Design and Implementation of a Tuning-Fork Gyroscope with Low Thermoelastic Damping

This paper presents the design and implementation of a tuning-fork gyroscope with low thermoelastic damping (TED). Based on a numerical model of TED, a multiple-beam tuning-fork structure is designed with low TED in its two operation modes. A collection of electrostatic transducers are utilized to operate the tuning-fork structure. A simple yet robust one-mask fabrication process is employed to implement this gyroscope design on silicon-on-insulator (SOI) wafers. The highest measured Qs of the fabricated MB-TFGs in vacuum are 255,000 in the drive-mode and 103,000 in the sense-mode, at a frequency of 15.7kHz. Under a frequency difference of 4Hz between the two modes (operation frequency is 16.8kHz) and a drive-mode vibration amplitude of 3.0 mu m, the measured rate sensitivity is 80 mu V-pp/degrees/s with an equivalent impedance of 2.5M Omega. The calculated overall rate resolution of this device is 0.37 degrees/hr/root Hz.