Abstract
Ultrasonic actuators, their working principles, basic structures, and typical characteristics are described in this article, in which we focus on ultrasonic motors based on friction driving and piezoelectric transducers. Methods of generating unidirectional rotation/motion from ultrasonic vibrations are categorized into two groups: hybrid-vibration-type and traveling-wave-type methods. The expected performance of each hybrid-vibration type method is discussed using an electrical equivalent circuit model. This article also illustrates several practical configurations for both rotary and linear motions as well as a recent attempt to improve the efficiency and lifetime.
