The development of Torque Mirror Control Method for Driving Ultrasonic Motor

我们从事超声波电机（USM）的开发已有15年以上的历史。当然，我们的兴趣不仅是提出高功率的小型盘式电机，而且还在于用于电动机的最佳控制系统。到这个时候，USM被认为是一个坚韧的驱动器，因为它既没有承诺长寿命，也没有保持恒定的速度。我们已经开始了对脚的研究，发现几乎所有的研究人员和制造公司普遍采用的控制方法是不稳定和不正确的。他们未能将电机锁定在正确的共振状态，导致稳定性差，寿命短。在本研究中，我们开发了完善的锁相驱动器，并同时实现恒流或恒压控制。借助该电路，我们能够在恒流模式下测量超声波电动机样机的静态特性，并发现在相对较小的负载转矩下速度降低的简单而奇怪的现象，这有助于我们提出一种新的摩擦片滑动理论。我们还发现，对于运行在一定的小范围内的转矩负载，电机的寿命几乎是无限的。本报告介绍了课题组在研究期间的研究过程，并参考了以往论文的理论背景。即使该技术目前还没有应用于任何电机产品，但详细展示如何设计优秀的USM和实际控制电路板也是非常重要的。最后，希望能对广大研究人员提高电机效率，自行研制完善的伺服系统有所帮助。

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.