Angle Offset-Assisted Positioning of Railway Vehicles in Tunnel Environments

Accurate localization of railway vehicles is one of the key requirements for development of high-efficiency automatic train control systems. This paper proposes an angle offset-assisted positioning (AOAP) scheme for improving the localization of railway vehicles in tunnel environments. Our AOAP system consists of a wireless sensor network (WSN), where anchor nodes or sensors are distributed along the railway tracks to collect the signals transmitted by a target node installed a train. Based on the information obtained by the anchor nodes from the target node, the position of the target node or the train is initially estimated. However, radio signals experience transmission delay, which makes this estimated position have a bias from the real position. Hence, the initially estimated train´s position is updated with the aid of the angle offset estimated. In this contribution, we address the effect of angle offset error on the positioning accuracy. It can be shown that our AOAP approach is capable of providing more accurate positioning than the conventional least square approach without considering angle offset.