Noise analysis and modeling for a digital control architecture for Lissajous frequency-modulated MEMS gyroscope with amplitude-modulated readout

Abstract

We report a digital control architecture that demodulates both amplitude-modulated (AM) and frequency-modulated (FM) rate information simultaneously from a gyroscope working in Lissajous frequency-modulated (LFM) mode. The angular rate information is derived from both quadrature (X and Y) resonance modes of the gyroscope simultaneously. A noise model for the AM signal processing channel of the LFM gyroscope is built, analyzed and compared with that of a conventional AM gyroscope, which shows that methods to improve the performance of the conventional AM gyroscope can also be applied to the AM signal processing channel of the LFM gyroscope. The angular rate output obtained from the AM information of the LFM gyroscope has better noise characteristics, which therefore supplements the low precision inadequacy of the FM signal channel of the LFM mode. Tests on the same gyroscope working in different control architectures are conducted. The angle random walk (ARW) and bias instability (BI) of the AM channel of the proposed architecture are 0.51 deg √h−1 and 1.8 deg h−1, respectively, which are better than the results obtained from the FM channel in the same architecture, with values of 0.99 deg √h−1 and 4.3 deg h−1, respectively. Also ARW amd BI of the same gyroscope working in conventional AM mode is 0.50 deg √h−1 and 5.2 deg h−1, respectively.