A Simple Yet Effective Subway Self-Positioning Method Based on Aerial-View Sleeper Detection

With the rapid development of urban underground rail vehicles, subway positioning, which plays a fundamental role in the traffic navigation and collision avoidance systems, has become a research hot spot these years. Most current subway positioning methods rely on localization beacons densely preinstalled alongside the railway tracks, requiring massive costs for infrastructure and maintenance, while commonly lacking flexibility and anti-interference ability. In this article, we propose a low-cost and real-time visual-assisted self-localization framework to address the robust and convenient positioning problem for subways. First, we perform aerial-view rail sleeper detection based on the fast and efficient YOLOv8n network. The detection results are then used to achieve real-time correction of mileage values combined with geometric positioning information, obtaining precise subway locations. Front camera videos for subway driving scenes along a 6.9-km route are collected and annotated from the simulator for validation of the proposed method. Experimental results show that our aerial-view sleeper detection algorithm can efficiently detect sleeper positions with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${F}1$ </tex-math></inline-formula>-score of 0.929 at 1111 frames/s and that the proposed positioning framework achieves a mean percentage error (MPE) of 0.1%, demonstrating its continuous and high-precision self-localization capability.