Dynamic Error Analysis And Calibration For Laser Gyro Strapdown Inertial Navigation System

The inertial instruments are key components of the INS, which determines the precision of inertial navigation. However, for the strapdown inertial navigation system, when the carrier is in the dynamic environment, the mechanical environment is complex, the introduction of dynamic errors in the output of the inertial instruments because of the disturbance of dynamic torque on the internal structure of inertial instrument is inevitably, and should not be neglected. Therefore,research on the dynamic errors of the inertial instruments is of great significance in improving precision of inertial navigation. In this article, the laser gyro strapdown inertial navigation system is researched, the mechanism of producing dynamic error is analyzed, the dynamic error model is established and the corresponding calibration method is proposed for the dynamic error model of the accelerometer portfolio.For mechanically dithered ring laser gyro, by analyzing the effect of the external input angular acceleration on the jitter axis in the dynamic environment and solving the corresponding vibration equation, the output of the jitter axis is got at this time. According to the principle of mechanically dithered ring laser gyro output signal reading circuit, the effect of jitter axis output on the gyro’s is observed, and the dynamic error model of laser gyro is given according to this. In the process of building the model, two cases of coincidence and noncoincidence of input axis and jitter axis are considered, and the situations of jitter axis being rigid and flexible are analyzed respectively for the noncoincidence. It’s a storage of theory for subsequent research of laser gyro dynamic errors and an important thought for improving the output precision that the dynamic error model is built.For the quartz flexible accelerometer, the dynamic error model is established based on the method of mechanism analysis, and considering the influence of size effect on the accelerometer output, the model is improved. According to the established dynamic error model and the analysis of the methods of orthogonal three-axis and biaxial uniform angualr rate input for the three-axis turntable, the method of making the middle ring shaft and outer ring shaft of the turntable rotate at the same time is used to calibrate the error model, and the data is dealt with by the harmonic analysis method and least squares fitting method. According to the selection of calibration method and experiment design criterion, the specific calibration experiment is designed, and the estimation standard of calibration accuracy is given. The calibration method can get the total error coefficients of theinertial measuring unit by one-time calibration. It has been verified by the simulation that the calibration precision is high. In conclusion, the calibration method has the good engineering application value.