Dynamical Characterization Of Electrostatically Driven Micromirrors Under Parametric Excitation

MEMS(Micro-Electro-Mechanical System)micromirror is an optical component that scans cyclically in a one-dimensional or two-dimensional area by changing the propagation direction of the light beam.Among them,electrostatically driven micromirrors are widely used in various fields of people’s daily life because of their simple structure,low power consumption,fast response speed and high compatibility.With the rapid development of science and technology and the improvement of living standard,people also put forward higher requirements on the working performance of MEMS micromirrors.As a typical MEMS device,MEMS micromirror is a multiphysical field coupled nonlinear system with multiple nonlinear factors,which have a very negative impact on the performance of the micromirror and can even lead to the failure of the MEMS micromirror in a serious way.Therefore,it is necessary to carry out the research on the nonlinear dynamics of the micromirror system,to deeply study and master the vibration mechanism of the MEMS micromirror,and to provide guidance and theoretical basis for the dynamic design and optimization of the micromirror,so as to better improve the working performance to meet the complex usage requirements.In this paper,a one-dimensional electrostatically driven MEMS micromirror is used as the object of study,and the reliability,parametric excitation vibration and stiffness nonlinear effects of the micromirror are thoroughly studied and analyzed as follows:1.The amplitude-frequency response characteristics of the micromirror system under the main resonance are analyzed,and the effects of comb gap,excitation voltage and other factors on the amplitude-frequency response curve are studied.The actual model of the micromirror is established and the reliability of the micromirror is analyzed from both modal and stress aspects.2.In order to accurately analyze the vibration response characteristics of the micromirror system,a seventh order polynomial is used to fit the capacitance variation of the micromirror comb and establish the kinetic equations to investigate the parametric resonance problem of the system under different parameters.The influence law of the change of the micro-mirror structure parameters on the torsion angle under static condition is analyzed;the amplitude-frequency response curve equation is obtained by applying the multi-scale method to the system dynamics equation for regression analysis,and the effect law of the system parameters on the change of the resonance amplitude under resonance condition is analyzed and verified numerically;finally,the stability of the subharmonic parametric resonance of the system is analyzed and verified numerically by the Runge-Kutta method.3.In order to investigate the influence law of electrostatic force nonlinearity and stiffness nonlinearity on the nonlinear dynamics characteristics of the micromirror system,the dynamics equations of the MEMS micromirror system considering the stiffness nonlinearity are established,and the frequency response equations of the system are obtained by the multiscale method.The effects of different structural parameters such as comb gap and overlap length between combs on the polynomial fitting parameters of the electrostatic moment are studied,and the changes of the system amplitude-frequency response under different factors are analyzed.Finally,the variation of the system vibration characteristics under different parameters was studied.