Self-calibration of scale factor error for fiber optic gyroscope based on joint rotation modulation method of dual INS

Abstract

In a rotation modulated marine fiber optic gyroscope inertial navigation system (FOG-INS), the FOG scale factor error would couple with the earth's rotation angular velocity to produce equivalent upward and northward gyro drift error, as well as with the ship swaying and inertial measurement unit (IMU) rotation modulation angular velocity to produce short term dynamic error, which limits its long-time accuracy. A method of online estimation and self-calibration of scale factor error for FOGs is proposed based on joint rotation modulation of dual three-axis rotation modulated marine FOG-INS (DTRM FOG-INS). An observation equation is established based on the spatial angular relationship between the horizontal rotation axis of the DTRM FOG-INS to implement online estimation filtering. The results of semi-physical simulation show that the estimation accuracy of the FOG scale factor error is better than 1 ppm, and the positioning error caused by the FOG scale factor error is compensated online by using the output correction method, which effectively suppresses the growth of the positioning error of the DTRM FOG-INS. The turntable simulation experiment also verifies the effectiveness of the proposed method. The maximum positioning error of the DTRM FOG-INS is reduced by 25% and 40% respectively in the 300 hours of pure inertial navigation experiment. The algorithm is derived in earth-centered earth-fixed (ECEF) frame, therefore it is also suitable for navigation in polar regions.