Research On Coupling Error Characteristic Of Laser/Fiber Hybrid Inertial Navigation System

Based on the advantages of ring laser gyro(RLG)with good bias stability,high scale factor linearity and fiber optic gyro(FOG)with no inertial damping structure,small angle random walk,our group put forward the concept about RLG/FOG hybrid inertial navigation system.In order to remove the damping structure of inertial navigation system,the two types of gyros are mixed and matched.Long time dynamic navigation accuracy of the system is ensured by good bias stability of RLG and attitude measurement of high precision is realized by small random walk of FOG.Due to RLG’s jitter component,the difference in output mode and frequency between the kinds of gyros,The hybrid inertial navigation system have the coupling error,which reduce attitude measurement accuracy.The research content of the article mainly includes:1、The paper explores the mechanism of Allan variance oscillation phenomenon by combining theoretical analysis and simulation verification,and revels the coupling error is actually a periodic signal related to jitter of RLG.Simulation results show that the coupling error will not lose the position accuracy of the system,but reduce angular resolution,thus affecting the high precision attitude measurement of the system.2、It is proved that frequency of the coupling error is equivalent to the jitter coupling output frequency in the case of under sampling through the theoretical derivation of under sampling.A series of experiments are designed to explore the source of the periodic signal and exclude the relationship between the source of the signal and attitude,the prototype of shell and the bandwidth of the FOG.The data preprocessing algorithm of FOG is designed to process the output of FOG.The results show that the time series analysis method and wavelet denoising method can reduce the output variance of FOG by more than 95%.3、The wavelet filtering is used to process the original data,and the magnitude of position error and attitude error have not change after processing.But the attitude angle oscillation is obviously weakened and angular resolution is significantly improved after filtering.The resolution of pitch,roll and yaw angle is improved by more than 50%compared with that before filtering.This is of great significance for high precision attitude measurement of RLG/FOG hybrid inertial navigation system.