Tunnel scene loRa-mesh ad hoc network big dipper positioning system

Abstract

The application discloses a tunnel scene LoRa-Mesh self-organizing network Beidou positioning system, comprising: a tunnel scene modeling module, which is used for generating a tunnel three-dimensional structure model and outputting structure deviation correction parameters; a deployment parameter generation module, which is used for generating a LoRa-Mesh backbone node deployment coordinate set, a Beidou positioning signal transmitting unit deployment coordinate set and a coverage parameter set; a LoRa-Mesh backbone node self-organizing network module, which is used for completing deployment and constructing a LoRa-Mesh network; a Beidou positioning signal transmitting module, which is used for completing deployment and reporting, via LoRa-Mesh, the deployment coordinates and working state data of a transmitting unit; a Beidou positioning signal simulation generation module, which is used for generating adaptive pseudo data one by one in combination with Beidou satellite original data; and a pseudo data issuing and transmitting control module, which is used for issuing pseudo data and controlling a transmitting unit to transmit Beidou radio frequency positioning signals. The application realizes stable coverage and continuous transmission of Beidou positioning signals in a tunnel, and improves positioning precision, system reliability and tunnel scene adaptation capability.

Description

Technical Field

[0001] This invention relates to the field of indoor positioning technology in tunnels, and more particularly to a LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios. Background Technology

[0002] Tunnels, as enclosed and narrow transportation infrastructure, play an important role in highway and railway transportation networks. However, BeiDou satellite signals are easily blocked and attenuated by the concrete lining structure inside tunnels, causing positioning terminals to lose lock and making it impossible to achieve continuous and stable positioning, which brings great inconvenience to vehicle navigation and personnel monitoring inside tunnels.

[0003] Existing tunnel positioning solutions mainly suffer from the following technical defects:

[0004] The drawbacks of wired networking solutions: such as positioning systems based on optical cables, RS485 buses, and Ethernet, require the laying of a large number of cables, which not only results in high construction costs and long cycles, but also requires interrupting tunnel traffic during later maintenance, making them extremely inflexible in adapting to the renovation of existing tunnels.

[0005] The drawbacks of a single wireless gateway solution: For example, positioning systems based on LoRa gateways and WiFi gateways have limited coverage (usually ≤500 meters). When deploying multiple gateways, it is necessary to solve the problem of excessive fiber cores and coordination between gateways. Furthermore, the impact of tunnel bends, variable cross-section sections, bifurcation points, and pipeline distribution on signal coverage is not adequately considered, which can easily lead to coverage blind spots of ≥5%.

[0006] The drawbacks of full LoRa-Mesh networking: The use of full LoRa-Mesh networking for BeiDou positioning signal transmission units leads to high system costs, a lack of security protection mechanisms, and significant latency issues for the transmission unit furthest from the signal source.

[0007] Defects of single-sided deployment: Tunnels typically have at least two lanes (one-way or two-way). If the LoRa-Mesh backbone nodes or transmitters are deployed only on the same side of the tunnel, large trucks passing by can easily block the BeiDou positioning signal, affecting the positioning effect.

[0008] Pseudo-data compatibility defects: Existing BeiDou positioning signal generation modules are mostly set in the upstream stage, and do not fully integrate the network status of backbone nodes, the actual deployment of the transmitting unit and other system data. They only output general signal parameters in batches based on modeling parameters, which leads to the mismatch between pseudo-data and the actual working scenario of the transmitting unit, and affects positioning accuracy.

[0009] Therefore, how to provide a LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0010] One objective of this invention is to propose a LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios. This invention achieves stable coverage and continuous transmission of BeiDou positioning signals within tunnels through 3D tunnel modeling, LoRa-Mesh topology state determination, and BeiDou positioning pseudo-data unit-level generation and distribution control. It has the advantages of flexible deployment, high positioning continuity, strong network self-healing capability, and good engineering adaptability.

[0011] The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to embodiments of the present invention includes:

[0012] The tunnel scene modeling module is used to acquire tunnel as-built drawing data and tunnel 3D laser scanning point cloud data, perform ICP iterative registration and fusion on the drawing data and point cloud data, and generate a tunnel 3D structural model and tunnel structural deviation correction parameters.

[0013] The deployment parameter generation module is used to generate a set of deployment coordinates for LoRa-Mesh backbone nodes, a set of deployment coordinates for BeiDou positioning signal transmitting units, and a set of coverage parameters based on the tunnel's three-dimensional structural model and tunnel structural deviation correction parameters.

[0014] The LoRa-Mesh backbone node self-organizing module is used to deploy LoRa-Mesh backbone nodes and execute LoRa-Mesh self-organizing network based on the deployment coordinate set. The LoRa-Mesh backbone node includes a Beidou positioning signal transmission module, which generates a LoRa-Mesh topology matrix, link status data and backbone node takeover rule parameter set.

[0015] The BeiDou positioning signal transmission module is used to complete the deployment based on the deployment coordinate set and to report the actual deployment coordinate data and the working status data of the BeiDou positioning signal transmission unit through LoRa-Mesh.

[0016] The BeiDou positioning signal simulation generation module is used to jointly process the original data of no less than four BeiDou satellites, the coverage parameter set, the link status data and the working status data of the transmitting unit after the LoRa-Mesh topology matrix is ​​stabilized, and generate adaptive pseudo data one by one for the deployment coordinate set of the BeiDou positioning signal transmitting unit.

[0017] The pseudo-data delivery and transmission control module is used to send adapted pseudo-data to the corresponding BeiDou positioning signal transmission unit via LoRa-Mesh, and control the BeiDou positioning signal transmission unit to convert the adapted pseudo-data into BeiDou radio frequency positioning signals for transmission in the tunnel.

[0018] Optionally, the tunnel as-built drawings in the tunnel scene modeling module include the tunnel longitudinal section, cross section, plan layout, and electromechanical pipeline diagram; the process of acquiring the tunnel 3D laser scanning point cloud data involves scanning the entire tunnel interior with a 3D laser scanner to obtain high-precision point cloud data; when there are two or more tunnel entrances, at least two tunnel entrance equipment rooms shall install: a BeiDou positioning signal simulation generation module and a deployment parameter generation module, with one tunnel entrance equipment room installing the tunnel scene modeling module, and each equipment room sharing the data of the tunnel scene modeling module and managing the LoRa-Mesh backbone nodes nearby; when any tunnel entrance equipment room fails due to a fault, the LoRa-Mesh backbone nodes to which they belong shall be taken over by the equipment room of another tunnel entrance through the LoRa-Mesh network.

[0019] Optionally, the process of generating the tunnel 3D structural model and tunnel structural deviation correction parameters in the tunnel scene modeling module includes:

[0020] The tunnel as-built drawings data are converted into tunnel GIS vector data to establish the initial geometric skeleton of the tunnel.

[0021] The process involves denoising and voxel downsampling of the tunnel's 3D laser scanning point cloud data to generate preprocessed point cloud data. Based on the tunnel's initial geometric skeleton, coordinate system initialization is performed on the preprocessed point cloud data to generate initial point cloud pose parameters. In each iteration, the preprocessed point cloud data is transformed to the tunnel GIS vector data coordinate system according to the initial pose parameters. Nearest neighbor search is used to obtain the set of corresponding points in the point cloud and the set of corresponding points in the vector data. The rigid body transformation matrix is ​​calculated, and the initial pose parameters are updated. The mean square error of the set of corresponding points in the point cloud and the set of corresponding points in the vector data before and after the iteration is calculated. The iteration is terminated when the mean square error is less than a preset error threshold or the number of iterations reaches a preset upper limit, and the final rigid body transformation matrix is ​​output. Based on the final rigid body transformation matrix, coordinate correction is performed on the tunnel's initial geometric skeleton to generate a 3D tunnel structural model. Tunnel structural deviation correction parameters are extracted based on the final rigid body transformation matrix.

[0022] Optionally, the process of generating the LoRa-Mesh backbone node deployment coordinate set, the BeiDou positioning signal transmitting unit deployment coordinate set, and the coverage parameter set in the deployment parameter generation module includes: extracting tunnel axis orientation information, tunnel cross-sectional width information, curved section location and curvature radius information, and bifurcation location information based on the tunnel's three-dimensional structural model; dividing the tunnel into straight sections, curved sections, and bifurcation sections according to the tunnel axis orientation information; in the straight sections, calculating the backbone node basic deployment spacing based on the maximum one-way communication distance of the LoRa-Mesh backbone nodes, introducing a preset proportion of redundancy based on the basic deployment spacing, and generating the LoRa-Mesh backbone node deployment coordinates corresponding to the straight sections along the tunnel axis; in the curved sections, calculating the curved section deployment spacing based on the curvature radius and the maximum one-way communication distance of the LoRa-Mesh backbone nodes, and generating the corresponding LoRa-Mesh backbone node deployment coordinates at the corner positions of the curved sections; and generating the bifurcation sections at the fish-mouth positions of the bifurcation sections. The corresponding LoRa-Mesh backbone node deployment coordinates are used. Based on the generated LoRa-Mesh backbone node deployment coordinate set, the deployment starting position of the BeiDou positioning signal transmitting unit is calculated within the jurisdiction of each LoRa-Mesh backbone node according to the staggered deployment rule on both sides of the tunnel. According to the coverage radius of the BeiDou positioning signal transmitting unit and the tunnel width information, the deployment spacing of adjacent BeiDou positioning signal transmitting units on the same side is generated in straight sections according to the formula for calculating the spacing between transmitting units. In curved sections, the deployment spacing of transmitting units is generated according to the point-to-point chord length relationship. A preset proportion of redundancy is introduced on the basis of the deployment spacing to generate the BeiDou positioning signal transmitting unit deployment coordinate set. According to the LoRa-Mesh backbone node deployment coordinate set and the BeiDou positioning signal transmitting unit deployment coordinate set, the jurisdiction of the transmitting unit corresponding to each backbone node is calculated to generate a coverage parameter set. The coverage parameter set and the deployment coordinate set are associated and stored for use in the deployment of LoRa-Mesh backbone nodes and the deployment of BeiDou positioning signal transmitting units.

[0023] Optionally, the process of executing LoRa-Mesh self-organizing network and generating LoRa-Mesh topology matrix, link status data and backbone node takeover rule parameter set in the LoRa-Mesh backbone node self-organizing network module includes:

[0024] Based on the deployment parameter generation module outputting the LoRa-Mesh backbone node deployment coordinate set, LoRa-Mesh backbone nodes are deployed along the tunnel axis at preset spacing in the straight section of the tunnel, LoRa-Mesh backbone nodes are deployed on the tunnel wall on the side of the maximum arc length in the curved section of the tunnel, and corresponding LoRa-Mesh backbone nodes are deployed at the fish mouth position of the bifurcation section.

[0025] After deployment, each LoRa-Mesh backbone node sends a network access request via broadcast, receives response information from neighboring backbone nodes, completes identity authentication and neighbor discovery, and establishes an initial LoRa-Mesh topology based on the exchanged node identifiers and location information.

[0026] Based on the initial LoRa-Mesh topology, each LoRa-Mesh backbone node calculates link reachability according to the communication quality information with neighboring backbone nodes, generates a LoRa-Mesh topology matrix containing node connection relationships and communication paths, and continuously updates link status data.

[0027] When any LoRa-Mesh backbone node detects a link interruption with its neighboring backbone node or a communication quality lower than a preset threshold, route recalculation is triggered. An alternative communication path is selected based on the LoRa-Mesh topology matrix, and the corresponding link status data is updated.

[0028] When a LoRa-Mesh backbone node fails and is unable to manage the BeiDou positioning signal transmitting units under its jurisdiction, other LoRa-Mesh backbone nodes whose communication quality with the transmitting unit meets the reception conditions shall take over the management relationship of the BeiDou positioning signal transmitting unit and update the backbone node takeover rule parameter set.

[0029] Optionally, the process of performing pseudo-data remapping and distribution after the BeiDou positioning signal transmitting unit is taken over includes: reading the deployment coordinates, coverage parameters, and working status data of the BeiDou positioning signal transmitting unit being taken over; constructing a pseudo-data generation constraint set in combination with the corresponding tunnel structure parameters; regenerating BeiDou positioning pseudo-data that matches the BeiDou positioning signal transmitting unit being taken over based on the pseudo-data generation constraint set and the original BeiDou satellite data; distributing the BeiDou positioning pseudo-data to the BeiDou positioning signal transmitting unit being taken over through the corresponding LoRa-Mesh communication path according to the updated backbone node takeover rule parameter set; and receiving pseudo-data reception confirmation information.

[0030] Optionally, the BeiDou positioning signal transmission module includes BeiDou positioning signal transmission units staggered on both sides of the tunnel according to the transmission unit deployment coordinate set output by the deployment parameter generation module. The BeiDou positioning signal transmission unit receives BeiDou positioning pseudo data through its affiliated LoRa-Mesh backbone node, converts the pseudo data into BeiDou positioning radio frequency signals for transmission, collects its own actual deployment coordinates and working status data and reports them to the BeiDou positioning signal simulation generation module through its affiliated LoRa-Mesh backbone node, and continuously receives BeiDou positioning pseudo data forwarded by the corresponding backbone node according to the updated management relationship when the backbone node takes over. This ensures continuous transmission of radio frequency signals.

[0031] Optionally, the process of generating adaptive pseudo-data in the BeiDou positioning signal simulation generation module includes:

[0032] It receives raw data from no less than four Beidou satellites, reads the tunnel 3D structure model, the set of coordinates for the launch unit deployment, and the set of coverage parameters from the tunnel scene modeling module, reads the current link status data and the set of parameters for the backbone node takeover rules from the LoRa-Mesh backbone node, and reads the working status data from the Beidou positioning signal launch unit.

[0033] Based on the set of deployment coordinates of the transmitting units, an independent data processing instance is established for each BeiDou positioning signal transmitting unit according to a one-to-one correspondence. In each data processing instance, the actual deployment coordinates, coverage parameters, tunnel structure parameters of the tunnel segment to which the corresponding transmitting unit belongs, and the current management backbone node identifier are loaded.

[0034] In each data processing instance, the raw data of BeiDou satellites are geometrically mapped to the deployment coordinates of the corresponding launch unit, the spatial geometric relationship parameters between the satellites and the launch unit are calculated, and the set of available satellites is filtered based on the coverage parameters and tunnel structure parameters.

[0035] Based on the selected set of available satellites, and combined with the spatial geometric relationship parameters of the corresponding launch units, the pseudorange parameters, time synchronization parameters and signal frequency band parameters that match the BeiDou positioning signal launch units are calculated unit by unit, and BeiDou positioning pseudo data that is adapted to the deployment location, coverage area and tunnel structure of the launch units are generated.

[0036] The pseudo-data of BeiDou positioning generated for each BeiDou positioning signal transmitting unit will be bound and stored with the corresponding transmitting unit identifier.

[0037] Optionally, the LoRa-Mesh topology matrix stability means that the following conditions are met within a preset time window: after each LoRa-Mesh backbone node completes the node access and routing information exchange, the node connection relationship in the LoRa-Mesh topology matrix remains unchanged; within the time window, the link status data reported by each LoRa-Mesh backbone node does not trigger link interruption, node takeover, or route recalculation operations; the next-hop node identifier corresponding to any backbone node in the LoRa-Mesh topology matrix is ​​consistent with the forwarding table entry; when all three conditions are met simultaneously, the LoRa-Mesh topology matrix is ​​determined to be in a stable state, triggering the BeiDou positioning signal simulation generation module to perform the adaptation pseudo-data generation operation for the BeiDou positioning signal transmitting unit.

[0038] Optionally, the pseudo-data delivery and transmission control module includes, after generating the BeiDou positioning pseudo-data, classifying and packaging the BeiDou positioning pseudo-data according to the LoRa-Mesh topology matrix and the management relationship of the backbone nodes, and delivering it to the target LoRa-Mesh backbone node through the corresponding LoRa-Mesh communication path. The LoRa-Mesh backbone node forwards the BeiDou positioning pseudo-data to the corresponding BeiDou positioning signal transmitting unit under its jurisdiction, receives the pseudo-data reception confirmation information reported by the BeiDou positioning signal transmitting unit through the LoRa-Mesh backbone node, determines the pseudo-data delivery status, and re-executes the corresponding pseudo-data delivery operation when no reception confirmation information is received or a delivery anomaly is detected. After the pseudo-data is successfully delivered, the module controls the BeiDou positioning signal transmitting unit to continuously transmit BeiDou positioning radio frequency signals based on the BeiDou positioning pseudo-data.

[0039] Optionally, this patent constructs a LoRa-Mesh topology matrix, continuously collects link status data, and sets a set of backbone node takeover rule parameters to uniformly model and dynamically maintain the connection relationship and routing status between backbone nodes.

[0040] Optionally, this patent incorporates the communication and management relationship between the BeiDou positioning signal transmission module and the backbone nodes into a unified topology constraint by introducing the backbone node management relationship, LoRa-Mesh topology matrix, and pseudo-data transmission control logic.

[0041] The beneficial effects of this invention are:

[0042] (1) Improved positioning adaptation accuracy: After the LoRa-Mesh topology matrix is ​​stabilized, the BeiDou positioning signal simulation generation operation is performed. The tunnel modeling parameters, coverage parameter set, link status data and BeiDou positioning signal transmission unit working status data are jointly processed. Corresponding BeiDou positioning pseudo data is generated for each set of coordinates deployed by the transmission unit. This avoids the mismatch between the unified pseudo data and the actual deployment environment, and improves the consistency and accuracy stability of the positioning results in the tunnel.

[0043] (2) System coordination and operation logic optimization: The system is configured in the order of tunnel scene modeling, LoRa-Mesh self-organizing network construction, Beidou positioning signal transmission unit deployment, and Beidou positioning pseudo data generation and distribution, so that the data generated in each stage can be fully utilized in subsequent links, forming a clear data flow relationship, reducing information redundancy between modules, and improving the overall system operation efficiency and coordination stability.

[0044] (3) Enhanced engineering adaptability and reliability: The LoRa-Mesh self-organizing network method is adopted to complete the data transmission within the system, reducing the cabling requirements in the tunnel. Combined with the staggered deployment of the transmitting units and the backbone node takeover mechanism, the signal coverage continuity is guaranteed. Through pseudo-data classification and distribution and reception confirmation control, the continuous operation of Beidou positioning signal transmission is maintained, improving the deployment adaptability and operational reliability of the system in complex tunnel environments.

[0045] (4) By constructing a tunnel backbone node topology and node takeover rules based on LoRa-Mesh, this invention can trigger topology reconstruction and path recalculation when a backbone node fails, enabling the communication link to be rebuilt simultaneously along the tunnel in both the forward and reverse directions, forming a chain-like bidirectional protection mechanism. At the same time, a clear jurisdiction and forwarding relationship is established between the Beidou positioning signal transmission module and the backbone node. When the original governing backbone node fails, the transmission module is automatically taken over by other nearby and communicatively reachable LoRa-Mesh backbone nodes in the topology, realizing continuous operation of positioning signal control and data transmission, thereby effectively avoiding positioning interruption caused by single-point failure and improving the reliability and stability of the tunnel positioning system. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 This is a module connection diagram of the LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios proposed in this invention;

[0048] Figure 2 This is a schematic diagram showing the staggered arrangement of backbone nodes and transmitting units of the LoRa-Mesh self-organizing network BeiDou positioning system in a tunnel scenario proposed in this invention.

[0049] Figure 3 This is a diagram of the transformation of a single-direction two-lane highway tunnel using the LoRa-Mesh self-organizing network BeiDou positioning system in a tunnel scenario proposed in this invention.

[0050] Figure 4 This is a diagram illustrating the deployment of LoRa-Mesh backbone nodes in the LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios proposed in this invention.

[0051] Figure 5 This is a diagram showing the bending point of a branch line in an embodiment of the LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios proposed in this invention. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0053] refer to Figures 1-5 The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios includes:

[0054] The tunnel scene modeling module is used to acquire tunnel as-built drawing data and tunnel 3D laser scanning point cloud data, perform ICP iterative registration and fusion on the drawing data and point cloud data, and generate a tunnel 3D structural model and tunnel structural deviation correction parameters.

[0055] The deployment parameter generation module is used to generate a set of deployment coordinates for LoRa-Mesh backbone nodes, a set of deployment coordinates for BeiDou positioning signal transmitting units, and a set of coverage parameters based on the tunnel's three-dimensional structural model and tunnel structural deviation correction parameters.

[0056] The LoRa-Mesh backbone node self-organizing module is used to deploy LoRa-Mesh backbone nodes and execute LoRa-Mesh self-organizing network based on the deployment coordinate set. The LoRa-Mesh backbone node includes a Beidou positioning signal transmission module, which generates a LoRa-Mesh topology matrix, link status data and backbone node takeover rule parameter set.

[0057] The BeiDou positioning signal transmission module is used to complete the deployment based on the deployment coordinate set and to report the actual deployment coordinate data and the working status data of the BeiDou positioning signal transmission unit through LoRa-Mesh.

[0058] The BeiDou positioning signal simulation generation module is used to jointly process the original data of no less than four BeiDou satellites, the coverage parameter set, the link status data and the working status data of the transmitting unit after the LoRa-Mesh topology matrix is ​​stabilized, and generate adaptive pseudo data one by one for the deployment coordinate set of the BeiDou positioning signal transmitting unit.

[0059] The pseudo-data delivery and transmission control module is used to send adapted pseudo-data to the corresponding BeiDou positioning signal transmission unit via LoRa-Mesh, and control the BeiDou positioning signal transmission unit to convert the adapted pseudo-data into BeiDou radio frequency positioning signals for transmission in the tunnel.

[0060] In this embodiment, the tunnel as-built drawings in the tunnel scene modeling module include the tunnel longitudinal section, cross section, plan layout, and electromechanical pipeline diagram. The acquisition process of the tunnel 3D laser scanning point cloud data involves scanning the entire tunnel interior with a 3D laser scanner to obtain high-precision point cloud data. When there are two or more tunnel entrances, at least two tunnel entrance equipment rooms are equipped with: a BeiDou positioning signal simulation generation module and a deployment parameter generation module. One tunnel entrance equipment room is equipped with the tunnel scene modeling module. Each equipment room shares the data of the tunnel scene modeling module and manages the LoRa-Mesh backbone node nearby. When any tunnel entrance equipment room fails due to a fault, the LoRa-Mesh backbone node to which it belongs is taken over by the equipment room of another tunnel entrance through the LoRa-Mesh network.

[0061] In this embodiment, the process of generating the three-dimensional tunnel structure model and tunnel structure deviation correction parameters in the tunnel scene modeling module includes:

[0062] The tunnel as-built drawings data are converted into tunnel GIS vector data to establish the initial geometric skeleton of the tunnel.

[0063] The tunnel as-built drawing data includes the tunnel longitudinal section, cross section, plan layout, and electromechanical pipeline diagrams. First, the as-built drawings are digitized and analyzed to unify the scale and coordinate labeling information, and establish the correspondence between the drawing coordinate system and the actual engineering coordinate system. Then, the tunnel centerline element is extracted from the plan layout, the tunnel axial elevation information is extracted from the longitudinal section, and the tunnel cross section outline dimension information is extracted from the cross section. Vectorization processing is performed on the elements to generate a set of two-dimensional geometric elements of the tunnel consisting of point elements and line elements.

[0064] The set of two-dimensional geometric elements of the tunnel is mapped to the geographic information coordinate system to form tunnel GIS vector data. The tunnel centerline is represented by continuous line elements, the tunnel cross-section outline is represented by closed polygon elements, and the longitudinal elevation information is used as an attribute field and associated with the corresponding centerline node and cross-section elements.

[0065] Based on the tunnel centerline elements in the tunnel GIS vector data, node sampling is performed on the tunnel centerline according to a preset axial sampling interval to generate a skeleton node sequence arranged along the tunnel axis. At each skeleton node, a local cross-sectional geometric description is generated by mapping the tunnel cross-sectional contour elements at the corresponding location. By connecting and interpolating the skeleton node sequence and the local cross-sectional geometric description, an initial geometric skeleton of the tunnel that continuously changes along the tunnel axis is constructed, which is used as the initial geometric reference for the registration and fusion of the tunnel's 3D laser scanning point cloud data.

[0066] The process involves denoising and voxel downsampling of the tunnel's 3D laser scanning point cloud data to generate preprocessed point cloud data. Based on the tunnel's initial geometric skeleton, coordinate system initialization is performed on the preprocessed point cloud data to generate initial point cloud pose parameters. In each iteration, the preprocessed point cloud data is transformed to the tunnel GIS vector data coordinate system according to the initial pose parameters. Nearest neighbor search is used to obtain the set of corresponding points in the point cloud and the set of corresponding points in the vector data. The rigid body transformation matrix is ​​calculated, and the initial pose parameters are updated. The mean square error of the set of corresponding points in the point cloud and the set of corresponding points in the vector data before and after the iteration is calculated. The iteration is terminated when the mean square error is less than a preset error threshold or the number of iterations reaches a preset upper limit, and the final rigid body transformation matrix is ​​output. Based on the final rigid body transformation matrix, coordinate correction is performed on the tunnel's initial geometric skeleton to generate a 3D tunnel structural model. Tunnel structural deviation correction parameters are extracted based on the final rigid body transformation matrix.

[0067] In this embodiment, during the ICP iterative registration process of tunnel GIS vector data and tunnel 3D laser scanning point cloud data, the tunnel 3D structural model constructed from the tunnel GIS vector data is used as the reference model, and the tunnel 3D laser scanning point cloud data is used as the data to be registered. Based on the initial pose parameters of the current point cloud, the point cloud data is transformed to the coordinate system of the reference model. On the surface of the reference model, the nearest reference point is searched for each sampling point in the point cloud. The set of corresponding points in the point cloud and the set of corresponding points in the vector are established to form a set of one-to-one corresponding point pairs.

[0068] After obtaining the set of corresponding point pairs, the rigid body transformation matrix is ​​calculated based on the least squares criterion. Specifically, with the objective function of minimizing the sum of squared distances between the corresponding point sets in the point cloud and the corresponding point sets in the vector, the rotation and translation parameters are jointly solved to obtain the optimal rotation matrix and optimal translation vector that minimize the sum of squared distances. The rigid body transformation matrix is ​​constructed from the rotation matrix and the translation vector, and the rigid body transformation matrix is ​​used to describe the spatial attitude correction relationship of the point cloud data relative to the tunnel GIS vector data.

[0069] After solving the rigid body transformation matrix, the rigid body transformation matrix is ​​used to perform a spatial transformation on the point cloud data, update the position distribution of the point cloud data in the reference model coordinate system, and update the initial pose parameters of the point cloud so that the updated initial pose parameters of the point cloud are consistent with the rotation matrix and translation vector obtained in the current iteration. Based on the updated initial pose parameters of the point cloud, the corresponding point search is re-executed to construct a new set of corresponding point pairs, and a new rigid body transformation matrix is ​​solved again.

[0070] The process of "corresponding point matching - transformation matrix solution - point cloud transformation - pose parameter update" is repeatedly iterated. After each iteration, the average distance or sum of squared distances of the corresponding point pairs is calculated. When the distance metric is less than the preset error threshold, or when the number of iterations reaches the preset upper limit, the iteration process is terminated. The final output rigid body transformation matrix serves as the optimal spatial transformation relationship between the tunnel 3D laser scanning point cloud data and the tunnel GIS vector data. Based on this, high-precision alignment between the point cloud data and the tunnel GIS vector data is achieved, generating a 3D tunnel structural model. At the same time, tunnel structural deviation correction parameters corresponding to construction deviations are extracted.

[0071] In this embodiment, the process of generating the LoRa-Mesh backbone node deployment coordinate set, the BeiDou positioning signal transmitting unit deployment coordinate set, and the coverage parameter set in the deployment parameter generation module includes: extracting tunnel axis orientation information, tunnel cross-sectional width information, curved section location and curvature radius information, and bifurcation location information based on the tunnel's three-dimensional structural model; dividing the tunnel into straight sections, curved sections, and bifurcation sections according to the tunnel axis orientation information; calculating the backbone node basic deployment spacing based on the maximum one-way communication distance of the LoRa-Mesh backbone nodes in the straight sections, introducing a preset proportion of redundancy based on the basic deployment spacing, and generating the LoRa-Mesh backbone node deployment coordinates corresponding to the straight sections along the tunnel axis; and calculating the basic deployment coordinates based on the curvature radius and the maximum one-way communication distance of the LoRa-Mesh backbone nodes in the curved sections. The one-way communication distance calculation method is used to determine the deployment spacing in curved sections. Corresponding LoRa-Mesh backbone node deployment coordinates are generated at the corners of curved sections. At the fish-mouth positions of bifurcation sections, corresponding LoRa-Mesh backbone node deployment coordinates are generated. Based on the generated set of LoRa-Mesh backbone node deployment coordinates, and following the staggered deployment rules on both sides of the tunnel, the starting position for the deployment of BeiDou positioning signal transmitting units is calculated within the jurisdiction of each LoRa-Mesh backbone node. Based on the coverage radius of the BeiDou positioning signal transmitting units and the tunnel width information, the deployment spacing of adjacent BeiDou positioning signal transmitting units on the same side is generated in straight sections according to the unit spacing calculation formula. In curved sections, the unit deployment spacing is generated according to the point-to-point chord length relationship. A preset percentage of redundancy is introduced based on the deployment spacing to generate a set of BeiDou positioning signal transmitting unit deployment coordinates.

[0072] In this embodiment, the spacing between BeiDou positioning signal transmitting units is determined based on the coverage radius of a single transmitting unit and the tunnel width to ensure continuous and blind-spot-free positioning signal coverage within the tunnel. The coverage area of ​​a single BeiDou positioning signal transmitting unit is considered as a circular region with its deployment location as the center and a coverage radius of R. The tunnel width W is used as the coverage constraint, and the maximum spacing D between two adjacent transmitting units along the tunnel axis satisfies D=2. Where R is the coverage radius of a single BeiDou positioning signal transmitting unit, and W is the tunnel width;

[0073] In the straight section of the tunnel, adjacent transmitting units are arranged along the tunnel axis according to the arrangement spacing D to ensure that the coverage areas of adjacent transmitting units intersect in the tunnel width direction and avoid coverage blind spots. In the curved section of the tunnel, the corresponding positions of adjacent transmitting units on the coverage circle are regarded as two points on the arc, and the arrangement spacing D is used as the point-to-point chord length to compensate for the impact of tunnel curvature on the coverage range and ensure continuous coverage in the curved section.

[0074] In actual deployment, after determining the theoretical spacing D based on the above-mentioned spacing calculation relationship, a preset margin is introduced to correct the spacing, making the actual spacing smaller than the theoretical calculated value. This is to adapt to construction errors and changes in the actual signal propagation environment. The corrected spacing of the transmitting units is used as part of the deployment parameters for equipment deployment and pseudo-data generation. Based on the LoRa-Mesh backbone node deployment coordinate set and the BeiDou positioning signal transmitting unit deployment coordinate set, the coverage area of ​​the transmitting unit corresponding to each backbone node is calculated, generating a coverage parameter set. The coverage parameter set is associated with and stored with the deployment coordinate set for LoRa-Mesh backbone node deployment and BeiDou positioning signal transmitting unit deployment.

[0075] In this embodiment, the process of executing LoRa-Mesh self-organizing network and generating LoRa-Mesh topology matrix, link status data and backbone node takeover rule parameter set in the LoRa-Mesh backbone node self-organizing network module includes:

[0076] Based on the deployment parameter generation module outputting the LoRa-Mesh backbone node deployment coordinate set, LoRa-Mesh backbone nodes are deployed along the tunnel axis at preset spacing in the straight section of the tunnel, LoRa-Mesh backbone nodes are deployed on the tunnel wall on the side of the maximum arc length in the curved section of the tunnel, and corresponding LoRa-Mesh backbone nodes are deployed at the fish mouth position of the bifurcation section.

[0077] After deployment, each LoRa-Mesh backbone node sends a network access request via broadcast, receives response information from neighboring backbone nodes, completes identity authentication and neighbor discovery, and establishes an initial LoRa-Mesh topology based on the exchanged node identifiers and location information.

[0078] Based on the initial LoRa-Mesh topology, each LoRa-Mesh backbone node calculates link reachability according to the communication quality information with neighboring backbone nodes, generates a LoRa-Mesh topology matrix containing node connection relationships and communication paths, and continuously updates link status data.

[0079] When any LoRa-Mesh backbone node detects a link interruption with its neighboring backbone node or a communication quality lower than a preset threshold, route recalculation is triggered. An alternative communication path is selected based on the LoRa-Mesh topology matrix, and the corresponding link status data is updated.

[0080] When a link interruption causes an adjacent LoRa-Mesh backbone node to be unable to manage the BeiDou positioning signal transmitting unit under its jurisdiction, another LoRa-Mesh backbone node whose communication quality with the transmitting unit meets the reception conditions shall take over the management relationship of the BeiDou positioning signal transmitting unit and update the backbone node takeover rule parameter set.

[0081] In this embodiment, the process of pseudo-data remapping and distribution after the BeiDou positioning signal transmitting unit is taken over includes: reading the deployment coordinates, coverage parameters, and working status data of the BeiDou positioning signal transmitting unit being taken over; constructing a pseudo-data generation constraint set in combination with the corresponding tunnel structure parameters; regenerating BeiDou positioning pseudo-data that matches the BeiDou positioning signal transmitting unit being taken over based on the pseudo-data generation constraint set and the original BeiDou satellite data; distributing the BeiDou positioning pseudo-data to the BeiDou positioning signal transmitting unit being taken over through the corresponding LoRa-Mesh communication path according to the updated backbone node takeover rule parameter set; and receiving pseudo-data reception confirmation information.

[0082] In this embodiment, the BeiDou positioning signal transmission module includes BeiDou positioning signal transmission units staggered on both sides of the tunnel according to the transmission unit deployment coordinate set output by the deployment parameter generation module. The BeiDou positioning signal transmission unit receives BeiDou positioning pseudo data through its affiliated LoRa-Mesh backbone node, converts the pseudo data into BeiDou positioning radio frequency signals for transmission, collects its own actual deployment coordinates and working status data and reports them to the BeiDou positioning signal simulation generation module through its affiliated LoRa-Mesh backbone node, and continuously receives BeiDou positioning pseudo data forwarded by the corresponding backbone node according to the updated management relationship when the backbone node takes over. This ensures continuous transmission of radio frequency signals.

[0083] In this embodiment, the process of generating adaptive pseudo-data in the BeiDou positioning signal simulation generation module includes:

[0084] It receives raw data from no less than four Beidou satellites, reads the tunnel 3D structure model, the set of coordinates for the launch unit deployment, and the set of coverage parameters from the tunnel scene modeling module, reads the current link status data and the set of parameters for the backbone node takeover rules from the LoRa-Mesh backbone node, and reads the working status data from the Beidou positioning signal launch unit.

[0085] Based on the set of deployment coordinates of the transmitting units, an independent data processing instance is established for each BeiDou positioning signal transmitting unit according to a one-to-one correspondence. In each data processing instance, the actual deployment coordinates, coverage parameters, tunnel structure parameters of the tunnel segment to which the corresponding transmitting unit belongs, and the current management backbone node identifier are loaded.

[0086] In each data processing instance, the raw data of BeiDou satellites are geometrically mapped to the deployment coordinates of the corresponding launch unit, the spatial geometric relationship parameters between the satellites and the launch unit are calculated, and the set of available satellites is filtered based on the coverage parameters and tunnel structure parameters.

[0087] Based on the selected set of available satellites, and combined with the spatial geometric relationship parameters of the corresponding launch units, the pseudorange parameters, time synchronization parameters and signal frequency band parameters that match the BeiDou positioning signal launch units are calculated unit by unit, and BeiDou positioning pseudo data that is adapted to the deployment location, coverage area and tunnel structure of the launch units are generated.

[0088] The pseudo-data of BeiDou positioning generated for each BeiDou positioning signal transmitting unit will be bound and stored with the corresponding transmitting unit identifier.

[0089] In this embodiment, the LoRa-Mesh topology matrix stability means that the following conditions are met within a preset time window: after each LoRa-Mesh backbone node completes the node access and routing information exchange, the node connection relationship in the LoRa-Mesh topology matrix remains unchanged; within the time window, the link status data reported by each LoRa-Mesh backbone node does not trigger link interruption, node takeover, or route recalculation operations; the next-hop node identifier corresponding to any backbone node in the LoRa-Mesh topology matrix is ​​consistent with the forwarding table entry; when all three conditions are met simultaneously, the LoRa-Mesh topology matrix is ​​determined to be in a stable state, and the BeiDou positioning signal simulation generation module is triggered to perform the adaptation pseudo-data generation operation for the BeiDou positioning signal transmitting unit.

[0090] In this embodiment, the pseudo-data delivery and transmission control module includes, after generating the BeiDou positioning pseudo-data, classifying and packaging the BeiDou positioning pseudo-data according to the LoRa-Mesh topology matrix and the management relationship of the backbone nodes, and delivering it to the target LoRa-Mesh backbone node through the corresponding LoRa-Mesh communication path. The LoRa-Mesh backbone node forwards the BeiDou positioning pseudo-data to the corresponding BeiDou positioning signal transmitting unit under its jurisdiction. It receives the pseudo-data reception confirmation information reported by the BeiDou positioning signal transmitting unit through the LoRa-Mesh backbone node, determines the pseudo-data delivery status, and re-executes the corresponding pseudo-data delivery operation when no reception confirmation information is received or a delivery anomaly is detected. After the pseudo-data is successfully delivered, it controls the BeiDou positioning signal transmitting unit to continuously transmit BeiDou positioning radio frequency signals based on the BeiDou positioning pseudo-data.

[0091] In this embodiment, the patent constructs a LoRa-Mesh topology matrix, continuously collects link status data, and sets a set of backbone node takeover rule parameters to uniformly model and dynamically maintain the connection relationship and routing status between backbone nodes.

[0092] In this embodiment, the patent incorporates the communication and management relationship between the BeiDou positioning signal transmission module and the backbone nodes into a unified topology constraint by introducing the backbone node management relationship, LoRa-Mesh topology matrix and pseudo-data distribution control logic.

[0093] Example: To verify the feasibility of this invention in practice, it was applied to a one-way two-lane highway tunnel reconstruction project, such as... Figure 3 A one-way, two-lane highway tunnel is 3.06 kilometers long, with a net width of 10 meters and a net height of 5 meters. The straight section is 2.7 kilometers long, and there is one fork in the road, dividing it into two curved sections (each 0.18 kilometers long, with a curvature of 500 meters). Electromechanical pipelines have already been laid inside the tunnel, and the positioning system needs to be upgraded. Upgrade requirements: no wiring required during construction; signal coverage blind spots ≤1%; positioning accuracy ≤1.5 meters; and continuous system reliability ≥99.9%.

[0094] (1) Tunnel scene modeling and implementation:

[0095] Collect all the as-built drawings of the tunnel and use the RIEGLVZ-400 3D laser scanner to scan the entire interior of the tunnel with a scanning resolution of 1cm to obtain high-precision point cloud data.

[0096] ArcGIS software was used to convert the as-built drawings into GIS vector data. The point cloud data and GIS data were then fused using the ICP iterative nearest point algorithm to correct construction deviations. The resulting 3D model had an error of 3cm from the actual structure, which met the accuracy requirements.

[0097] A 3D structural model of the tunnel was generated, clarifying the structural parameters of each area; a deployment point map was output, planning 7 LoRa-Mesh backbone nodes (1 every 0.9 km on straight sections, and 1 each at corners and bifurcations on curved sections), and 201 BeiDou positioning signal transmitting units; the coverage radius of the transmitting units was determined to be R=20 meters, and the interval D=2 was calculated. =2 ≈2×17.3=34.6 meters, after retaining a 10% margin, take 30 meters, the corresponding chord length of the two bending sections at the bifurcation is D; generate a construction feasibility report, synchronize all deployment parameters to the backbone nodes and save them to the pseudo-data generation module database.

[0098] (2) Deployment and implementation of LoRa-Mesh backbone nodes:

[0099] According to the deployment point map, install 5 backbone nodes staggered on both sides of the tunnel (e.g., Figure 4 The calculation method is as follows:

[0100] For the straight section: backbone node equipment (using E52-400NW22S LoRa-Mesh modules) with a coverage distance of 0.9 km (diameter) is used. The 2.7 km section is divided into three segments, with 4 backbone nodes configured. Among them, the backbone node at tunnel entrance A is equipped with a directional antenna facing into the tunnel, covering 450M; the other three backbone nodes are equipped with omnidirectional antennas, and backbone node 4 (equipped with dual LoRa-Mesh main and backup modules) is deployed at the fish mouth of the bifurcation.

[0101] After the fork, it splits into two curved sections (each 0.18 km long, with a bending radius of 500 meters):

[0102] Fork in the bend section 1: (as shown in the image) Figure 5 Backbone node 5 is configured at tunnel entrance B and is deployed on the tunnel wall on the side with the largest arc length. Backbone node 5 and backbone node 4 are two adjacent LoRa-Mesh backbone nodes with an arc length of 180 meters. The vertical distance (arch height) from the chord to the vertex of the corresponding arc is 8.17 meters (calculated as follows), which is less than the width of the tunnel of 10 meters. Backbone node 5 and configured backbone node 4 are at line of sight and can communicate with each other via LoRa-Mesh.

[0103] The vertical distance from the chord to the vertex of the arc (called the arch height, denoted as h) corresponding to a radius of curvature R = 500m and an arc length s = 180m is calculated in three steps:

[0104] a. Calculate the central angle θ (in radians):

[0105] According to the arc length formula s=Rθ, we can transform it to get θ=s / R. Substituting the values, we get: θ=180 / 500=0.36rad;

[0106] b. Derivation of the formula for calculating arch height:

[0107] The relationship between the arch height h, radius R, and central angle θ is h = R[1−cos(θ / 2)];

[0108] Derivation logic: Draw a perpendicular line from the center of the circle to the chord, the length of which is Rcos(θ / 2). The arch height is the difference between the radius and the length of this perpendicular line.

[0109] c. Substitute numerical values ​​to calculate the arch height:

[0110] h=R[1−cos(θ / 2)]=500×(1−cos(0.36 / 2))=500×(1−0.983668)=500×0.016332=8.17(m);

[0111] Conclusion: The vertical distance (arch height) from the chord to the apex of the arc is approximately 8.17m.

[0112] Bifurcation bend 2: As can be seen from the above calculations, backbone node 4 can completely cover bend 2.

[0113] The backbone nodes are fixed to the tunnel sidewall with expansion bolts, and the installation height is slightly higher than the height of a large truck (e.g., 4.2 meters). All nodes are ≤4m away from the power interface to ensure stable power supply.

[0114] Networking and Data Upload: After the backbone node is powered on, it automatically completes the network setup, tests the signal strength of adjacent nodes to be ≥-75dBm, and the data transmission rate to be ≥100kbps; forwards the modeling and deployment parameters to each transmitting unit; collects its own actual coordinates, network link status and other data, summarizes the status data of each transmitting unit within its jurisdiction, and uploads it to the BeiDou positioning signal simulation generation module at both ends of the tunnel.

[0115] (3) Deployment and implementation of BeiDou positioning signal transmitting units:

[0116] According to the deployment point map, a total of 196 Beidou positioning signal transmitting units are staggered on both sides of the tunnel, with an installation height of 3 meters. They are fixed to the side wall brackets with snap-fit ​​and are staggered from the installation positions of the backbone nodes to avoid signal interference.

[0117] according to Figure 4 This allows for the use of 196 BeiDou positioning signal transmitting units, as shown in the table below:

[0118] Beidou positioning signal transmitting unit Number of tunnel walls on the left Number of tunnel walls on the right Subtotal Quantity Backbone node 1 to backbone node 2 15 15 30 Backbone node 2 to backbone node 1 14 14 28 backbone node 2 to backbone node 3 15 15 30 backbone node 3 to backbone node 2 14 14 28 backbone node 3 to backbone node 4 15 15 30 backbone node 4 to backbone node 3 14 14 28 backbone node 4 to backbone node 5 5 5 10 Backbone node 4 to tunnel entrance C 6 6 12 Total quantity 98 98 196

[0119] Instructions for quantity calculation:

[0120] Backbone node 1 to backbone node 2: The distance is 900 meters. Backbone node 1 (installed on the left tunnel wall) manages up to 450 meters. In the left tunnel, one BeiDou positioning signal transmitting unit is configured every 30 meters, for a total of 15 units. In the right tunnel, backbone node 1 manages up to 465 meters. Starting from 15 meters in the direction from backbone node 1 to backbone node 2, one BeiDou positioning signal transmitting unit is configured every 30 meters, for a total of 15 units. It is estimated that there will be 30 units on both sides.

[0121] From backbone node 2 to backbone node 1: the distance is 900 meters. Backbone node 2 (installed on the right tunnel wall) manages up to 420 meters (30 meters away from the farthest transmitting unit in the left tunnel of backbone node 1). In the left tunnel, one BeiDou positioning signal transmitting unit is configured every 30 meters, totaling 14 units. In the right tunnel, backbone node 1 manages up to 435 meters. Starting from 15 meters in the opposite tunnel from backbone node 2 towards backbone node 1, one BeiDou positioning signal transmitting unit is configured every 30 meters, totaling 14 units. It is estimated that there are 28 units on both sides.

[0122] The configuration of the BeiDou positioning signal transmission units from backbone node 2 to backbone node 3 and from backbone node 3 to backbone node 4 is the same as that from backbone node 1 to backbone node 2.

[0123] The configuration of the BeiDou positioning signal transmission units from backbone node 3 to backbone node 2 and from backbone node 4 to backbone node 3 is the same as that from backbone node 2 to backbone node 1.

[0124] Backbone nodes 4 to 5 have an arc length of 180 meters. Five Beidou positioning signal transmitting units can be configured with an arc length of 30 meters (corresponding to a chord length of 29.99 meters; chord lengths less than 30 meters can meet signal coverage requirements). (Backbone node 5 at tunnel entrance B has one built-in Beidou positioning signal transmitting unit).

[0125] Similarly, 6 backbone nodes are configured from backbone node 4 to tunnel entrance C;

[0126] Each of the above five backbone nodes is equipped with one BeiDou positioning signal transmitting unit.

[0127] Therefore, a total of 201 (=5+196) BeiDou positioning signal transmission units are actually used.

[0128] Hardware configuration: All transmitting units integrate a LoRa module (SX1278 chip) and a BeiDou positioning signal transmitting module (SYN2309 BeiDou / GNSS signal forwarding module). The LoRa module is specifically used to receive deployment parameters and pseudo data forwarded by the LoRa-Mesh backbone node, with a communication frequency band of 433MHz, ensuring stable data transmission. The BeiDou positioning signal transmitting module is responsible for converting the pseudo data into BeiDou positioning radio frequency signals (frequency band of 1561MHz) for transmission.

[0129] Status feedback: After deployment and debugging are completed, the system collects status data such as actual deployment coordinates and operating voltage, and uploads it to the pseudo data generation module through the backbone node; thus completing the preparation work for pseudo data reception.

[0130] (4) Deployment and operation of the BeiDou positioning signal simulation generation module:

[0131] Deployment: Since tunnel entrances B and C are close to each other, while tunnel entrance A is far from both B and C, a pseudo-data generation module is deployed in the equipment rooms at both ends of tunnel entrances A and B. Each module is equipped with 4 transmitting antennas / feeders and Beidou receiving antennas to ensure unobstructed satellite signal reception. A tunnel scene modeling module is deployed in the equipment room at tunnel entrance A. Under normal circumstances, the equipment room at tunnel entrance A manages backbone nodes 1, 2, and 3, while the equipment room at tunnel entrance B manages backbone nodes 5 and 4.

[0132] Full data integration: Retrieves deployment parameters stored in the modeling module, receives status data from 5 backbone nodes and 201 BeiDou positioning signal transmission units uploaded by backbone nodes, and simultaneously receives raw data from BeiDou-2 / 3 dual-mode satellites to complete full data integration with an integration latency of 8ms.

[0133] Pseudo-data generation and distribution: Based on integrated data, exclusive pseudo-data is generated for each transmitting unit, with a pseudo-range error of 0.3 meters, a time synchronization accuracy of 8ms, and an update frequency of 12Hz; pseudo-data is distributed according to the jurisdiction of the backbone node, and the transmitting unit sends back confirmation information after receiving it, with a transmission success rate of 100%.

[0134] Implementation effect verification:

[0135] Positioning accuracy: Eight vehicle-mounted terminals and four personnel terminals were deployed in different areas such as straight sections, curved sections and bifurcations of the tunnel. After 24 hours of continuous testing, the positioning accuracy of all terminals was ≤1.2 meters, which is better than the design target of 1.5 meters. The pseudo-data is accurately adapted to the target.

[0136] Coverage and stability: The BeiDou positioning signal strength at any location within the tunnel was ≥-100dBm, with a coverage blind zone ≤0.3%; simulating a fault in one pseudo-data generation module and a fault in one backbone node, the system was able to quickly switch over without any positioning interruption, achieving a continuous operation reliability of 99.96%.

[0137] Construction efficiency: No additional wiring is required throughout the entire process, the construction period is 8 days, which is 65% shorter than the traditional wired solution and 55% lower in construction costs. It is fully compatible with the renovation needs of existing tunnels and does not affect traffic.

[0138] The embodiments demonstrate that by placing the BeiDou positioning signal simulation generation module in the final stage, the present invention achieves full data integration and accurate pseudo-data generation, effectively improving positioning accuracy. It also has advantages such as no wiring, no blind spots in coverage, high reliability, and low cost, and is particularly suitable for the renovation of tunnels that have already been opened to traffic, thus having engineering application value.

[0139] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios, characterized in that: include: The tunnel scene modeling module is used to acquire tunnel as-built drawing data and tunnel 3D laser scanning point cloud data, perform ICP iterative registration and fusion on the drawing data and point cloud data, and generate a tunnel 3D structural model and tunnel structural deviation correction parameters. The tunnel scene modeling module includes tunnel as-built drawings such as longitudinal section, cross section, plan layout, and electromechanical pipeline diagrams. The acquisition process of the tunnel's 3D laser scanning point cloud data involves scanning the entire tunnel interior with a 3D laser scanner to obtain high-precision point cloud data. When there are two or more tunnel entrances, at least two tunnel entrance equipment rooms are equipped with BeiDou positioning signal simulation generation modules and deployment parameter generation modules. One tunnel entrance equipment room is equipped with a tunnel scene modeling module. Each equipment room shares the data from the tunnel scene modeling module and manages the LoRa-Mesh backbone nodes in the nearest location. When any tunnel entrance equipment room fails due to a fault, its associated LoRa-Mesh backbone nodes are taken over by the equipment room at another tunnel entrance via the LoRa-Mesh network. The deployment parameter generation module is used to generate a set of deployment coordinates for LoRa-Mesh backbone nodes, a set of deployment coordinates for BeiDou positioning signal transmitting units, and a set of coverage parameters based on the tunnel's three-dimensional structural model and tunnel structural deviation correction parameters. The LoRa-Mesh backbone node self-organizing module is used to deploy LoRa-Mesh backbone nodes and execute LoRa-Mesh self-organizing network based on the deployment coordinate set. The LoRa-Mesh backbone node includes a Beidou positioning signal transmission module, which generates a LoRa-Mesh topology matrix, link status data and backbone node takeover rule parameter set. The BeiDou positioning signal transmission module is used to complete the deployment based on the deployment coordinate set and to report the actual deployment coordinate data and the working status data of the BeiDou positioning signal transmission unit through LoRa-Mesh. The BeiDou positioning signal simulation generation module is used to jointly process the original data of no less than four BeiDou satellites, the coverage parameter set, the link status data and the working status data of the transmitting unit after the LoRa-Mesh topology matrix is ​​stabilized, and generate adaptive pseudo data one by one for the deployment coordinate set of the BeiDou positioning signal transmitting unit. The pseudo-data delivery and transmission control module is used to send adapted pseudo-data to the corresponding BeiDou positioning signal transmission unit via LoRa-Mesh, and control the BeiDou positioning signal transmission unit to convert the adapted pseudo-data into BeiDou radio frequency positioning signals for transmission in the tunnel.

2. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 1, characterized in that, The process of generating the 3D tunnel structure model and tunnel structure deviation correction parameters in the tunnel scene modeling module includes: The tunnel as-built drawings data are converted into tunnel GIS vector data to establish the initial geometric skeleton of the tunnel. Denoising and voxel downsampling are performed on the 3D laser scanning point cloud data of the tunnel to generate preprocessed point cloud data. Based on the initial geometric skeleton of the tunnel, coordinate system initialization is performed on the preprocessed point cloud data to generate the initial pose parameters of the point cloud. In each iteration, the preprocessed point cloud data is transformed to the tunnel GIS vector data coordinate system based on the initial pose parameters of the point cloud. The nearest neighbor search is used to obtain the set of points corresponding to the point cloud and the set of points corresponding to the vector. The rigid body transformation matrix is ​​calculated and the initial pose parameters of the point cloud are updated. Calculate the mean square error between the point cloud set and the vector set before and after the iteration. Terminate the iteration when the mean square error is less than the preset error threshold or the number of iterations reaches the preset upper limit, and output the final rigid body transformation matrix. Based on the final rigid body transformation matrix, coordinate correction is performed on the initial geometric skeleton of the tunnel to generate a three-dimensional structural model of the tunnel. Based on the final rigid body transformation matrix, tunnel structural deviation correction parameters are extracted.

3. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 2, characterized in that, The process of generating the LoRa-Mesh backbone node deployment coordinate set, the BeiDou positioning signal transmitting unit deployment coordinate set, and the coverage parameter set in the deployment parameter generation module includes: Based on the three-dimensional structural model of the tunnel, information on the tunnel axis orientation, tunnel cross-sectional width, location and radius of curvature of curved sections, and location of bifurcation points are extracted. Based on the tunnel axis alignment information, the tunnel is divided into straight sections, curved sections, and bifurcation sections along the tunnel axis direction; In the straight section, the basic deployment spacing of the backbone nodes is calculated based on the maximum one-way communication distance of the LoRa-Mesh backbone nodes. A preset proportion of redundancy is introduced on the basis of the basic deployment spacing, and the deployment coordinates of the LoRa-Mesh backbone nodes corresponding to the straight section are generated along the tunnel axis. In the curved section, the deployment spacing of the curved section is calculated based on the bending radius and the maximum one-way communication distance of the LoRa-Mesh backbone node. The corresponding LoRa-Mesh backbone node deployment coordinates are generated at the corner position of the curved section. The corresponding LoRa-Mesh backbone node deployment coordinates are generated at the fish mouth position of the bifurcation section. Based on the generated set of LoRa-Mesh backbone node deployment coordinates, and following the staggered deployment rules on both sides of the tunnel, the starting position of the BeiDou positioning signal transmitting unit is calculated within the jurisdiction of each LoRa-Mesh backbone node. Based on the coverage radius of the BeiDou positioning signal transmitting unit and the tunnel width information, the deployment spacing of adjacent BeiDou positioning signal transmitting units on the same side is generated in the straight section according to the formula for calculating the spacing between transmitting units. In the curved section, the deployment spacing of the transmitting units is generated according to the point-to-point chord length relationship. A preset proportion of redundancy is introduced on the basis of the deployment spacing to generate a set of BeiDou positioning signal transmitting unit deployment coordinates. Based on the deployment coordinate set of LoRa-Mesh backbone nodes and the deployment coordinate set of BeiDou positioning signal transmitting units, the jurisdiction of the transmitting unit corresponding to each backbone node is calculated, a coverage parameter set is generated, and the coverage parameter set is associated and stored with the deployment coordinate set for use in the deployment of LoRa-Mesh backbone nodes and BeiDou positioning signal transmitting units.

4. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 3, characterized in that, The process by which the LoRa-Mesh backbone node self-organizing module executes LoRa-Mesh self-organizing network and generates LoRa-Mesh topology matrix, link status data, and backbone node takeover rule parameter set includes: Based on the deployment parameter generation module outputting the LoRa-Mesh backbone node deployment coordinate set, LoRa-Mesh backbone nodes are deployed along the tunnel axis at preset spacing in the straight section of the tunnel, LoRa-Mesh backbone nodes are deployed on the tunnel wall on the side of the maximum arc length in the curved section of the tunnel, and corresponding LoRa-Mesh backbone nodes are deployed at the fish mouth position of the bifurcation section. After deployment, each LoRa-Mesh backbone node sends a network access request via broadcast, receives response information from neighboring backbone nodes, completes identity authentication and neighbor discovery, and establishes an initial LoRa-Mesh topology based on the exchanged node identifiers and location information. Based on the initial LoRa-Mesh topology, each LoRa-Mesh backbone node calculates link reachability according to the communication quality information with neighboring backbone nodes, generates a LoRa-Mesh topology matrix containing node connection relationships and communication paths, and continuously updates link status data. When any LoRa-Mesh backbone node detects a link interruption with its neighboring backbone node or a communication quality lower than a preset threshold, route recalculation is triggered. An alternative communication path is selected based on the LoRa-Mesh topology matrix, and the corresponding link status data is updated. When a LoRa-Mesh backbone node fails and is unable to manage the BeiDou positioning signal transmitting units under its jurisdiction, other LoRa-Mesh backbone nodes whose communication quality with the transmitting unit meets the reception conditions shall take over the management relationship of the BeiDou positioning signal transmitting unit and update the backbone node takeover rule parameter set.

5. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 4, characterized in that, The process of pseudo-data remapping and distribution after the BeiDou positioning signal transmitting unit is taken over includes: reading the deployment coordinates, coverage parameters, and working status data of the BeiDou positioning signal transmitting unit being taken over; constructing a pseudo-data generation constraint set in combination with the corresponding tunnel structure parameters; regenerating BeiDou positioning pseudo-data that matches the BeiDou positioning signal transmitting unit being taken over based on the pseudo-data generation constraint set and the original BeiDou satellite data; distributing the BeiDou positioning pseudo-data to the BeiDou positioning signal transmitting unit being taken over through the corresponding LoRa-Mesh communication path according to the updated backbone node takeover rule parameter set; and receiving pseudo-data reception confirmation information.

6. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 5, characterized in that, The BeiDou positioning signal transmission module includes BeiDou positioning signal transmission units staggered on both sides of the tunnel, based on the transmission unit deployment coordinate set output by the deployment parameter generation module. Each BeiDou positioning signal transmission unit receives BeiDou positioning pseudo-data through its affiliated LoRa-Mesh backbone node, converts the pseudo-data into BeiDou positioning radio frequency signals for transmission, collects its own actual deployment coordinates and working status data, and reports them to the BeiDou positioning signal simulation generation module through its affiliated LoRa-Mesh backbone node. When a backbone node undergoes a takeover switch, it continuously receives BeiDou positioning pseudo-data forwarded by the corresponding backbone node according to the updated management relationship, maintaining continuous radio frequency signal transmission.

7. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 6, characterized in that, The process of generating adaptive pseudo-data in the BeiDou positioning signal simulation generation module includes: It receives raw data from no less than four Beidou satellites, reads the tunnel 3D structure model, the set of coordinates for the launch unit deployment, and the set of coverage parameters from the tunnel scene modeling module, reads the current link status data and the set of parameters for the backbone node takeover rules from the LoRa-Mesh backbone node, and reads the working status data from the Beidou positioning signal launch unit. Based on the set of deployment coordinates of the transmitting units, an independent data processing instance is established for each BeiDou positioning signal transmitting unit according to a one-to-one correspondence. In each data processing instance, the actual deployment coordinates, coverage parameters, tunnel structure parameters of the tunnel segment to which the corresponding transmitting unit belongs, and the current management backbone node identifier are loaded. In each data processing instance, the raw data of BeiDou satellites are geometrically mapped to the deployment coordinates of the corresponding launch unit, the spatial geometric relationship parameters between the satellites and the launch unit are calculated, and the set of available satellites is filtered based on the coverage parameters and tunnel structure parameters. Based on the selected set of available satellites, and combined with the spatial geometric relationship parameters of the corresponding launch units, the pseudorange parameters, time synchronization parameters and signal frequency band parameters that match the BeiDou positioning signal launch units are calculated unit by unit, and BeiDou positioning pseudo data that is adapted to the deployment location, coverage area and tunnel structure of the launch units are generated. The pseudo-data of BeiDou positioning generated for each BeiDou positioning signal transmitting unit will be bound and stored with the corresponding transmitting unit identifier.

8. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 7, characterized in that, The LoRa-Mesh topology matrix stability means that the following conditions are met within a preset time window: After each LoRa-Mesh backbone node completes the exchange of node network access and routing information, the node connection relationship in the LoRa-Mesh topology matrix remains unchanged. Within the time window, the link status data reported by each LoRa-Mesh backbone node did not trigger link interruption, node takeover, or route recalculation operations. In the LoRa-Mesh topology matrix, the next-hop node identifier corresponding to any backbone node must be consistent with the forwarding table entry; When all three conditions are met, the LoRa-Mesh topology matrix is ​​determined to be in a stable state, triggering the BeiDou positioning signal simulation generation module to perform the adaptation pseudo-data generation operation for the BeiDou positioning signal transmitting unit.

9. The LoRa-Mesh self-organizing network BeiDou positioning system for tunnel scenarios according to claim 8, characterized in that, The pseudo-data transmission and control module includes, after generating BeiDou positioning pseudo-data, classifying and packaging the BeiDou positioning pseudo-data according to the LoRa-Mesh topology matrix and the management relationship of the backbone nodes, and transmitting it to the target LoRa-Mesh backbone node through the corresponding LoRa-Mesh communication path. The LoRa-Mesh backbone node forwards the BeiDou positioning pseudo-data to the corresponding BeiDou positioning signal transmitting unit under its jurisdiction. It receives the pseudo-data reception confirmation information reported by the BeiDou positioning signal transmitting unit through the LoRa-Mesh backbone node, determines the pseudo-data transmission status, and re-executes the corresponding pseudo-data transmission operation when no reception confirmation information is received or a transmission anomaly is detected. After the pseudo-data is effectively transmitted, it controls the BeiDou positioning signal transmitting unit to continuously transmit BeiDou positioning radio frequency signals based on the BeiDou positioning pseudo-data.

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