An On-line Monitoring Method For Highway Operation Condition Based On Distributed Optical Fiber Acoustic Sensing

Highway congestion has a serious impact on the people's travel experience,reducing social mobility.In addition,expressway speeding is the main cause of highway accidents.Therefore,to realize the intelligent management of expressway,real-time monitoring of traffic parameters such as traffic flow and speed can provide the basis for emergency evacuation of road congestion and violation penalty of vehicle speeding,thus reducing vehicle driving delay and reducing traffic accidents.At present,the extraction methods of traffic parameters mainly rely on microwave radar,ground induction coil,ultrasonic detector,video etc.These methods are not suitable for large-scale detection,and the traffic information obtained is less and is easily affected by extreme weather.In this paper,an online monitoring scheme for highway operating condition based on distributed optical fiber acoustic sensing is proposed.Compared with traditional sensing technology,distributed optical fiber acoustic sensing technology is not affected by bad weather and can be used for long-distance monitoring.It can realize real-time distributed measurement of traffic flow,headway spacing,speed and other traffic parameters of each section of expressway.In addition,the plan is to incorporate video surveillance technology for the capture of the speed and the infraction of speeding,and it will make a sense of the form of the sensation and the visual bonding.this paper specific work content is as follows:1.This paper summarizes the current monitoring technologies in the intelligent transportation system,introduces the advantages of distributed optical fiber acoustic sensing,and expounds the research status and sensing principle of distributed optical fiber acoustic sensing technology.2.To design a high-speed road traffic operation based on distributed fiber-optic sonic sensor technology.The sensing optical fiber is laid in the green belt of the expressway,and the optical signal demodulation device is used to send the optical pulse signal.The vibration signal generated by the vehicle movement along the optical fiber is demodulated into electrical signal for the modulation information of the optical phase and polarization state,etc.,and it is collected and transmitted to the signal processing host in real time.According to the collected spatio-temporal signal,the movement track of the passing vehicle is obtained,and the movement and other traffic parameters are extracted according to the motion track.Combined with video monitoring technology,illegal phenomena such as overspeed are captured for evidence collection.3.In the process of distributed optical fiber sensing,a method of track extraction of optical fiber space-time sensing signals based on image processing techniques such as Hough transform is designed to calculate traffic flow,speed and other traffic parameters.In the time domain,the signals collected by distributed optical fiber acoustic sensing are accumulated to form a two-dimensional space-time response graph.The trajectory of the moving vehicle under simple background noise is accurately extracted with image processing techniques such as expansion,filtering and Hough transform.4.An intelligent recognition algorithm for speeding vehicle license plate information based on improved LeNet-5 convolution neural network is studied in the process of illegal collection.Through simulation analysis,the optimal number of feature maps of C1 and C3 layers is determined,and the convolution rule of C3 layer is changed.ReLu is used as the activation function,and Softmax is used as the output layer.The improved convolutional neural network has a license plate recognition rate of 98.46%.