Train accurate localization using ultra wide band radio and time reversal
Résumé
In guided transport, the precise localization of trains is vital for nominal operation of the transport system. In a propagation environment such as a railway line, an effective localization sensor is complex to design since it must operate in the presence of many fixed and mobile obstacles constituted by the infrastructure and the trains. In order to design a sensor delivering high localization performance, we propose the use of so-called spectral diversity techniques also found under the name of ultra wide band radio. In this work, this radio technique is associated to the time reversal technique, taking advantage of the complex railway propagation environment. The objective is to obtain a reliable and robust localization of rail vehicles by focusing radio signals from a ground balise to the track and, therefore, to the passing train receiving antennas. A theoretical model, simulations and an experimental validation were developed on the properties of energy focusing of time reversal taking into account very different types of environment. Several parameters related to antenna configurations were investigated. The contributions of time reversal to the accuracy of the positioning system are measured by comparing an ultra wide band positioning system alone and then, combining it with time reversal.