A Dynamic Gyro Scale Factor Error Calibration Method for RINSs

In the rotational inertial navigation system (RINS), the horizontal gyro drift can be modulated when the IMU rotates around the z axis. At the same time, the scale factor error of the z gyro can be offset by forward and reverse rotation. However, in the forward and backward rotation, the gyro scale factor error will still cause the heading angle output error. Moreover, the change of the scale factor error of the fiber optic gyros(FOG) is sensitive to temperature changes, which makes it difficult to calibrate gyro scale factor error accurately. Therefore, in this paper, a method to calibrate the scale factor errors of two RINSs dynamically is proposed. During the movement of vehicle, the heading angle difference between the RINS1 and RINS2 is calculated real time, the scale factor errors of RINS1 and RINS2 could be estimated at the same time with the least squares filtering algorithm. The simulation experiments show that when RINS1 and RINS2 adopt a reasonable rotation strategy, the gyro scale factor errors were less than 0.5ppm. In the vehicle experiment, the heading angle error caused by the gyro scale factor error is kept below 5'. And the method significantly improves the problem that scale factor error affected by temperature changes during navigation process, and at the same time solves the problem of the calibration coefficient error in the dynamic situation.