FBG Urban Railway Axle Counting Technology

Urban rail transit is characteristic for its large transportation quantity, high speed, safety, punctuality, environment-friendly and so on. It has great significance for relieving traffic congestion and improving urban atmosphere.Signal monitoring system for vehicle circulation is an important technique equipment for urban rail transit safety which is the same with the railway transportation. But the operation efficiency of urban rail transit is higher and is a small marshalling, high density and small train interval, so its train signal monitoring is harder than the railway.Right now the urban rail transit monitoring mostly adopts railway circuit technology and electromagnetic account-stalk technology and these technologies will be affected by environmental factors, which is detrimental to the railway's safety training. Fiber grating sensing technology is successfully applied in the measurement of stress and temperature due to its high accuracy and sensitivity, corrosion resistance, low cost and so on.This paper has developed account-stalk-health monitoring sensing technology according to the theory of Fiber grating. Its principle is when wheels come through, the strain of the rail will give rise to the change of the central wavelength of the FBG sensor。We can get the dynamic strain curve after demodulating it. Then count its pulse peak of strain we can get the corresponding amount of the wheel axle and the train condition of the wheel axle, which is "strain-account-stalk and monitoring technology in short. The main aim of this technology is:calculating the amount of the wheel axle, determining the condition of track jam and deciding the train's operation direction This technology can be used to monitor the weight of the wheel axle and the safety condition of the wheels such as:loose, out of circularity,train's overload and so on..This paper introduces the theoretical basis of fiber grating sensing technology's application in the account-stalk system of the urban rail. We design the account-stalk system of the urban rail based on FBG according to the requirement of intelligence and other functions in the monitoring technology of the operation of urban rail train combination with the features of the fiber grating sensor and the computer technology.This paper also introduce this system's structure,local installation technology, signal processing technology including the demodulator,PC's communication, data processing,ways of deciding the direction of the peak of the wheel axle and its successfully application in Wuhan garage track of urban rail in detail.The strain-account-stalk of fiber grating and its probationary experiment approves that,this technology is characteristic of reliable,accuracy and out of local maintenance which conquers the defects of popular use "track circuit "technology and "electromagnetic account-stalk" technology realizing the automatic of the block signal of the urban rail transit's accurately acquisition and the train's health status monitoring.