A self-calibration method based on the observation of sawtooth type velocity errors in dual-axis rotation-modulating INS

In order to restrain the velocity error and improve the navigation precision of dual-axis rotation-modulating INS, the effect of calibration error during one modulated period is analyzed and the `observable´ of the calibration error by the sawtooth type velocity are pointed out. A self-calibration method for dual-axis rotation-modulating INS is brought out, and a calibration rotation sequences is designed base on the discussion of sawtooth type velocity. The method can estimate the gyroscope and accelerator scale factor error and the misalignment in short startup time and the estimate precision is respectively less than 4ppm and “7” in simulation experiments. Laboratory experiment results indicate that the calibration method restrain the sawtooth type velocity error effectively and achieve the navigation requirement of 1nmile/24h, which is valuable in engineering for improving the navigation precision and reducing the startup time of dual-axis rotation-modulating INS.