A ring-type traveling wave linear ultrasonic motor based on in-plane third-order modal vibration

Abstract This paper proposes a new type of circular ring traveling wave linear ultrasonic motor with incomplete teeth. The motor’s movable slider is pressed against the end face of the tooth structure on the outer surface of the circular ring vibrator under a certain pre-pressure, four piezoelectric ceramic plates are evenly distributed at 90° intervals on the inner side of the circular structure, and four sets of driving teeth are arranged at 45° intervals from the position of the piezoelectric ceramic plates.When the motor is in operation, only one driving tooth works, and the life of the ultrasonic motor can be increased by rotating the different working teeth. The motor operates in two in-plane third-order bending modes that are orthogonal to each other at the same frequency. The dynamic design and simulation of the vibrator was carried out using ANSYS finite element software to analyze the effect of the structure on the mode. The principle prototype was fabricated, and the operating mode of the vibrator was measured using a laser Doppler vibrometer (LDV), and the vibration characteristics and output performance of the prototype were tested. Experimental results show that the motor runs smoothly at the excitation voltage of 240 V peak-to-peak, the excitation frequency of 30.459 kHz and the pre-pressure of 0.6 N, with the maximum output force of 90 mN and the motor no-load speed of 102 mm/s.