A method and system for positioning of rail transit

Abstract

The application discloses a rail transit positioning method and system, which comprises the following steps: connecting a device for inquiring with a time server to complete time synchronization during train running; periodically transmitting a handshake broadcast message to a responding device on a track where the train runs according to a time slot allocation period; receiving the broadcast message and responding to the handshake response information after preparation; selecting a responding device that meets the conditions from multiple responding devices to start positioning; transmitting two inquiry signals to the selected responding device according to the time slot allocation; responding to the position information according to a fixed signal format; analyzing the received responding position information and reporting the position information of the train in real time; and stopping the transmission of the inquiry signal when the distance between the inquiring device and the responding device is less than a preset threshold. The application can realize train positioning under the condition that satellites are unavailable.

Description

Technical Field

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

[0002] Rail transit mainly includes high-speed rail and subways, both of which are already in large-scale use in China, especially high-speed rail, which is gradually being rolled out globally. The primary issue for rail transit is traffic safety. Train location information is crucial for ensuring safe train operation. Existing track positioning methods include manual reporting, time-based train control systems, and satellite technology. Each has its advantages and disadvantages. Manual reporting suffers from poor real-time performance and accuracy; malfunctions in the train control system can lead to chaos and serious accidents. Satellite signals have limited coverage in subway traffic. Under extreme conditions, existing technologies are insufficient to meet train safety requirements.

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

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

[0005] This application discloses a method for positioning in rail transit, which includes: Step 1: During the train's journey, the interrogation device connects to the time server to complete time synchronization; the train's locomotive is equipped with an interrogation device with a directional antenna, and transponder devices with omnidirectional antennas are installed at equal intervals along the train's track; Step 2: The interrogation device at the front of the train periodically transmits handshake broadcast messages to the response devices on the track along the train's route according to the time slot allocation. The response devices receive the broadcast messages and respond with handshake response messages after they are ready. The interrogation device selects one of the response devices that meets the following conditions from among the multiple handshake response devices to begin positioning: the condition is that the current interrogation device has not yet performed positioning and the nearest response device is normally synchronized in the time slot. Step 3: The interrogation equipment at the front of the train sends two interrogation signals to the selected response equipment according to the time slot allocation. The response equipment responds with the position information according to a fixed signal format. The interrogation equipment 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 interrogation signals and repeats steps 2 to 4.

[0006] Furthermore, the time server is synchronized with the train operation control system to ensure the accuracy of location information reporting.

[0007] Furthermore, both the interrogation device and the response device are uniquely identified by a number, and the signal format they transmit contains this number.

[0008] Furthermore, the handshake broadcast information includes an inquiry identifier, the current time, and the frame slot number, and the handshake response information includes an acknowledgment identifier, the local time, and the frame slot number.

[0009] Furthermore, the time slot allocation refers to dividing each period into two time slots with a period of P milliseconds. The first time slot has a length of m milliseconds and is used for ranging, while the second time slot has a length of N microseconds and is used for broadcasting and data transmission. The interrogating device uses odd-numbered time slots, and the responding device uses even-numbered time slots.

[0010] Furthermore, the response location information includes the longitude, latitude, altitude of the response device, and system processing delay.

[0011] Furthermore, the location information includes distance measurement data, longitude, latitude, altitude data, and confidence level; the distance measurement data is the distance between the interrogating device and the responding device; the confidence level is divided into three levels: Level 1 indicates that the difference between the two distance measurement results in the positioning time slot is large, with the lowest confidence level; Level 2 indicates that the difference between the two distance measurement results in the positioning time slot is small, with high confidence level; Level 3 indicates that the difference between the two distance measurement results in the positioning time slot is small and matches the latitude and longitude distance, with the highest confidence level.

[0012] Furthermore, the system processing delay includes the signal processing calculation delay of the response device and the hardware link delay.

[0013] Furthermore, the formula for calculating the distance is: D=(T-T1-T2) c / 2 Where D is the distance between the interrogation device and the response device, c is the speed of light, T is the total time for the interrogation device to transmit the interrogation signal and receive the response signal, T1 is the system processing delay of the interrogation device, and T2 is the system processing delay of the response device.

[0014] This application also discloses a rail transit positioning system and a method for implementing the above-mentioned rail transit positioning, which includes: A single interrogation unit, employing 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; Multiple response units, using omnidirectional antennas, are used to receive interrogation signals and transmit response location signals. The longitude, latitude, and altitude of the location signal are fixed in the response unit during installation.

[0015] Due to the adoption of the above technical solution, this application has the following advantages: by forming a positioning system with a single interrogation device and multiple response devices, it supports the real-time measurement of the train's own position information during high-speed operation, solves the train positioning problem under the condition that satellites are unavailable, and enriches the positioning technology means in the field of rail transit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is a flowchart illustrating a method for positioning in rail transit according to an embodiment of this application; Figure 2 This is a schematic diagram of a rail transit positioning system according to an embodiment of this application. Detailed Implementation

[0018] The present application will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only some, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of the present application.

[0019] See Figure 1 This application provides an embodiment of a method for positioning in rail transit, which includes: Step 1: During the train's journey, the interrogation device connects to the time server to complete time synchronization; the train's locomotive is equipped with an interrogation device with a directional antenna, and transponder devices with omnidirectional antennas are installed at equal intervals along the train's track; Step 2: The interrogation device at the front of the train periodically transmits handshake broadcast messages to the response devices on the track along the train's route according to the time slot allocation. The response devices receive the broadcast messages and respond with handshake response messages after they are ready. The interrogation device selects one of the response devices that meets the following conditions from among the multiple handshake response devices to begin positioning: the condition is that the current interrogation device has not yet performed positioning and the nearest response device is normally synchronized in the time slot. Step 3: The interrogation equipment at the front of the train sends two interrogation signals to the selected response equipment according to the time slot allocation. The response equipment responds with the position information in a fixed signal format. The interrogation equipment 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 interrogation signals and repeats steps 2 to 4.

[0020] Optionally, the time server is synchronized with the train operation control system to ensure the accuracy of location information reporting.

[0021] Optionally, both the interrogation device and the response device are uniquely identified by a number, and the signal format they transmit contains the number.

[0022] Optionally, the handshake broadcast information includes an inquiry identifier, the current time, and the frame slot number, and the handshake response information includes an acknowledgment identifier, the local time, and the frame slot number.

[0023] Optionally, the time slot allocation refers to dividing each period into two time slots with a period of P milliseconds. The first time slot has a length of m milliseconds and is used for ranging, while the second time slot has a length of N microseconds and is used for broadcasting and data transmission. The interrogating device uses odd-numbered time slots, and the responding device uses even-numbered time slots.

[0024] Optionally, the response location information includes the longitude, latitude, altitude of the response device, and system processing delay.

[0025] Optionally, the location information includes distance measurement data, longitude, latitude, altitude data, and confidence level; the distance measurement data is the distance between the interrogating device and the responding device; the confidence level is divided into three levels: Level 1 indicates that the difference between the two distance measurement results in the positioning time slot is large, with the lowest confidence level; Level 2 indicates that the difference between the two distance measurement results in the positioning time slot is small, with high confidence level; Level 3 indicates that the difference between the two distance measurement results in the positioning time slot is small and matches the latitude and longitude distance, with the highest confidence level.

[0026] Optionally, the system processing delay includes the signal processing calculation delay of the response device and the hardware link delay.

[0027] Optionally, the distance is calculated using the following formula: D=(T-T1-T2) c / 2 Where D is the distance between the interrogation device and the response device, c is the speed of light, T is the total time for the interrogation device to transmit the interrogation signal and receive the response signal, T1 is the system processing delay of the interrogation device, and T2 is the system processing delay of the response device.

[0028] See Figure 2 This application also provides an embodiment of a rail transit positioning system, which implements the rail transit positioning method described in the above embodiment, comprising: A single interrogation unit 201 employs 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 202 employ omnidirectional antennas to receive interrogation signals and transmit response position signals. The longitude, latitude, and altitude of the position signals are fixed within the response units during installation.

[0029] To better illustrate the positioning method of this application, a comprehensive example is provided to explain the above process. Taking subway rail transit as an example, assume that the onboard interrogation device is identified as A0, with longitude, latitude, and altitude location information of (X0, Y0, Z0), and one responding device is identified as B1, with longitude, latitude, and altitude location information of (X1, Y1, Z1). The synchronization time between the interrogation device and the train control system is T0, and the time slot rule is: a time slot period of 50ms, with the second time slot being the broadcast message, so the broadcast period is also 50ms. Initially, the interrogation device transmits handshake broadcast information at a period of 50ms. After receiving the broadcast information, the responding device B1 sets its local time and responds to the handshake information in the next time slot. When the handshake response information conforms to the time slot rule, the interrogation device begins to transmit an interrogation signal to B1 at a period of 50ms. The responding device receives the interrogation signal and checks whether it conforms to the time slot rule. If it does, 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. From Z0, D and (X1, Y1, Z1), X0 and Y0 can be calculated, and thus the position information of the train can be obtained.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A method for positioning in rail transit, characterized in that, include: Step 1: During the train's journey, the interrogation device connects to the time server to complete time synchronization; the train's locomotive is equipped with an interrogation device with a directional antenna, and transponder devices with omnidirectional antennas are installed at equal intervals along the train's track; Step 2: The interrogation device at the front of the train periodically transmits handshake broadcast messages to the response devices on the track along the train's route according to the time slot allocation. The response devices receive the broadcast messages and respond with handshake response messages after they are ready. The interrogation device selects one of the response devices that meets the following conditions from among the multiple handshake response devices to begin positioning: the condition is that the current interrogation device has not yet performed positioning and the nearest response device is normally synchronized in the time slot. Step 3: The interrogation equipment at the front of the train sends two interrogation signals to the selected response equipment according to the time slot allocation. The response equipment responds with the position information according to a fixed signal format. The interrogation equipment 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 interrogation signals and repeats steps 2 to 4. The time slot allocation refers to dividing each period into two time slots with a period of P milliseconds. The first time slot has a length of m milliseconds and is used for ranging. The second time slot has a length of N microseconds and is used for broadcasting and data transmission. The interrogating device uses odd-numbered time slots, and the responding device uses even-numbered time slots. The formula for calculating the distance is: D=(T-T1-T2) c / 2 Where D is the distance between the interrogation device and the response device, c is the speed of light, T is the total time for the interrogation device to transmit the interrogation signal and receive the response signal, T1 is the system processing delay of the interrogation device, and T2 is the system processing delay of the response device.

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

3. The method for positioning rail transit according to claim 1, characterized in that, Both the interrogation device and the response device are uniquely identified by a number, and the signal format they transmit contains this number.

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

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

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

7. The method for positioning rail transit according to claim 5, characterized in that, The system processing delay includes the signal processing calculation delay of the response device and the hardware link delay.

8. A rail transit positioning system, implementing the rail transit positioning method according to any one of claims 1-7, characterized in that, include: A single interrogation unit, employing 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; Multiple response units, using omnidirectional antennas, are used to receive interrogation signals and transmit response location signals. The longitude, latitude, and altitude of the location signal are fixed in the response unit during installation.

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