Sliding Mode Control Of Torsinal MEMS Micromirror

MEMS micromirrors have been applied in many applications such as optical switches,high definition display, optical coherence tomography, digital light projector and barcodescanner, MEMS micromirrors have attracted great attention in the academic and industrialfields. Enhanced transient performance and high positioning accuracy are required in theapplication of MEMS micromirror-based optical switches. The MEMS micromirror isrequired to precisely follow the sine or triangular trajectories for imagingapplications.Considering the requirements in the MEMS micromirror-based applications, theobjective of this thesis is to design and implement control strategies for MEMS micromirrorbased on sliding mode control (SMC) theory,the main contents are listed as follows:(1) A first-order SMC scheme and a second-order Twisting algorithm are implementedfor a2D electrostatic MEMS micromirror with sidewall electrodes. The objective is toimprove the transient and positioning performance of the system. The effectiveness of theproposed schemes is verified through MATLAB simulation and experiment based onfield-programmable gate array (FPGA) hardware. Compared with open-loop control system,the simulation and experimental results show that the closed-loop control system with theproposed schemes has better transient response and positioning performance. Compared withfirst-order SMC, the better positioning performance is achieved by using Twisting control.(2) A second-order sliding mode control scheme with integral sliding surface isdesigned and implemented for a2D electrostatic MEMS torsinal micromirror with sidewallelectrodes. The proposed2-SMC is comprised of two parts, equivalent control and switchingcontrol. The stability of the closed-loop control system is guaranteed using Lyapunov stabilitytheory. The performance of the closed-loop control system is verified though experimentsincluding set-point control, tracking control and disturbance rejection test. The experimentalresults show that the transient response, positioning and tracking performance are improvedwith the proposed scheme.(3) An integral sliding mode control is designed and implemented for a magneticMEMS micromirror. A magnetic micromirror-based laser scanning system is developed,1Dimage was obtained under the closed-loop control system. The experimental resultsdemonstrate that the proposed scheme can significantly improve the transient response ascompared to traditional open-loop control and PID control. The closed-loop controlledmagnetic MEMS micromirror follows the given sine and triangle trajectories precisely withthe proposed scheme.