Research On Technologies Of Train Collision Avoidance For Rail Transit

Railway signal system in broad definition refers to a multiple closed-loop control system with the features of centralized command and distributed control,whose various components are safety equipment and then integrated via communication and network technology to constitute a complex system including traffic dispatching control,train control system and centralized monitoring,etc.Train control system is a crucial part of signal system and a core system to guarantee train safety segregation control on the primary purpose of collision avoidance.In pace with the advance of communication technology,sensing technology and intelligent technology,the next generation intelligent traffic system will be a comprehensive and well-organized system with the advanced intelligent information technology to realize the states' holographic perception,diagnosis,identification and decision of mobile equipment,fixed facilities and service demand in rail transit.The prevention of train collision accidents is still the main task of the next-generation intelligent traffic system,thus the technology and measures of train collision avoidance is required to be constantly refined.Firstly,indirect information transmission between trains is the most widely-used method to achieve the state perception and it guarantees the train collision protection consequently.However,the reliability of train interval control can't be effectively improved in this way because of its overdependence on ground control center.Secondly,the current research mainly gives priority to the two points: radio propagation mechanism of the bidirectional train-ground wireless channels and also the structure of collision protection system.Studies on the radio propagation mechanism of the train-train wireless channels,the model of service access and resource reuse about the on-board equipment aren't paid enough attention.In addition,the research objects of train collision protection are mainly on collision between trains,collision between trains and obstacles.Although the management department has promoted the “three-in-one”(human protection,facilities protection and technical protection)safety system construction,the protection technique for the collision protection of trackside workers needs to be further refined.Therefore,on the analysis of current research's deficiency,the related theory and methods of train collision protection are further studied.Train-train and train-human collision protection are studied systematically through the modern technology of train-train direct communication,multi-band transceiver technology and microwave radar multi-target detection.Firstly,the thesis analyzes “blindness” problems between trains due to the functions' deterioration of the train-ground communication network or control center,and proposes a collision protection system based on train-train communication superimposed with the existing train control system.Train-train communication technique is used to realize the direct interaction of information between trains and the operational state is perceived,thus reaching the purpose of collision protection between trains.Secondly,the thesis investigates the signal equipment required information interaction and the remarkable demand of machine-type communication service in the next generation rail transit system.Furthermore,a classification of the rail signal equipment's machine-type communication service prediction model is put forward and a service model on Markov modulation Poisson distribution process is also designed,which is verified by simulation to be highly consistent with service distribution in the real scene.Besides,complexity and high accuracy can be well balanced.In addition,the paper takes account of the full-time and highly sensitive features of microwave radar,also given the problems like bad weather affecting observation distance,unable sending advancing information timely due to guard's carelessness and the complex structure of GPS-based train approach warning system.Train-human collision avoidance system with multi-target radar detection is also presented.On this basis,the combination of radar and machine vision detection technology makes up for the high false alarm rate of radar detection and improves the train-human collision avoidance strategy of train collision protection.At last,a multi-band direct communication system for train-train collision avoidance is designed and simulated,which proves that the designed system can meet the performance requirements.Moreover,the prototype device of the train-human collision avoidance system is designed and implemented.Some tests are performed in the real scenes to reveal that it has strong adaptability to terrain environment.