Design of cost-effective reliable MEMS gyroscopes for underwater/under-ice applications

Underwater/under-ice navigation systems are dependent on the precision of the embedded inertial measurement unit. The performance of MEMS-based gyroscopes, one of the most important inertial sensors, is heavily affected by fabrication imperfection and environmental variation. In this paper we propose and optimize a new mechanical structure for Z-axis tuning-fork gyroscopes along with atmospheric pressure packaging. We have focused on, first, applying gap-varying capacitive sensing method to enhance the sensor resolution, and second, optimizing the design by modifying the location and shape of suspending frame/cantilevers as well as tuning their parameters to make the gyroscope structure more robust against fabrication variation. Our numerical analyses show that the optimized gyroscope structure is more immune to fabrication imperfection, and the proposed sensing structure is able to provide better output capacitance response to external rotation, compared to the previously published work.