A GNSS/trackmap cooperative train positioning method for satellite-based train control

The accurate and reliable train positioning is of great significance for modern railway train control systems. To achieve the satellite-based train control with advantages in cost efficiency and adaptability, Global Navigation Satellite Systems (GNSSs), such as GPS, GALILEO and BDS (BeiDou Navigation Satellite System), are with great potentials for reducing the cost and realizing a better interoperability. The trackmap database is capable of providing the effective information for enhancing the positioning performance. In this paper, we use the concept of a Virtual Balise (VB) to enable a scheme for satellite-based train control that is interoperable with current CTCS (Chinese Train Control System). With the aid from a trackmap, the integration concerning the GNSS, odometer and map database is realized by using a nonlinear filter. In addition, unlike the existing works on VB capture with a loose-coupled structure, a novel solution for determining the status of VB capture and position calibration is proposed where the trackmap can positively estimate the relative situation between the train and the target Balise. Based on the cooperation between GNSS and the trackmap, both the functions of train location determination and Balise message control can be realized for generating the moving authorities for the trains. Results of simulations illustrate the capability and performance of the proposed solution for perspective implementations.