Low power and low cost sensor for train velocity estimation

Nowadays railway vehicle speed sensors suffer from insufficient measurement accuracy. E. g. the Doppler radar is prone to adverse weather conditions while wheel speed sensors are not sufficiently robust against wheel slip and wheel wear. However, since velocity sensors are safety relevant components, it becomes clear that conventional sensors are not able to cover all the requirements for an everyday use. To overcome these deficiencies, we introduce a new train speed sensor based on an electromagnetic measurement principle. It does not require physical contact to the surface. Therefore, it does not suffer from slip or wheel wear. Furthermore, it works reliably under various weather conditions so that it offers high availability. We present the technical basis of the sensor and the algorithm for speed estimation based on the raw sensory data. We show results from tests on a test bench and tests on a railway vehicle which was operated on a test track. We compare the sensor results quantitatively with a high accuracy GNSS receiver and a laser tachymeter.