01°), and good speed stability of over 10 h, etc. The miniature motor has been successfully applied to laser resonant cavity as a precise driving element