Research On Principle And Driving Performance Of Opto-electrostatic Torsional Driving Based On PLZT Ceramic

Micro(small)precision drive technology is the key technology in the development of micro,fine and advanced technology industries such as Micro-Electro-Mechanical System(MEMS)and Micro-Opto-Electro-Mechanical Systems(MOEMS).Traditional driving methods such as electrostatic drive,piezoelectric drive,electrothermal drive and electromagnetic drive generally have the defects of wire connection,external excitation power,poor independence and electromagnetic interference.Compared with the traditional drive methods,the opto-electrostatic hybrid driving method based on lanthanum-doped lead zirconate titannate(PLZT)ceramic has the advantages of without external excitation electromagnetic source,no electromagnetic interference,remote light control and wireless energy transmission,which is suitable for remote non-contact operation in vacuum independent environmental space or closed clean environmental space.In this paper,taking the application of the opto-electrostatic hybrid driving method based on PLZT ceramic in the field of micro drive as the background,the theoretical analysis,simulation analysis and experimental verification are used to investigate the multi-physics fields coupling of PLZT ceramic under the excitation of light source and the influence of the external physical field,one opto-electrostatic torsional driving method based on PLZT ceramic is proposed,the analysis of the mathematical model and feasibility of the driving method,the driving performance are carried out,and the influence of factors including light source and size on the driving performance is experimentally verified,the closed-loop control of the opto-electrostatic torsional driving is studied in the end,it is intended to provide theoretical reference for the application of light-controlled smart material PLZT ceramics in engineering fields such as micro-drive.The mechanisms of anomalous photovoltaic effect,pyroelectric effect and piezoelectric effect of PLZT ceramic are revealed under the excitation of ultraviolet light source with wavelength of 365 nm,and the mathematical model of multi-physics fields coupling of PLZT ceramic in the stages of illumination and light stop is established.Based on the theoretical analysis of the photon energy of PLZT ceramics,a multi-physics fields coupling model including an applied bias electric field is proposed and verified experimentally;the experimental results show that the bias electric field does not affect the photo deformation of PLZT ceramic during the light illumination stage and light stop stage,which further verifies the accuracy of the proposed model.Combined with the light source excitation scheme,the opto-electrostatic torsional driving method based on PLZT ceramic is proposed.Taking the electrostatic drive torsion arm structure as the driving load,the opto-electrostatic torsional driving modes based on PLZT ceramic single-chip and bimorph are determined;and the dynamic response of the opto-electrostatic torsional driving mode based on PLZT ceramic single-chip is analyzed.The mathematical model of the opto-electrostatic torsional driving voltage,torsion angle,driving deformation are established;according to the size parameters of the opto-electrostatic torsional actuator,the driving voltage when the actuator reaches the critical state is calculated.On the basis of the static photovoltage of PLZT ceramic and its electrical model,the curves of the driving voltage and the driving deformation of under different light intensities are obtained by numerical calculation and simulation analysis;meanwhile,the finite element simulation of the stress and natural frequency of the actuator in critical and stable states is carried out,and the validity and reliability of the opto-electrostatic torsional driving method are verified.Based on the electrical model of PLZT ceramic,the equivalent electrical model of opto-electrostatic torsional driving method is established,and the expressions of the opto-electrostatic torsional driving voltage and the time constant are derived.The opto-electrostatic torsional actuator is fabricated with polymethyl methacrylate(PMMA)and copper foil,and an experimental platform for driving performance is built.According to the equivalent electrical model of the opto-electrostatic torsional driving method and the experimental results,the variation rule of the driving voltage and output deformation of the opto-electrostatic torsional actuator with time under different light intensities is obtained;the results show that there is no hysteresis phenomenon between the driving voltage and the output deformation of the opto-electrostatic torsional actuator,so the actuator has faster response speed.The correctness of the mathematical model of the opto-electrostatic torsional driving is verified by comparing the theoretical and experimental curves of the output deformation of the opto-electrostatic torsional actuator.The variation rule of driving performance under different loads is tested experimentally,the results show that the smaller the length of copper foil,the larger the driving voltage and the slower the response speed.Based on the mathematical model of the opto-electrostatic torsional driving,the influence of the size of PLZT ceramic and the load,the different positions of the copper foil and other factors on the opto-electrostatic torsional driving performance is analyzed theoretically and experimentally.According to the analysis results,when the PLZT ceramic with a larger size is used as the driving source under the same polarization condition,the driving voltage and output deformation of the actuator are larger and the response speed is faster.When the length of the torsion arm increases or the width decreases,the output deformation of the actuator will increase,but the driving voltage and response speed remain unchanged.When the plate space decreases,the driving voltage decreases and the response speed increases,the electrostatic force and the output deformation need to be specifically analyzed.The driving voltage and response speed will not change with the change of copper foil position,but the output deformation when the copper foil is attached on the left side is smaller than that when the copper foil is attached on the right side.Based on the driving characteristics of the opto-electrostatic torsional driving method,taking the driving voltage and the output deformation of the opto-electrostatic torsional actuator as the control object,the principle of the closed-loop control strategy is studied.The ON-OFF closed-loop control theoretical model of the driving voltage of the opto-electrostatic torsional actuator is constructed,and the parameters of the control model are identified,the driving voltage and the output deformation expressions of the actuator in the illumination stage and the light stop stage under different light intensities are obtained respectively.According to the on-off closed-loop control simulation process,the closed-loop control simulations under different target voltages and different target deformations of the opto-electrostatic torsional actuator are carried out respectively.The results show that the closed-loop control of drive voltage and output deformation have good control effect,which verifies the effectiveness of the proposed ON-OFF control strategy.This study verifies the feasibility of the opto-electrostatic torsional driving method based on PLZT ceramic,and demonstrates the driving principle and driving performance,laying a foundation for the application of PLZT ceramic in engineering fields such as MEMS and MOEMS.