Correlation based velocity estimation during acceleration phases with application in rail vehicles

A reliable and precise velocity measurement is an important component of new train location systems. Several ways of measurement, e.g. with an optical sensor, GPS and eddy current sensors have already been under examination. This paper covers the velocity determination via correlation analysis using the measurement data of an eddy current sensor system. The common cross correlation is well suited to measure constant speeds. However, during phases of acceleration it is not sufficient for good accuracy due to a signal warp. For this reason a model based approach for signal rewarp will be presented in this paper, that eliminates or at least minimizes the influence of acceleration. Besides its main application in signal pre-processing for the velocity determination via cross correlation, the results of this algorithm can afterwards be used as an estimation of the acceleration as well.