Robust routing method of unmanned aerial vehicle cluster based on multi-gateway rapid switching

Abstract

The invention discloses a robust routing method for an unmanned aerial vehicle cluster based on multi-gateway rapid switching, and the method comprises the steps: taking m unmanned aerial vehicles capable of carrying out 4G communication as gateway nodes, and forwarding data to a rear-end cloud server through cellular service; the method comprises the following steps: taking n unmanned aerial vehicles incapable of performing 4G communication as data acquisition nodes, and connecting to any unmanned aerial vehicle capable of performing 4G communication through a Batman-adv self-organizing network so as to obtain the capability of communicating with a back-end cloud server; and the back-end cloud server is used for receiving, processing and forwarding the data traffic. In order to solve the problem that the Batman-adv unmanned aerial vehicle node cannot switch the gateway in a short time, the ARP cache optimization method based on the gateway shared IP address is adopted, the rapid switching of the gateway is effectively realized, and stable and reliable network connection is ensured.

Description

Technical Field

[0001] The present invention relates to the field of gateway switching in a multi-UAV network system, and in particular to a robust routing method for a UAV cluster based on fast switching of multiple gateways. Background Art

[0002] Drones can be used to temporarily deploy communication networks in natural disaster areas and remote areas, participate in search and rescue activities in disaster-stricken areas, and monitor field environment data. In the data collection scenario, multiple drones collaborate to complete data collection tasks. Non-gateway drones regularly monitor real-time data and send data to gateway drones through self-organizing networks. The latter sends data to the back-end cloud server through cellular networks or satellite networks. As the core hub of data transmission, the stability of gateway drones is related to the reliability of the entire system. To avoid single point failures, most existing drone networks use multiple gateways so that they can switch to other normal gateways when a gateway fails.

[0003] However, due to the instability of the wireless network environment and the complexity of the actual geographical environment, communication links often face various interferences and potential risks. Insufficient power supply, sudden failures, and dynamic adjustments to the network topology may cause the gateway to exit the network, and other data collection drones connected to the gateway will be affected, resulting in data loss. It also takes a certain amount of time to restore the gateway drone function, which aggravates the data loss. In actual needs, it is usually hoped that other gateways can take over their responsibilities after a gateway fails, and the shorter the switching time, the better. However, the existing drone routing protocol cannot adapt to multiple gateways and does not consider the gateway failure problem in the multi-gateway drone scenario. For example, the gateway switching delay of the Batman-adv routing protocol can reach 32 seconds, which cannot effectively deal with sudden failure problems in actual applications. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a robust routing method for drone clusters based on fast switching of multiple gateways in response to the defects involved in the background technology.

[0005] The present invention adopts the following technical solutions to solve the above technical problems: A robust routing method for a drone cluster based on multi-gateway fast switching, wherein the drone cluster includes m drones capable of 4G communication and n drones that cannot perform 4G communication, and the method comprises the following steps: Step 1), m drones capable of 4G communication are used as gateway nodes, n drones that cannot communicate with 4G are used as data collection nodes, and the backend cloud server is used to receive, process and forward data traffic from the gateway nodes; Step 2), m drones capable of 4G communication establish a TCP network connection with the backend cloud server; Step 3), all drones start the Batman-adv protocol, run the protocol parameter configuration script, initialize their neighbor list configuration, and periodically send broadcast messages to neighbor nodes to perform neighbor detection; Step 4), each drone uses the Batman-adv routing algorithm to calculate the optimal path to other nodes in the network based on the received broadcast message and its neighbor list, and updates its source node list and routing table; Step 5), the gateway node broadcasts its gateway status to other nodes. After receiving the status, the data collection node updates its gateway list, selects the gateway node with the highest link quality from the gateway list according to the link quality, and obtains the IP address assigned by the gateway node; Step 6), the data collection node establishes a data transmission path with the backend cloud server via the selected gateway node to perform data transmission; at the same time, the data collection node periodically sends an ARP request message to the selected gateway to detect the reachability of the selected gateway and determine whether the selected gateway is faulty; Step 7), when the gateway node selected by the data collection node exits the network due to a fault, the data collection node broadcasts an ARP request message about the gateway to the network; Step 8), after receiving the ARP request message, the remaining gateway nodes send an ARP reply message to the data collection node that sent the ARP request message. The data collection node updates its ARP cache according to the arrival time of the ARP reply message, reselects a gateway node that is working normally, and resumes data transmission with the backend cloud server.

[0006] As a further optimization scheme of the robust routing method of the drone cluster based on multi-gateway fast switching of the present invention, in step 3), the specific steps of the drone running the protocol parameter configuration script as a gateway node are: Step 3.1.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.1.2), turn off the DAT mechanism of the Batman-adv protocol; Step 3.1.3), set the current node as the gateway node; Step 3.1.4), configure the gateway IP address to the preset IP address.

[0007] As a further optimization scheme of the robust routing method of the drone cluster based on multi-gateway fast switching of the present invention, in step 3), the specific steps of the drone running protocol parameter configuration script as a data collection node are: Step 3.2.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.2.2), turn off the DAT mechanism of the Batman-adv protocol, and change the gateway switching mode of the Batman-adv protocol to fast switching; Step 3.2.3), set the current node as a non-gateway node; Step 3.2.4), configure the ARP cache time parameters.

[0008] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: The present invention designs a robust routing method for drone clusters based on multi-gateway fast switching, uses the Batman-adv routing protocol to form a drone self-organizing network, allocates the same IP address to all gateways, so that the drone does not need to change the IP configuration at the IP layer, optimizes the neighbor discovery process of the IP protocol stack and its interaction with the routing protocol, and by optimizing the aging time of ARP cache entries, non-gateway drones can periodically send ARP requests to detect connections with gateways, and can obtain MAC addresses of other available gateways when a gateway fails, thereby ensuring a stable and reliable network connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic structural diagram of the implementation of the present invention.

[0010] Figure 2 It is a schematic diagram of the process of the present invention.

[0011] Figure 3 A schematic diagram of a gateway switching time test without using the Batman-adv routing protocol of the present invention; Figure 4 This is a schematic diagram of the gateway switching time test in a stable scenario of the present invention; Figure 5 A schematic diagram of a gateway switching time test in a low mobility scenario according to the present invention; Figure 6 It is a schematic diagram of the gateway switching time test in the high mobility scenario of the present invention. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings: The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete, and will fully express the scope of the present invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0013] In order to solve the problem of gateway drone failure in a multi-drone data acquisition system, the present invention adopts a gateway switching method based on ARP cache optimization of gateway shared IP addresses, uses the Batman-adv protocol to form a drone self-organizing network, and assigns the same IP address to all gateways, so that drones do not need to change IP configuration at the IP layer, optimizes the neighbor discovery process of the IP protocol stack and its interaction with the routing protocol; in addition, by optimizing the aging time of ARP cache entries, non-gateway drones can periodically send ARP requests to detect connections with gateways, and can obtain MAC addresses of other available gateways when a gateway fails, ensuring a stable and reliable network connection.

[0014] like Figure 1 , Figure 2 As shown, the present invention discloses a robust routing method for a drone cluster based on multi-gateway fast switching, wherein the drone cluster includes m drones capable of 4G communication and n drones that cannot perform 4G communication, and the method includes the following steps: Step 1), m drones capable of 4G communication are used as gateway nodes, n drones that cannot communicate with 4G are used as data collection nodes, and the backend cloud server is used to receive, process and forward data traffic from the gateway nodes; Step 2), m drones capable of 4G communication establish a TCP network connection with the backend cloud server; Step 3), all drones start the Batman-adv protocol, run the protocol parameter configuration script, initialize their neighbor list configuration, and periodically send broadcast messages to neighbor nodes to perform neighbor detection; Step 4), each drone uses the Batman-adv routing algorithm to calculate the optimal path to other nodes in the network based on the received broadcast message and its neighbor list, and updates its source node list and routing table; Step 5), the gateway node broadcasts its gateway status to other nodes. After receiving the status, the data collection node updates its gateway list, selects the gateway node with the highest link quality from the gateway list according to the link quality, and obtains the IP address assigned by the gateway node; Step 6), the data collection node establishes a data transmission path with the backend cloud server via the selected gateway node to perform data transmission; at the same time, the data collection node periodically sends an ARP request message to the selected gateway to detect the reachability of the selected gateway and determine whether the selected gateway is faulty; Step 7), when the gateway node selected by the data collection node exits the network due to a fault, the data collection node broadcasts an ARP request message about the gateway to the network; Step 8), after receiving the ARP request message, the remaining gateway nodes send an ARP reply message to the data collection node that sent the ARP request message. The data collection node updates its ARP cache according to the arrival time of the ARP reply message, reselects a gateway node that is working normally, and resumes data transmission with the backend cloud server.

[0015] The specific steps for the drone as a gateway node to run the protocol parameter configuration script in step 3) are: Step 3.1.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.1.2), turn off the DAT mechanism of the Batman-adv protocol; Step 3.1.3), set the current node as the gateway node; Step 3.1.4), configure the gateway IP address to the preset IP address.

[0016] The specific steps for the drone running the protocol parameter configuration script as a data collection node in step 3) are as follows: Step 3.2.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.2.2), turn off the DAT mechanism of the Batman-adv protocol, and change the gateway switching mode of the Batman.adv protocol to fast switching; Step 3.2.3), set the current node as a non-gateway node; Step 3.2.4), configure the ARP cache time parameters.

[0017] The present invention uses the Raspberry Pi 4B development board as the drone embedded device. All drones communicate with each other through the built-in wireless network card of the Raspberry Pi 4B development board using the Batman-adv protocol, forming a self-organizing network when powered on. Each gateway drone is configured with a wireless 4G communication module through a USB interface, and a TCP network connection is established between a nearby base station and a back-end cloud server with a public network IP address to achieve data interaction between the embedded device and the cloud server.

[0018] The present invention tests the gateway switching time of the robust routing method of the drone cluster based on multi-gateway fast switching. The network topology tested is as follows: Figure 1 As shown in the figure, nodes A and B are used as gateways, and nodes C, D, and E are used as data collection nodes. Node C is programmed to report data to the cloud server regularly. It can access the Internet directly through gateway A, or connect to gateway B via relay nodes D or E. The path from node C to the gateway is derived by the Batman-adv protocol routing algorithm.

[0019] The test scenarios of the present invention are divided into three types, namely stable scenarios, low mobility scenarios and high mobility scenarios, to test the performance of the robust routing method of the drone cluster based on multi-gateway fast switching under the interference caused by the motion state of the drone. In the stable scenario, all nodes are in a stationary state to simulate the relatively stationary state of the drone; in the low mobility scenario, by shaking the Raspberry Pi 4B development board left and right, the data acquisition node C is in motion and the other nodes are in a stationary state; in the high mobility scenario, by shaking the Raspberry Pi 4B development board left and right, the data acquisition nodes C, D, and E are in motion and the gateway nodes A and B are in a stationary state.

[0020] The present invention simulates a gateway failure by manually turning off the power of the gateway randomly during data transmission, and uses a Ping tool to simulate the drone data reporting stage. The data acquisition node continuously Pings the cloud server with a public IP address, and the ICMP message from the data acquisition node is first delivered to the gateway node and forwarded to the cloud server via the gateway node. In the present invention, the gateway switching time is defined as the time interval between the failure of the original gateway and the successful switching of the new gateway. Since this time interval is difficult to measure directly, the present invention observes the arrival time of the last and first ICMP reply messages received before and after the gateway failure through a network tool on the basis of the data acquisition node continuously Pinging the cloud server, and calculates the time difference to obtain the gateway switching time.

[0021] Figure 3 The switching time of the Batman-adv protocol gateway before the gateway switching algorithm of the present invention is adopted is shown. The test is performed in a stable scenario. The results show that in five tests, the switching time from the failure of the gateway to the switching of other gateways to restore communication reached more than 20 seconds, and the longest time reached 32 seconds.

[0022] Figure 4 , Figure 5 , Figure 6 The gateway switching time of the present invention in stable scenario, low mobility scenario and high mobility scenario is shown respectively. The results show that after using the present invention, the fastest switching time is 0.0837 seconds and the slowest switching time is 1.3236 seconds. In different test scenarios (stable scenario, low mobility scenario and high mobility scenario), the average switching time of the system is kept at a low level, which are 0.4051 seconds, 0.4317 seconds and 0.4721 seconds respectively. All test data in the three scenarios are averaged and the total average gateway switching time is 0.4363 seconds.

[0023] The present invention discloses a robust routing method for a drone cluster based on multi-gateway fast switching, wherein m drones capable of 4G communication are used as gateway nodes, and data is forwarded to a back-end cloud server through cellular services; n drones that cannot perform 4G communication are used as data collection nodes, and are connected to any drone capable of 4G communication through a Batman-adv self-organizing network to obtain the ability to communicate with the back-end cloud server; the back-end cloud server is used to receive, process and forward data traffic from. The present invention optimizes the neighbor discovery process of the IP protocol stack and its interaction with the routing protocol, and by optimizing the aging time of the ARP cache entry, non-gateway drones can periodically send ARP requests to detect the connection with the gateway, and can obtain the MAC addresses of other available gateways when the gateway fails, thereby ensuring a stable and reliable network connection.

[0024] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0025] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A robust routing method for a drone cluster based on multi-gateway fast switching, wherein the drone cluster includes m drones capable of 4G communication and n drones not capable of 4G communication, characterized in that: The following steps are involved: Step 1), m drones capable of 4G communication are used as gateway nodes, n drones that cannot communicate with 4G are used as data collection nodes, and the backend cloud server is used to receive, process and forward data traffic from the gateway nodes; Step 2), m drones capable of 4G communication establish a TCP network connection with the backend cloud server; Step 3), all drones start the Batman-adv protocol, run the protocol parameter configuration script, initialize their neighbor list configuration, and periodically send broadcast messages to neighbor nodes to perform neighbor detection; Step 4), each drone uses the Batman-adv routing algorithm to calculate the optimal path to other nodes in the network based on the received broadcast message and its neighbor list, and updates its source node list and routing table; Step 5), the gateway node broadcasts its gateway status to other nodes. After receiving the status, the data collection node updates its gateway list, selects the gateway node with the highest link quality from the gateway list according to the link quality, and obtains the IP address assigned by the gateway node; Step 6), the data collection node establishes a data transmission path with the backend cloud server via the selected gateway node to perform data transmission; at the same time, the data collection node periodically sends an ARP request message to the selected gateway to detect the reachability of the selected gateway and determine whether the selected gateway is faulty; Step 7), when the gateway node selected by the data collection node exits the network due to a fault, the data collection node broadcasts an ARP request message about the gateway to the network; Step 8), after receiving the ARP request message, the remaining gateway nodes send an ARP reply message to the data collection node that sent the ARP request message. The data collection node updates its ARP cache according to the arrival time of the ARP reply message, reselects a gateway node that is working normally, and resumes data transmission with the backend cloud server.

2. The robust routing method for drone clusters based on multi-gateway fast switching according to claim 1 is characterized in that: In step 3), the specific steps of the UAV running the protocol parameter configuration script as a gateway node are as follows: Step 3.1.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.1.2), turn off the DAT mechanism of the Batman-adv protocol; Step 3.1.3), set the current node as the gateway node; Step 3.1.4), configure the gateway IP address to the preset IP address.

3. The robust routing method for drone clusters based on multi-gateway fast switching according to claim 1 is characterized in that: In step 3), the specific steps of the drone running the protocol parameter configuration script as a data collection node are as follows: Step 3.2.1), activate the bat0 virtual port used by the Batman-adv protocol; Step 3.2.2), turn off the DAT mechanism of the Batman-adv protocol, and change the gateway switching mode of the Batman-adv protocol to fast switching; Step 3.2.3), set the current node as a non-gateway node; Step 3.2.4), configure the ARP cache time parameters.

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