Research On Key Technologies Of Robust Underwater Geomagnetic Matching Navigation

In recent years,with the increasing marine resource exploitation in various countries around the world,the related scientific research and military activities are increasing,and the research on underwater vehicle has got rapidly development.Due to the particularity of the use environment,the underwater vehicle has high requirements for long-range,high-precision autonomous passive navigation technology.Inertial navigation system(INS)is one of the most widely used navigation system for underwater vehicles because of its passive and autonomous characteristics.However,the characteristics of its error accumulation over time affect the accuracy of positioning.In order to improve the stability and accuracy of the inertial navigation system,the cumulative error must be timely corrected by other navigation means.Because geomagnetic navigation has the advantages of all-weather,passive,high concealment and all terrain,it can be combined with inertial navigation system to improve the accuracy of navigation and positioning,which has become a hot research topic.As a new navigation method,geomagnetic navigation is limited by some objective conditions.There are still many difficulties in its application to actual navigation.Only a few countries in the world have developed geomagnetic navigation system and tested it in practical application.The research on geomagnetic navigation system in China started late,and there are still many key technical problems to be solved.The underwater environment is complex and changeable,which requires higher reliability and accuracy of geomagnetic navigation.In order to improve the robustness of the system,some key technologies of underwater geomagnetic matching navigation are studied in this paper based on the analysis of the research progress of related technologies at home and abroad.The main contents are as follows(1)Geomagnetic data measurement and processing.The acquisition of high quality geomagnetic data is directly related to the construction accuracy of the geomagnetic background field,the analysis of matching area suitability and the performance of matching algorithm.This paper analyzes the selection of geomagnetic matching feature.Due to the particularity of underwater environment,the total strength of geomagnetic field with the advantages of easy measurement,high measurement accuracy,large amount of information and insensitivity to the change of magnetic field is generally selected as the matching feature.The measurement and processing of geomagnetic data are introduced,and the actual geomagnetic data processing flow and common methods are given.On the basis of obtaining accurate geomagnetic data,the construction of geomagnetic background field,geomagnetic matching algorithm and the suitability of geomagnetic map are studied.(2)Construction of local geomagnetic map by kriging method based on support vector machine optimization.In order to build a high-precision local geomagnetic map,based on the brief analysis of the common methods of building geomagnetic map,this paper focuses on the research of the method of building local geomagnetic map based on Kriging interpolation.In Kriging interpolation method,how to choose the appropriate variogram model is related to the accuracy of interpolation.In order to solve the problem of subjectivity in the selection of variogram model in the conventional Kriging method,support vector machine is used to optimize it.Starting from the spatial transformation trend of known sample data points,least square support vector machine is used to fit the experimental variogram.This method can fit variogram adaptively according to different spatial sample data,which overcomes the subjectivity of choosing variogram model in conventional Kriging method,improves the interpolation accuracy,ensures the accuracy of local geomagnetic map construction,and lays a foundation for robust geomagnetic matching navigation.(3)Improved ICCP algorithm based on affine transformation.The Iterative Closest Contour Point(ICCP)algorithm is a common matching algorithm in underwater geomagnetic aided inertial navigation system.In practical applications,ICCP algorithm can only perform rigid transformation including rotation and translation transformation.Especially when scale error exists,the accuracy and stability of ICCP algorithm will be affected.In order to solve this problem,on the basis of studying the ICCP algorithm and the principle of affine transformation,considering that the affine transformation can not only solve the rotation and translation transformation,but also solve the scale transformation,so the affine transformation and the ICCP algorithm are combined.Therefore,the problem that the ICCP algorithm is prone to mismatching when there is a scale error is overcome,and the robustness of the algorithm is improved.Simulation experiments verify the performance of the improved algorithm.(4)The suitability analysis of matching area.Matching area suitability analysis is one of the key technologies in geomagnetic aided inertial navigation system.Through matching area suitablity analysis,it is possible to select an area with obvious feature changes and rich information as a matching area,thereby effectively improving the real-time and accuracy of navigation.Based on the multicriterion decision analysis theory,the principal component analysis method and the analytic hierarchy process are combined to give a comprehensive evaluation model of matching area suitablity.Firstly,according to the geomagnetic characteristic parameters of the matching area,the principal component analysis method and the analytic hierarchy process are used to determine the key feature parameters of the matching area and the corresponding weights.Then,the comprehensive evaluation values of each matching area are calculated according to the model.The larger the comprehensive evaluation value,the better the matching suitablity.The experiment verifies the effectiveness of the comprehensive evaluation model,ensures the matching effect of the matching algorithm,and improves the robustness of the geomagnetic aided inertial navigation system.Based on the above research,a comprehensive simulation experiment of geomagnetic aided inertial navigation system is carried out in a sea area of Bohai Sea.The test results show that the matching area suitablity analysis can effectively improve the matching effect of the matching algorithm and reduce the mismatch;the improved ICCP algorithm can effectively improve the reliability and accuracy of matching;so as to further improve the robustness of the whole navigation system.