System-level simulation and experiment for levitation control of micromachined electrostatically suspended accelerometer

It is proposed in this paper a micromachined electrostatically suspended accelerometer (MESA) based on non-silicon micro-electromechanical systems technology. The MESA is designed in sandwich-like structure, which was composed of three main parts: proof mass, upper stator and lower stator. The system design of levitation control base on centralized control strategy is also presented which including the multiplex frequency detection way and six degree of freedom (six-DOFs) control. The control voltages reflect the input acceleration. The control with bias voltage is used for the initial levitation along axial direction for the approximate linear model can be constructed near the null position. In order to levitate the PM along Z-axis, the levitation control based on de-centralized control strategy was introduced, which was based on proportional integral derivative (PID) control for the MESA. The damping coefficient along Z-axis was calculated by analytical solution. According to the Routh criterion analysis of the characteristic equation, the scopes of PID control parameters were defined. An Achitect/Coventorware model was built to simulate the initial levitation, 10 Hz square wave time response and 0.5 g acceleration disturbance input response. The design of the control system which including detection and control modules is introduced and circuit design is also presented. Experiment show that the control principle is reasonable. The pulse input acceleration experiment and simulation also proves that the MESA can act as multi-axis accelerometer. The quick-response performance and global stability are in agreement with the dynamic simulation.