Suppressing the mechanical quadrature error of a quartz double-H gyroscope through laser trimming

In this paper, we introduce a z-axis quartz gyroscope using a double-H tuning fork, which has a high sensitivity. However, it also causes a large mechanical quadrature error. The laser trimming method is used to suppress this error at quartz level. The trimming law is obtained through the finite element method (FEM). A femtosecond laser processing system is used to trim the gold balancing masses on the beams, and experimental results are basically consistent with the simulated ones. The mechanical quadrature error is suppressed by 96%, from 26.3° s^-1 to 1.1° s^-1. Nonlinearity changes from 1.48% to 0.30%, angular random walk (ARW) is reduced from 2.19° h^-1/2 to 1.42° h^-1/2, and bias instability is improved by a factor of 7.7, from 197.6° h^-1 to 25.4° h^-1.