Measurement Method And Accuracy Analysis Of Installing Matrix Errors Among The Sensors Of Satellite Geomagnetic Measurement System

Geomagnetic navigation requires the establishment of a global or local geomagnetic field data library.The use of satellite-borne magnetic measurement equipment can measure the earth's magnetic field globally,all-weather and with high precision.This paper develops the study of the installing matrix and installation error between the magnetometers and the star sensors of the satellite geomagnetic measurement system.Firstly,the scheme of satellite geomagnetic measurement ground calibration system was designed.The composition of the ground calibration system is introduced,including the non-magnetic test platform,monitoring system and detection system.In order to accurately measure the ground magnetic field with a magnetometer and obtain the representation of the magnetometer's sensitive axis in the geographic coordinate system,a single-axis vertical non-magnetic turntable is used as the test equipment.The monitoring system acts as an aid to compensate for the output of the magnetometers and provides accurate geomagnetic field vector information.The detection system processes the data obtained from the ground calibration test to determine the installation matrix.Secondly,the error sources in the ground calibration test were analyzed and the relevant coordinate systems were established.The working principle of the star sensor and magnetometer was introduced.Based on this,the error model of the magnetometer is established.The relationship between the output of the magnetometers and the rotation angle,rotation error and installation error of the turntable is established in combination with the non-magnetic turntable.Three different installing modes of fixture where the three magnetometers and three star sensors are fixed were designed on the turntable.The harmonic analysis method was used for the output of the magnetometers to solve the initial installation angle of the magnetometers relative to the turntable and the verticality of the body mounting base and the perpendicularity between the three axes of the magnetometers.Using the above information,the representation of the unit vectors of the magnetometers in the geographic coordinate system is obtained.At the same time,the star sensor performs stargazing,the representation of the optical axis vector of the star sensor in the inertial coordinate system was calculated,and with the known latitude and longitude and time information of the test site,the transformation matrix between the inertial coordinate system and the geographic coordinate system is achieved.Then the representation of the star sensor optical axis vector in the geographic coordinate system is obtained.Finally,using the geographic coordinate system as a bridge,the installation matrix between the magnetometers and the star sensor is obtained.Thirdly,the uncertainty analysis and Monte Carlo simulation method are used to analyze the error of the magnetometers parameters.The error accuracy of the initial installation angle,the three-axis perpendicularity of the magnetometers,and the perpendicularity of the mounting base are obtained by using the synthetic formula of uncertainty.The identification curve of the parameters was drawn by Monte Carlo simulation,and the standard deviation of each parameter was consistent with the uncertainty acquired by analytical method.In combination with the optical axis measurement accuracy of the star sensor,the uncertainty of each element in the mounting matrix is analyzed using uncertainty.Finally,the expression of the three-dimensional geomagnetic field in the case of actual star sensors stargazing and magnetometer measurement in satellite geomagnetic survey is given.The influence of the installation matrix errors on the measurement of the earth's magnetic field is analyzed,and the uncertainties of the three components of the geomagnetic field are given.In short,the design of the entire ground calibration system,the test method of the installation matrix,the error analysis,and the influence of the installation matrix and the verticality error in the actual test are completed.