| 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 a practical application 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 prosperous application background. But our country hasn't been succeeded in this area. In this thesis, we analyze the designing method and manufacture, 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. Introduce the development and characteristic of piezoelectric materials, especially Introduce the history of USM in the world. The characteristic of USM and the general application of USM in other countries. State the meaning and content of this thesis.2. Compare the longitudinal-torsional composite USM with the traveling wave type USM completely. Analyze the mechanics of exciting elliptical vibration locus-of material particles, the excited modes of USM, the contact status of friction section, and designing and controlling methods of the two kinds of USM.3. Introduce the math model of longitudinal-torsional composite USM, which give the relationship between physical dimensions and the resonance frequency. Analyze modal matching of the longitudinal- torsional composite USM and the effect of structure of USM on resonance frequencies. The general rules of the realizing modal matching by changingthe structure of composite USM is sum up. At last, the designing method of stator of the longitudinal-torsional composite USM has been set up.4. The measure and control system of USM is designed, which is universality on the application of USM. First introduce the design principle and structure of system, then stress each part of hardware and each module's fuction and its performance process of software. Finally, we experiment with this system by testing characteristic of USM, and conclude that the system is availability.5. Analyze characteristic of USM which include orientation precision, dynamic character and mechanical character. On the research of orientation precision, discuss the choice of DELTA2 and length of step based on the theory and experiment, ensure that the orientation precision of USM within 0.025 degree. On the research of dynamic character and mechanical character, we have a lot of theoretic analysis and testing experiments, which prove that the longitudinal-torsional composite USM have character of rapidly start and rapidly turn-off, and the turn-off time is less than starting time. The starting time is about 6-8 millisecond, and the turn-off time is about 2-4 millisecond.The torque of USM which we developed has reached 8.5 N.m, the orientation precision of it within 0.025 degree. In our country, at present, these achievements keep ahead. |
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