A Train Running Status Online Monitoring System And Method Based On Time-frequency Diagram

At present,every years there's lots of traffic accident happened at home and abroad because of derail,which threatens people's life and property safety seriously and brings about a negative impact for economic growth.With the increase of the speed and bearing capacity of the train,train running status monitoring has become increasingly important.In this thesis,a new method is proposed to monitor train running state with a distributed optical fiber vibration sensing(DOFVS)system based on the phase sensitive optical time-domain reflectometer((37)-OTDR).This method uses distributed optical fiber to pick up track vibration signal caused by the running train.The signals are transformed for time-frequency diagrams from which we can dig train vibration signal characteristics by short-time Fourier transform,thereby,we can realize train running status monitoring.The main research details in this thesis are as follows:(1)First of all,this thesis analyzes the technology type and sensing principle of the distributed optical fiber sensing technology.And this thesis analyzes the distributed optical fiber vibration sensing technology and the monitoring principle of using it to monitor track running state.(2)Secondly,this thesis analyzes characteristics of train track signals and emphatically introduces characteristics in frequency domain,which is called time-frequency diagram.And this thesis introduces the principle of Nonlocal Means Filtering and its effects on time-frequency diagram.(3)Thirdly,according to the demand,this thesis designs the train running status online monitoring system based on the distributed optical fiber vibration sensing technology with(37)-OTDR,and concretely introduces the system's structure and hardware implementation.Importantly,this thesis designs the monitoring algorithm for track vibration signals in detail,including signal acquisition,analysis,processing.(4)Finally,performance indexes of this monitoring system are introduced,and the effects of NLM filtering are evaluated by comparison.Then this thesis makes a field test and analyzes the results.Because this system can work,it should be promoted.