A Novel Compensation Method for Eliminating Precession Angular-Rate Bias in MEMS Rate-Integrating Gyroscopes

The structural asymmetry of the MEMS rate-integrating gyro (RIG) mode produces a threshold and an angle-dependent bias (ADB) that cause gyroscopes operating in this mode to stop working at input rates below the threshold and degrade the linearity of the output angle. This defect in the RIG output angle is actually caused by a precession angular-rate bias that results from both damping asymmetry (anisodamping) and stiffness asymmetry (anisostiffness). This paper describes a novel compensation method based on Fourier series fitting combined with a multiple iteration technique. The proposed compensation method can significantly reduce both the input rate threshold and ADB. Simulations indicate that the threshold and ADB caused by anisodamping and anisostiffness can be reduced by three orders of magnitude. An experimental application of this method produced a MEMS RIG threshold as low as 0.05 degrees per second, representing an improvement of two orders of magnitude and lower than has previously been reported.