Research On RFID-based Monitoring System For EMU Components

High-speed railway in our country has been development rapidly,and up to now,there are over 20000-km operational lines,so it is very important to ensure safety in the daily operations of the EMU.During the routine running of the EMU,some parts are prone to detaching due to the impacts,such as the brake pads,the car bottom antenna and the various protective covers.At present,it is inefficient to screen the foreign object by manual work between on the intervals of the train operation.Therefore,it is highly necessary to find an effective and low-cost system for the real-time monitoring of the parts detached.So,it has social and economic benefits to research on the detecting method and tracing method for the falling parts of the EMU.This thesis focus on the phenomenon of parts detachment of EMU.It is possible to realize the detection of the existence of label to implement for real-time detection of the existence of the binding parts,through the installations of electronic tags on the detachable parts.The reader will install in the central of each compartment,and the label will be full covered.The reader connects to the PC server through the CAN bus,so,the system can be made up into a network.This system is a UHF detection system featuring multiple readers and huge amounts of active tags,which aims to detect the existence of the tags under the condition of the high-speed running EMU.Once a tag missing,it can acquire the kilometer mark from the train data in time.The purpose is to narrow the search scope?In this thesis,the principle,structure of RFID as well as the background and significance of the research topic are introduced firstly,then,using 860-960MHz RF chip AS3990 and low-power master controller MSP430F2274,a hardware system is established.The main work of the Paper is to around how to realize the inspection for existence of the tag quickly and low power.In order to reduce the energy consumption of communication and prolong the life time of the label that should be as much as possible to reduce the delivery time and quantity of the data for the active label.The improved algorithm has been used which combining the polling and frame-time slot ALOHA algorithm,the labels will reply the reader only a bit in a query.When a reader sends out a searching frame which the length is F,the reader generates a 0/1 sequence and stores it.Upon K round query,the reader generates a matrix F*K based on the information tag replied.The PC server,based on the same compression algorithm to generate a same matrix,and contrastes the matrix with the matrix generated by readers to determine the existence of the tags.The realization method of a bit transfer of the algorithm was described in detail.According to the simulation results,this algorithm greatly reduces the tag communication quantity and working times,which can save the energy consumption of the batteries.To increase efficiency of the detection,a new algorithm was presented which the reply slot of the tags are fixed.In allusion to the interference faced by the multiple readers,according to the characteristics of the reader on a straight line,the graph coloration and power control algorithm was presented to optimize the readers' working sequence.According to the simulation results,the algorithm greatly reduces the interference and wastes of the time slot.Meanwhile,in order to improve the detection speed more,the FDMA(Frequency Division Multiple Access)is studied,the parallel working modes which has minute channels the of the readers are analyzed also,and the comparisons was made.Relatively,this scheme is more efficient and the detection is more quickly.At last,a scheme based on the values of RSSI is studied for the searching of the lost tags in the sectional lines and the depots.The scheme adopts the omnidirectional and directional antenna to search.The first step is to search the tag signal with a omnidirectional antenna,and then switch into a directional antenna once finding the signal.According to the receiving field RSSI values,the target will be approached gradually.