Design And System-Level Simulation Of A Micromachined Electrostatically Suspended Accelerometer

As an inertial sensor, accelerometer is widely used in these fields such as aviation, aerospace, navigation, measuring and so on. Based on the MEMS technology, a micromachined electrostatically suspended accelerometer (MESA) has been paid more and more attention due to its advantages like high accuracy, small scale and low cost. It is becoming more and more popular in research institutions at home and abroad. The six-DOF electrostatic levitated micro-accelerometer can work by detecting the differential capacitance between the electrodes and proof mass in order to measuring the linear and angular displacements. The proof mass?s six-DOF suspension is kept stable through the balance of electrostatic forces and torques. The accelerations including three linear and three angular acceleration can be measured using the same suspended proof mass. Its sensitivity, stiffness, range and bandwidth can be flexibly adjusted due to different application environments.In this paper, the design of six-DOF suspended micro-accelerometer is illustrated. And the air damping effects are studied to optimize the damping holes of the proof mass. Besides, the models of capacitance and electrostatic forces of the accelerometer are established. Last, the system-level modeling and simulation of the six-axis suspended micro-accelerometer are performed.The main contents and results of this paper are as follows: 1. The structure and principle of the six-DOF electrostatic levitated micro-accelerometer are illustrated. Meanwhile, the dynamic models about measuring six-DOF accelerations are established. The dynamic equations of linear and angular acceleration measurement obtained lay the theory foundation for design of this high-precision six-DOF micro-accelerometer.2. The air damping effect of the six-DOF electrostatic micro-accelerometer is analyzed. In order to optimize the design of the proof mass, circular and square damping holes varying in its quantity (sixteen or twenty-five holes), dimensions and arranges to form twelve structures are used to calculate the squeeze damping coefficients of the microaccelerometer. The optimized result of the proof mass shows that the least damping coefficient of the structure is twenty-five square damping holes with rounded arrangement.3. The capacitances, electrostatic forces and torques model are settled in this paper. And every detecting electrodes? capacitance is obtained by the model. Moreover, the formulas of calculating the electrostatic forces and torques are derived. Then, the results are verified by the numerical solutions which are obtained from the finite element analysis.4. The electromechanical system models of the six-axis electrostatic suspended micro-accelerometer are established and simulated. The process-level model, physical level model, device-level model and system-level model are established in CoventorWare. Furthermore, the levitation and acceleration?s detection of micro-accelerometer are simulated by the system-level model. The modeling and simulation can provide the effective way to design the complex system of the micro-accelerometer and give the instructions to design the parameters of the micro-machining process and control systems.