MEMS Capacitive Accelerometer Using Close Loop Methodology

Abstract

This project is the analysis summery of close-loop MEMS Accelerometer. It describes its modeling, simulation result and analysis. In general, we are using the MEMS Accelerometer are of open loop type because it is low cost low performance inertial sensor. But it’s Operating Range, Bandwidth, and Stability to parametric change towards its surrounding environment and Accuracy is less which resists the operators to use it for wide range of operation. So the close-loop accelerometer comes in the picture. Aerospace, missiles and navigation systems generally choose the close-loop configuration because of its accuracy and precise output with respect to the open-loop accelerometer. The purpose of this project is to simulate the close-loop arrangement of MEMS Capacitive accelerometer in MATLAB/Simulink and study its performance. The movement of the seismic mass of accelerometer is examine by the commercially achievable capacitance measuring integrated circuit (MS3110 IC). The output of the capacitance measuring IC is fed to the actuation figure which is used for the self-test purpose for the MEMS structure which generates the restoring force to the proof mass which brings back the proof mass to its nominal position. The feedback voltage is supply to the to the MEMS structure for self-test reason to operate the sensor in the close-loop arrangement. In Spite of restoring force take the Proof Mass to its mean position but the restoring force or “Electrostatic Force” is directly related to the square of the voltage generated by the capacitive measuring IC, so that nonlinearity is existing in the frame. So for deal with this nonlinearity controller tuning is as a difficult task. In this project the close-loop configure is simulated and analyzed in ±1g acceleration range.