Geomagnetic Navigation and Positioning Methods

Chapter 4 introduces the composition of the geomagnetic field and the basic principles of the geomagnetic field that can be used for navigation and positioning, as well as the method of creating geomagnetic reference maps for navigation and positioning. This chapter focuses on the process and method of implementing navigation and positioning on the basis of geomagnetic reference maps. As one of the important technologies in the multi-source fusion navigation and positioning system, geomagnetic navigation and positioning have the advantages of a wide range of applications, strong anti-electromagnetic interference capability, and the ability to work around the clock, providing a passive and autonomous navigation and positioning technology path for motion carriers in underground, underwater, and other scenarios where satellite signal reception is limited (Fisher and Raquet in Air & Space Power Journal, 24 –33, 2011; Goldenberg et al. in Location, And Navigation Symposium, 684–694, 2006; Wilson et al. in Proceedings of the 2006 National Technical Meeting of The Institute of Navigation, Monterey, CA, January 2006, pp. 770–779; Li et al. in A geomagnetic positioning method suitable for indoor free motion carriers, Beijing, 2018). Geomagnetic navigation and positioning use the characteristic that the geomagnetic field intensity has a different distribution with a change in geospatial location to achieve the positioning of the motion carrier. The geomagnetic navigation and positioning system obtains the geomagnetic field characteristic data on the motion trajectory through the magnetometer installed on the motion carrier and matches it with the pre-stored geomagnetic field model or geomagnetic reference map to determine the real-time position and correct the inertial guidance error. All seven geomagnetic elements of the geomagnetic field described in Chap. 4 can be used as geomagnetic feature data or a combination of them. The selection of geomagnetic positioning feature data mainly requires the following considerations: (1) significant spatial variation; (2) slow change with time; (3) accurate measurement by measuring instruments; and (4) low influence by external interference. According to the basic principle of geomagnetic navigation and positioning, which is similar to the gravity aided navigation and positioning method. Two working systems are required: a pre-processing system and a real-time positioning system. The pre-processing system is mainly based on the process introduced in Chap. 4 to complete the preparation of geomagnetic reference data. This chapter introduces the implementation process of the real-time positioning system, which mainly includes real-time measurement of geomagnetic fields and positioning calculation. The implementation of geomagnetic navigation and positioning focuses on three aspects: (1) magnetometer sensors; (2) real-time measurement methods; and (3) navigation and positioning algorithms. According to the different carriers and scenarios of geomagnetic positioning applications, there are certain differences in the process of geomagnetic navigation and positioning implementation, which are mainly reflected in the above three aspects. In this chapter, different application scenarios of geomagnetic positioning are categorized, and the specific implementation process for different application scenarios is given (Jun et al. in Journal of Astronautics 05:1467–1472, 2008). For the convenience of description, “geomagnetic navigation and positioning” is referred to as “geomagnetic positioning” in this chapter.