Multi-Degree of Freedom Tuning Fork Gyroscope Demonstrating Shock Rejection

This paper presents a z-axis MEMS tuning fork rate gyroscope with multi-degree of freedom (DOF) sense modes designed to provide structural robustness to environmental drifts. This concept combines the temperature robustness of multi-DOF sense modes with the common mode rejection capabilities of tuning fork architectures. The device consists of an antiphase actuated 2-DOF drive mode where each drive mass contains a 2-DOF sense mode, thus forming an overall 6-DOF mechanical system. The flat gain region of the 2-DOF sense mode provides immunity to both environmental variations and fabrication imperfections, while the anti-phase forcing of the drive mode induces an anti-phase Coriolis response allowing for the cancellation of common mode inputs such as ambient vibrations. Impulse responses were used to characterize the effect of acceleration loads on the device where a differential signal resulted in 14 dB of reduction in amplitude versus a single output.