Research On Inertial/Geomagnetic Navigation Method

As a reactive and full-autonomous navigation system,geomagnetic navigation has the advantages of low cost,anti-jamming,small size and so on,which can effectively make up for the shortcomings of other navigation systems.Starting from the accurate construction of local geomagnetic map,after the calibration and compensation of carrier magnetic field,the geomagnetic matching or inertial / geomagnetic integrated navigation is carried out,forming the basic method system of geomagnetic navigation system.In this paper,theoretical research and method improvement will be carried out in the above four aspects,hoping to have some reference for the future geomagnetic matching and inertial / geomagnetic integrated navigation technology research.The basis of geomagnetic navigation is to convert geomagnetic information into digital geomagnetic map quickly and accurately.In order to reflect the rich detail information of local geomagnetic map,the construction method of pre stored geomagnetic map based on Kriging interpolation is studied;the validity and accuracy of different interpolation methods are examined by cross validation index,and threshold is added in the algorithm to speed up the composition time.This method can accurately reflect the spatial variation characteristics of local geomagnetic map and effectively solve the problem of high-resolution geomagnetic anomaly map preparation.It is inevitable that there will be errors in geomagnetic survey,which limits the accuracy and application range of geomagnetic navigation.Firstly,a parameterized magnetometer error model including many kinds of errors is established,and the magnetic field calibration and compensation formula of the carrier is given.In view of the limited condition of the attitude maneuver of the surface-based carrier,two modes of attitude free and small attitude heading maneuver are discussed,and an adaptive particle swarm optimization calibration algorithm for real-time adjusting and updating parameters is proposed.This method is simple and easy to operate,and can accurately calibrate the error parameters.After compensation,the geomagnetic measurement can meet the requirements of high-precision geomagnetic navigation.In order to solve the problem that the traditional geomagnetic matching algorithm based on magnetic contour matching and iterative closest contour points can not correct the track stretching error,and the scalar algorithm is easy to mismatch in the area where the geomagnetic characteristics are not obvious,a vector iterative closest contour points matching algorithm based on affine transformation is proposed.The algorithm adds affine transformation and vector constraint,so that the matching track can be as close to the real as possible,the trajectory is not affected by the gentle trend of the geomagnetic isocline,and the matching accuracy is improved.In order to effectively combine the advantages of geomagnetic navigation and inertial navigation,improve the navigation accuracy.Using the difference between geomagnetic matching position and the position indicated by INS as the observation measurement,and using Kalman filter as the integrated navigation estimator,the loose integrated navigation system model of inertial / geomagnetic is established.Taking the difference between the geomagnetic intensity of the position indicated by the inertial navigation system and the actual geomagnetic intensity as the observation measurement,and using extended Kalman filter as the integrated navigation estimator,the inertial / geomagnetic tight integrated navigation system model is established.In view of the defects of EKF,such as linearization approximation error,unscented Kalman filter uses unscented transform to replace linearization approximation,so as to obtain higher positioning accuracy and improve the performance of tight integrated navigation system.Theoretical analysis and simulation results show that the loose integrated navigation has high positioning accuracy because of the direct correction of the inertial track by geomagnetic matching,and the tight integrated navigation has good real-time performance due to the direct use of measurement information.