Working principle and design of a linear ultrasonic motor with ring-type stator

This paper presents a new idea for constructing ring-type linear ultrasonic motor. The stator of proposed motor contains two driving feet, sixteen pieces of piezoelectric ceramic plates and three rings-inner ring, middle ring and outer ring. The proposed ultrasonic motor forms elliptical movements on the driving feet by the superposition of stretching and bending vibration of the metal rings. This paper presents the working principle of proposed motor. By using FEM method, the proposed motor is designed and analyzed. By adjusting the structure parameters, the resonance frequencies of two working modes were tuned to be close. And by transient analysis, the elliptical motion trajectories of nodes on the driving feet are obtained and verify the theoretical feasibility.