Investigation on azimuth effect of FOG INS multi-position alignment in magnetic field

Due to its working mechanism, characteristics of the Fiber Optic Gyro (FOG) appear to be severely affected by ambient magnetic fields. Bias sensitivity to magnetic fields is an important parameter of FOG. Internal and external magnetic fields of inertial navigation system (INS) based on FOG both can cause gyro drift error. This will bring precision degradation during alignment of INS. To eliminate alignment error caused by magnetic fields and improve the performance of INS, based on magnetic fields distribution analysis of the system, a novel multi-position alignment process which substantially utilizing rotation ability of the INS with inertial measurement unit (IMU) indexing for error modulation is proposed. Experiments on different initial azimuth indicate that the method is effective. In addition, residual alignment error is discussed.