| The ultrasonic motor (USM) is a new type of working mechanism that has different construction, characteristics and operating principles than the commonly used conventional electromagnetic motor. It is a kind of motor with a completely new driving principle to obtain turning force. USM takes use of converse piezoelectric effect of piezoelectric ceramics to excite the mechanical vibration at ultrasonic range, then its rotor or slider is propelled by friction force. Compared with conventional electromagnetic motor, the ultrasonic motor has many performances and features: compactness in size, high-torque at a low-speed range, fast response, insensitive to magnetic fields, high holding torque when power is off, and so on. Since the ultrasonic motor has the good performances and characteristics that differ from those of the electromagnetic motor, it will play an important role in certain special applications. And it is becoming a new and advanced theme for study in the world.This paper mainly studied on the rotary traveling wave ultrasonic motor and its control. And the controlling system of USM is established. The basic contents are as follow:In this paper, the development of the piezoelectric ultrasonic motor at home and abroad is systematically reviewed. The important significance of the study on USM is stated. And the operating principle, classification, features and its applications are summarized in the end.Piezoelectric ceramic, the core of the piezoelectric ultrasonic motor, is systematically researched. Based on the piezoelectric effect, the piezoelectric equations are derived. Several parameters that influence the performances of piezoelectric ceramic are discussed. The operating mechanism and characteristics of ultrasonic motor are studied.Based on relevant theory of the ultrasonic motor, the author discussed the design and the working of USM at the beginning of designing of the stator. The experimental sample devices of traveling wave ultrasonic motor are designed and manufactured. And the experiment of testing the performances of USM is carried out. We testand analyze some key parameters that influence the performing characteristic of USM.The DDS technology is used to solve the driving source and control mode. A high-performance driving and controlling signal-generator is designed. And the frequency and the phase can be adjusted precisely. The projects of changing the frequency-dividing ratio or changing the accumulate step are presented. Comparing to the two projects, the advantage and the drawback are discussed in detail.For studying the characteristic of USM, the testing and controlling system of USM is established on the platform of Lab VIEW software. Combining hardware with software, the performing parameters of USM are obtained and the speed of USM is controlled conveniently by computer based on the platform. It is available for the further study of the closed-loop control of USM. |
