A 0.035°/h Quad-Mass Gyroscope With an Initial Frequency Difference Operating Under Mode Matching

Abstract

For MEMS (Micro-Electromechanical System) Coriolis vibrating gyroscopes, mode matching provides exceptionally high mechanical sensitivity. Typically, mode-matching gyroscopes require a completely symmetrical structure, resulting in two identical degenerate modes from a dynamics perspective. However, this requirement imposes strict demands on manufacturing precision. This letter introduces a quad-mass gyroscope with an initial frequency split, which relaxes the symmetry requirements of the micro-manufacturing process while maintaining high performance. The proposed design features an ultra-strong, quasi-linear tuning capability achieved through bias voltage and a differentiated design for the drive and readout comb capacitors. These innovations minimize mechanical noise and maximize capacitive gain sensitivity. Additionally, direct current bias voltage is applied to suppress quadrature errors caused by torsional stiffness. This state-of-the-art design achieves a low-noise, low-demodulation-error quad-mass gyroscope, capable of detecting angular rate thresholds as low as 0.001°/s. Experimental results demonstrate a bias instability of 0.035°/h, as indicated by the Allan variance curve, and an angular random walk noise of 0.0093°/ $\surd $ h. Beyond its superior performance, this design effectively mitigates micromachining process imperfections, making it highly suitable for mass production.