Study on nonlinear error calibration of fiber optical gyroscope scale factor based on LSTM

•The coupling effect of input velocity and temperature is considered.•A new fast calibration method is established.•LSTM is used to comepensation the nonlinear error.•The calibration time is shortened by 30% while the angle measurement error is reduced by 70%. The calibration accuracy of the inertial navigation system (INS) has a non-negligible effect on its actual navigation performance. As the core component of the INS, the scale factor error of the fiber optical gyroscope (FOG) is one of the main error sources of the INS, which has a vital impact on the navigation accuracy. Generally, the scale factor of FOG is considered to be a constant value, but with the increasing demand for the accuracy of FOG, the scale factor error can not be ignored, how to calibration the FOG scale factor at different input velocity rates and temperature has attracted people's attention. The traditional calibration methods usually select several fixed temperature points and input velocity points, then the scale factor error is compensated by linear fitting or piecewise fitting. In order to improve the calibration accuracy, our paper considers the coupling effect of input velocity rate and temperature and designs a calibration experiment at continuous input velocity rates and temperature, the calibration time is shortened by 30%, then we propose a nonlinear error compensation method based on the LSTM. The experimental result shows that the std error of the FOG scale factor is reduced from 280 ppm to 13 ppm and the angle measurement error is reduced by 70%, which verify the effectiveness of our method.