A rapid testing scheme for dual-axis rotational fiber optic inertial navigation system

In response to the problem the error drift in high-precision fiber optic inertial navigation systems (INSs) after changes in the operating environment or long-term storage, which affects the self-alignment and navigation accuracy of the INS. A new pre-launch testing method is designed using the inner and outer frame rotating axes of a dual-axis rotational INS. The novel three-position alignment method inherits the advantages of traditional two-position and continuous rotation alignment methods, which can counteract or modulate gyroscope drift. At the same time, it effectively suppresses the impact of the gyroscope scale factor error on self-alignment accuracy. The four-position rapid calibration method is based on the high-precision three-position self-alignment, and it excites related error parameters using the inner and outer frame rotating axes, based on the change in the first and second-order terms of the navigation velocity error increment curve before and after the rotation of inertial measurement unit, it achieves calibration of all error parameters except for installation errors within 235 s , the total time for alignment and calibration is less than 9 mins .Simulation and physical experiment results indicate that the three-position self-alignment results are no longer affected by the upward gyroscope scale factor error, in the experiment, when the upward gyroscope scale factor error reached 200 ppm , the alignment result of the azimuth differed from the north-seeker by only 4″.The calibration results for the four-position method show that the maximum root mean square error (RMSE) of the accelerometer scale factor error is 2.58 ppm , the maximum RMSE of the constant bias is 1.69 × 10⁻⁴ m s − 2 , the maximum RMSE of the gyroscope scale factor error is 3.92 ppm , and the maximum RMSE of the constant drift is 0.0016 ∘ h − 1 .These results meet the requirements for high-precision INS and provide an effective solution to improve the navigation accuracy of high-precision dual-axis rotational fiber optic INS.