Track Detection Of Track Signal Based On Fiber Optical Sensor

With the continuous expansion of Chinese high-speed rail network scale,the continuous improvement of train speed,real-time accurate grasp of the train running position,direction and speed and other information,to ensure the safety of high-speed rail operation is crucial,so the train safety monitoring technology has put forward higher requirements.At present,Chinese railway safety monitoring mainly relies on ground equipment and wireless communication means,with high construction cost and high operation and maintenance cost.Based on Phase Sensitive Optical time-domain Reflectometer(Phase Sensitive Optical Time Domain Reflectometer)of distributed Optical fiber vibration sensing technology,can to distributed sensing fiber along the external disturbances,all-round continuous monitoring.System maintenance cost is low,anti-electromagnetic interference ability is strong,in the event accurate positioning,concealment,environmental adaptability and other aspects of irreplaceable advantages.Based on the phase sensitive optical time-domain reflectometer(?-OTDR)technology,the basic principles of study the rail track vibration signal based on optical fiber sensor monitoring technology,innovative apply this technique to monitoring field of train tracks on a railway line,realize long-distance distributed vibration signal detection and collection.In this paper,based on the phase sensitive optical time-domain reflectometer(?-OTDR)technology,it is innovatively proposed to apply the technology to the real-time monitoring of train running track on railway track,to realize long-distance distributed vibration signal detection and collection.This subject takes the running track of high-speed train as the research object.Through the acquisition of track vibration signals in the process of train moving,as well as the processing and analysis of signal characteristics,train position,speed,running direction and train length can be obtained in real time.In order to determine whether the train is running normally on the way,and whether there is an emergency,so that convenient for timely scheduling,so as to improve the safety of train operation.This paper mainly completed the following aspects of research work:1.In the first chapter,we introduces the background and significance of this research.This paper mainly introduces the research status and application status of train vibration signal and train running track detection.It makes us fully realize the necessity of train track monitoring and the advantages and disadvantages of current technology.2.In the second chapter we introduces the basic principle and development of optical fiber sensing technology and OTDR technology.And main applications of ?-OTDR technology is introduced.According to the mathematical model of ?-OTDR technology,this paper discusses the implementation ?-OTDR technology.Therefore,it is feasible to realize real-time acquisition of train vibration signals.3.In the third chapter,we design and study a vibration signal based on the technology of ?-OTDR feature extraction method.A strategy is proposed which based on ?-OTDR vibration signal spectrum feature extraction and feature selection strategy.The strategy consists of signal preprocessing,spectral feature selection,and spectral feature extraction.First,the signal preprocessing module performs first-order smoothing on the original signal.The spectrum feature selection module performs time-frequency analysis of the filtered signal based on short-time Fourier transform(STFT)on the filtered signal.Considering the physical characteristics of signal attenuation of OTDR technology,each sampled position point is used as a classifier.The k-means clustering algorithm is used to optimize the feature extraction of energy entropy.4.In the fourth chapter,a train trajectory monitoring method based on ?-OTDR technology is designed and studied,realizing the real-time monitoring of train trajectory.The method uses ?-OTDR technology to collect the rail vibration signal in real time,and uses the method described in Chapter 3 for feature extraction of the original signal.The energy entropy amplitude feature is used to determine the effective signal of the train travel.The train driving model is matched by analyzing the effective signals of the trains at different times.Then the global piecewise regression algorithm is used to obtain the information of the train travel trajectory such as train position,speed and driving direction.In order to improve the accuracy of online monitoring,there should also be online updates of the train signal threshold.We added the weighting coefficients of the online threshold and the offline database,and initially realized the intelligent recognition of the track trajectory detection.