Longitudinal And Torsional Characteristics Of The Composite Type Ultrasonic Motor

The ultrasonic motor (USM) is a new type of motor that has been developed in recent twenty years. It's different from traditional electromagnetic motors in principle. Ultrasonic vibration is excited by the converse piezoelectric effect of piezoelectric materials and magnified by the elastic body. With the friction coupling, the rotation of the rotor or moving of the slider is generated. USM is characterized by the low speed, high torque, simple structure and directly load-driving. It isn't disturbed by the electromagnetic field. USM can carry out self-holding without electric power. All of these characters make USM practical applications in some special areas. USM has various forms. Only traveling wave type USM achieves industrialization and has fully designing theory. Others are in application in small-scale or in the phase of experiment and exploring.The important direction of USM's development is realization of large torque. At present the research of USM with torque more than INm has been done mainly in Japan. This kind of USM has prospective application background. But our country hasn't been succeeded in this area. In this thesis, we analyze the designing method and measure and control of character of longitudinal-torsional composite USM with large torque systematically.The research work and achievements of this thesis are as following:1. Introducing the development, the history of USM in the world and the characteristic of USM and the general application of USM in other countries; stating the meaning and content of this thesis.2. Analyzing the mechanics of exciting elliptical vibration locus of material particles, the excited modes of USM, the contact condition of friction section.3. Introducing the theoretic background for the FEA of the mode and the resonance frequency, the FEA software ANSYS and the procedure of modal analysis; setting up FEA model for longitudinal and torsional mode analysis; analyzing the effect of different structures and sizes on the longitudinal and torsional resonance frequency of hollow cylinder; presenting measures for improvement; summarizing possible methods for modalmodal matching of the longitudinal and torsional vibration, which may help to design the structure of USM.4. Designing the universal measure and control system of USM; introducing the general design principle and structure of system, then each specific part; finally experimenting with this system by testing characteristic of USM and concluding that the system's availability.5. Analyzing characteristics of USM, which include precise positioning, dynamic character and stepping character; in the research of precise positioning, discussing the choice of DELTA 1, DELTA2 and length of step based on the theory and experiment, and ensuring the positioning of USM of 0.025 degree; in the research of dynamic character, analyzing the dynamic performance, which proves that the longitudinal-torsional composite USM have character of rapidly transient response and the turn-off time is less than starting time; in the research of stepping character, analyzing the relation between dynamic performance and stepping character.The torque of USM has reached 8N.m, and the positioning of USM is within 0.025 degree. These achievements prove its advancement in our country.