Error analysis and compensation for dual-axis inertial navigation system with horizontal rotation modulation

Rotational inertial navigation system can significantly improve the navigation accuracy by rotating the inertial measurement unit about gimbals periodically. The precise calibration for installation errors and scale factor errors in rotational inertial navigation system can contribute to better navigation performance further. Especially in application requiring excellent azimuth precision, the horizontal rotation modulation will be badly required to modulate the vertical sensors' errors as periodic variation, which can make inhibiting effect on the navigation errors. However, it also enlarges the impact of specific errors, which contains gyro's scale factor error and the installation errors of inertial components. To meet the requirement of navigation precision, this paper has made error analysis and established mathematical model for a proposed horizontal rotation modulation in dual-axis rotational inertial navigation system. The crucial error parameters can be calibrated based on the measurements of attitude and velocity output without additional equipment. The results of experiment performed in an actual system demonstrate that navigation accuracy has been improved significantly, fully illustrating the significance and necessity of the calibration for specific errors in the horizontal rotation modulation.