Robust velocity measurement for railway applications by fusing eddy current sensor signals

A robust odometer function providing a precise location information is a key element for modern on-board train location systems. In this paper, a robust and reliable velocity measurement with an eddy current sensor system is proposed. The sensor system is suitable especially for railway applications as no further installations are required on the track beyond the currently existing infrastructure. Two different methods of velocity measurement based on the eddy current sensor system are presented. As the system consists of two sensors in direction of movement, the most common way is a cross-correlation of the sensor signals to obtain the vehicle velocity. In addition, the shape of the sensor signals allows a frequency analysis, yielding an alternative measurement of the velocity. Fusing the velocity data in a Kalman filter provides an exact and precise location information of increased reliability.