Pseudolite-Based Lane-Level Vehicle Positioning in Highway Tunnel

In intelligent transportation system (ITS) applications, vehicles require robust and accurate positioning where global navigation satellite system signals are not available. However, despite extensive research, vehicle positioning with lane-level accuracy in a confined tunnel environment remains a challenging task. In this study, a positioning system based on a synchronized pseudolite system is proposed to enable low-latency and high-accuracy vehicle localization in tunnels. The pseudolites with cascading synchronization are deployed one-dimensionally. The effect of the cascading synchronization is analyzed; and a base station selection strategy is proposed to solve this problem. Fusion mechanization of the vehicle positioning system, digital elevation model, and laser ranging are adopted to provide three-dimensional positioning. Furthermore, deep integration is implemented using a low-cost inertial measurement unit to improve positioning accuracy and stability. The proposed localization solution is experimentally verified using a 4.6 km highway tunnel environment. The results of seven repeated experiments show that the positioning error is better than 11.55 cm.