Laterally oscillated and force-balanced micro vibratory rate gyroscope supported by fish hook shape springs

A new concept micro vibratory rate gyroscope supported by fish hook shape springs, where the oscillating position sensing and force balancing take place on the wafer surface, has been developed. The gyroscope consists of: a grid-type planar mass; LT shape position sense electrodes for detecting the Coriolis motion; pairs of force-balancing electrodes to improve the linearity and dynamic range; prominence shape comb-drive electrodes to improve the resolution by increasing the oscillating displacement; fish hook shape springs to match the first and second modes with the mass oscillating and position sensing modes, respectively. Due to the relatively high stiffnesses of the proposed fish hook shape springs except in the desired directions, the gyroscope tends to be quite insensitive to the environmental vibrations or shocks, maintaining the electromechanical stability. It also features that the resonant frequencies associated with lateral vibration modes are not likely to be varied by the change in thickness of the poly-silicon structure, which guarantees the uniform sensitivity of products. Experimental results show that the gyroscope has the resolution of 0.1 degree per second at 2 Hz, the bandwidth of 100 Hz, and the dynamic range of 90 degree per second.