Research On The Sliding Mode Variable Structure Control Of Silicon MEMS Gyroscope

Silicon micro-machined gyroscopes have been widely noticed and used because of its small size, low cost, high reliability and so on. The MEMS vibrational gyroscope is based on Coriolis effect, and the rotational rate can be obtained by measuring the sense mode vibration generated by the Coriolis acceleration. In order to ensure the precision of the MEMS gyroscope, the vibration amplitude of the drive mode should be controlled precisely. In this thesis, in order to always keep the amplitude of the gyroscope drive mode stable, the closed-loop control system based on sliding mode control method has been selected and investigated. The main contents are as follows:(1)The research status of the control methods for micro-machined gyroscopes are investigated, both the advantages and disadvantages of each method are presented and compared. The development history of the sliding mode control method is expounded and the advantages of this method are analyzed.(2)The principle and mathematical model of the silicon micro-machined gyroscope are introduced. The sliding mode surface and reaching law are designed according to the control requirement and the mathematical model of the sliding mode controller is established, whose parameters are optimized.(3)The system level simulation model is established by Simulink software, and the system function is simulated, including the convergence rate, the tracking error, the jittering of the sliding mode surface and the anti-jamming capability of the system. The simulation results demonstrate that the sliding mode controller has excellent ability to handle the instantaneous and continuous pulse noise, white noise and gain reduction.(4)The sliding mode controller is described by the Verilog language in FPGA platform. In this section, the real-time frequency tracking algorithm, the real-time phase synchronization algorithm and the integration algorithm are proposed, and the main modules are realized including the reference signal generator, the frequency tracking and the integrator, etc. The functionality of each module is verified through the Modelsim simulation software.(5)The test platform is constructed for the closed-loop system. Each single module and the whole system are tested. The test results demonstrate that the sliding mode controller designed in this thesis can well operate to control the driving mode amplitude of the gyroscope.