Research On The Electrostatic Force Closed-loop System Of High Precision Micro-optical Accelerometer

The accuracy of traditional micro mechanical accelerometer cannot meet the needs of high precision, and the accuracy of the emerging MOEMS accelerometer has been greatly improved while the dynamic range is too small which limits its application, therefor a closed-loop feedback control scheme based on MOEMS accelerometer was designed in this paper to improve its dynamic range in the premise of ensuring high sensitivity.Firstly, we introduced the structure and working principle of the open loop system of the MOEMS accelerometer and then gave the output of the system through which we knew the sensitivity of the system was greatly improved and the horizontal crosstalk was also effectively suppressed. After that we analyzed the contradiction between the sensitivity and the dynamic range of the open loop system and proposed the scheme design of the closed loop structure of MOEMS accelerometer, meanwhile the point was raised that the closed-loop feedback control is realized through static electricity which leads to the study of open-loop and closed-loop capacitive accelerometer.In this paper, the structure and electrostatic actuation of the open-loop capacitive accelerometer were analyzed and simulated which illustrated the low-pass feature of structure and the unstable point of electrostatic actuation. Then the dynamic output of the open loop system was obtained by Simulink simulation; Mathematical model of the closed loop capacitive accelerometer was carried out and the dynamic output results were obtained by Simulink simulation. Compared with the open loop system, the closed loop system can effectively improve the dynamic range and working bandwidth of the system. Finally, the closed-loop system of capacitive accelerometer was designed and simulated by Pspice whose results illustrated that the feedback loop adopted with electrostatic was feasible which lay the foundation for the later experiment and pave the way for transplanting the closed loop module into the existing MEOMS system in the future.