Masters Thesis

Design of Mems Decoupled Gyroscope.

MEMS (Micro-electro-mechanical systems) gyroscopes are widely used as an inertial measurement unit in different industrial applications. MEMS are the device that combines mechanical and electrical components on a small silicon wafer with components sized in the range of a micro meter. Amongst all the gyroscopes available, vibratory gyroscopes are most simple in construction and are widely used. In vibratory rate gyroscope, sensitivity is achieved by reducing frequency mismatch and this is mostly done by selecting the common beam topology. However, due to the common beam, mechanical coupling effect is introduced, which might affect the overall stability of the device. Thus, this is a challenging part for a designer to achieve higher sensitivity, while maintaining stability. In this thesis a new 2-DOF vibratory rate gyroscope is proposed that has two independent axis of vibration with a mechanical coupling measure. Design includes selection of structural parameter, as well as driving and sensing topology. The structural design parameters of drive and sense beams are carefully selected so as to achieve maximum sensitivity, while reducing the overall coupling between the drive and sense mechanism. The design showed improved decoupling and sensing sensitivity. From the simulation, the displacement sensitivity is in the range of 3nm/(°/sec) and capacitance change is in the range of femto Farad. Furthermore, the angular rate table and capacitance results are provided in this paper to verify device performance.

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