Research And Development Of Control Method For MEMS Based Nir Spectrometer

MEMS based NIR spectrometer has become a research hotspot in the field of portable NIR spectrometer study.However,the MEMS micromirror,due to the characteristic change and external vibration factors,has an angular deflection which affects the performance of the NIR spectrometer after a long-term run.Moreover,the conventional control methods have difficulties in meeting the requirements of NIR spectrometer because of the variable coupling.This paper aims to research the control strategies to solve the problems above.The research background is firstly presented in this paper.In addition,the actuation characteristics of the electrothermal MEMS micromirror system are introduced,and the primary cause of the angular deflection is analyzed in detail in chapter 2.The coupling characteristics and feasible variable pairing method are analyzed through the test of driving voltage and deflection angle of the X and Y axis of the MEMS micromirror.Finally,the parameters of the transfer function model are identified based on the LSE.First of all,the relative gain analysis and the decoupling network design are carried out in chapter 3.According to the actual operating conditions of the MEMS micromirror,a modified PID decoupling control system is formed and the simulation is carried out to handle the variables coupling and disturbance of the system.In chapter 4,the disturbance observer and model predictive control are firstly described in theory.Furthermore,the compound control system based on DOB and MPC is designed with the consideration of the coupling and disturbances of the system.The simulation results demonstrate that the compound system has excellent disturbance rejection properties.The deflection angle and repeatability of the MEMS based NIR spectrometer are debugged and tested on the practical experiment test platform in chapter 5.The test results demonstrate that the deflection angle of the MEMS micromirror,which is better than the required 0.01 in the project,was controlled around 0.005 under the effect of closed-loop control system.The control methods of MEMS based NIR spectrometer designed in this paper,have excellent performance in the decoupling and disturbance rejection properties.And they provide great reference value for promoting the development of portable MEMS based NIR spectrometer.