Analysis on the influence of three-axis turntable nonorthogonal error on gyro calibration of SINS

Calibration accuracy of the inertial navigation system (INS) has a great influence on navigation accuracy of the inertial navigation system. Currently the turntable being used has reached a high accuracy, the three axis turntable coordinate system is usually regarded as orthogonal coordinate system referenced by gyro misalignment, so the nonorthogonal error of turntable is not taken into account in the calibration. In this paper nonorthogonal error factors of the three-axis turntable are detailedly analyzed, and the orthogonal coordinate system that has nothing to do with the turntable is established, then the impact of the factors on the calibration results using the method mentioned in this paper is deduced according to the simplified output model of fiber-optic gyroscope(FOG). Theoretical analysis shows that, no matter whether the turntable be orthogonal or not, the initial position error of turntable will not affect the results of calibration; when the three axis of three-axis turntable are orthogonal to each other, the accurate results is obtained; When the three axis of three-axis turntable are nonorthogonality to each other, it has great influence on the misalignment factors, but little influence on scale factors of FOG.