Abstract
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.
Highlights
The rotating traveling wave ultrasonic motor is a type of micromotor that uses the inverse piezoelectric effect of piezoelectric ceramics to generate a low-amplitude high-frequency stator vibration, and the rotor is driven by utilizing the friction between the stator and the rotor.1–6 In order to design the effective friction pair on the contact surface between the stator and the rotor, a positive pressure must be applied normal to the contact interface, known as the ultrasonic motor pre-pressure (F)
Some researchers established the spatial domain analysis model of the contact interface of the traveling wave ultrasonic motor under the steady state, and on this basis, they calculated that the axial modal force caused by the pre-pressure is more than five times larger than that caused by the load
Where MS, CS, and Ks are the stator modal mass, damping, and modal stiffness, respectively; y is the stator amplitude; Δ is the electromechanical coupling coefficient that reflects the ability of the piezoelectric body to convert the electrical excitation into a mechanical response; u is the excitation voltage; and Fn is the reaction force of the stator contact interface, which is positively related to the pre-pressure
Summary
The rotating traveling wave ultrasonic motor is a type of micromotor that uses the inverse piezoelectric effect of piezoelectric ceramics to generate a low-amplitude high-frequency stator vibration, and the rotor is driven (and carries a load) by utilizing the friction between the stator and the rotor. In order to design the effective friction pair on the contact surface between the stator and the rotor, a positive pressure must be applied normal to the contact interface, known as the ultrasonic motor pre-pressure (F). Some researchers established the spatial domain analysis model of the contact interface of the traveling wave ultrasonic motor under the steady state, and on this basis, they calculated that the axial modal force caused by the pre-pressure is more than five times larger than that caused by the load. This shows that the preload plays a major role in the vibration state of the stator.. The pre-pressure influences on the no-load speed and locked-rotor torque of the traveling wave ultrasonic motor were studied. It supports the subsequent development of an adaptive pre-pressure ultrasonic motor the authors aim to develop
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
