Seamless train localization based on BDS/INS/odometer/MM multi-sensor navigation system

BeiDou Navigation Satellite System (BDS) has been widely applied in areas including communication and transportation, emergency rescue, public security etc., making remarkable benefit in social and economic aspects. The integration of BDS and Inertial Navigation System (INS) has meant that it gives greater access to a more consistent and accurate positioning capability than ever before. However, during the long BDS outages, the performance of the integration system degrades greatly because of the characteristics of the Inertial Measurement Unit (IMU) – the sensor error would be accumulated with time when it operates in a standalone mode. In this paper, a BDS/INS/odometer/Map-matching (MM) positioning methodology for train navigation applications is proposed and evaluated by the real test conducted in the western regions of China. This method is proposed to solve the problem of train positioning during BDS outages when the trains pass through the signal obstructed areas, like bridges, tunnels and valleys. The seamless transition of the train operation in various scenarios can be therefore maintained. When the train operated in the open-sky environments, the BDS signals are available to provide accurate positioning, the BDS/INS are integrated to correct the INS errors by BDS measurements and calculate the velocity by odometer in navigation frame. Meanwhile, the integration system are also delivered accurate positioning measurements in high updated rate. In the case of BDS signals blocked, the integrated system can be seamless switched to the INS/odometer integration mode, the integrated system corrects the INS errors by using odometer measurements so as to provide continuous and acceptable positioning performance. In addition, MM technology is applied to improve the precise. In order to evaluate the proposed system, a real experiment was conducted in the western regions of China. The experimental results indicate that the proposed system can provide the accurate and continuous positioning service in both open-sky and BDS obstructed environments.