Controller design for a closed-loop micromachined accelerometer

This paper presents control strategies for the design of a digital closed-loop micromachined accelerometer. The microsystem is composed of a mechanical part sensitive to the external acceleration, and a fully integrated electronic part devoted to the readout and control. A feedback control approach was used from the beginning of the sensor design in order to reach a good trade-off between circuit complexity and control requirements (inputs/outputs required for identification, sampling frequency, controller order, ……). The measurement performance is linked to the closed-loop sensitivity functions and a controller design based on a pole placement method with sensitivity functions shaping is proposed. Simulation results forecast excellent performance and this identification/controller design procedure was successfully applied to an early microsensor prototype.