Automatic train control system based on crack wave

2022-07-23
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Automatic train control system based on crack waveguide communication

[Abstract] this paper introduces the composition, principle and function of automatic train control system based on crack waveguide communication

[Key words] ATC (automatic train control), crack waveguide, waveguide information, waveguide information base station

1 overview

there are many ways to realize the automatic train control system based on communication. There are such forces as laying cable rings, leaking cables, crack waveguides and installing wireless spread spectrum radio stations along the trackside. The cross cable ring method is a relatively mature technology at present. Because it requires laying the cross cable ring along the whole track, the installation workload is large, the maintenance is troublesome, and its linear loss is larger than that of the slotted waveguide. ATC (automatic train control system) based on communication means such as cable ring or leaky cable exchanges vehicle position information through station and trackside equipment. The position in the train route needs to be measured by on-board odometer (synchronized by the intersection of cable ring) and sent to the cable ring on the track through on-board communication antenna, and then sent to the station control equipment after being processed by trackside equipment, The station control equipment will then forward this information to the subsequent trains. The subsequent trains know the position of the previous train, and can maintain the running distance between the two trains according to the pre-defined safe running principle to realize the moving block. At present, there are only a few successful applications of the wireless spread spectrum radio method. Although the system has the advantages of less equipment, low cost, convenient installation and easy maintenance, it is necessary to install signal relay equipment in the subway tunnel (especially at the corners), and its transmission power should not be too large. By using the wireless spread spectrum radio and slot waveguide as the communication medium, and using the slot waveguide as the antenna of the radio station, the problem of signal transmission of the radio station in the subway tunnel is completely solved. It is a safe, reliable and advanced signal system, which is most suitable for use in the subway environment. This paper mainly introduces the structure, principle and function of automatic train control system based on crack waveguide communication

2 system composition and principle

the automatic train control system based on split waveguide communication adopts the mode of laying split waveguide (slot antenna) along the track, based on the waveguide information network and wireless spread spectrum radio, adopts TDMA (time division multiple access) multiple access communication mode, and realizes the two-way continuous communication and train positioning between the train and trackside equipment through the collection of wired and wireless networks, Finally, the moving block signal control system is realized

2.1 waveguide information network

waveguide information network is used to ensure the two-way continuous transmission of information between the train and local ATS (Automatic Train Supervision) - automatic train monitoring system and control center. The waveguide information network is composed of a plurality of waveguide information communication units and a vehicle mounted waveguide information mobile station. Figure 1 shows the structure of the waveguide information network

waveguide information base station is composed of station computer, wireless spread spectrum radio, data acquisition card, passive filter, slot detection transmitter, coupler, etc. The mobile station, a large manufacturer of experimental machines in Jinan, is composed of on-board computers, on-board radio stations, data acquisition cards, narrow slot detection receivers, etc. Signal transmission refers to transmitting and receiving signals through ATS central control room, station computer, on-board computer, on-board radio and directional antenna on the train. Trackside unit is connected with crack waveguide through coaxial cable, and the crack waveguide is used as the carrier to transmit real-time train information in two directions

waveguide information base station and trackside ATP (automatictrainprotection)/ATO (automatictrainoperation) - Automatic Train Protection/automatic train operation are wired connections. Trackside ATP/att form an interval link through optical fiber, pigtail, optical distribution frame, optical transceiver, etc. The wireless network between the waveguide information base station and the waveguide information mobile station implements the IEEE802.11 and IEEE802.3 standards. The operating system can be windowsnt4.0, Linux, Windows2000, etc

waveguide information uses wireless spread spectrum radio for network communication. The frequency hopping time and the time division multiplexing period greatly reduce the cost and synchronization of the modified special materials. The communication in each control section has a certain overlapping coverage area to ensure a smooth transition when the train runs to the boundary of the control area. The network operating system is installed on the main control computer of the station. The system identifies each train according to the different identification of the on-board computer of each train and the different wireless card configuration. Use large-scale database software (such as Oracle, Sybase, etc.) to obtain train operation data sent by on-board computer through data acquisition software of data acquisition card, and analyze, calculate, query, count, update and store the data. On board and station control software sends, downloads and updates required data through waveguide information

the waveguide information base station is also responsible for: receiving and processing the data of the on-board computer, sending the data of the main control computer, receiving the train positioning data, processing the train operation data collected by the data acquisition card, providing the HMI (human machine interface) interface, receiving the train control information sent by the HML and sending it through the message module, providing the TCP/IP communication interface, providing the serial port communication interface, etc

2.2 communication unit

the communication unit in the system is a wireless and wired communication network composed of slotted waveguide (used to radiate electromagnetic wave carrier), waveguide coaxial converter (used to feed RF carrier signal to slotted waveguide), coaxial cable, terminal load (used to eliminate anti bow quilt), waveguide information base station, trackside ATP/ATO, Park Company link and equipment along the line. Figure 2 shows the basic composition of the communication unit

The communication unit in the

system is the foundation of the waveguide information network, which is responsible for the information management and train control of each station. The information is exchanged through the communication network such as the section link and B in the control, so that the control center can dispatch and manage each train. Each communication unit, local ATS, trackside ATP/ATO, computer interlocking and track circuit form a signal control station. Platform signal equipment such as annunciator, screen door and emergency stop button shall be controlled by interlocking equipment of signal control station. The signal control station is mainly responsible for: initializing network configuration, wireless network management, data recording, data processing, tracking zero train, speed calculation, providing operator interface, train control system interface, on-board computer information exchange, etc

2.3 waveguide information base station

the waveguide information base station is generally located near the waveguide and can also be installed in the signal equipment room. It is mainly composed of the following equipment: passive filter, wireless modem, crack waveguide detection carrier generator, multiplexer, coupler power supply, etc. It is the most basic part of the waveguide information network unit and the workstation for vehicle ground communication with the vehicle mobile station

2.4 waveguide information mobile station

there is a waveguide information mobile station in the cabs at both ends of the train. Including on-board radio station, on-board ATP/ATO equipment, interface circuit, beacon receiving antenna and decoder. The on-board computer shall be installed with a special data acquisition card as a mobile workstation, and the operating system, database, special data acquisition software, etc. shall be installed. Mainly responsible for: data initialization, wireless network connection, obtaining position information, speed calculation, control area handover communication, information exchange with station computer, data recording, data processing, train control system (narrow gap risk detection receiver) interface, etc

2.5 microwave slot waveguide

the microwave slot waveguide system is used as the vehicle ground bidirectional data transmission medium. The microwave slot waveguide system is the key part of the waveguide information network. It is a transmission system with wide bandwidth that can simultaneously transmit data, voice and video signals, which is used for vehicle ground bidirectional continuous data transmission and train positioning

the slotted waveguide is a hollow aluminum rectangular tube with narrow slots at the top, so that the microwave within the carrier frequency range can radiate evenly along the slotted waveguide. The receiver can receive the signal radiated by the waveguide slot at an appropriate position above the waveguide. The receiver obtains useful data through signal processing. Figure 3 shows the transmission mode of the slotted waveguide. Trackside atp/ato - voice, video and data

TDMA is used as the communication organization and management mode of the system. TDMA (time division multiple access) - time division multiple access is a multiple access communication technology that all users use the same RF bandwidth and transmit time-sharing in a certain order. The waveguide information base station gives a synchronization signal to each train and pre assigns a fixed time slot to each RJ train. Each train exchanges information with the waveguide information base station in its own time slot (the specific time element and time slot division need to be determined according to the technical indicators of the spread spectrum radio, generally one time slot is about 10ms). Direct sequence spread spectrum and frequency hopping are used to prevent interference. The waveguide information base station uses coaxial cable to connect with the slot waveguide, and exchanges information with the vehicle radio through the slot waveguide. The information exchange between the train and the trackside unit is completed in a fixed time slot. The system detects the position of each train many times per second. Using time division multiple access (TDMA) method, it can control up to 30 trains at the same time. The data exchanged includes train number, current relative position, current running speed, running time, running distance, arrival time, clearing time, etc. the train controls the train operation and accurate positioning through on-board ATP/ATO. Figure 4 is the TDMA schematic diagram

The project has built several sets of demonstration projects

2.7 calculation of train running distance

running distance of the train 2 waveguide crack spacing x the number of cracks detected from the relative starting point

the current speed of the train is calculated according to the position information and the corresponding running time. The train sends the speed information and relative position release message to the trackside base station, and then transmits it to the control center through the remote control unit

2.8 train positioning

each train has its own positioning function to determine its own speed distance curve. The train initializes, updates data or stops accurately through on-board sensor and reading information of trackside beacon. When the train passes, the beacon installed in the road is used to determine the absolute position and running direction of the train. The train sends its position information to trackside ATP through the waveguide information to ensure survival. Since the slot waveguide is used with narrow slots on its top, the absolute position of the train can be obtained by counting the slots of the slot waveguide and comparing the beacons

2.9 protection of moving block area

trackside equipment collects the position information of all trains, manages each train, and determines the safety protection section according to the real-time position, speed and train information of the train. Trackside equipment provides each on-board ATP with a fault safety restricted position where subsequent trains cannot enter the "protection range" of the current train

3 summary

due to the automatic train control system based on split waveguide communication, the track is divided into different control areas. Each control area consists of station computer, wireless spread spectrum radio and waveguide information. The waveguide is physically arranged so that each control area overlaps each other. With the waveguide information as the transmission medium, the stations can be reliably covered by radio without blind areas, Using the waveguide crack to locate the train can greatly improve the positioning accuracy of the train. Through continuous train ground two-way communication, the

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