Train Localization with Particle Filter and Magnetic Field Measurements

In this paper a particle filter for absolute train localization based on magnetic field measurements is proposed. The filter utilizes distortions of the earth magnetic field introduced by ferromagnetic infrastructure components along the railway track. The distortions are characteristic for a certain part of the track network and therefore are a source of position information. The particle filter introduced in this paper incorporates a prior created map of these distortions to estimate the train position. This only requires low-cost passive magnetometers and a simple movement model that accounts for the limited dynamics of a train. The feasibility of the approach is demonstrated in an evaluation with measurements collected on a train driving in a rural area. Overall a position root mean square error below four meters could be achieved, proving that the magnetic field is a viable source of position information that is independent from other localization systems like GNSS.