| With the development of train control technology,communication based train control(CBTC) will be developed. Train integrity monitoring is one of the key safety-related factors.In the case that the track circuit is not available, train integrity monitoring will become a newproblem to be resolved using onboard devices. Studying a new train integrity monitoringmethod has important theoretical and practical significance.Recently, with the development of communication, network and computer technology,some advanced technologies have been adopted by railway transportation. The Global Positi-oning System (GPS) positioning, such as Global Navigation Satellite System (GNSS), is oneof the widely used technologies. At present, using GPS to monitor train integrity hasn’tmature theory, it can be used with end of train device as an redundancy system. In the processof moving train, the availability and accuracy of GPS-based systems can be degraded due toblocking of the satellite signals at the end of the train. In the incomplete condition that lessthan four satellites are visible, the train end will fail to position via GPS and train integritymonitoring algorithm based on GPS positioning algorithm in incomplete condition by usingcommunication method and head of the train positioning information. The core idea ofpositioning algorithm with three GPS satellites is to establish a virtual satellite combined withpositioning information of train head, thereby to achieve an additional constraint equation,then adding the equation to the set of three equations came from visible satellites would gainthe positioning of end of the train. Even in the normal work period of GPS, the algorithms canstill be very valuable as a supplement. Finally the length of train will be calculated by usingpositioning information of the head and end of train and train integrity will be monitored.Detailed mathematical positioning algorithms are deduced in this thesis. Also, an experimenthas been carried out to verify the algorithms. The accuracy of the positioning algorithms canmeet the requirement of train integrity monitoring. |
