Research On A Longitudinal-bending Hybrid Stepping Piezoelectric Actuator And Its Control System

Compared to traditional electromagnetic motors,piezoelectric actuators can easily achieve fast precision positioning with simple structure.In addition,their characteristics wouldn't be changed,when the working environments are full of electromagnetic interference.Because of those advantages,piezoelectric actuators are favored and have been widely used in the field of precision driving.In recent years,the researches on piezoelectric actuators continue to be deepen as the requirements for the precision driving equipment continue to increase.At present,one of the key research directions of piezoelectric actuators is to achieve large stroke with nanometer positioning.The structures of piezoelectric actuators,the power supply and the control methods would affect the positioning accuracy of the piezoelectric actuators.Therefore,the studies of piezoelectric actuators and their control systems are meaningful.Firstly,a new type of stepping piezoelectric actuator is proposed in this paper.The piezoelectric actuator is mainly composed of two longitudinal-bending hybrid transducers and one runner.Based on the structure of the piezoelectric actuator,the driving principle is analyzed in detail.The longitudinal motions of the transducers are used to lock the runner,while the bending motions of them are used to drive the runner linearly;The four exciting signals are applied on the two transducers are analyzed,and the phase shifts among the four signals are used to control the movement direction of the runner.The finite element models of the transducers were established.The modal simulation and static simulation of the transducers were performed.The structural parameters of the transducers were optimized and established,and the operating principle of the piezoelectric actuator was further verified.In order to test the charactristics of the piezoelectric atuator,a prototype was assembled.Secondly,according to the stepper piezoelectric actuator proposed in this paper,a driving power supply has been developed.The power supply includes the DC voltage stabilizing circuit and the linear amplification circuit.The DC voltage stabilizing circuit and the linear amplification circuit were designed and simulated respectively.The circuit board and the power supply were manufactured.The performances of the power supply were test.The results show that the power supply can output 4 signals with amplitude,frequency,and phase adjusted independently,and the ranges of the amplitude,frequency and phase shifts are-200V~+200V,0~1k Hz and-?~+? respectively;Its ripple is tested to be lower than 200 m V;and its linearity is lower than 0.5%,when the input voltage is lower than 9V.Thirdly,in order to test the characteristics of the piezoelectric actuator and the closed loop control motion of the piezoelectric actuator,a control system is set up.The control system includes hardware and software parts.The hardware part is composed of one upper computer,one lower computer,one DAQ of PCI1716,one DAQ of PCI 1721,one displacement sensor,one power supply and one piezoelectric actuator.For the software part: the communication method of the upper and lower computer were set up;a DOS system disk with USB flash disk boot was made;the driving programs of PCI1716 and PCI1721 were written;and the open loop and closed loop controls were programed based on the MATLAB Simulink Real-Time platform.Finally,based on the work as described above,the output characteristics of the two transducers were tested.The results show that the displacement repeatability of them is good,and the operating principle of the piezoelectric actuator is further verified by the test data.The output characteristics of the piezoelectric actuator were tested.The results are analyzed: a long travel motion with nanometer resolution of 30 nm is achieved;the maximum speed is tested to be 720.650 ?m/s,when the frequencies of the excitation signals are 60 Hz;and the maximum thrust is tested to be about 15 N.The PID control experiments of the piezoelectric actuator were carried out,which included the test of positioning accuracy and the test of sinusoidal displacement curve tracking.The positioning accuracy of the piezoelectric actuator is tested to be ±50 nm,and the piezoelectric actuator has a good dynamic tracking characteristic.