Structure design and finite element analysis of a new multi-degree-of-freedom ultrasonic motor

In this paper, a new multi-degree-of-freedom (MDOF) ultrasonic motor is designed. The motor is composed of four rectangular vibrators which are arranged as the Chinese word `ten'. The stator is driven by a composite of bending vibrations in two orthogonal directions. In the design process, the finite element model is established to find the anti-symmetric and symmetric modes of the stator. Structural dimensions that affect modal frequencies are selected and optimized. Through harmonic response simulation, the running state of the stator under sinusoidal signal is obtained and results show bending vibration is preferred. According to the analysis results, a motor prototype is made. Flexible hinges are used to improve the motor structure at the connecting position. The prototype has good output characteristics and the speed of the rotor can reach 0.122r/s under 400V voltage. The new motor has a certain reference value in the research of MDOF ultrasonic motors.