| The ultrasonic motor(USM) utilizes the converse piezoelectric effect and the friction coupling operation between stator and rotor to drive, as is quite different from traditional electro-magnetic motor. Miniature cylindrical piezoelectric ultrasonic motors play a notable part in accurate control fields for their merits of small volume, simpleness of structure and no cementation that have made them good market prospects. Hence, it is significant to explore novel structure of miniature cylindrical piezoelectric ultrasonic motors. Furthermore, drive circuit is important to exert excellent control capability of the motor.In this dissertation, a novel miniature piezoelectric ultrasonic motor of free-shaft fixed structure using circular bending vibration modes is introduced in detail. Meanwhile design scheme of miniature drive circuit of AT89C2051 micro controller unit (MCU) is described.Firstly, history of USM and research on miniature cylindrical piezoelectric ultrasonic motor is briefly reviewed, as well as the content and purpose of this dissertation. Secondly, characteristics of piezoelectric ceramic are introduced, the operation mechanism of miniature cylindrical piezoelectric ultrasonic motor is also discussed. And than, the finite element analysis (FEA) mode of stator and rotor is deduced, optimized structure dimensions of stator and rotor are calculated by FEA software. Influencing factors of stator vibrations are investigated here and helpful conclusions are made. Prototype motors are made, the input impedance and speed character tests are done, as is locked-rotor tests. Tests data indicate possible practical applications of the prototype motor.Fianlly, commonly used drive circuits of USM are summarized and a design scheme of miniature drive circuit of AT89C2051 micro controller unit (MCU) is presented. |
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