A review on piezoelectric ultrasonic motors for the past decade: Classification, operating principle, performance, and future work perspectives

Hundreds of piezoelectric ultrasonic motors (PUSMs) have been proposed for scientific researches and developed for commercial applications in the past decade. They are surveyed and mainly classified into three types: standing wave motor (SWM), traveling wave motor (TWM) and hybrid modes motor (HMM), according to their operating principles. These different types of PUSMs are discussed in detail, in terms of their operating principles, structures, features and performances. The methods to realize the multi-degree-of-freedom (multi-DOF) motions of the PUSMs are also investigated based on the basic operating principles of the SWM, TWM and HMM. Some practical applications and representative designs of the PUSMs are introduced briefly. Finally, further efforts and research perspectives of the PUSM are summarized. This review contributes to a comprehensive understanding of the state of arts of the PUSM.