Simultaneous Train Localization and Radio Transmitter Mapping with TDoA and Magnetic Field Measurements

Kurzfassung

This paper proposes a simultaneous localization and mapping (SLAM) algorithm that jointly estimates the position of a train on a railway track and the positions of track-side radio transmitters to enable accurate train localization in areas where satellite-based systems are not available. The algorithm uses odometer and magnetometer measurements and combines them with signal of opportunity time difference of arrival (TDoA) measurements to track-side radio transmitters. To solve the SLAM problem, pose-graph optimization is combined with a magnetic field-based loop closure detection that exploits the position dependent distortions in the Earth magnetic field encountered along railway tracks. We proof the feasibility of the algorithm in an evaluation with real odometer and magnetometer measurements from the railway domain and simulated TDoA measurements. The evaluation shows that the SLAM algorithm enables long-term stable train position estimation and that the radio transmitters can be localized with meter-level accuracy.