Characteristic Analysis and Experimental Study of Spherical Ultrasonic Motor with Multi-degree-of-freedom

A novel MDOF (multi-degree-of-freedom) spherical ultrasonic motor with three stators built-in is proposed aiming at high power density and compact structure. Firstly, the structure of the motor is described in detail. The motor realizes the three-degree-of-freedom movement of the spherical rotor through three ring stators. In addition, a structure for simultaneously applying pre-pressure to multiple stators is proposed. Then the working principle of the MDOF motion is analyzed. Based on the finite element software, the modal, harmonic response and transient analysis of the stator are carried out to solve the motion process and characteristic analysis of the stator vibration. Finally, the prototype is fabricated and tested. The frequency-impedance curve is measured by the impedance analyzer TH2829A to obtain its resonant frequency. Through rotation speed experiment, its frequency-speed characteristic curve and the maximum output speed of the motor are obtained. The rationality of MDOF spherical ultrasonic motor is proved.