| A navigation technique with many potential applications is geomagnetic matching.It has benefits including strong autonomy,high concealment,low cost,and all-weather compared to conventional satellite navigation,gravity navigation,astronomical navigation,and terrain matching navigation systems.It has steadily developed into a center of navigation research both domestically and internationally in recent years.Because of the complicated spatiotemporal evolution features of the geomagnetic field,both secular variation and short-term variation in time scale will have an impact on the quality of geomagnetic data,decreasing the precision of matching navigation;Geomagnetic matching navigation is based on one element or multielement,Several geomagnetic elements have distinct spatial properties,which also affect the accuracy of geomagnetic matching navigation.In order to increase the precision of geomagnetic matching navigation,it is crucial to analyze the temporal and spatial properties of the geomagnetic field.Based on this,the author of this paper investigated and analyzed the spatiotemporal features of the geomagnetic field,completing the following research primarily:(1)Based on the spatial properties of the geomagnetic field,a method for choosing the best quantity of geomagnetic features for geomagnetic matching has been developed.The spatial distribution properties of several geomagnetic feature quantities were investigated using geomagnetic contour maps,geomagnetic slope values,cumulative gradient values,and geomagnetic roughness values.The relationship between geomagnetic spatial attributes and geomagnetic matching accuracy was then examined using geomagnetic matching simulation experiments and the mean absolute difference(MAD)algorithm.The viability of choosing the best quantity of geomagnetic features based on geomagnetic spatial properties was confirmed.(2)Two models,IGRF13 and WMM2020,were examined and their correctness was determined using data from geomagnetic stations that were locally observed.Geomagnetic data during magnetic quiet periods from geomagnetic stations and the quadratic polynomial fitting method were used to determine the secular variation value of the geomagnetic field based on measured data.In order to compare and examine the model data with this value,which was taken as a true value.It was discovered that the IGRF13 model,as opposed to the WMM2020 model,is more trustworthy when it comes to rectifying the secular variation of the geomagnetic field in local locations.(3)A method for correcting geomagnetic static daily variation was proposed,which combines the average base value calculation method with the daily variation data mean method.Based on the calculation results of the deviation,a method based on the average value method was selected from various calculation methods for the basic values of geomagnetic daily variation to extract geomagnetic daily variation data.On this basis,a method was proposed to eliminate geomagnetic static daily variation on the measurement day by using the average daily variation data of the previous few days.The experimental results show that the above methods can to some extent correct the influence of geomagnetic static diurnal changes in the measurement process of geomagnetic data.In order to increase the precision of geomagnetic matching navigation,this paper studies and analyzes the effects of changes in the geomagnetic field on the quality of geomagnetic data on a time scale.It then suggests appropriate solutions and chooses the best geomagnetic element based on the spatial characteristics of various geomagnetic features. |
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