| With the continuous development of industrial manufacturing technology,the demand for precision manufacturing and processing technology is increasing.As a kind of precision actuator,piezoelectric actuator has the characteristics of simple structure,large stroke and no electromagnetic interference,etc.,and has been widely studied in the fields of precision machining,biomedical,semiconductor manufacturing,optical focusing,and testing of micro-mechanical properties of materials.Due to the limitation of current driving methods of piezoelectric actuators,it is necessary to increase the amplitude of the driving waveform to increase the speed of the actuator,which will lead to greater vibration of the actuator in the process of motion,and the life of the piezoelectric element will be greatly affected under the high frequency and high amplitude waveform excitation.In order to ensure that the piezoelectric actuator can achieve high speed under the excitation of small voltage waveform,and to improve the service life of the piezoelectric element and the stability of the actuator,the idea of DCUltrasonic compound is proposed in this paper.This paper introduces the basic theory of piezoelectric actuator and gives the basic calculation formula of piezoelectric stack and flexible hinge.The characteristics of the DC driving waveform and the ultrasonic driving waveform are analyzed,the mathematical model of the coupled driving waveform is established,and the realization mechanism of the coupled driving waveform and the piezoelectric stack driving mechanism are expounded.The friction characteristics of the driving foot and the guide rail under three friction states were studied in depth,and the change law of the displacement,pressure and friction between the driving foot and the guide rail during the driving process were revealed,and the cause of motion of the actuator was explained.Furthermore,the coupled DC-Ultrasonic waveform,the piezoelectric stack driving mechanism and the contact friction mechanism of the actuator were compound,and the realization scheme of the DC-Ultrasonic compound driving method was proposed.A prototype model of the compound actuator was developed,the characteristics of the compound driving method were analyzed,and the working principle of the actuator was explained in detail.The static simulation analysis of the stator driving foot is carried out by using the finite element simulation method.The deformation and displacement movement law along the coordinate axis were studied,and the stator,stator-guide modes were simulated respectively,and the optimal driving frequency range was obtained under the excitation of the ultrasonic driving waveform.The experimental performance test system was built under the coupled waveform excitation of the actuator,and the basic characteristics of the actuator were tested.The test results show that the maximum output speed of the actuator is 70.26 mm/s,and the maximum thrust of the actuator can reach 1.36 N,and the adjustable output of the load force of the actuator can be realized by adjusting the DC voltage.In addition,the paper further studies the realization method of bidirectional microdisplacement of the actuator,and realizes the optional output of the excitation waveform by controlling the signal acquisition board card with Lab VIEW software.The feasibility of the bidirectional micro-displacement motion of the actuator is verified by the excitation of sine wave.The bidirectional micro-displacement testing system of the actuator was built,and the bidirectional micro-step displacement characteristics of the actuator were tested by using different types of DC driving waveforms.The bidirectional test results show that the optimal forward and reverse step distances of the actuator are 13 nm and 23 nm respectively,which verifying that the actuator can achieve high precision micro displacement under the condition of open loop. |
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