The development of Torque Mirror Control Method for Driving Ultrasonic Motor

点击翻译按钮获取中文摘要

We have been involved in developing ultrasonic motors (USM) for more than 15 years. Our interest is, of course, not only to propose high-powered small disc motors, but also in the optimum control system as to the application for servomotor. By this time, USM was thought to be a tough actuator to drive, because it neither promised a long life nor kept a constant speed. We have started the research about the feet and found mat the methods of control, which are commonly adopted by almost all of the researchers and manufacturing companies, are unstable and incorrect. They failed to lock the motor to the correct state of resonance, which caused lack of stability and short life. In this study, we have developed perfect PLL (Current phase lock of the motor) driver, and realized constant current or voltage controller simultaneously. With the aid of this circuit, we were able to measure static characteristics of the USM prototype under constant current mode, and discovered the simple and strange phenomena of speed reduction under relative small load torque, which helped us to propose a new sliding theory of friction plate. We also found that, as for as operated in certain small range of torque load, the life of the motor is almost unlimited. In this report, me process of the study during the period of the grant is disclosed, and the theoretical backgrounds in our past papers are referred. It is also basically important, even if this technology is not applied to any motor products right now, to show how to design an excellent USM and actual control circuit board in detail. Finally, we hope it will help all the researchers to improve the motor efficiency and to build a perfect servo system by themselves.