Development of High Performance MEMS Accelerometer for Inertial Navigation

Abstract

Accelerometer is an important sensor of inertial navigation system. Focus of new developments is a low cost, small size sensor with high performance that meets the requirements of navigation. In this research work a multi wafer magnetic MEMS accelerometer design is proposed and analyzed for inertial navigation. Capacitive pick off is used to sense deflection of sensor mass and permanent magnet & coil is used for rebalancing of deflected mass of the sensor. System steady state sensitivity is 1mA/g which means that means 1mA is required to balance the force of 1 g input on the proof mass of this sensor when operated in a close loop system. System is designed to measure the input acceleration up to ±10g with resolution of 10μg. Total capacitive area of sensor is 11 mm2 with gap of 10 μm and capacitive pickoff coefficient is designed to be 6635 pF/rad. Permanent magnet with thickness of 330 μm and radius of 700 μm and soft magnet material coating is used. Out of plane coil with total 144 turns, 12 layers and cross-section area 20μm x20μm is used. Fabrication process outlines for both, the magnetic system and coils are proposed separately. Stress analysis for flexures of sensing pendulum has been carried out. Close loop frequency response analysis is carried out with a proposed PID controller.