The Multi-position Systematic Calibration Method For FOG Strapdown Inertial Navigation System

Calibration technology is a key technology in the field of SINS,which is essentially an error compensation technology.According to the different observations,it can be divided into discrete calibration and systematic calibration.Because the former is more mature than the latter in research methods,discrete calibration is often used to determine the mathematical model of inertial units.Discrete calibration relies on high precision three-axis turntable to carry out a series of experiments to obtain the parameters of gyroscope and accelerometer.It has many experimental steps and need a long time for calibration,and the calibration accuracy restricted by turntable can not be further improved.In order to make calibration more efficient,,more and more scholars turn to research systematic calibration.This paper introduces two general methods of systematic calibration,filter method and analytical method,which represent two different research directions of systematic calibration.Compared with the analytical method,the filtering method is simple,does not involve complex mathematical derivation,and the design of calibration path is relatively simple.The parameters extended to the state variables will obtain a 30-dimensional large-scale system.In order to reduce the difficulty of experimental design and improve the filtering accuracy,the dimension reduction processing is carried out in this paper.Using an observability analysis method based on row elementary transformation can be used to identify which states in the equation of state can be observed,which states cannot be observed,and which state coupling can be observed.In order to reduce the system dimension,independent observable variables are retained,and non-observable are eliminated.Finally,according to the reduced dimension system,Calibration path are designed.The simulation results show that the scheme is theoretically feasible.After that,the experiment was carried out,and the results were compared with the discrete calibration results.By comparing the course angle curves of four groups of five-stage sea state experiments,it can be clearly seen that the compensation effect of systematic scheme is better than that of discrete calibration.Therefore,this systematic calibration has engineering practical value.