UAV-WSN-based construction method for underground emergency rescue communication network

Abstract

The present invention belongs to the field of mine emergency rescue. Disclosed is a UAV-WSN-based construction method for an underground emergency rescue communication network. The method comprises: performing communication network self-reconstruction on the basis of surviving WSN nodes: constructing local networks with the surviving WSN nodes themselves as key nodes; using UAVs to discover the reconstructed networks and construct communication links, thereby constructing local networks comprising UAVs and a WSN; constructing communication links between adjacent UAVs to connect different local networks comprising UAVs and a WSN so as to construct a UAV-WSN-based global network, thereby completing construction of an emergency rescue communication network. Starting with nodes, the present invention achieves construction of a global emergency communication network in an accident-affected area by means of node-based self-reconstruction and UAV-assisted network connection while improving the capability of nodes to support emergency rescue, thereby improving existing emergency rescue methods, improving emergency rescue efficiency, and also providing a new approach for emergency rescue.

Description

A Method for Constructing an Downhole Emergency Rescue Communication Network Based on UAV-WSN Technical Field

[0001] This invention belongs to the field of mine emergency rescue, and in particular relates to a method for constructing an emergency rescue communication network based on UAV-WSN. Background Technology

[0002] Shallow coal resources are becoming increasingly depleted, and the depth of coal mining in my country is gradually increasing. Due to the complex geological conditions and coal deposits in underground mines, coal mine safety accidents are frequent. Gas and roof collapse accidents are among the most common and serious hazards in coal mines, causing roadway rock collapses and blockages. This not only traps miners and disrupts communication networks but also severely impacts emergency rescue efforts.

[0003] For emergency rescue missions, establishing an emergency communication network is a crucial guarantee. Wireless sensor networks (WSNs) have been applied to emergency rescue missions, but their limited mobility and energy, as well as the impact of damage to wireless sensor nodes during accidents, limit their effectiveness in emergency rescue. Rescue robots, such as unmanned aerial vehicles (UAVs), can effectively improve emergency rescue efficiency. Therefore, emergency rescue systems combining UAVs and WSNs have significant application potential in restoring emergency communication networks at accident sites.

[0004] Therefore, it is essential to study the construction method of underground emergency communication network based on UAV-WSN. This can enable the construction of emergency communication network in the event of large-scale roadway collapse or roadway isolation after gas and roof accidents, thereby guiding emergency rescue. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing an emergency rescue communication network based on UAV-WSN, which fully combines the advantages of UAV and WSN, enabling the efficient establishment of an emergency communication network after an accident occurs in the well, and guiding emergency rescue.

[0006] To achieve the above objectives, this invention proposes a method for constructing an downhole emergency rescue communication network based on UAV-WSN, and adopts the following technical solution:

[0007] A method for constructing a downhole emergency rescue communication network based on UAV-WSN includes the following steps:

[0008] Step 1: Before the accident, deploy prefabricated WSN nodes in the underground roadway, connect them to the underground communication ring network, and maintain low power consumption operation or sleep mode; after the accident, deploy UAVs in the accident area.

[0009] Step 2: After the accident, the surviving WSN nodes switch to emergency rescue mode, send electromagnetic signals to the surrounding area, discover other surviving nodes, and build a local network with the surviving WSN nodes as the core, so as to realize the self-reconstruction of the communication network.

[0010] Step 3: Use UAVs to discover local networks centered around key nodes and build communication links to form a local network that includes UAVs and WSNs;

[0011] Step 4: Establish communication links between adjacent UAVs, connect different local networks containing UAVs and WSNs, build a global network based on UAV-WSN, and complete the construction of the emergency rescue communication network.

[0012] Furthermore, the prefabricated WSN node is a heterogeneous node. A half-shell radome protection structure is installed on the outside of the prefabricated WSN node. The communication reliability of the prefabricated WSN node is achieved through the heterogeneous node approach. The installation of the half-shell radome protection structure provides a certain impact protection function for the core components, while reducing the electromagnetic loss of electromagnetic waves passing through the shell and further improving the communication reliability of the node.

[0013] Furthermore, heterogeneous nodes are achieved by designing heterogeneous modules with communication methods including WiFi and UWB; the half-shell radome adopts a sandwich structure, and the sandwich structure includes a frequency selective surface (FSS). Through the frequency selective surface with different structures, efficient transmission of communication frequency bands for different communication methods is achieved.

[0014] Furthermore, the switching mechanism for the prefabricated WSN node to switch from low-power operation or sleep state to emergency rescue state originates from the semi-shell radome protection structure. The semi-shell radome protection structure monitors surface stress through an internal stress monitoring device. When the detected stress value exceeds a preset threshold, the node is awakened and enters emergency rescue state.

[0015] Furthermore, when deploying UAVs after an accident, if the accident completely blocks the tunnel, the UAVs are deployed using the pipeline channels opened in the accident area by the drilling machine; if the tunnel is not completely blocked by the accident, the UAVs fly along the overhead space of the tunnel to achieve deployment.

[0016] Furthermore, the communication network self-reconfiguration in step 2 includes self-reconfiguration between the remaining WSN nodes and reconfiguration between the remaining WSN nodes and the remaining existing underground safety and safety system nodes. First, the information of neighboring nodes is determined through the handshake mechanism between nodes and data packet exchange. Then, communication links are constructed between the remaining prefabricated WSN nodes and between the remaining prefabricated WSN nodes and the remaining existing underground safety and safety system nodes. The existing underground safety and safety system nodes are base stations, gateways, and APs used for underground monitoring, personnel positioning, and communication.

[0017] Furthermore, since the prefabricated WSN nodes are heterogeneous nodes, and the existing safety and emergency response system nodes in the well also have multiple communication methods, during the communication network self-reconfiguration process, the prefabricated WSN nodes switch communication methods according to the heterogeneous communication switching strategy. The heterogeneous communication switching strategy is as follows: when a node senses an accident and starts the self-reconfiguration method, it uses the communication link established with the discovered neighboring nodes and the RSSI attenuation formula to inversely deduce the electromagnetic wave transmission medium and adaptively switch to the communication method that is more suitable for signal transmission under this medium.

[0018] Furthermore, based on the aforementioned heterogeneous communication handover strategy, the efficient neighbor node discovery strategy in the self-reconstruction method is as follows:

[0019] Step 1: Based on the heterogeneous communication switching strategy, switch to the most suitable communication method after the incident to complete the first round of neighbor node discovery and communication link construction;

[0020] Step 2: Switch the communication mode again to complete the subsequent N rounds of node discovery and communication link construction, where N is the communication mode of the prefabricated WSN node minus 1, and the node self-reconstruction time in each round is less than the time in Step 1.

[0021] Furthermore, in step 3, regarding the collapse and blockage of the roadway rock mass caused by the accident, the method of using UAVs to discover and build communication links is as follows: deploy multiple UAVs to search the reconstructed local network in the accident area, and then achieve network connectivity in the accident area through the coordinated deployment of UAVs.

[0022] Furthermore, in step 3, regarding the collapse and blockage of the tunnel caused by the accident, the specific process of using UAVs to discover and establish communication links is as follows: When the UAV searches for a key node in the reconstructed network within the communication radius, this key node is set as the center, and the UAV moves outward along the center until it reaches the point where the connection with this key node is broken. The UAV then searches around the center 360° until the search is completed. If other nodes are found, the final position of the UAV is the point where the found nodes coincide. If no other nodes are found, the final position of the UAV is the position closest to the key node. After the UAV position is determined, communication connections are established between each UAV, thereby constructing a network topology between UAVs and between UAVs and WSNs, and realizing network connectivity.

[0023] Furthermore, in step 3, the method for discovering and establishing a communication link using UAV in response to the roadway isolation caused by the accident is as follows: a stable communication link is established between the UAV and the key network nodes; after the stable channel is established, the position of the UAV is adjusted to achieve network connectivity.

[0024] Furthermore, in step 3, for the situation of roadway isolation caused by the accident, the method for constructing a stable communication channel between the UAV and the node is as follows: adjust the different flight speeds and flight altitudes of the UAV, measure the channel quality between the UAV and the node, select the UAV operating parameters with the best channel quality that have the least impact on the signal strength of the receiving node, and construct a channel model under the corresponding parameters.

[0025] Furthermore, in steps 3 and 4, when constructing communication links between UAV and WSN, and between UAVs, it is necessary to consider the environment, the distance between them, and the impact of electromagnetic interference in order to obtain a stable communication link. The way to obtain a stable communication link is to construct an air-to-ground channel between UAV and WSN, and an air-to-air channel between UAVs.

[0026] Furthermore, the channel model is modeled using a geometry-based statistical method.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention discloses a method for constructing an downhole emergency rescue communication network based on UAV-WSN. Combining the advantages of UAV and WSN, starting with WSN nodes, and improving the nodes' ability to support emergency rescue, the invention achieves the framework of a global emergency communication network for the accident area through the self-reconstruction of remaining WSN nodes and the connectivity of UAV-assisted networks. This improves existing emergency rescue methods and enhances the efficiency of emergency rescue. Attached Figure Description

[0029] Figure 1 is a flowchart of the method provided by the present invention;

[0030] Figure 2 is a schematic diagram of the node composition;

[0031] Figure 3 shows the FSS structure that satisfies the wave transmission properties of wireless signals in the 2.4GHz band;

[0032] Figure 4 shows the composition of the heterogeneous node module with STM32F030C8T6 as the main control chip.

[0033] Figure 5 is a schematic diagram of node and UAV deployment;

[0034] Figure 6 is a schematic diagram of the node self-reconstruction method;

[0035] Figure 7 shows the heterogeneous communication switching strategy of prefabricated WSN nodes in the self-reconfiguration method;

[0036] Figure 8 shows the efficient neighbor node discovery strategy based on heterogeneous communication switching strategy in the self-reconstruction method;

[0037] Figure 9 is a schematic diagram of network connectivity achieved through UAV based on a self-reconfigurable network;

[0038] Figure 10 is a schematic diagram of the search for key nodes in the reconstructed network by a specific UAV;

[0039] The labels in the diagram are as follows: 1. Remaining existing underground safety and refuge system nodes; 2. Remaining prefabricated WSN nodes; 3. Mobile nodes (miners); 4. Damaged safety and refuge system nodes; 5. Damaged prefabricated WSN nodes. Detailed Implementation

[0040] The technical solution will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] As shown in Figure 1, the present invention provides a method for constructing a downhole emergency rescue communication network based on UAV-WSN, comprising the following steps:

[0042] Step 1: Before the accident, deploy prefabricated WSN nodes in the underground roadway, connect them to the underground communication ring network, and maintain low power consumption operation or sleep mode; after the accident, deploy UAVs in the accident area.

[0043] Step 2: After the accident, the surviving WSN nodes switch to emergency rescue mode, send electromagnetic signals to the surrounding area, discover other surviving nodes, and build a local network with the surviving WSN nodes as the core, so as to realize the self-reconstruction of the communication network.

[0044] Step 3: Use UAVs to discover local networks centered around key nodes and build communication links to form a local network that includes UAVs and WSNs;

[0045] Step 4: Establish communication links between adjacent UAVs, connect different local networks containing UAVs and WSNs, build a global network based on UAV-WSN, and complete the construction of the emergency rescue communication network.

[0046] As shown in Figures 2 and 3, the prefabricated WSN nodes are heterogeneous nodes, achieving reliable communication through heterogeneous communication. A protective structure is used to protect the nodes and improve their physical survivability. This protective structure is achieved through a semi-shell radome with a frequency selective surface (FSS) sandwich structure. Figure 3 shows the FSS structure that meets the wave transmission properties of 2.4GHz wireless signals, where D is 40mm, L2 is 2.415mm, L1 is 4mm, h2 is 1.5748mm, and h1 is 0.035mm. Furthermore, the supporting medium shown in blue is F4B220 with a dielectric constant of 2.2 and a loss tangent of 0.0009, and the metal shown in yellow is copper.

[0047] Heterogeneous communication of prefabricated WSN nodes is achieved by designing heterogeneous modules. Figure 4 shows the composition of a heterogeneous node module with STM30F030C8T6 as the main control chip. The communication methods include WiFi and UWB.

[0048] Figure 5 illustrates the deployment methods of prefabricated WSN nodes and UAVs. Prefabricated WSN nodes are deployed before the accident, and UAVs are deployed after the accident. After the accident, the remaining prefabricated WSN nodes switch from low-power operation or dormancy to emergency rescue mode. When deploying UAVs, if the accident causes complete blockage of the tunnel, the pipeline channel opened by the drilling machine in the accident area is used to achieve UAV deployment. If the tunnel caused by the accident is not completely blocked, the UAV flies along the top space of the tunnel to achieve UAV deployment.

[0049] Figure 6 illustrates a communication network self-reconstruction method based on surviving prefabricated WSN nodes, including self-reconstruction between surviving prefabricated WSN nodes (shown in Figure 6(D)) and reconstruction between surviving prefabricated WSN nodes and surviving existing downhole safety and avoidance system nodes (shown in Figure 6(A), (B), and (C)). Nodes first determine the information of neighboring nodes through a handshake mechanism and data packet exchange, and then construct communication links between surviving nodes.

[0050] Since the prefabricated nodes are heterogeneous nodes, and the existing safety and disaster prevention system nodes in the well also have multiple communication methods, the prefabricated WSN nodes need to switch communication methods during the self-reconfiguration process. Figure 7 shows the heterogeneous communication switching strategy of the prefabricated nodes in the self-reconfiguration method. That is, based on the communication link established with the discovered neighboring nodes, the electromagnetic wave transmission medium is deduced through the RSSI attenuation formula, and then the communication method more suitable for signal transmission under this communication medium is adaptively switched.

[0051] Figure 8 further illustrates the efficient neighbor node discovery strategy based on heterogeneous communication switching in the self-reconstruction method: First, the communication mode most suitable for the post-accident is switched according to the heterogeneous communication switching strategy to complete the first round of neighbor node discovery and communication link construction; then, the communication mode is switched again to complete the subsequent N rounds of neighbor node discovery and communication link construction; where N is the number of communication modes available to the prefabricated WSN node minus 1, and the node self-reconstruction time in subsequent rounds is less than the time in the first round.

[0052] Figure 9 illustrates network connectivity achieved via UAVs based on a self-reconfigurable network. Links L_1 to L_6 are communication links for global network connectivity via UAVs. To address the roadway rock collapse and blockage caused by the accident, multiple UAVs are deployed to perform network reconstruction searches of the accident environment, thereby constructing a global network for the accident area, as shown by L_5 in Figure 9. To address the roadway isolation caused by the accident, stable communication channels are constructed between UAVs and nodes. While ensuring that communication connections between them are not interrupted due to environmental factors and UAV influences, the positions of the UAVs are adjusted to achieve network connectivity, as shown by L_1 in Figure 9.

[0053] Figure 10 shows a specific UAV's search for key nodes in the reconstructed network. The UAV finds the remaining node N1 at position P1, then sets node N1 as the center and moves outwards along the center until it reaches the point where it is disconnected from node N1, P2. Using the distance between nodes N1 and P2 as the radius, it searches around the center 360°. When it reaches P2', it finds node N2. Therefore, at this point, the UAV's position may be the midpoint of the line connecting N1 and N2.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art within the scope of the technology disclosed in this invention, based on the technical solution and inventive concept of the present invention, should be covered within the protection scope of this invention. Therefore, the protection scope of this invention should be determined by the scope of the claims.

Claims

1. A method for constructing an downhole emergency rescue communication network based on UAV-WSN, characterized in that, Includes the following steps: Step 1: Before the accident, deploy prefabricated WSN nodes in the underground roadway, connect them to the underground communication ring network, and maintain low power consumption operation or sleep mode; after the accident, deploy UAVs in the accident area. Step 2: After the accident, the surviving WSN nodes switch to emergency rescue mode, send electromagnetic signals to the surrounding area, discover other surviving nodes, and build a local network with the surviving WSN nodes as the core, so as to realize the self-reconstruction of the communication network. Step 3: Use UAVs to discover local networks centered around key nodes, build communication links, and construct a local network that includes UAVs and WSNs; Step 4: Establish communication links between adjacent UAVs, connect different local networks containing UAVs and WSNs, build a global network based on UAV-WSN, and complete the construction of the emergency rescue communication network.

2. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 1, characterized in that, The prefabricated WSN node is a heterogeneous node, which is achieved by designing heterogeneous modules with WiFi and UWB communication methods. The prefabricated WSN node is protected by a half-shell radome structure, which adopts a sandwich structure and includes a frequency selective surface.

3. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 2, characterized in that, The switching mechanism for prefabricated WSN nodes to transition from low-power operation or sleep mode to emergency rescue mode originates from the semi-shell radome protection structure. The semi-shell radome protection structure monitors surface stress through an internal stress monitoring device. When the detected stress value exceeds a preset threshold, the node is awakened and enters emergency rescue mode.

4. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 1, characterized in that, When deploying UAVs after an accident, if the accident completely blocks the tunnel, the UAVs are deployed using the pipeline channels opened by the drilling machine in the accident area; if the accident does not completely block the tunnel, the UAVs fly along the overhead space of the tunnel to achieve deployment.

5. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 3, characterized in that, The communication network self-reconfiguration in step 2 includes self-reconfiguration between the remaining WSN nodes and reconfiguration between the remaining WSN nodes and the remaining existing underground safety and safety system nodes. First, the information of neighboring nodes is determined through the handshake mechanism between nodes and data packet exchange. Then, communication links are constructed between the remaining WSN nodes and between the remaining WSN nodes and the remaining existing underground safety and safety system nodes. The existing safety and emergency response system nodes in the mine consist of base stations, gateways, and access points used for underground monitoring, personnel positioning, and communication.

6. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 5, characterized in that, During the self-reconfiguration process of the communication network, the prefabricated WSN nodes switch communication modes according to the heterogeneous communication switching strategy. The specific heterogeneous communication switching strategy is as follows: when a node senses an accident and starts the self-reconfiguration method, it uses the RSSI attenuation formula to back-calculate the electromagnetic wave transmission medium based on the communication link established with the discovered neighboring nodes, and adaptively switches to the communication mode that is more suitable for signal transmission under this medium.

7. A method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 6, characterized in that, Based on the heterogeneous communication handover strategy, the efficient neighbor node discovery strategy in the self-reconstruction method is as follows: Step 1: Based on the heterogeneous communication switching strategy, switch to the most suitable communication method after the incident to complete the first round of neighbor node discovery and communication link construction; Step 2: Switch the communication mode again to complete the subsequent N rounds of node discovery and communication link construction, where N is the communication mode available to the prefabricated WSN node minus 1, and the node self-reconstruction time in each round is less than the time in Step 1.

8. The method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 4, characterized in that, In response to the rock mass collapse and blockage in the tunnel caused by the accident, the specific process of using UAVs to discover and establish communication links is as follows: When a UAV searches for a key node in the reconstructed network within the communication radius, this key node is set as the center. The UAV moves outward from the center until it reaches the point where the connection with this key node is broken, and searches around the center 360° until the search is completed. If other nodes are found, the final position of the UAV is the point where the found nodes coincide. If no other nodes are found, the final position of the UAV is the closest position to the key node. After the UAV position is determined, communication connections are established between each UAV, thereby constructing a network topology between UAVs and between UAVs and WSNs, realizing network connectivity.

9. A method for constructing a downhole emergency rescue communication network based on UAV-WSN according to claim 4, characterized in that, To address the roadway isolation caused by the accident, the method for using UAVs to detect and establish communication links is as follows: adjust the different flight speeds and altitudes of the UAVs, measure the channel quality between the UAVs and key nodes, select the UAV operating parameters with the best channel quality (i.e., the least impact on the signal strength of the receiving nodes), and construct a stable channel model under the corresponding parameters; after the stable channel is constructed, adjust the position of the UAVs to achieve network connectivity.

10. A method for constructing a downhole emergency rescue communication network based on UAV-WSN according to any one of claims 8 or 9, characterized in that, The methods to achieve stable communication links between UAV and WSN, and between UAVs, are to construct an air-to-ground channel between UAV and WSN, and an air-to-air channel between UAVs, respectively.

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