Research On Train Blind Area Location Algorithm Based On ZigBee

With the rapid development of railway construction in China,the number and scale of railway tunnels are growing.But due to the satellite positioning blind spots created by the tunnel shield,the train cannot be tracked with satellite navigation and positioning system when running in a tunnel,which is not good for the safety of passengers and train.In addition,although there are a variety of train positioning methods applied in various countries,the shortcomings and deficiencies are exposed in varying degrees in different application environments.In order to conduct real time and complete positioning of running train in the tunnel,to make up for the deficiency of satellite navigation and positioning blind area,this paper presents an improved RSSI centroid localization algorithm based on ZigBee technology,and weighted centroid localization algorithm,as well as simulation and measurement on the two algorithms.First of all,this paper analyses the characteristics of ZigBee technology and the composition and function of each layer,by comparing the performance of several short-range wireless communication technologies,the advantages of ZigBee technology in train positioning are obtained;secondly,this paper analyses node localization algorithm of wireless sensor network,also analyses and compares several common positioning algorithms,to find out shortcomings and bring up with improvement plan;thirdly,this paper analyses the signal transmission characteristics in the tunnel,calculates the Doppler shift effect on signal transmission,based on which discusses and analyses the RSSI distance and three edge measurement.As for the shortcomings of the algorithms demonstrated in the application,this paper improves traditional algorithm by increasing beacon nodes,redefining and selecting intersection region.Simulation result shows that,the improved algorithm is of higher accuracy and more stable performance than the traditional RSSI triangle centroid location algorithm.This paper sets experimental nodes according to the characteristics of the tunnel,conducts practical measurement of train positioning in blind spot based on the simulation experiment verification of practicality of improved algorithm,statistically analyses the positioning result and error under different speeds.The experimental result shows that,the improved algorithm can be used to locate the train in blind area of satellite positioning,its precision can meet application requirements.