Miniaturization of a longitudinal–bending hybrid linear ultrasonic motor

Based on the bonded-type structure, miniaturization of a longitudinal–bending hybrid linear ultrasonic motor is carried out. In this new design, only two pieces of ceramic plates are employed. The outer electrode surface of each ceramic plate is divided into two equal parts, which are excited by two voltages with phase difference separately. Then, the first longitudinal and fourth bending modes are generated in the motor. Finite element method is adopted to realize the modal degeneration and confirm the final structural parameters of the motor. The vibration modes of the prototype are measured by a scanning laser Doppler vibrometer. The no-load speed and the maximum output force of the prototype are tested to be 487 mm/s and 2.3 N, respectively. The weight of the miniaturized ultrasonic motor is about 8.5 g; its power density is about 1.97 times that of the previous bolt-clamped one.