Research On Modeling And Closed-Loop Control Of The Electromagnetic MEMS Torsional Micromirror

MEMS torsional micromirrors have been applied widely in many applications such as optical switches, medical imaging, high-definition projection, Optical Coherence Tomography and so on. MEMS torsional micromirrors have huge market potential and important research value, and have already attracted high attention in academia and industry from home and abroad. Taking that electromagnetic MEMS torsional micromirrors have advantages of low voltage operation and large scanning range into account, this thesis selects an electromagnetic MEMS torsional micromirror with hard magnetic properties as the research object. Combining with performance requirements in the applications based on MEMS torsional micromirror, this thesis studies on modeling and control of the electromagnetic MEMS torsional micromirror by means of theoretical analysis, finite element simulation and experimental research methods. Specific research work and the main contributions include the following aspects:1. For MEMS torsional micromirror with hard magnetic properties, use the Finite Element Method and electromagnetism theory to establish a mathematic model of the relationship between input current and output angle. According to energy transfer process of the micromirror, the mathematical model can be divided into Electric-Coils parts, Magnetic Actuator parts and the mechanical parts for torsional scanner. This thesis gives the Electro-Coils parts and the Magnetic Actuator parts of the hard-magnetic films. The Electro-Coils parts are a general model that is easy to iteratively analyze with Finite Element Method and the Magnetic Actuator is suitable for non-uniform magnetic field.2. For the MEMS torsional micromirror with physical quantities, such as electricity, magnetism, force and so on, firstly, the COMSOL Multiphysics is used to simulate the micromirror with three dimensional simulation test, and discuss the relationship between driving current and output angle under scanning the current parameters in three dimensional steady and transient coupled solution analysis. Secondly, build a laser scanning platform based on MEMS electromagnetic micromirror, main work including design voltage controlled current amplifier circuit, design data acquisition system based on FPGA. And then, test inherent frequency and open-loop performance of the micromirror. Finally, use the simulation and experimental results to verify the accuracy of established mathematical model.3. Combining fast response and accurate switch characteristics in optical switch based on MEMS micromirror, this thesis designs a variety of closed-loop control algorithm apply to the electromagnetic MEMS torsional micromirror, including PID control, the improved PID control, the sliding mode control with PD form, the integral sliding mode control with PID form. The objective is to improve the transient and positioning performance of the system. Through the comparison between simulation and experimental analysis, the system can effectively overcome the shaking of micromirror and has a better transient performance under the integral sliding mode control. It has important research value for optical switch based on electromagnetic MEMS torsional micromirror...