Integrated rail transit positioning and communication method and system, device, and medium

Abstract

The present invention pertains to the field of train positioning and communication for rail transit signaling systems, and relates to an integrated rail transit positioning and communication method and system, a device, and a medium. The present invention is aimed at modifying and redesigning a frame format of a secondary surveillance radar, and achieves train positioning for signaling system control purposes by means of time-division multiplexing of a communication frame and a positioning frame, performing ranging between a plurality of vehicle-mounted tags and ground base stations, and querying a built-in electronic map. In addition, the present invention provides three train-to-ground methods, i.e., positioning frame-based point-to-point communication, communication frame-based broadcasting, and communication frame-based point-to-point communication, to enable train control information interaction between a train and a control center, and thereby achieve communication and positioning integration. Compared with the prior art, the present invention provides a standby communication positioning system for a rail transit signaling system, which improves signaling system communication and positioning reliability, and switches to an active system when the signaling system fails, thereby ensuring the normal operation of a train operation control system.

Description

Rail transit positioning and communication integrated method, system, device and medium TECHNICAL FIELD

[0001] The present application relates to the field of train positioning and communication of rail transit signal system, and particularly relates to a rail transit positioning and communication integrated method, system, device and medium based on secondary radar. BACKGROUND

[0002] Currently, the city rail mostly adopts a communication based train automatic control system (CBTC). Based on real-time and accurate positioning information of the train and bidirectional information transmission between the train and the ground, the train can run safely and efficiently. Therefore, the positioning system and the bidirectional communication system between the train and the ground play a crucial role in the operation control of the city rail train. The failure of the communication and positioning subsystems leads to the degraded operation of the train or even the parking of the train, which endangers the operation order of the train on the whole line and reduces the operation efficiency. On the other hand, the failure of the communication and positioning subsystems endangers the train operation safety and causes casualties. At present, there is no emergency backup communication and positioning subsystem in the city rail in China, which has certain safety hazards.

[0003] Several main positioning technologies applied in the urban rail transit have their own characteristics and limitations.

[0004] Transponder positioning: through the interaction between the vehicle-mounted query device on the train and the ground transponder laid along the line, point positioning is realized, and high safety and train-ground information transmission functions are provided. However, it only supports point positioning, has high cost and cannot meet the continuous positioning demand.

[0005] Axle counter positioning: the axle counter device is used to monitor the change of the vehicle axle number in the track section to determine the train position, which has strong environmental adaptability and low maintenance requirement, but the positioning accuracy is limited to the track section, does not have the continuous positioning capability and does not support the train-ground communication.

[0006] Global satellite navigation system (GNSS) positioning: the continuous positioning in the global range is realized by means of satellite signals, and the device is simple to maintain. However, in the signal blocked environment such as city high-rise buildings, tunnels or mountainous areas, the positioning accuracy is greatly reduced, and even cannot be used.

[0007] Speed measurement positioning: the running distance is obtained by measuring the running speed of the train and integrating, including the odometer and Doppler radar method. This method is easily affected by the cumulative error and needs to be calibrated regularly, and belongs to relative positioning, which needs to be combined with other technologies to determine the absolute position.

[0008] Secondary Surveillance Radar (SSR) is widely used in civil aviation and military fields, which adopts interactive communication method, i.e. ground station transmits specific coded inquiry signal, and transponder installed on the aircraft receives the inquiry signal and responds back to realize the positioning of the air target.

[0009] The existing urban rail transit train communication positioning subsystem mainly has the following defects:

[0010] 1. No emergency backup communication and positioning subsystem is set, when the existing system fails, the train cannot run normally, which reduces the train efficiency and endangers the train safety;

[0011] 2. Only the on-board equipment can directly obtain the vehicle positioning state from the positioning subsystem, the ground system cannot directly obtain the vehicle positioning state from the positioning subsystem, and can only return the vehicle positioning state through the communication subsystem;

[0012] 3. The communication subsystem and the positioning subsystem are independently set, which has high cost;

[0013] 4. Some positioning subsystems cannot realize continuous positioning;

[0014] 5. The use environment of some positioning subsystems is limited.

[0015] CN117775082A discloses a rail transit backup degraded operation system and method based on secondary radar, which includes a secondary radar system, a vehicle-mounted ATP system, an OC system and an ATS system, the secondary radar system performs train positioning and speed measurement, and the vehicle-mounted ATP system, the OC system and the ATS system control train operation in combination with the secondary radar system. However, it does not provide specific train positioning and communication means based on secondary radar.

[0016] SUMMARY

[0017] The purpose of the present application is to overcome the defects of the prior art and provide a rail transit positioning and communication integrated method, system, device and medium based on secondary radar.

[0018] The purpose of the present application can be achieved by the following technical solutions:

[0019] According to a first aspect of the present application, there is provided a secondary radar-based integrated positioning and communication method for rail transit, which is based on a plurality of vehicle-mounted tags and a plurality of ground base stations, and utilizes time-division multiplexing of communication frames and positioning frames to achieve train positioning and train-ground bidirectional communication between trains and between trains and a train control center, wherein train positioning is achieved through positioning frame communication between the vehicle-mounted tags and the ground base stations, temporary data exchange between trains and between trains and the train control center is achieved in a communication broadcast frame or a communication unicast frame on demand, and train-ground bidirectional communication between trains and between trains and the train control center is achieved through communication confirmation frames.

[0020] As a preferred technical solution, the positioning frame includes two formats, namely a Poll message sent by the vehicle-mounted tag to the ground base station and a Response message sent by the ground base station to the vehicle-mounted tag, and the two formats are distinguished by a function code.

[0021] As a preferred technical solution, the frame structure of the Poll message includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a timestamp, a train position, a train speed, a data payload, and a data length.

[0022] As a preferred technical solution, when the vehicle-mounted tag sends the Poll message for positioning, if there is data to be transmitted, the data is completely placed in the data payload field of the Poll message.

[0023] As a preferred technical solution, the frame structure of the Response message includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a timestamp, a movement authority, a data payload, and a data length.

[0024] As a preferred technical solution, when the ground base station replies to the Response message for positioning, if there is data to be transmitted, the data is completely placed in the data payload field of the Response message.

[0025] As a preferred technical solution, the implementation method of train positioning is that the vehicle-mounted tag and the ground base station perform distance measurement based on the positioning frame through the SDS-TWR method to respectively obtain the distance between the two vehicle-mounted tags at the train head and the nearest first ground base station, the distance between the two vehicle-mounted tags at the train tail and the nearest second ground base station, and the distance between the two vehicle-mounted tags at the train head, the distance between the two vehicle-mounted tags at the train tail, and the distance between the train head and the train tail, utilize the positions of the ground base stations in the database to calculate the position (x, y, z) of the train in the coordinate system through a trilateration algorithm, and project (x, y, z) onto an electronic map of the track through a projection algorithm to finally determine the position of the train.

[0026] As a preferred technical scheme, the ranging by the SDS-TWR method is specifically: messages are mutually sent between the vehicle-mounted label and the ground base station, and relevant time stamps are recorded, and a time of flight T between the secondary radar label and the base station is obtained by substituting into the following formula tof The time of flight T tof is multiplied by the speed of light to obtain a distance value between the vehicle-mounted label and the ground base station,

[0027] Wherein, T round1 is a time interval between the vehicle-mounted label sending a message to the ground base station and receiving a message returned by the ground base station, T round2 is a time interval between the ground base station sending a message to the vehicle-mounted label and receiving a message returned by the vehicle-mounted label, T reply1 is a time interval between the ground base station receiving a message sent by the vehicle-mounted label and sending a feedback message to the vehicle-mounted label, and T reply2 is a time interval between the vehicle-mounted label receiving a message sent by the ground base station and sending a feedback message to the ground base station.

[0028] As a preferred technical scheme, the vehicle-mounted label and the ground base station communicate every certain period or on demand, realizing two-way communication between the vehicle and the ground, that is, the train reports train number, train position and speed information to the train control center, and the train control center sends a movement authorization, line data, temporary speed limit information, grade conversion information, operation adjustment information and maintenance information to the train.

[0029] As a preferred technical scheme, the frame structure of the communication broadcast frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a data payload and a data length.

[0030] As a preferred technical scheme, the frame structure of the communication unicast frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a data payload and a data length.

[0031] As a preferred technical scheme, the frame structure of the communication acknowledgement frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, an acknowledgement flag and a data length.

[0032] As a preferred technical scheme, the vehicle-mounted label and the ground base station can both communicate with other devices, and broadcast communication or unicast communication is selected according to specific communication requirements;

[0033] When broadcast communication is performed, the vehicle-mounted label and the ground base station send communication data to all device IDs;

[0034] In the process of unicast communication, the vehicle-mounted label and the ground base station send communication data to a specific device ID, and when the device receives the unicast communication frame, it first checks whether the destination address ID is the device ID of itself, and if not, it is directly discarded, and if so, it sends a unicast acknowledgement frame to the device of the source address ID; if the transmitting end does not receive the unicast acknowledgement frame within a limited time, it repeatedly sends the data frame after a preset interval until it no longer sends the data frame after reaching the timeout.

[0035] As a preferred technical solution, the method comprises the following steps:

[0036] initializing data;

[0037] judging whether the current is in a positioning period for sending a positioning frame,

[0038] if in the positioning period, assembling the positioning frame and judging whether there is a point-to-point data transmission requirement, if yes, appending point-to-point data after the positioning frame and sending the positioning frame, otherwise, directly sending the positioning frame;

[0039] if not in the positioning period, entering a communication frame sending link to perform vehicle-ground bidirectional communication.

[0040] According to a second aspect of the present application, a secondary radar-based rail transit positioning and communication integrated system is provided, comprising a plurality of ground base stations and a plurality of vehicle-mounted labels, the ground base stations being connected through a rail transit existing network and a train control center, and the vehicle-mounted labels being connected with a vehicle-mounted safety computer through a serial port and a network port.

[0041] As a preferred technical solution, the ground base station is equipped with an omnidirectional antenna, which is installed on the wall on both sides of the track or is erected on the roadside at a height, the installation height is flush with the antenna of the vehicle-mounted label, and the distance between the antenna and the wall surface is greater than a preset distance threshold.

[0042] As a preferred technical solution, the ground base stations are deployed in a zigzag shape along both sides of the tunnel, and the deployment density of the base stations is increased at the curved sections.

[0043] As a preferred technical solution, the vehicle-mounted label is equipped with a directional antenna, the antenna is located on both sides above the train head and the train tail, and it is ensured that there is no obstruction near the antenna.

[0044] As a preferred technical solution, considering the characteristics of bidirectional operation of the train, two sets of vehicle-mounted labels and antennas are arranged at the train head and the train tail respectively.

[0045] According to a third aspect of the present application, an electronic device is provided, comprising a memory and a processor, the memory storing a computer program, and the processor implementing the method when executing the program.

[0046] According to a fourth aspect of the present application, a computer readable storage medium is provided, having stored thereon a computer program which, when executed by a processor, implements the method.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] (1) The present application realizes the integration of positioning and communication of rail transit based on secondary radar, provides a backup communication positioning system for the rail transit signal system, provides redundancy backup for the existing communication subsystem and positioning subsystem, improves the reliability of signal system communication and positioning, and switches to the main system when a fault occurs, thereby ensuring the normal work of the train operation control system, enhancing the emergency capability of the CBTC system of urban rail transit, and guaranteeing the train operation efficiency and train safety.

[0049] (2) The train position can be obtained by the vehicle and the train control center at the same time, which is different from other schemes that can only obtain the train position at one side of the vehicle or the ground.

[0050] (3) The present application realizes the functions of the positioning subsystem and the communication subsystem in CBTC by secondary radar communication and positioning integration, and only one set of secondary radar equipment is needed to realize the functions, thereby reducing the construction and maintenance cost and improving the system utilization efficiency.

[0051] (4) In the present application, communication and interaction can be carried out between the vehicle and the ground / vehicle-to-vehicle, and broadcast and unicast can be selected according to the needs.

[0052] (5) The present application redundantly designs the vehicle-to-ground / vehicle-to-vehicle two-way communication process, thereby improving the reliability and success rate of vehicle-to-ground communication. BRIEF DESCRIPTION OF DRAWINGS

[0053] Fig. 1 is a schematic diagram of the system structure of the present application;

[0054] Fig. 2 is a schematic diagram of the deployment of the ground base station;

[0055] Fig. 3 is a schematic diagram of the deployment of the vehicle-mounted label;

[0056] Fig. 4 is a schematic diagram of the positioning principle of the present application;

[0057] Fig. 5 is a schematic diagram of double-sided two-way ranging (DS-TWR);

[0058] Fig. 6 is a flowchart of secondary radar communication and positioning integration;

[0059] Fig. 7 is a flowchart of the transmission process of the secondary radar at the transmitting end;

[0060] Fig. 8 is a flowchart of the transmission process of the secondary radar at the receiving end. DETAILED DESCRIPTION

[0061] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts should fall within the scope of the present application.

[0062] Unless otherwise defined, technical terms or scientific terms used in the present application should be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms "one", "a", "an", "the", and similar terms in the present application do not denote a singular number or quantity but denote the presence of at least one, equivalent to the meaning of the singular number or quantity. The terms "include", "contain", "have", and any variations thereof in the present application are intended to cover the non-exclusive inclusion; for example, a process, method, system, product or device including a series of steps or modules (units) is not limited to the listed steps or units, but can further include steps or units not listed or can further include other steps or units inherent to the process, method, product or device. The terms "connect", "connected", "couple" and similar terms in the present application are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The term "multiple" in the present application refers to two or more. The term "and / or" describes the association relationship between the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects. The terms "first", "second", "third" and the like in the present application are only to distinguish similar objects, and do not represent a specific order of the objects.

[0063] The present application mainly solves the following problems:

[0064] 1. The secondary radar communication positioning integration provides an emergency backup communication positioning system for urban rail transit, and only one set of equipment is needed to complete train positioning and bidirectional communication.

[0065] 2. The communication between the train and the ground and between the trains, including unicast / broadcast and other multiple modes, is realized.

[0066] 3. The continuous positioning function is realized.

[0067] Firstly, the present embodiment provides a secondary radar-based rail transit positioning and communication integrated system. When the existing communication subsystem or positioning subsystem of the train fails, the system can be switched to the present system to realize continuous and accurate positioning of the train and bidirectional communication between the train and the ground, so as to ensure the normal work of the train operation control system and guarantee the train operation efficiency and driving safety.

[0068] The present application is based on secondary radar communication positioning integration, through positioning frame, communication broadcast frame, communication unicast frame, communication confirmation frame, only using a set of equipment can realize the function of positioning subsystem and communication subsystem in CBTC.

[0069] The track traffic positioning communication integrated system of the present application comprises a plurality of ground base stations and a plurality of vehicle-mounted tags.

[0070] The plurality of vehicle-mounted tags measures the plurality of ground base stations, and obtains the train position by combining with an electronic map.

[0071] Meanwhile, the vehicle-mounted tags and the ground base stations communicate every certain period or on demand, to realize one-way train-ground communication between the train and the train control center. That is, the train reports train number (device ID number), train position and speed information to the train control center. The train control center sends MA (mobile authorization), line data, temporary speed limit information, grade conversion information, operation adjustment information and maintenance information to the train. The train and the train, and the train and the train control center exchange temporary data on demand in the form of broadcast frame or unicast frame, and are confirmed through the communication confirmation frame.

[0072] As shown in FIG. 1, the track traffic positioning communication integrated system comprises a plurality of ground base stations and a plurality of vehicle-mounted tags. The ground base stations are connected with the train control center through the existing network of urban rail transit. The vehicle-mounted tags are connected with the vehicle-mounted safety computer through a serial port, a network port or the like.

[0073] The ground base stations are equipped with omnidirectional antennas, which are installed on the walls on both sides of the track or are erected on the roadside at a height equal to the height of the antennas of the vehicle-mounted tags. The distance between the antennas and the wall surface is greater than a preset distance threshold, so as to avoid the ranging error caused by the reflection of the signals emitted by the omnidirectional antennas to the wall surface.

[0074] As shown in FIG. 2, the ground base stations are arranged in a zigzag shape along the two sides of the tunnel. In addition, in order to ensure the positioning accuracy, the base station deployment density is increased at the curved track in the embodiment.

[0075] The vehicle-mounted tags are equipped with directional antennas, which are located on both sides above the train head and the train tail, and the antennas are ensured to be not blocked.

[0076] Considering the characteristics of the bidirectional operation of the train, two sets of vehicle-mounted tags and antennas are arranged at the train head and the train tail respectively, as shown in FIG. 3.

[0077] Based on the above system, the embodiment provides a track traffic positioning and communication integrated method based on secondary radar. The method is based on multiple vehicle tags and multiple ground base stations, and utilizes time division multiplexing of communication frames and positioning frames to realize train positioning and train-to-train and train-to-control center two-way communication. The train positioning is realized through positioning frame communication between the vehicle tags and the ground base stations. The train-to-train and train-to-control center two-way communication is realized through temporary data interaction in communication broadcast frames or communication unicast frames and communication confirmation frames.

[0078] 1. Positioning frame structure

[0079] In the embodiment, the positioning frame includes two formats, which are a Poll message sent by a vehicle tag to a ground base station and a Response message sent by the ground base station to the vehicle tag. The two formats are distinguished by a Function Code.

[0080] The frame structure of the Poll message is shown in Table 1.

[0081] Table 1 Frame structure of the Poll message

[0082] When the vehicle tag sends the Poll message for positioning, if there is data to be transmitted, the data is completely placed in the "data payload" field of the Poll message.

[0083] The frame structure of the Response message is shown in Table 2.

[0084] Table 2 Frame structure of the Response message

[0085] When the ground base station replies the Response message for positioning, if there is data to be transmitted, the data is completely placed in the "data payload" field of the Response message.

[0086] 2. Train positioning

[0087] In the embodiment, the ranging positioning function is realized through multi-point ranging and querying of the built-in electronic map by utilizing the ranging positioning frame interaction mode between the ground base stations and the vehicle tags. The ranging positioning frame is initiated by the vehicle tag, the SDS-TWR technology is adopted, and the ranging results of the vehicle tag and the ground base station in the last period are written into the message in the next period to realize the ranging function.

[0088] Specifically, the onboard tags and ground base stations use the SDS-TWR method to measure distances based on positioning frames. This involves obtaining the distances between the two onboard tags at the front of the train and their nearest first ground base station, and the distances between the two onboard tags at the rear of the train and their nearest second ground base station. Additionally, the distances between the two onboard tags at the front and rear of the train, as well as the distances between the front and rear of the train, are also obtained. Using the locations of the ground base stations in the database, a trilateration algorithm is used to calculate the train's position (x, y, z) in the coordinate system. This position is then projected onto an electronic map of the track using a projection algorithm, ultimately determining the train's location. Consequently, both the onboard computer and the train control center can obtain the train's position. In one embodiment, as shown in FIG4, the obtained distances include: the distance L1 between vehicle tag M1 and ground base station A1, the distance L2 between vehicle tag M2 and ground base station A1, the distance L4 between vehicle tag M3 and ground base station A2, the distance L5 between vehicle tag M4 and ground base station A2, the distance L3 between M1 and M2 known at the time of installation, the distance L6 between M3 and M4, and the distance L7 between the front and rear of the vehicle.

[0089] As shown in Figure 5, the ranging method using SDS-TWR involves: exchanging messages between the vehicle-mounted tag and the ground base station and recording relevant timestamps; substituting these timestamps into the following formula to obtain the flight time T between the secondary radar tag and the base station. tof Flight time T tof Multiply by the speed of light to obtain the distance between the corresponding vehicle-mounted tag and the ground base station.

[0090] Among them, T round1 T is the time interval between the vehicle-mounted tag sending a message to the ground base station and receiving a message back from the ground base station. round2 T is the time interval between the ground base station sending a message to the vehicle tag and receiving a message back from the vehicle tag. reply1 T is the time interval between when the ground base station receives a message from the vehicle-mounted tag and when it sends a feedback message to the vehicle-mounted tag. reply2 The time interval between when the vehicle-mounted tag receives a message from the ground base station and when it sends a feedback message back to the ground base station.

[0091] 3. UWB communication frames

[0092] This invention improves upon the positioning frame by adding custom data for transmitting two-way vehicle-to-ground communication information. Data is transmitted transparently during the transmission process. This invention includes three communication frame message types: communication broadcast frames, communication unicast frames, and communication acknowledgment frames. These three message types are distinguished by Function Codes, and their frame structures are shown in Tables 3-5.

[0093] Table 3 Communication Broadcast Frame Structure

[0094] Table 4 Communication unicast frame structure

[0095] Table 5 Communication acknowledgement frame structure

[0096] 4. Train-ground communication

[0097] As shown in FIG. 6, the rail transit positioning and communication integrated method includes the following steps:

[0098] initializing data;

[0099] determining whether the current is in a positioning period for sending a positioning frame,

[0100] if in the positioning period, assembling the positioning frame and determining whether there is a point-to-point data transmission requirement, if yes, appending the point-to-point data after the positioning frame and sending the positioning frame, otherwise, directly sending the positioning frame;

[0101] if not in the positioning period, entering a communication frame sending link to perform train-ground bidirectional communication.

[0102] In an embodiment, the secondary radar vehicle-mounted tag sends a positioning frame to a trackside base station every 50 ms, if there is a point-to-point communication requirement when the positioning frame is sent, the point-to-point data is appended after the positioning frame, and if there is a communication requirement during the sending of the positioning frame, a broadcast communication frame (or a point-to-point communication frame) is sent.

[0103] The specific flow is as follows:

[0104] Step 1, completing initialization of data, entering Step 2;

[0105] Step 2, when the device sends a message, first determining whether it is a positioning frame sending period; if yes, entering Step 3, if not, entering Step 6;

[0106] Step 3, performing a positioning stage, assembling a positioning frame, determining whether there is point-to-point data to be sent in the cache, if yes, entering Step 4, if not, entering Step 5;

[0107] Step 4, appending the point-to-point data after the positioning frame, entering Step 5;

[0108] Step 5, sending the positioning frame, entering Step 2;

[0109] Step 6, performing a pure data sending stage, determining whether there is data to be sent in the cache, if yes, entering Step 7, if not, entering Step 2;

[0110] Step 7, judging whether the data in the cache is broadcast data, if yes, entering step 8, if not, entering step 9;

[0111] Step 8, assembling a broadcast frame, entering step 10;

[0112] Step 9, assembling a point-to-point data frame, entering step 10;

[0113] Step 10, sending the communication frame, entering step 2.

[0114] Both the on-board tag and the ground base station can communicate with other devices, and broadcast communication or unicast communication is selected according to specific communication requirements.

[0115] When performing broadcast communication, the on-board tag and the ground base station send communication data to all device IDs.

[0116] When performing unicast communication, the on-board tag and the ground base station send communication data to specific device IDs. When a device receives a unicast communication frame, it first checks whether the destination address ID is its own device ID. If not, it directly discards it. If yes, it sends a unicast acknowledgement frame to the device with the source address ID. If the transmitting end does not receive a unicast acknowledgement frame within a limited time, it repeatedly sends the data frame after a preset interval until it no longer sends the data frame after a timeout.

[0117] As shown in FIG. 7, when performing communication, the transmitting end includes the following steps:

[0118] S101, judging whether it is in a communication period, if yes, entering step S102, otherwise, directly ending;

[0119] S102, judging whether there is data to send, if yes, entering step S103, otherwise, directly ending;

[0120] S103, putting the data into the sending cache area;

[0121] S104, judging whether it is a broadcast frame, if yes, sending communication data to all device IDs, and entering step S101, otherwise, entering step S105;

[0122] S105, sending communication data to specific device IDs, and judging whether a unicast acknowledgement frame is received within a limited time, if yes, deleting the sent data in the cache area, and entering step S101, otherwise, waiting for a period of time, and entering step S101.

[0123] As shown in FIG. 8, when performing communication, the receiving end includes the following steps:

[0124] S201, receiving a data packet;

[0125] S202, judging whether it is a broadcast frame, if yes, receiving and processing, otherwise, entering step S203;

[0126] S203, judging whether the target device ID is itself, if yes, receiving and processing, further sending an acknowledgement message, otherwise, discarding the frame.

[0127] The electronic device includes a central processing unit (CPU) that can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded from a storage unit into a random access memory (RAM). Various programs and data required for device operation can also be stored in the RAM. The CPU, ROM, and RAM are connected to each other through a bus. An input / output (I / O) interface is also connected to the bus.

[0128] Various components in the device are connected to the I / O interface, including: an input unit such as a keyboard, a mouse, etc.; an output unit such as various types of displays, a speaker, etc.; a storage unit such as a magnetic disk, an optical disk, etc.; and a communication unit such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0129] The processing unit performs various methods and processes described above, such as steps 1-10. For example, in some embodiments, steps 1-10 can be implemented as a computer software program that is tangibly embodied in a machine-readable medium, such as the storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed on the device via the ROM and / or the communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more of steps 1-10 described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform steps 1-10 by any other appropriate means, such as by means of firmware.

[0130] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, exemplary types of hardware logic components that can be used include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip systems (SOCs), complex programmable logic devices (CPLDs), etc.

[0131] Program code for carrying out methods of the present application can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / operations specified in the flowchart diagrams and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine as a stand-alone software package, or entirely on a remote machine or server.

[0132] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable storage medium can include, but are not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fibers, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the foregoing.

[0133] The above descriptions are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for integrating positioning and communication of rail transit based on secondary radar, characterized in that, The method is based on multiple vehicle tags and multiple ground base stations, and utilizes time-sharing multiplexing of communication frames and positioning frames to realize train positioning and train-ground two-way communication between trains and between trains and a train control center, wherein train positioning is realized through positioning frame communication between vehicle tags and base stations, temporary data interaction between trains and between trains and the train control center is realized through communication broadcast frames or communication unicast frames on demand, and communication confirmation frames are used for confirmation, thereby realizing train-ground two-way communication between trains and between trains and the train control center.

2. The method according to claim 1, wherein, The positioning frames include two formats, namely a Poll message sent by a vehicle tag to a ground base station and a Response message sent by a ground base station to a vehicle tag, and the two formats are distinguished by a function code.

3. The method according to claim 2, wherein, The frame structure of the Poll message includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a timestamp, a train position, a train speed, a data payload, and a data length.

4. The method according to claim 3, wherein, When the vehicle tag sends the Poll message for positioning, if data needs to be transmitted, the data is completely placed in the data payload field of the Poll message.

5. The method of claim 2, wherein the method is a method of integrating positioning and communication for rail transit based on secondary radar. The frame structure of the Response message includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a timestamp, a movement authorization, a data payload, and a data length.

6. The method according to claim 5, wherein, When the ground base station replies to the Response message for positioning, if data needs to be transmitted, the data is completely placed in the data payload field of the Response message.

7. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The implementation method of train positioning is that, based on positioning frames between the vehicle tags and the ground base stations, ranging is performed through the SDS-TWR method to obtain distances between two vehicle tags at the train head and the nearest first ground base station, distances between two vehicle tags at the train tail and the nearest second ground base station, distances between the two vehicle tags at the train head, distances between the two vehicle tags at the train tail, and a distance between the train head and the train tail, and the position (x, y, z) of the train in a coordinate system is calculated through a three-edge positioning algorithm using the positions of the ground base stations in a database, and (x, y, z) is projected onto an electronic map of the track through a projection algorithm to finally determine the position of the train.

8. The method according to claim 7, wherein, The distance measurement by the SDS-TWR method is specifically: through mutual sending of messages between the vehicle-mounted tag and the ground base station and recording of relevant time stamps, substituting into the following formula to obtain the time of flight T between the secondary radar tag and the base station tof , multiplying the time of flight T tof by the speed of light to obtain the distance value between the vehicle-mounted tag and the ground base station, where T round1 is the time interval between the on-board tag sending a message to the ground base station and receiving the message returned by the ground base station, round2 is the time interval between the ground base station sending a message to the on-board tag and receiving the message returned by the on-board tag, reply1 is the time interval between the ground base station receiving the message sent by the on-board tag and sending a feedback message to the on-board tag, reply2 is the time interval between the on-board tag receiving the message sent by the ground base station and sending a feedback message to the ground base station.

9. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The vehicle tags and the ground base stations communicate every certain period or on demand to realize train-ground two-way communication, namely, the train reports train number, train position, and speed information to the train control center, and the train control center sends movement authorization, line data, temporary speed limit information, grade conversion information, operation adjustment information, and maintenance information to the train.

10. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The frame structure of the communication broadcast frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a data payload, and a data length.

11. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The frame structure of the communication unicast frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a data payload, and a data length.

12. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The frame structure of the communication confirmation frame includes a preamble, a frame type identifier, a function code, a source address ID, a destination address ID, a sequence number, a confirmation flag, and a data length.

13. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The vehicle-mounted label and the ground base station can communicate with other devices, and broadcast communication or unicast communication is selected according to specific communication requirements; In the broadcast communication, the vehicle-mounted label and the ground base station send communication data to all device IDs; In the unicast communication, the vehicle-mounted label and the ground base station send communication data to specific device IDs, and when a device receives a unicast communication frame, it first checks whether the destination address ID is the device ID of itself, and if not, it is directly discarded, and if so, it sends a unicast acknowledgement frame to the device of the source address ID; If the transmitting end does not receive a unicast acknowledgement frame within a limited time, it repeatedly sends the data frame after a preset interval until it no longer sends the data frame after timeout.

14. The method of claim 1, wherein the method is a method of integrated positioning and communication for rail transit based on secondary radar. The method comprises the following steps: initializing data; determining whether the current is in the positioning period of sending a positioning frame, if it is in the positioning period, assembling the positioning frame and determining whether there is a point-to-point data transmission requirement, if there is, appending point-to-point data to the positioning frame and sending the positioning frame, otherwise, directly sending the positioning frame; if it is not in the positioning period, entering the communication frame sending link and performing bidirectional communication between the vehicle and the ground.

15. A secondary radar-based integrated positioning and communication system for rail transport, characterized in that, The system comprises a plurality of ground base stations and a plurality of vehicle-mounted labels, the ground base stations are connected through the existing network of urban rail transit and the train control center, and the vehicle-mounted labels are connected with the vehicle-mounted safety computer through a serial port and a network port.

16. The integrated positioning and communication system for rail transit based on secondary radar according to claim 15, characterized in that, The ground base station is equipped with an omnidirectional antenna, which is installed on the wall on both sides of the track or is erected on the roadside at a height, the installation height is flush with the antenna of the vehicle-mounted label, and the distance between the antenna and the wall surface is greater than a preset distance threshold.

17. The integrated positioning and communication system for rail transit based on secondary radar according to claim 15, characterized in that, The ground base stations are arranged in a zigzag shape along both sides of the tunnel, and the deployment density of the base stations is increased at the curved sections.

18. The integrated positioning and communication system for rail transit based on secondary radar according to claim 15, characterized in that, The vehicle-mounted label is equipped with a directional antenna, which is located on both sides above the train head and tail, and no obstruction is ensured near the antenna.

19. The integrated positioning and communication system for rail transit based on secondary radar according to claim 15, characterized in that, Considering the characteristics of bidirectional operation of the train, two sets of vehicle-mounted labels and antennas are arranged at the train head and tail.

20. An electronic device comprising a memory and a processor, said memory having stored thereon a computer program, characterized in that, The processor executes the program to implement the method of any one of claims 1-14.

21. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the method of any one of claims 1-14.

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