| The driving device of MOEMS micromirror is the key part of the system,the modulation of intensity and phase of incident light and the gating of optical path can be realized by applying different driving device.The present driving modes for micromirror can be divided into piezoelectric,electromagnetic,electricheating and electrostatic actuation.All of these driving modes need to be connected by wires and excited by electromagnetic,so it is vulnerable to electromagnetic interference and can not be operated in an isolated environment.Therefore,it is very significative for the research on light-activated micromirror drived by PLZT ceramic and control strategy of optical excitation.Compared with the traditional actuator of micromirror,the light-driven micromirror using PLZT ceramic does not require hard-wire connections to extra power,and have advantages of clean driving,remote light-driven and free from electromagnetic interferences.Therefore,the light-driven micromirror is suitable for remote non-contact control in an isolated environment,such as the clean operating space and vacuum environment.In this paper,the non-conatct closed-loop control for micromirror device can be realized by the photo-induced characteristic of PLZT ceramic,The new driving mechanisms are designed for the application of PLZT ceramic in the translation and rotation mechanism of micromirror respectively.The closed-loop servo control model of the proposed driving mechanisms can be deduced based on multi-physics fields coupling model of PLZT ceramic,then the simulation analysis and experimental verification will be implemented.The coupling relationships of multi-physics fields of PLZT ceramic is explained on the basis of the mechanism analysis of the anomalous photovoltaic effect,the pyroelectric effect and piezoelectric effect of PLZT ceramic,which is irradiated by ultraviolet light.The mathematical modeling of multi-physics fields coupling of PLZT ceramic are established during illumination and light off phases.On the basis of the discussion of structure selections for light-activated micromirror,the overall design scheme of micromirror is given.The key parameters of translation agency,such as stiffness,actual amplification and natural frequency are analyzed and calculated.on the base of which,the geometrical parameters of translation agency are determined,and the finite element analysis method is used to analyse the mechanical characteristic.The rotation angle of photovoltaic-electrostaic hybrid actuated micromirror is derived,and the relationship between rotation angle and photovoltage of PLZT ceramic is researched.The closed-loop control theoretical model of the photo-induced micro displacement of PLZT ceramic,the deflection of PLZT/PVDF laminated cantilever beam and the photovolatge of PLZT ceramic can be duduced based on the mathematical model of photo-induced multi-physics coupling fields,respectively.The mathematical simulation of the proposed driving mechanisms is conducted by MATLAB sortware based on ON-OFF control strategy.The simulation results show that the closed-loop servo control of micromirror driving device can be realized by applying ON-OFF control strategy to the PLZT ceramic and the noval composite driving mechanism based on PLZT ceramic.Experimental researches for the photo-induced micro displacement closed-loop control of PLZT ceramic,the deflection closed-loop control of PLZT/PVDF laminated cantilever beam and the photovoltage closed-loop control of PLZT ceramic are implemented,respectively.The experimental results show that the photovoltage and photo-induced deformation of PLZT ceramic can be controlled by ON-OFF control strategy with a high dynamical control precision,and a large displacement output can be obtained by the PLZT/PVDF laminated cantilever beam composite driving mechanism.Thus the proposed novel optical control driving mechanisms are feasible and the control strategies are effective. |
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