Pre-pressure influences on the traveling wave ultrasonic motor performance: A theoretical analysis with experimental verification

In order to improve the output performance of the rotating traveling wave ultrasonic motor and study the optimal pre-pressures under different loads, the theoretical calculation and experimental verification on a TRUM-70H ultrasonic motor were carried out. The dynamic model of an ultrasonic motor is established, and the influence of pre-pressure on the mechanical properties of the ultrasonic motor is analyzed. Taking the TRUM-70H ultrasonic motor as the object of study, the relationship between the optimum pre-pressure and the load torque is analyzed. A multi-functional testing platform for an ultrasonic motor is built to verify the theoretical derivation results, and the reason for the error is also pointed out. According to the conclusion, the pre-pressure should be selected according to the load when the ultrasonic motors are assembled. The results show that there is a coupling relationship between the pre-pressure and the load torque on the speed of the ultrasonic motor. In the effective working range of the ultrasonic motor, the optimum pre-pressure is approximately linearly positively correlated with the load torque. When the pre-pressure is set according to the actual load demand during assembly, the output efficiency of the ultrasonic motor can be improved.