Rail transit positioning method and system

Abstract

The invention discloses a rail transit positioning method and system, and the method comprises the steps: querying a device to be connected with a time server in the running process of a train, so as to complete time synchronization; an inquiry device at the head of the train periodically transmits handshake broadcast information to a response device on a track on which the train runs according to time slot distribution, the response device receives the broadcast information and responds to handshake response information after the broadcast information is ready, and the inquiry device selects a response device meeting the condition from a plurality of handshake response devices to start positioning; the inquiry equipment at the train head transmits inquiry signals to the selected response equipment twice according to time slot distribution, the response equipment responds to the position information according to a fixed signal format, and the inquiry equipment analyzes the received response position information and reports the position information of the train in real time; and when the distance between the inquiry equipment and the response equipment is smaller than a preset threshold value, the inquiry equipment at the train head stops transmitting the inquiry signal. According to the invention, train positioning can be realized under the condition that satellites are unavailable.

Description

Technical Field

[0001] The present application relates to the field of rail transit technology, and in particular to a method and system for rail transit positioning. Background Art

[0002] Rail transit primarily consists of high-speed rail and subways. Both are already in widespread use in China, with high-speed rail, in particular, gradually expanding globally. The primary concern for rail transit is safety, and train location information is crucial for safely controlling train operations. Existing methods for track positioning include manual reporting, time-based train control systems, and satellite technology, each with its own advantages and disadvantages. Manual reporting suffers from poor real-time and accuracy issues, train control system anomalies can cause confusion and lead to serious accidents, and satellite signal coverage for subways is limited. Under extreme conditions, existing technical solutions struggle to meet train safety requirements.

[0003] Existing rail transit positioning technologies are limited and cannot meet the requirements for safe operation under various conditions. Summary of the Invention

[0004] In view of this, the present application provides a method and system for rail transit positioning, which supports real-time measurement of the train's own position information during high-speed travel and can achieve train positioning when satellites are unavailable.

[0005] The present application discloses a method for rail transit positioning, which includes:

[0006] Step 1: While the train is moving, the interrogation device connects to the time server to synchronize time. The train's locomotive is equipped with an interrogation device with a directional antenna, and the track along which the train is traveling is equipped with omnidirectional transponders at equal intervals.

[0007] Step 2: The train's interrogation device periodically transmits a handshake broadcast message to the transponders on the track along which the train is traveling, according to the allocated time slots. The transponders receive the broadcast message and, when ready, respond with a handshake response message. The interrogation device selects a qualified transponder from among the multiple handshaking transponders to begin positioning. The condition is that the interrogation device is not currently positioning and is closest to the transponder with the nearest time slot being synchronized normally.

[0008] Step 3: The train's interrogation device transmits two interrogation signals to the selected transponder according to the time slot allocation. The transponder responds with position information in a fixed signal format. The interrogation device analyzes the received response position information and reports the train's position information in real time.

[0009] Step 4: When the distance between the interrogation device at the front of the train and the response device on the track is less than a preset threshold, the interrogation device at the front of the train stops transmitting the interrogation signal and repeats steps 2 to 4.

[0010] Furthermore, the time server is synchronized with the train operation control system to ensure the accuracy of position information reporting.

[0011] Furthermore, the inquiry device and the answering device are both identified by unique numbers, and the signal formats transmitted by them both contain the digital identification.

[0012] Furthermore, the handshake broadcast information includes an inquiry identification number, a current time and a frame time slot number, and the handshake response information includes a response identification number, a local time and a frame time slot number.

[0013] Furthermore, the time slot allocation refers to dividing each cycle into multiple time slots with P milliseconds as a cycle, the first time slot in the multiple time slots is m milliseconds long and is used for ranging, (Pm) / N time slots are N microseconds long and are used for broadcasting and data transmission, the inquiring device uses odd time slots and the answering device uses even time slots; P = m + N / 1000.

[0014] Furthermore, the response location information includes the longitude, latitude, altitude and system processing delay of the response device.

[0015] Furthermore, the location information includes ranging data, longitude and latitude data, and confidence; the ranging data is the distance between the interrogating device and the responding device; the confidence is divided into four levels, level 1 indicates that the difference between the two ranging results in the positioning time slot is large, and the credibility is the lowest; level 2 indicates that the difference between the two ranging results in the positioning time slot is small, and the credibility is high; level 3 indicates that the difference between the two ranging results in the positioning time slot is small, and matches the longitude and latitude distance, and the credibility is the highest.

[0016] Furthermore, the system processing delay includes the signal processing calculation delay and hardware link delay of the answering device.

[0017] Furthermore, the distance is calculated as follows:

[0018] D=(T-T1-T2)*c / 2

[0019] Where D is the distance between the interrogating device and the responding device, c is the speed of light, T is the total time between the interrogating device transmitting the interrogation signal and receiving the response signal, T1 is the system processing delay of the interrogating device, and T2 is the system processing delay of the responding device.

[0020] The present application also discloses a rail transit positioning system, which implements the above-mentioned rail transit positioning method, comprising:

[0021] A single interrogation unit uses a directional antenna to periodically transmit interrogation signals and handshake broadcast signals and receive response signals, calculate and report location information in real time;

[0022] Multiple response units use omnidirectional antennas to receive interrogation signals and transmit response position signals, wherein the latitude, longitude and altitude of the position signals are fixed in the response units when they are installed.

[0023] Due to the adoption of the above-mentioned technical solution, the present application has the following advantages: a positioning system is formed by a single inquiry device and multiple response devices, which supports the train to measure its own position information in real time during high-speed travel, solves the problem of train positioning under conditions where satellites are unavailable, and enriches the positioning technical means in the field of rail transit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0025] Figure 1 A schematic flow chart of a rail transit positioning method according to an embodiment of the present application;

[0026] Figure 2 A schematic diagram of a rail transit positioning system according to an embodiment of the present application. DETAILED DESCRIPTION

[0027] The present application is further described with reference to the accompanying drawings and embodiments. The embodiments described are only a part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0028] See also Figure 1 , the present application provides an embodiment of a rail transit positioning method, which includes:

[0029] Step 1: While the train is moving, the interrogation device connects to the time server to synchronize time. The train's locomotive is equipped with an interrogation device with a directional antenna, and the track along which the train is traveling is equipped with omnidirectional transponders at equal intervals.

[0030] Step 2: The train's interrogation device periodically transmits a handshake broadcast message to the transponders on the track along which the train is traveling, according to the allocated time slots. The transponders receive the broadcast message and, when ready, respond with a handshake response message. The interrogation device selects a qualified transponder from among the multiple handshaking transponders to begin positioning. The condition is that the interrogation device is not currently positioning and is closest to the transponder with the nearest time slot being synchronized normally.

[0031] Step 3: The train's interrogation device transmits two interrogation signals to the selected transponder according to the time slot allocation. The transponder responds with position information in a fixed signal format. The interrogation device analyzes the received response position information and reports the train's position information in real time.

[0032] Step 4: When the distance between the interrogation device at the front of the train and the response device on the track is less than a preset threshold, the interrogation device at the front of the train stops transmitting the interrogation signal and repeats steps 2 to 4.

[0033] Optionally, the time server is synchronized with the train operation control system to ensure the accuracy of position information reporting.

[0034] Optionally, the inquiry device and the answering device are both identified by unique numbers, and the signal formats transmitted by them both contain the digital identification.

[0035] Optionally, the handshake broadcast information includes an inquiry identification number, a current time and a frame time slot number, and the handshake response information includes a response identification number, a local time and a frame time slot number.

[0036] Optionally, the time slot allocation refers to dividing each cycle into multiple time slots with P milliseconds as a cycle, the first time slot in the multiple time slots is m milliseconds long and is used for ranging, (Pm) / N time slots are N microseconds long and are used for broadcasting and data transmission, the inquiring device uses odd time slots, and the answering device uses even time slots; P=m+N / 1000.

[0037] Optionally, the response location information includes the longitude, latitude, altitude and system processing delay of the response device.

[0038] Optionally, the location information includes ranging data, longitude and latitude data, and confidence; the ranging data is the distance between the interrogating device and the responding device; the confidence is divided into four levels, level 1 indicates that the difference between the two ranging results of the positioning time slot is large, and the credibility is the lowest; level 2 indicates that the difference between the two ranging results of the positioning time slot is small, and the credibility is high; level 3 indicates that the difference between the two ranging results of the positioning time slot is small, and matches the longitude and latitude distance, and the credibility is the highest.

[0039] Optionally, the system processing delay includes a signal processing calculation delay and a hardware link delay of the answering device.

[0040] Optionally, the distance is calculated as follows:

[0041] D=(T-T1-T2)*c / 2

[0042] Where D is the distance between the interrogating device and the responding device, c is the speed of light, T is the total time between the interrogating device transmitting the interrogation signal and receiving the response signal, T1 is the system processing delay of the interrogating device, and T2 is the system processing delay of the responding device.

[0043] See also Figure 2 The present application also provides an embodiment of a rail transit positioning system, which implements the rail transit positioning method described in the above embodiment, including:

[0044] A single interrogation unit 201, using a directional antenna, is used to periodically transmit interrogation signals and handshake broadcast signals and receive response signals, calculate and report location information in real time;

[0045] The plurality of response units 202 use omnidirectional antennas to receive interrogation signals and transmit response position signals, wherein the latitude, longitude, and altitude of the position signals are fixed in the response units when they are installed.

[0046] To better describe the positioning method of the present application, a comprehensive example is given here to illustrate the above process. Taking subway rail transit as an example, it is assumed that the identification number of the on-board interrogation device is A0, the latitude and longitude position information is (X0, Y0, Z0), the identification number of one response device is B1, the latitude and longitude position information is (X1, Y1, Z1), the synchronization time between the interrogation device and the train control system is T0, and the time slot rule is: 50ms as the time slot period, the second time slot as the broadcast message, then the broadcast period is also 50ms. At the beginning, the interrogation device transmits a handshake broadcast message with a period of 50ms. After receiving the broadcast message, the response device B1 sets the local time and responds to the handshake message in the next time slot. When the handshake response message meets the time slot rule, the interrogation device starts to transmit an interrogation signal to B1 with a period of 50ms. The response device receives the interrogation signal and checks whether it meets the time slot rule. If it meets the rule, it immediately transmits a response signal. At the query device end, the distance D between the two can be calculated based on the signal transmission and reception time and various processing delays. The height Z0 of the train is often known data. X0 and Y0 can be calculated from Z0, D and (X1, Y1, Z1), thereby obtaining the train's position information.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A method for rail transit positioning, characterized in that: include: Step 1: While the train is moving, the interrogation device connects to the time server to synchronize time. The train's locomotive is equipped with an interrogation device with a directional antenna, and the track along which the train is traveling is equipped with omnidirectional transponders at equal intervals. Step 2: The train's interrogation device periodically transmits a handshake broadcast message to the transponders on the track along which the train is traveling, according to the allocated time slots. The transponders receive the broadcast message and, when ready, respond with a handshake response message. The interrogation device selects a qualified transponder from among the multiple handshaking transponders to begin positioning. The condition is that the interrogation device is not currently positioning and is closest to the transponder with the nearest time slot being synchronized normally. Step 3: The train's interrogation device transmits two interrogation signals to the selected transponder according to the time slot allocation. The transponder responds with position information in a fixed signal format. The interrogation device analyzes the received response position information and reports the train's position information in real time. Step 4: When the distance between the interrogation device at the front of the train and the response device on the track is less than a preset threshold, the interrogation device at the front of the train stops transmitting the interrogation signal and repeats steps 2 to 4.

2. The rail transit positioning method according to claim 1, characterized in that: The time server is synchronized with the train operation control system to ensure the accuracy of position information reporting.

3. The rail transit positioning method according to claim 1, characterized in that: The inquiry device and the answering device are both identified by unique numbers, and the signal formats transmitted by them both contain the digital identification.

4. The rail transit positioning method according to claim 1, characterized in that: The handshake broadcast information includes an inquiry identification number, a current time and a frame time slot number, and the handshake response information includes a response identification number, a local time and a frame time slot number.

5. The rail transit positioning method according to claim 1, characterized in that: The time slot allocation refers to dividing each cycle into multiple time slots with P milliseconds as a cycle. The first time slot in the multiple time slots is m milliseconds long and is used for ranging. The (Pm) / N time slots are N microseconds long and are used for broadcasting and data transmission. The inquiring device uses odd time slots and the answering device uses even time slots; P = m + N / 1000.

6. The rail transit positioning method according to claim 1, characterized in that: The response location information includes the longitude, latitude, altitude and system processing delay of the response device.

7. The rail transit positioning method according to claim 1, characterized in that: The location information includes ranging data, longitude and latitude data, and confidence level. The ranging data is the distance between the interrogating device and the responding device. The confidence level is divided into four levels: level 1 indicates that the difference between the two ranging results in the positioning time slot is large, and the confidence level is the lowest; level 2 indicates that the difference between the two ranging results in the positioning time slot is small, and the confidence level is high; level 3 indicates that the difference between the two ranging results in the positioning time slot is small, and the distance matches the longitude and latitude, and the confidence level is the highest.

8. The rail transit positioning method according to claim 6, characterized in that: The system processing delay includes the signal processing calculation delay of the answering device and the hardware link delay.

9. The rail transit positioning method according to claim 1, characterized in that: The distance is calculated as follows: D=(T-T1-T2)*c / 2 Where D is the distance between the interrogating device and the responding device, c is the speed of light, T is the total time between the interrogating device transmitting the interrogation signal and receiving the response signal, T1 is the system processing delay of the interrogating device, and T2 is the system processing delay of the responding device.

10. A rail transit positioning system, which implements the rail transit positioning method according to any one of claims 1 to 9, characterized in that: include: A single interrogation unit uses a directional antenna to periodically transmit interrogation signals and handshake broadcast signals and receive response signals, calculate and report location information in real time; Multiple response units use omnidirectional antennas to receive interrogation signals and transmit response position signals, wherein the latitude, longitude and altitude of the position signals are fixed in the response units when they are installed.

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