Design and finite element analysis of a new stack ultrasonic motor based on in-plane mode

This paper presents a novel piezoelectric ultrasonic motor which is able to exert the strong actuating power of piezoelectric stacks. It is a linear standing wave motor with simple structure and high positioning speed. Elliptical motion at the driving point is achieved by simultaneously matching the natural frequencies of two operating modes of the device. The matched resonance is taken to be the operating frequency at which both modes can be excited. A prototype motor is developed and numerically analyzed. Vibration characteristics of the motor, such as mode shapes, natural frequencies, output displacement in frequency and time domains, electrical impedance of the stacks and trajectories of the driving point, are obtained from finite element analysis. The results confirm that the motor has high electromechanical efficiency with good mechanical output characteristics.