An SOI-MEMS tuning fork gyroscope with linearly coupled drive mechanism

This paper presents a new tuning fork gyroscope structure with a highly linear coupling mechanism that keeps the phases of the drive mode oscillating masses exactly opposite with the help of a symmetrically anchored ring-shaped spring. This structure eliminates the risk of drive mode instability due to any lower frequency structural modes and provides very linear drive mode oscillations together with very low g-sensitivity. The gyroscope is fabricated with the SOI-MUMPS process of MEMSCAP. The fabricated gyroscope has bias instability and angle random walk of 200 deg/hr and 5.47 deg/Vhr, respectively, according to Allan Variance curve. The g-sensitivy and scale factor are measured as 9.3 (deg/hr)/g and 12 mV/(deg/sec) with an R² nonlinearity of 0.05%.