Magnetic Field Map Construction and Matching

Magnetic field-based indoor positioning technology leverages the magnetic perturbations caused by ferromagnetic materials within buildings, enabling precise location tracking. This technology offers distinct advantages, such as independence from existing infrastructure, signal stability, and resilience to human obstructions. This chapter provides an overview of the core concepts and popular technologies associated with indoor magnetic field matching positioning. It begins by introducing the measurement model and calibration algorithm for magnetometers, followed by an in-depth exploration of the principles behind magnetic map construction. Additionally, various data collection solutions are discussed, including professional methods and crowdsourcing-based methods. The chapter also presents a grid-based magnetic map generation method, which uses sparsely collected magnetic field vectors to interpolate continuous magnetic fields. Furthermore, two widely used magnetic matching algorithms are examined: the particle filter-based method and the magnetic sequence-based method. Finally, the chapter addresses the challenges and future development trends in indoor magnetic field positioning.