Optical EngineeringFusion of finite impulse response filter and adaptive Kalman filter to suppress angle random walk of fiber optic gyroscopes
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We present a new fusion structure of finite impulse response (FIR) filter and adaptive Kalman filter to suppress the angle random walk (ARW) of the fiber optic gyroscopes (FOGs). In our proposed fusion filter, a low-pass FIR filter first decomposes the discrete-time rotation rate into an approximation part and a detailed part. The detailed part is then put into an adaptive Kalman filter, which generates an increment part to compensate the high-frequency components of the rotation rate suppressed by the FIR filter. Different from the existing adaptive mechanism that modifies the covariance matrix of the error in the predicted estimate to cover model error, our proposal adaptively modifies the state equation of the Kalman filter to give a more accurate model. Therefore, it has the ability to distinguish the high-frequency components of the rotate rate from the high-frequency ARW noise. The new fusion structure integrates the advantages of these two filters. Experiments showed that with this new proposal, the ARW of a specific FOG had been reduced from 0.03741 deg/√h to 0.00976 deg/√h when the tap order M reached 1000, and the tracking error in dynamic cases was smaller than the digital resolution of the FOG.