High Accuracy Estimation of Velocity and Position for Railway Vehicles using Ferromagnetic Inhomogeneities

High accurate sensors for velocity and position estimation of railway vehicles are highly recommended for modern train control and train protection systems like the ETCS. To overcome the shortcomings of nowadays sensors, the Difference Inductance Sensor (DIS) as a detector of ferromagnetic inhomogenities along the railway track was developed. The variation of the ferromagnetic materials along the railway track leads to a distinct ferromagnetic signature for each track segment. These signatures can be used to estimate the velocity and in combination with a track map the position of the railway vehicle without the necessity of additional sensors. In this paper, the measurement principle, the signal filtering and the operation principle for the velocity and the position estimation with the DIS is specified. The accuracy of the DIS is evaluated under real world conditions on the test and validation center in Wegberg-Wildenrath (PCW) and compared with a Galileo-GNSS receiver and a LASER-tachymeter (TS15). Results show that the DIS and the ferromagnetic inhomogenities provide good velocity and localization estimations.