Map-Based Inertial Navigation for GNSS-Free and Safe Train Localization

The paper proposes to exploit the benefits of Inertial Navigation Systems (INS) and details a map-based railway inertial navigation. The method relies on an accurate heading measurement and allows location of the train hybridizing an INS with a digital map without any other sensor such as GNSS or wheel sensor. The map consists of a set of Virtual Georeferenced Heading Beacons (VGHB). Position information is provided to the INS when the measured heading crosses the heading of a VGHB among a selection of eligible VGHB. The position measurement accuracy depends on the VGHB position accuracy and on the precision of the VGHB heading detection which relies on both INS heading accuracy and train mechanical heading repeatability over the tracks. The accuracy and the integrity of the solution is studied on a set of hundreds of hours of GNSS-denied urban data. In 99% of cases the map-based GNSS-free inertial navigation gets less than 1.4 m across errors and less than 3.4 m along errors. It outperforms the solution using the GNSS without the digital map which gets less than 3.2 m across errors and less than 3.6 m along errors.