Improving the Measurement Accuracy of SINS Through Calibration on Horizontal Three-axis Turntable

Abstract

To optimize the systematic calibration of strapdown inertial navigation system (SINS), this paper derives a systematic calibration model according to the relationship between IMU's errors and velocity errors output by navigation algorithm of IMU. Then, the advantages of horizontal three-axis turntable (3AT) where IMU errors are calibrated were utilized to decouple the mounting misalignments of the IMU, and an equal interval rotation test plan was designed to provide 16 rotation stimuli for the IMU. On the basis of it, the three sets of coupling relations of IMU's mounting misalignments were decoupled, and the systematic calibration model was applied successfully in identifying 21 errors, including scale factor errors, biases and mounting misalignment. The simulation results show that, when the accelerometers and gyros in the IMU were at the accuracies of 10μg and 0.01/h, respectively, the uncertainty of the accelerometer biases was 3.6g and of the gyro's biases was 0.004/h. Finally, a 24h pure inertial navigation simulation was conducted in static positions. The attitude errors of systematic calibration are 6 in the x-and y-directions, and 2.2 in the z-direction, respectively, the maximum velocity error of systematic calibration was smaller than 0.3m/s. These results fully demonstrate the effectiveness of the systematic calibration method for the IMU calibrated on horizontal 3AT. This method suppresses the effects of turntable errors, and enhances the calibration accuracies of IMU.