Design And Implementation Of Train Positioning And Communication System Based On Environment Awareness

In the fourteenth five year plan,China clearly proposes to speed up the construction of a transportation power,build a modern comprehensive transportation system,speed up the networking of urban agglomeration and metropolitan rail transit,speed up the digital transformation of rail transit,and strengthen the construction of ubiquitous perception,terminal networking,and intelligent dispatching system of rail transit.In order to implement the development goals,China continues to expand the construction scale of rail transit.In the background of large-scale and intelligent development,the dynamic control of train is very difficult.It is necessary to accurately locate the train and maintain real-time and reliable communication with the central control platform.The traditional train positioning equipment is balise,which has the disadvantages of high cost,difficult maintenance,more radio interference and discontinuous positioning information.This paper proposes a train positioning scheme based on binocular vision and two-dimensional code,which has the advantages of low cost,high accuracy,fast speed and continuous positioning information.This paper completes the selection of optical beacon,and selects QR code which is easy to locate in the image,fast decoding and error correction ability as the optical beacon.In order to reduce the influence of image motion distortion,this paper selects aruco code with smaller coding density.In order to speed up the ranging and recognition speed of two-dimensional code,this paper designs a region extraction scheme based on feature color and sliding window.In this paper,the ZBar algorithm is optimized to speed up the recognition speed of twodimensional code.The test results show that the system designed in this paper can achieve centimeter level positioning accuracy in a short time(less than 100 ms).In order to improve the ubiquitous perception ability of the train,millimeter wave radar,which has been widely used in the automobile,is used as the sensor for the forward ranging and obstacle avoidance of the train.However,millimeter wave radar has the disadvantage of high false alarm rate in the tunnel scene of rail transit.In this paper,the tunnel scene of millimeter wave radar is optimized,which effectively reduces the false alarm rate of the radar and improves the safety level of the train.The station train communication system needs to be updated.At present,trains generally use narrow-band GSM-R network for communication,which has been unable to meet the needs of intelligent development of rail transit.In order to solve the problem of communication bandwidth and speed,this paper designs an image transmission system based on LTE;Aiming at the reliability problem,this paper designs a command and control transmission system based on QPSK modulation,and carries out the transceiver simulation test on the software radio platform,which verifies the feasibility and performance of the relevant scheme.In response to the call of rail transit network,this paper explores the train network,and applies ad hoc protocol and TTE protocol in train network.On this basis,NS3 is used for network simulation.When the packet loss rate is 0,the maximum delay is less than 10 ms and the average delay is 2.082 Ms.