Research On Multi-degree-of-freedom Ultrasonic Motor Based On Bending Vibration

Multi-degree-of-freedom ultrasonic motor is a new type of motor which developed on the basis of single-degree-of-freedom motor. It has a wide application prospect in medical equipment,precision equipment, monitoring equipment, robots and other fields. However, there is still a lack of systematic research. In the view of existing problems, the paper presents a multi-degree-of-freedom ultrasonic motor which is based on the bending vibration of four rectangular structure vibrators, and the main research contents are as follows:The research status of multi-degree-of-freedom ultrasonic motor is classified and summarized.The characteristics of motors are analyzed and the content of the research is determined.Starting from the movement track of the driving foot, a multi-degree-of-freedom ultrasonic motor based on the bending vibration of rectangular structure is presented in this paper. The stator of the motor is ‘ten'- shaped structure, which is composed of four rectangular vibrators. The vibration of each vibrator is excited by the bending vibration of the ceramic plate, and the rotor of the motor is rotated in any direction by using the compound of the two direction.The model of the stator is established, and three required modes of the stator are found by means of modal analysis. The harmonic response analysis of the stator is carried out, and the amplitude of the driving foot is compared when the vibrators do bending vibration and the longitudinal vibration. The results show that the amplitude is larger when the rectangular structure do bending vibration. Through the optimum design of the stator structure, the mode frequency difference is reduced to less than 50 Hz, and the structural parameters of the motor are determined.The requirements ideal clamp should meet are analyzed, and the ‘mechanical drift'phenomenon of the flexible clamp is studied. The experimental results show that the ‘drift' is obviously relieved by using the straight beam clamp. The clamp of the multi-degree-of-freedom ultrasonic motor is designed and improved. The straight circular flexible hinge is finally adopted.The whole design of the motor is made, and the experimental study is carried out. The experimental results show that the motor performance is good. Under the voltage of 400 V, the speed of the rotor can reach 0.27r/s when two vibrators are driven and the speed can reach 0.41r/s when four vibrators are driven. The motor has a simple structure and fast output speed, so it has good application prospect.