Relay system for signal shielding bridge health state detection based on unmanned aerial vehicle

Abstract

The invention relates to the technical field of unmanned aerial vehicles, in particular to a relay system for signal shielding bridge health state detection based on an unmanned aerial vehicle. And comprehensive bridge health state evaluation can be provided for bridge surface disease identification and structural vibration analysis in a complex environment with limited or invalid GPS signals. The system comprises a ground terminal, an unmanned aerial vehicle-mounted relay unit, a bridge structure information collection unit, a bridge surface disease information collection unit, a data storage unit and an unmanned aerial vehicle ground station. And through a multi-link automatic switching function of the ground terminal, stable communication between the unmanned aerial vehicle and the ground terminal is ensured in a signal shielding environment. The system can efficiently and accurately detect bridge surface crack and corrosion diseases, and combines vibration signals to analyze inherent frequency and damping ratio characteristics of a bridge so as to evaluate the health condition of a bridge structure. The multi-modal data fusion and intelligent analysis functions of the system are beneficial to finding potential structural hidden dangers of the bridge in advance, and the efficiency and reliability of bridge detection are improved.

Description

Technical Field

[0001] The invention relates to the technical field of unmanned aerial vehicles, and in particular to a relay system for detecting the health status of a bridge obstructed by a signal from an unmanned aerial vehicle. Background Art

[0002] In the prior art, CN 115981355 A discloses an automatic cruise system for a UAV that can land quickly and accurately, including a UAV, a UAV remote control device, a GPS positioning device, a UAV take-off and landing platform, a visual recognition mark and a cruise control device; CN 109445454 A provides a UAV beam cruise detection method for bridge detection, which can perform fully automatic and accurate detection of bridge columns, eliminate detection blind spots, and ensure the comprehensiveness and accuracy of detection data; CN 113821044 A provides an autonomous navigation and stable control method for a bridge detection UAV based on reinforcement learning to solve the problems of lack of positioning signals under the bridge and inability to stabilize flight control under strong wind interference in UAV bridge detection technology; CN 114778551 A provides a UAV bridge surface disease detection method based on the fusion of laser and machine vision; CN 106645205 A provides a UAV bridge bottom surface crack detection method and system.

[0003] However, the drone relay system involved in the above patent still has many deficiencies in practical applications:

[0004] The drone system in the above patent relies on GPS for positioning and navigation. However, in complex environments such as under bridges and tunnels, GPS signals are easily blocked or interfered by bridge structures, resulting in unstable signals or even complete loss of signals. This makes it impossible for drones to accurately locate in these areas, resulting in the inability to complete flight missions autonomously. Existing GPS-based drone systems have serious limitations in the underbridge environment, which can easily lead to interruption or failure of detection tasks. Existing positioning technologies based on a single sensor are prone to positioning drift, data distortion or signal noise problems in the presence of insufficient visual features, unstable ambient lighting or dynamic obstacles, resulting in unstable flight trajectories, which in turn affects detection accuracy.

[0005] In the bridge bottom inspection environment, the drone not only needs to perform accurate navigation and positioning, but also needs to perceive the surrounding obstacles (such as bridge supports, cables, etc.) in real time and avoid them autonomously. The obstacle avoidance technology of existing drones shows great limitations in complex environments, especially in small spaces, dense obstacles or fast flight speeds, which are prone to collisions or attitude instability. In signal-blocking environments such as the bottom of a bridge, the communication link between the drone and the ground control station will also be seriously affected. Most existing systems rely on traditional radio communications. When drones enter areas such as the bottom of a bridge, the signal is easily blocked or interfered, resulting in unstable or even interrupted data transmission. In this case, the detection data cannot be transmitted back to the ground control station in a timely manner, and the detection results cannot be analyzed and processed in real time, affecting the detection efficiency and effect. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the problem to be solved by the present invention is how to solve the problems of the inability of UAVs to accurately locate in areas such as under bridges and tunnels, the positioning and flight stability of UAVs in the under bridge environment, the autonomous obstacle avoidance and flight stability of UAVs, and the unstable communication link.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides a relay system for detecting the health status of a bridge based on a signal obstruction of a drone, which includes constructing a relay system, including deploying a ground terminal, a drone-mounted relay unit, a bridge structure information collection unit, a bridge surface disease information collection unit, a data storage unit, and a drone ground station;

[0010] The ground terminal is fixedly installed on the side of the bridge and continuously collects bridge vibration signals through a multi-sensor fusion module; the drone is equipped with a camera and a lidar to collect information on bridge surface damage;

[0011] When the drone enters a signal-blocked area, the relay system automatically switches the communication mode:

[0012] a) The ground terminal acts as a relay node, receiving drone data and forwarding it to the base station;

[0013] b) In drone formation mode, the host drone acts as a relay node, receiving and forwarding data from slave drones;

[0014] The ground terminal or base station uploads the collected data to the cloud platform, extracts key parameters of the bridge health status through modal analysis methods, and generates an assessment report;

[0015] The relay system monitors the signal strength in real time. When all communication paths do not meet the requirements, the exception handling mechanism is triggered to temporarily store the data and re-upload it after the signal is restored.

[0016] As a preferred solution of the relay system for detecting the health status of bridges with signal obstruction based on drones of the present invention, wherein: the ground terminal unit is the core control and communication relay node of bridge health monitoring, which is used for the collection of bridge vibration signals, drone communication relay, and data management and transmission;

[0017] When the UAV performs inspection tasks and in a signal-blocking environment, the ground terminal unit ensures the integrity and accuracy of data transmission through the relay function. The ground terminal switches between Wi-Fi, LoRa and public communication networks according to the actual communication environment. The ground terminal processes and temporarily stores the collected bridge vibration signals and inspection data to ensure the continuity and integrity of the data.

[0018] As a preferred solution of the relay system for detecting the health status of bridges with signal obstruction based on drones of the present invention, the drone-borne relay unit is used for providing a communication relay function in the process of bridge health monitoring, and ensures the continuity of data transmission when the signal is obstructed or the communication link is interrupted;

[0019] The drone-mounted relay unit achieves reliable communication with ground terminals or other drones by integrating 5GHz Wi-Fi and LoRa modules. During the inspection process, when the direct connection between the drone and the ground terminal is blocked, the relay unit can automatically switch to the host role and serve as a relay node to provide communication support for other drones.

[0020] As a preferred solution of the relay system for signal obstruction bridge health status detection based on drones described in the present invention, the bridge structure information collection unit is used to collect dynamic characteristic data of the bridge structure during the bridge health monitoring process, mainly including the vibration signal, displacement, inclination angle and other structure-related physical parameters of the bridge. The bridge structure information collection unit integrates a variety of high-precision sensor modules, and provides important data for the analysis and evaluation of the bridge health status by real-time collection of the structural status information of the bridge.

[0021] As a preferred solution of the relay system for signal-obstructed bridge health status detection based on drones described in the present invention, the bridge surface disease information collection unit is used to collect disease information on the bridge surface during the bridge health monitoring process, mainly including the detection and recording of disease characteristics such as cracks, corrosion, and peeling; the bridge surface disease information collection unit integrates imaging equipment such as high-definition cameras and infrared sensors, and can collect high-resolution images and other relevant data in complex bridge environments, providing basic data for the evaluation of bridge surface diseases.

[0022] As a preferred solution of the relay system for detecting the health status of bridges based on signal obstruction of drones of the present invention, the data storage unit is used to store various data collected during the bridge health monitoring process, including vibration signals, displacement data, tilt angle information of the bridge structure, and image data of bridge surface diseases; the data storage unit can record data from the multi-sensor module in real time through a high-speed storage device;

[0023] The UAV ground station is used as the command and control center in the UAV bridge health monitoring system, responsible for the flight control, data management, task scheduling and communication relay functions of the UAV; the ground station communicates with the UAV in real time through a wireless communication link, receives bridge detection data transmitted by the UAV, and sends control instructions to ensure the smooth completion of the inspection task.

[0024] As a preferred solution of the relay system for detecting the health status of bridges blocked by signals from drones according to the present invention, when the drone enters the signal blocking area, the relay system automatically switches the communication mode:

[0025] When the drone inspection is not in progress, the ground terminal is fixedly installed on the side of the bridge to continuously collect the vibration signal of the bridge; the ground terminal transmits the vibration signal to a nearby base station through a multi-sensor fusion module, and the base station then uploads the data to the cloud platform. On the cloud data platform, the relay system analyzes the vibration characteristics of the bridge through the modal analysis method, extracts the parameters of the natural frequency and damping ratio, and evaluates the health status of the bridge: The specific process is as follows:

[0026] The relay system monitors the vibration signals of the bridge in real time through the ground terminal, which is fixedly installed at the structural node of the bridge and collects the vibration signals through the integrated multi-sensor fusion module.

[0027] The vibration data is preliminarily processed by the Linux controller, and the pre-processed vibration data is stored in the data storage module of the ground terminal;

[0028] The ground terminal uploads the vibration signal to the cloud server through the LoRa wireless communication module for centralized storage and management; when the communication link between the ground terminal and the base station is disconnected, the relay system will automatically traverse other ground terminals around and establish connections through Wi-Fi or LoRa; the relay system transmits data to the cloud through the connectable ground terminal to ensure timely data upload;

[0029] During data transmission, the relay system will distinguish the data of different nodes and mark which nodes have disconnected communication links, ensuring clear traceability records in subsequent data analysis and maintenance. At the same time, the relay system can dynamically adjust the communication path according to the node connection status to ensure the continuity of bridge health status monitoring. On the cloud platform, the data is deeply analyzed through modal analysis methods to extract key parameters such as the natural frequency and damping ratio of the bridge. Based on these parameters, the relay system generates a bridge health status assessment report and provides a reference for subsequent maintenance.

[0030] The relay system is equipped with a real-time detection function for abnormal signals to promptly identify significant frequency changes or modal anomalies in vibration signals. When an abnormality occurs in the bridge vibration signal, the relay system will automatically trigger an early warning and notify relevant maintenance personnel to conduct inspections and maintenance to ensure the safety of the bridge.

[0031] As a preferred solution of the relay system for detecting the health status of bridges based on signal obstruction of drones in the present invention, when the drone enters a complex structure area such as the bottom of a bridge for inspection, the wireless communication link directly with the base station or the ground terminal may be blocked due to the obstruction of the bottom structure of the bridge, including the ground terminal as a relay node and the drone formation relay mode, the details are as follows:

[0032] The ground-based terminal is used as a relay node:

[0033] When the drone is inspecting, the ground terminal automatically switches between the Wi-Fi module and the LoRa module according to the signal strength of the communication environment through an automatic switching mechanism. If the drone is blocked from communicating directly with the base station when inspecting the bottom of the bridge, the ground terminal will act as a relay node to receive the data transmitted by the drone and pass the data to the base station through the ground terminal to ensure that the bridge inspection data is real-time and complete; the specific process is as follows:

[0034] When the drone begins to inspect the bottom of the bridge, it first establishes a communication connection with the ground terminal and the base station through the 5GHz Wi-Fi and LoRa communication modules. The communication link between the drone and the base station is used to receive the bridge disease image data collected by the drone, while the communication link between the drone and the ground terminal remains silent.

[0035] During the drone inspection process, the relay system will monitor the communication signal strength with the base station in real time. When the drone enters a complex structure area such as the bottom of a bridge, the relay system will automatically detect that the communication signal between the drone and the base station is blocked due to obstruction or signal attenuation.

[0036] When it is detected that the drone cannot communicate directly with the base station, the relay system automatically switches to the mode where the ground terminal acts as a relay node. At this time, the drone sends the collected bridge disease image data to the ground terminal via Wi-Fi or LoRa module;

[0037] The ground terminal, as a relay node, is responsible for receiving the data transmitted by the drone, which includes information on bridge surface cracks, thread defects, and bridge corrosion images. The ground terminal performs preliminary preprocessing on the received data through its internal cache and data processing module.

[0038] As a preferred solution of the relay system for detecting the health status of bridges blocked by signals from drones according to the present invention, after receiving the data from the drone, the ground terminal transmits the data to the base station through the LoRa communication link with the base station. When the wireless signal environment is poor, the ground terminal has the ability to automatically select the best signal to ensure the stability of data transmission;

[0039] After the base station receives the data transmitted by the ground terminal, it uploads it to the cloud server for centralized processing and storage. At this time, the relay system conducts in-depth analysis of the data through the analysis platform and generates a bridge health status report.

[0040] As a preferred solution of the relay system for detecting the health status of bridges based on signal obstruction of drones in the present invention, the drone formation relay mode is as follows: In some complex situations, the ground terminal may not be able to directly connect to the drones in the inspection, and the drone formation collaborative working mode is introduced; the drone formation is divided into a host drone and a slave drone; when the ground terminal cannot communicate directly with the drone, the drones in the system will automatically adjust to the master-slave structure:

[0041] Host UAV as a relay node: The host UAV is responsible for maintaining connection with the ground terminal and transmitting the received inspection data back to the ground terminal or base station;

[0042] Slave drone: A drone that cannot communicate directly with a ground terminal transmits data to a host drone that can connect to a ground terminal. The host drone acts as a relay and transmits this data back to the ground terminal or base station.

[0043] In a second aspect, an embodiment of the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the relay system for detecting the health status of a bridge based on signal obstruction by an unmanned aerial vehicle as described in the first aspect of the present invention are implemented.

[0044] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the relay system for detecting the health status of a bridge obstructed by a signal from a drone as described in the first aspect of the present invention are implemented.

[0045] The beneficial effects of the present invention are as follows: the relay communication mechanism proposed by the present invention effectively solves the signal shielding problem at the bottom of the bridge and other complex structural areas. Through the ground terminal and UAV formation relay mode, the UAV can maintain reliable communication with the ground terminal or base station in a complex environment, ensuring the real-time and integrity of the detection data.

[0046] The present invention introduces a collaborative working mode between the ground terminal as a relay node and the UAV formation. Whether it is the ground terminal as a relay or the master-slave structure adjustment between the UAVs, it provides great flexibility for the system, can adapt to the inspection needs under different bridge structures and environments, and ensure the smooth transmission of data.

[0047] In addition to the drone inspection mode, the present invention also provides a mechanism for the ground terminal to continuously monitor the vibration signals of the bridge. Even if the drone is not performing the inspection task, the ground terminal can monitor the health status of the bridge in real time, collect and transmit data through multi-sensor fusion technology, and ensure the safety of the bridge in daily operation.

[0048] The system uses modal analysis and other methods to conduct an in-depth analysis of the vibration characteristics of the bridge and extract key parameters such as natural frequency and damping ratio. These data can accurately assess the health of the bridge, help predict potential structural risks, and provide a basis for bridge maintenance. In addition, the system also integrates image processing and pattern recognition algorithms to identify surface defects of the bridge, such as cracks, rust, and spalling. The high-resolution camera carried by the drone can obtain high-definition images of the bridge surface, and combined with the defect recognition algorithm, the structural damage on the bridge surface can be automatically detected and classified. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Figure 1 Flowchart of the relay system for UAV-based signal obstruction bridge health status detection;

[0051] Figure 2 A diagram of the computer equipment for the relay system for drone-based signal obstruction bridge health status detection;

[0052] Figure 3 Block diagram of the intelligent drone relay system for drone-based signal occlusion bridge health status detection relay system;

[0053] Figure 4 A physical picture of the Linux controller development board for the relay system for UAV-based signal obstruction bridge health status detection;

[0054] Figure 5 The communication link diagram of the relay system for the UAV-based signal obstruction bridge health status detection;

[0055] Figure 6 A comparison chart of various data of the relay system for UAV-based signal obstruction bridge health status detection. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0057] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0058] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0059] Example 1

[0060] Reference Figure 1-2 , which is the first embodiment of the present invention, provides a relay system for detecting the health status of a bridge based on a signal obstruction of an unmanned aerial vehicle, comprising:

[0061] Construct a relay system, including deploying ground terminals, drone-mounted relay units, bridge structure information collection units, bridge surface disease information collection units, data storage units, and drone ground stations;

[0062] The ground terminal is fixedly installed on the side of the bridge and continuously collects bridge vibration signals through a multi-sensor fusion module; the drone is equipped with a camera and a lidar to collect information on bridge surface damage;

[0063] When the drone enters a signal-blocked area, the relay system automatically switches the communication mode:

[0064] a) The ground terminal acts as a relay node, receiving drone data and forwarding it to the base station;

[0065] b) In drone formation mode, the host drone acts as a relay node, receiving and forwarding data from slave drones;

[0066] The ground terminal or base station uploads the collected data to the cloud platform, extracts key parameters of the bridge health status through modal analysis methods, and generates an assessment report;

[0067] The relay system monitors the signal strength in real time. When all communication paths do not meet the requirements, the exception handling mechanism is triggered to temporarily store the data and re-upload it after the signal is restored.

[0068] The ground terminal unit is the core control and communication relay node for bridge health monitoring, used for bridge vibration signal collection, UAV communication relay, and data management and transmission;

[0069] When the UAV performs inspection tasks and in a signal-blocked environment, the ground terminal unit ensures the integrity and accuracy of data transmission through the relay function. The ground terminal switches between Wi-Fi, LoRa and public communication networks according to the actual communication environment. The ground terminal processes and temporarily stores the collected bridge vibration signals and inspection data to ensure data continuity and integrity.

[0070] The drone-mounted relay unit is used to provide communication relay functions during the bridge health monitoring process and ensure the continuity of data transmission when the signal is blocked or the communication link is interrupted;

[0071] The drone-mounted relay unit integrates 5GHz Wi-Fi and LoRa modules to achieve reliable communication with ground terminals or other drones. During the inspection process, when the direct connection between the drone and the ground terminal is blocked, the relay unit can automatically switch to the host role and act as a relay node to provide communication support for other drones.

[0072] The bridge structure information collection unit is used to collect dynamic characteristic data of the bridge structure during the bridge health monitoring process, mainly including the vibration signal, displacement, inclination angle and other structure-related physical parameters of the bridge. The bridge structure information collection unit integrates a variety of high-precision sensor modules and collects the structural status information of the bridge in real time to provide important data for the analysis and evaluation of the bridge health status.

[0073] The bridge surface disease information collection unit is used to collect disease information on the bridge surface during the bridge health monitoring process, mainly including the detection and recording of disease characteristics such as cracks, corrosion, and spalling; the bridge surface disease information collection unit integrates imaging equipment such as high-definition cameras and infrared sensors, which can collect high-resolution images and other relevant data in complex bridge environments, providing basic data for the evaluation of bridge surface diseases.

[0074] The data storage unit is used to store various data collected during the bridge health monitoring process, including vibration signals, displacement data, tilt angle information of the bridge structure, and image data of bridge surface diseases; the data storage unit can record data from the multi-sensor module in real time through a high-speed storage device;

[0075] The UAV ground station is used as the command and control center in the UAV bridge health monitoring system. It is responsible for the flight control, data management, task scheduling and communication relay functions of the UAV. The ground station communicates with the UAV in real time through a wireless communication link, receives the bridge inspection data transmitted by the UAV, and sends control instructions to ensure the smooth completion of the inspection mission.

[0076] Preferably, the ground terminal unit includes a Linux controller, a WiFi module, and a LoRa module. As the core processing unit of the ground terminal, the Linux controller is responsible for managing and processing the received data, and controlling the communication with the drone and other terminal devices. The Wi-Fi module is used to establish a high-speed wireless communication link between the ground terminal and the drone. The LoRa module is used to provide a long-distance, low-power communication link, which is particularly suitable for data transmission when the drone is inspecting at the bottom of a bridge or in a signal-restricted area.

[0077] Further: The drone airborne relay unit includes a Linux controller, a Wi-Fi module and a LoRa module. The Linux controller, as the core control module of the drone airborne relay unit, is responsible for managing the drone's flight status, mission execution and real-time processing of multi-sensor data. The Wi-Fi module is used to establish a high-bandwidth communication link within a short distance, and is particularly suitable for real-time data transmission between the drone and the ground terminal or other drones. The LoRa module is used for long-distance, low-power communication, and is particularly suitable for data transmission when the signal is blocked or the environment is complex.

[0078] Further: The bridge structure information collection unit includes a multi-sensor fusion module, an accelerometer, a tilt angle sensor and a temperature sensor. The multi-sensor fusion module is the core part of the information collection unit and is responsible for integrating data from different sensors. The accelerometer is used to accurately capture the vibration signals of the bridge under different working conditions, help identify the vibration mode, natural frequency and other parameters of the bridge structure, and provide key data for bridge health status assessment. The tilt angle sensor is used to monitor the tilt changes of the bridge structure, especially under external conditions such as strong winds and loads, small tilt changes of the bridge may indicate structural health problems. The temperature sensor is used to detect temperature changes on the surface or inside the bridge.

[0079] Further: The bridge surface damage information collection unit includes a camera and a lidar. The camera is used to obtain high-resolution images of the bridge surface, which can clearly capture the details of the surface damage, such as the shape of cracks, the location and degree of corrosion. The lidar is used to build a three-dimensional model of the bridge surface, which can accurately capture the slight changes in the shape of the bridge surface.

[0080] Further: the data storage unit includes a data storage module and a data collection manager. The data storage unit includes a data storage module and a data collection manager. The data storage module is used to store various data obtained from the bridge health monitoring system, including bridge structure vibration data, displacement information, tilt angle, and damage images of the bridge surface. The data collection manager is responsible for centralized management and preliminary processing of the collected data.

[0081] like Figure 3 The block diagram of the intelligent drone relay system for bridge health status detection is shown below and is explained in detail.

[0082] Figure 3 The ground terminal shown in the figure includes a Linux controller, a WiFi module, and a LoRa module.

[0083] Linux controller: The Linux controller is the core processing unit of the ground terminal and transmits data to other modules through the RS232 interface. The Linux controller is connected to the data collection manager through RS232 to start the system and receive data from multiple sensors. The data collection manager is responsible for managing data collection, including functions such as connection, vibration data collection, and custom system settings. The Linux controller is also connected to the external network through the 1000BaseT Ethernet port for further data transmission.

[0084] Wi-Fi module and LoRa module: The Wi-Fi module operates in the 5GHz frequency band and is used for high-speed data transmission within a short distance. The LoRa module operates in the 433MHz frequency band and is suitable for long-distance, low-power data transmission. These two modules communicate with the Wi-Fi and LoRa modules on the drone through wireless communication links to ensure real-time data transmission.

[0085] Figure 3 The drone-mounted relay shown in the figure includes a Linux controller, a WiFi module, and a LoRa module.

[0086] Linux controller: The core processing unit on the drone controls flight status, mission execution, and sensor data processing. The Linux controller is connected to other devices on the drone via the USB interface, and is connected to the Wi-Fi module and LoRa module via the RS232 interface for data transmission. The data collection manager is responsible for managing data collection, including connection, disease image collection, custom system settings, and other functions.

[0087] Wi-Fi module and LoRa module: used to communicate with the ground terminal to ensure the stability of the communication link between the drone and the ground terminal.

[0088] Figure 3 The multi-sensor fusion module is connected to multiple sensors such as accelerometers, inclinometers, temperature sensors, etc. through the SPI interface, and is responsible for integrating and processing data from different sensors.

[0089] Defect image data collection: By connecting cameras, high-resolution images of the bridge surface are obtained to detect surface defects of the bridge, such as cracks, corrosion, etc.

[0090] Data storage module: used to store data from sensors.

[0091] Figure 3 The drone transmits the collected data to the ground terminal via the Wi-Fi module or LoRa module, and the ground terminal then uploads the data to the cloud or ground station through the 1000BaseT Ethernet port for centralized processing and storage.

[0092] The present invention provides a UAV-ARS unmanned aerial vehicle adaptive relay switching mechanism for bridge health status detection in a signal shielding environment:

[0093] Mechanism 1: Monitoring and transmission of bridge vibration signals.

[0094] When the drone inspection is not in progress, the ground terminal is fixed on the side of the bridge to continuously collect the vibration signal of the bridge. The ground terminal transmits the vibration signal to a nearby base station through a multi-sensor fusion module, and the base station then uploads the data to the cloud platform. On the cloud data platform, the system analyzes the vibration characteristics of the bridge through the modal analysis method, extracts parameters such as natural frequency and damping ratio, and evaluates the health status of the bridge. The specific process is as follows:

[0095] S1: Vibration data collection. When the drone is not performing inspection tasks, the system monitors the vibration signals of the bridge in real time through the ground terminal. The ground terminal is fixedly installed at the structural node of the bridge, and the vibration signal is collected through the integrated multi-sensor fusion module (including accelerometer, tilt sensor and temperature sensor). Each sensor is connected to the central control unit (Linux controller) through the SPI interface, and the collected real-time data is transmitted to the ground terminal.

[0096] S2: Data processing and storage. The vibration data is preliminarily processed by the Linux controller, including data filtering, denoising and preprocessing algorithms to ensure the accuracy and integrity of the data. The preprocessed vibration data is stored in the data storage module of the ground terminal and connected to the storage through the RS232 interface to ensure stable recording and long-term storage of the data.

[0097] S3: Data transmission. The ground terminal uploads the vibration signal to the cloud server through the LoRa wireless communication module for centralized storage and management. When the communication link between the ground terminal and the base station is disconnected, the system will automatically traverse other surrounding ground terminals and establish a connection through Wi-Fi or LoRa. The system transmits data to the cloud through a connectable ground terminal to ensure timely data upload. During the data transmission process, the system will distinguish the data of different nodes and mark which nodes have disconnected communication links to ensure clear traceability records in subsequent data analysis and maintenance. At the same time, the system can dynamically adjust the communication path according to the node connection status to ensure the continuity of bridge health status monitoring.

[0098] S4: Data analysis and health status assessment. On the cloud platform, the data is deeply analyzed through modal analysis methods to extract key parameters such as the natural frequency and damping ratio of the bridge. Based on these parameters, the system generates a bridge health status assessment report and provides a reference for subsequent maintenance.

[0099] S5: Real-time early warning mechanism. The system is equipped with a real-time detection function for abnormal signals, which can promptly identify significant frequency changes or modal anomalies in vibration signals. When an abnormality occurs in the bridge vibration signal, the system will automatically trigger an early warning and notify relevant maintenance personnel to conduct inspections and maintenance to ensure the safety of the bridge.

[0100] Mechanism 2: Relay communication in drone inspection mode.

[0101] When a drone enters a complex structure area such as the bottom of a bridge for inspection, the wireless communication link directly with the base station or ground terminal may be blocked due to the obstruction of the bottom structure of the bridge. To this end, the present invention proposes a flexible relay communication mechanism to ensure that the drone can maintain connection with the ground terminal or base station at any location, as follows:

[0102] 1. The ground terminal acts as a relay node: When the drone is inspecting, the ground terminal automatically switches between the Wi-Fi module and the LoRa module according to the signal strength of the communication environment through an automatic switching mechanism to ensure the continuity and stability of the connection with the drone. If the drone is blocked from communicating directly with the base station when inspecting the bottom of the bridge, the ground terminal will act as a relay node to receive the data transmitted by the drone and pass the data to the base station through the ground terminal to ensure the real-time and integrity of the bridge inspection data. The specific process is as follows:

[0103] S1: Initial communication establishment. When the drone begins to inspect the bottom of the bridge, it first establishes a communication connection with the ground terminal and the base station through the 5GHz Wi-Fi and LoRa communication modules. The communication link between the drone and the base station is used to receive the bridge disease image data collected by the drone, while the communication link between the drone and the ground terminal remains silent.

[0104] S2: Signal blocking detection. During the drone inspection, the system will monitor the communication signal strength with the base station in real time. When the drone enters a complex structure area such as the bottom of a bridge, the system will automatically detect that the communication signal between the drone and the base station is blocked due to occlusion or signal attenuation.

[0105] S3: Switching of the ground terminal relay node. When it is detected that the drone cannot communicate directly with the base station, the system automatically switches to the mode where the ground terminal acts as a relay node. At this time, the drone sends the collected bridge disease image data to the ground terminal via the Wi-Fi or LoRa module.

[0106] S4: Data reception and processing. The ground terminal acts as a relay node and is responsible for receiving data transmitted by the drone. The data includes information such as cracks on the bridge surface, thread defects, and bridge corrosion images. The ground terminal performs preliminary preprocessing on the received data through its internal cache and data processing module, such as data cleaning, filtering, and packaging.

[0107] S5: Data is uploaded to the base station. After receiving the data from the drone, the ground terminal will transmit the data to the base station through the LoRa communication link with the base station. If the wireless signal environment is poor, the ground terminal has the ability to automatically select the best signal to ensure the stability of data transmission.

[0108] S6: Data synchronization from base station to cloud platform. After receiving the data transmitted by the ground terminal, the base station uploads it to the cloud server for centralized processing and storage. At this point, the system conducts in-depth analysis of the data through the analysis platform and generates a bridge health status report.

[0109] 2. UAV formation relay mode: In some complex situations, the ground terminal may not be able to directly connect to the UAV in the inspection. For this reason, this system introduces the UAV formation collaborative working mode. The UAV formation is divided into master UAV and slave UAV. When the ground terminal cannot communicate directly with the UAV, the UAV in the system will automatically adjust to the master-slave structure:

[0110] Host UAV as a relay node: The host UAV is responsible for maintaining connection with the ground terminal and transmitting the received inspection data back to the ground terminal or base station.

[0111] Slave drone: A drone that cannot communicate directly with a ground terminal transmits data to a host drone that can connect to a ground terminal. The host drone acts as a relay and transmits this data back to the ground terminal or base station.

[0112] According to the above mechanism, a UAV relay communication algorithm for bridge health status detection in a signal shielding environment based on UAV-ARS is proposed:

[0113] S1: Set input:

[0114] Signal strength between the drone and the base station (Signal_Strength_UAV_BaseStation);

[0115] Signal strength between the UAV and the ground terminal (Signal_Strength_UAV_GroundTerminal);

[0116] Signal strength of communication between ground terminal and base station (Signal_Strength_GroundTerminal_BaseStation);

[0117] The preset signal strength threshold (Threshold_Strength);

[0118] UAV inspection data (UAV_Data);

[0119] Ground terminal buffer capacity (GroundTerminal_Buffer);

[0120] The identification of the master UAV in the UAV formation (Master_UAV);

[0121] Identification of the slave UAV in the UAV formation (Slave_UAV);

[0122] Set output: The UAV inspection data is successfully uploaded to the base station or cloud platform

[0123] S2: Initial communication establishment

[0124] The UAV starts the inspection task: When the inspection starts, the UAV attempts to establish communication connections with the base station and the ground terminal simultaneously through the 5GHz Wi-Fi and LoRa modules.

[0125] The communication link between the UAV and the base station is used to transmit inspection data (such as images of cracks and rust on the bridge surface). The communication link between the UAV and the ground terminal remains in a silent state and waits to be activated when needed.

[0126] S3: Signal block detection

[0127] Real-time monitoring of signal strength:

[0128] The system real-time monitors the communication signal strength Signal_Strength_UAV_BaseStation between the UAV and the base station.

[0129] If Signal_Strength_UAV_BaseStation ≥ Threshold_Strength, the UAV continues to transmit data through the base station.

[0130] If Signal_Strength_UAV_BaseStation < Threshold_Strength, go to step 3.

[0131] S4: Switching of the ground terminal as a relay node

[0132] Detect the signal strength of the ground terminal:

[0133] The system detects the communication signal strength Signal_Strength_UAV_GroundTerminal between the UAV and the ground terminal.

[0134] If Signal_Strength_UAV_GroundTerminal ≥ Threshold_Strength, the UAV switches to the ground terminal as a relay node and goes to step 4.

[0135] If Signal_Strength_UAV_GroundTerminal < Threshold_Strength, go to step 6 (UAV formation relay mode).

[0136] S5: The ground terminal receives and processes data

[0137] Data transmission to the ground terminal: The UAV transmits the inspection data UAV_Data to the ground terminal through the Wi-Fi or LoRa module. After receiving the data, the ground terminal performs preliminary processing, including data cleaning, filtering, and packaging.

[0138] Caching data: The ground terminal stores the processed data in GroundTerminal_Buffer to ensure that the data is not lost.

[0139] S6: The ground terminal uploads data to the base station

[0140] Detecting the signal strength between the ground terminal and the base station: The system detects the communication signal strength Signal_Strength_GroundTerminal_BaseStation between the ground terminal and the base station.

[0141] If Signal_Strength_GroundTerminal_BaseStation ≥ Threshold_Strength, the ground terminal transmits the data to the base station through the LoRa module.

[0142] If Signal_Strength_GroundTerminal_BaseStation < Threshold_Strength, the ground terminal caches the data and waits for the signal to recover before transmitting.

[0143] Data upload to the cloud platform: After receiving the data, the base station uploads it to the cloud platform, and the system performs further analysis and processing.

[0144] S7: UAV formation relay mode

[0145] The UAV formation switches to the master-slave mode: If the communication between the ground terminal and the UAV cannot be established, the system switches the UAV to the formation mode. The system designates one UAV as the master UAV Master_UAV, and the remaining UAVs as slave UAVs Slave_UAV.

[0146] Data transmission of slave UAVs: The slave UAVs Slave_UAV that cannot directly communicate with the ground terminal transmit the collected data to the master UAV Master_UAV.

[0147] The master UAV acts as a relay node: The master UAV Master_UAV is responsible for maintaining a connection with the ground terminal or the base station and transmitting the data of the slave UAVs to the ground terminal or the base station together.

[0148] Host UAV uploads data: The host UAV packages the data of the slave UAVs and uploads it through the communication link with the ground terminal or base station.

[0149] S8: Confirmation of successful data upload

[0150] Data upload confirmation: The system confirms whether the data has been successfully uploaded to the base station or cloud platform.

[0151] If the data is uploaded successfully, the current inspection task ends.

[0152] If the data is not uploaded successfully, the system continues to try to re-establish the communication link and repeats the above steps until the data is successfully uploaded.

[0153] S9: Exception handling mechanism

[0154] Continuous abnormality of the communication link: If the signal strength continues to be lower than the threshold Threshold_Strength within a certain period of time (for example, 5 minutes), the system will trigger the early warning mechanism and notify the maintenance personnel to check the communication equipment or interference factors in the bridge environment.

[0155] The following is combined with Figure 4 , the contents involved in the above embodiments are explained.

[0156] Step 1: Start the UAV inspection task. After the UAV starts the inspection task, the system first tries to establish a communication connection with the ground terminal and the base station. At this time, the system performs signal detection through the wireless communication module (Wi-Fi or LoRa module), and detects the signal strength between the UAV and the base station (Signal_Strength_UAV_BaseStation) and the signal strength between the UAV and the ground terminal (Signal_Strength_UAV_GroundTerminal).

[0157] Step 2: Detect the signal strength between the drone and the base station. The system first detects the signal strength between the drone and the base station (Signal_Strength_UAV_BaseStation). Based on the comparison between the signal strength and the preset threshold (Threshold_Strength), the system makes the following judgments:

[0158] If Signal_Strength_UAV_BaseStation≥Threshold_Strength, it indicates that the signal strength is sufficient and the system will continue to maintain direct communication with the base station. At this time, the drone uploads the detection data to the cloud platform through the base station and continues to execute the subsequent steps.

[0159] If Signal_Strength_UAV_BaseStation < Threshold_Strength, it indicates that the signal between the UAV and the base station is weak or interrupted. The system will enter the next step to detect the signal strength between the UAV and the ground terminal.

[0160] Step 3: Detect the signal strength between the UAV and the ground terminal. If the communication signal between the UAV and the base station is insufficient, the system automatically detects the signal strength (Signal_Strength_UAV_GroundTerminal) between the UAV and the ground terminal. Similarly, by comparing this signal strength with the preset threshold (Threshold_Strength), the system takes corresponding measures:

[0161] If Signal_Strength_UAV_GroundTerminal ≥ Threshold_Strength, the system will switch to the ground terminal as a relay node to ensure that the UAV can transmit data through the ground terminal. At this time, the UAV transmits data to the ground terminal via Wi-Fi or LoRa technology.

[0162] If Signal_Strength_UAV_GroundTerminal < Threshold_Strength, it indicates that the signal of the ground terminal is also insufficient. The system will not be able to directly transmit data through the base station or the ground terminal and will transfer to Step 5 to switch to the UAV formation mode.

[0163] Step 4: Data transmission with the ground terminal as a relay node. When the signal strength between the UAV and the ground terminal meets the conditions, the system automatically switches to the ground terminal as a communication relay node. The UAV transmits data to the ground terminal via the Wi-Fi or LoRa module. After receiving the data, the ground terminal processes the data, including data cleaning, filtering, and packaging operations to ensure data integrity. The processed data is transmitted to the base station via the LoRa module of the ground terminal, and then the base station uploads the data to the cloud platform.

[0164] Step 5: Switch to the UAV formation relay mode. If the signals between the UAV and the base station and the ground terminal are both insufficient, the system will automatically switch to the UAV formation mode. In this mode, the system divides the UAVs into a master UAV (MasterUAV) and slave UAVs (Slave UAV). The master UAV is responsible for acting as a relay node to maintain a communication connection with the ground terminal or the base station.

[0165] The master UAV establishes communication with the ground terminal: The master UAV will establish a communication link with the ground terminal via the Wi-Fi or LoRa module and simultaneously receive the inspection data transmitted by the slave UAVs.

[0166] Slave drone transmits data: The slave drone transmits the detection data to the host drone through the wireless communication module. The host drone then packages all the data and transmits it to the ground terminal or base station.

[0167] Step 6: The base station uploads data to the cloud platform. After the ground terminal or host drone completes data aggregation and preprocessing, the system transmits the processed data to the base station through the LoRa module or Wi-Fi module. After the base station receives the data, it uploads the data to the cloud platform through the network.

[0168] The data processing system on the cloud platform will further analyze the received data, including modal analysis, vibration signal analysis, image recognition and other operations, and generate a bridge health status report for managers' reference.

[0169] Step 7: Success of data upload and task completion. After each data transmission is completed, the system will check whether the data has been successfully uploaded to the cloud platform. If the data is successfully uploaded, the system will mark the inspection task as completed and end the task process.

[0170] If the upload is successful: the system records the mission completed and notifies the drone to return.

[0171] If the upload fails: the system will continue to try to reestablish the communication link until the data is successfully uploaded.

[0172] Step 8: Communication processing under abnormal conditions. If all communication paths (base station, ground terminal and host drone) cannot meet the signal strength requirements in a signal-blocked environment, the system will enter the abnormal processing mechanism. At this time, the drone will temporarily store the detection data and automatically try to re-upload it after the signal is restored. At the same time, the system will send an alarm to the ground control station, indicating that the current communication environment is abnormal or the drone inspection system is faulty, so that technicians can deal with the problem in time.

[0173] The following is combined with Figure 5 , the contents involved in the above embodiments are explained.

[0174] Figure 5 As shown in the figure, the ground terminal is connected to the drone cluster through the Wi-Fi module and the LoRa module; the ground terminal is connected to the base station through the LoRa module; the drone cluster is connected to the base station through the LoRa module; when the drone cluster is disconnected from the base station, it is reconnected to the base station through the ground terminal relay;

[0175] Figure 5The drone cluster shown in the figure is connected to the ground terminal through the Wi-Fi module and the LoRa module; when the drone cluster is disconnected from the ground terminal, the drone connected to the ground terminal is disconnected as the host and the connected drone is disconnected as the slave, the host and the slave are connected through the Wi-Fi module, and the slave data is transmitted to the ground terminal through the host;

[0176] Figure 5 As shown in the figure, the base station is connected to the data center via LoRa; the data center is connected to the monitoring cloud database, which is responsible for storing and managing the bridge detection data transmitted from the base station; the monitoring cloud database is connected to the monitoring cloud server, which is responsible for processing and analyzing the bridge detection data; the monitoring cloud server is connected to the data display platform, allowing users to view the analysis results and bridge health status reports in real time.

[0177] This embodiment also provides a computer device, which is suitable for the case where the signal of an unmanned aerial vehicle blocks the relay system for detecting the health status of a bridge, and includes a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the relay system for detecting the health status of a bridge based on the signal of an unmanned aerial vehicle blocking as proposed in the above embodiment.

[0178] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0179] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, a relay system for detecting the health status of a bridge blocked by a signal from a drone as proposed in the above embodiment is implemented.

[0180] In summary, 1. Efficient data transmission in complex environments:

[0181] The relay communication mechanism proposed in this invention effectively solves the signal shielding problem at the bottom of bridges and other complex structural areas. Through the ground terminal and UAV formation relay mode, the UAV can maintain reliable communication with the ground terminal or base station in complex environments, ensuring the real-time and integrity of the detection data.

[0182] 2. Flexible relay mechanism:

[0183] The present invention introduces a collaborative working mode between the ground terminal as a relay node and the UAV formation. Whether it is the ground terminal as a relay or the master-slave structure adjustment between the UAVs, it provides great flexibility for the system, can adapt to the inspection needs under different bridge structures and environments, and ensure the smooth transmission of data.

[0184] 3. All-weather monitoring and data transmission:

[0185] In addition to the drone inspection mode, the present invention also provides a mechanism for the ground terminal to continuously monitor the vibration signals of the bridge. Even if the drone is not performing the inspection task, the ground terminal can monitor the health status of the bridge in real time, collect and transmit data through multi-sensor fusion technology, and ensure the safety of the bridge in daily operation.

[0186] 4. Bridge health assessment:

[0187] The system uses modal analysis and other methods to conduct an in-depth analysis of the vibration characteristics of the bridge and extract key parameters such as natural frequency and damping ratio. These data can accurately assess the health of the bridge, help predict potential structural risks, and provide a basis for bridge maintenance. In addition, the system also integrates image processing and pattern recognition algorithms to identify surface defects of the bridge, such as cracks, rust, and spalling. The high-resolution camera carried by the drone can obtain high-definition images of the bridge surface, and combined with the defect recognition algorithm, the structural damage on the bridge surface can be automatically detected and classified.

[0188] Example 2

[0189] Reference Figure 2 - Figure 6 , which is the second embodiment of the present invention, experimentally verifies the relay switching function of the UAV communication relay system in a complex signal environment, with the aim of evaluating key performance indicators such as the system's stability under signal obstruction, delay during switching, packet loss rate, and communication interruption duration.

[0190] The experiment was conducted 25 times in total, with the goal of evaluating the performance of the UAV communication relay system in an actual bridge environment. The system was tested for stability under different flight paths and environmental conditions, with a focus on key indicators such as relay switching capability, signal strength changes, transmission delay, and data loss in signal blocking scenarios.

[0191] Experimental methods:

[0192] Step 1: Simulation environment setup:

[0193] Step 1.1: Select the environment under the Fifth Yangtze River Bridge to simulate the signal blocking scenario and ensure that the GPS signal is partially or completely ineffective.

[0194] Step 1.2: Set up obstacles to block the direct communication link between the drone and the ground terminal, and test the signal weakening and loss.

[0195] Step 2: Equipment Installation:

[0196] Step 2.1: A ground terminal is installed in an open area outside the bridge to receive data from the drone.

[0197] Step 2.2: The drone is equipped with a communication module and a relay drone is set up to transmit data. Ensure that the relay drone can cover the signal-blocked area and act as a relay node with the ground terminal.

[0198] Step 3: Data monitoring and collection:

[0199] Step 3.1: Use the signal strength analysis tool to monitor the communication signal strength between the drone and the ground terminal, and between the drone and the relay device in real time.

[0200] Step 3.2: Use logging tools to monitor key performance indicators such as packet loss rate, transmission delay, and duration of communication interruption during the switching process.

[0201] Experimental process:

[0202] The drone begins to fly in the simulated environment and initially maintains direct communication with the ground terminal. During this stage, the strength of the communication signal and the data transmission delay are recorded to obtain baseline data under normal communication conditions.

[0203] When the drone enters the signal blocking area, the direct communication signal gradually weakens. At this time, the UAV-ARS technology should automatically start the relay mode and continue to transmit data with the ground terminal through the relay drone.

[0204] Record key data before and after relay switching, including signal strength, transmission delay, and data loss during the switching process. These data are used to analyze the performance and stability of the relay switching process.

[0205] The following is combined with Figure 6 , the contents involved in the above embodiments are explained.

[0206] Figure 6 a Signal strength comparison chart (upper left): In terms of signal strength, before switching, the signal strength was generally low, ranging from 40.43dB to 59.87dB, showing the attenuation of the signal in the direct communication mode. After switching to the relay mode, the signal strength increased significantly, returning to the range of 62.39dB to 79.22dB, indicating that the relay drone effectively improved the stability of the communication signal in an obstructed environment.

[0207] Figure 6 b Data transmission delay comparison chart (upper right): The transmission delay shows a high and gradually rising trend before switching, ranging from 83.04ms to 117.15ms, especially when the signal is weak, the delay increases significantly. After switching to relay mode, the transmission delay is significantly reduced, remaining between 52.28ms and 88.87ms, and the fluctuation range is small, indicating that relay communication has a significant effect on reducing delay and ensuring the stability of data transmission.

[0208] Figure 6 c Packet loss rate comparison chart (lower left): The packet loss rate was relatively high before switching, ranging from 10.15% to 23.83%, especially when the signal was severely weakened. However, after switching to relay mode, the packet loss rate dropped significantly, from 2% to 7.92%, indicating that the system can effectively reduce data loss after switching to relay, ensuring the continuity and integrity of data transmission.

[0209] Figure 6 d Switching interruption duration diagram (lower right): The switching interruption time shows that there is a certain interruption time during the switching process, ranging from 0.55 seconds to 1.92 seconds, but the overall interruption duration is short, and in most experiments the interruption time is kept within 1.5 seconds, indicating that the system can quickly complete the relay switching and maintain the stability of the communication link.

[0210] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A relay system for detecting the health status of bridges using signals from drones, characterized in that: include, Construct a relay system, including deploying ground terminals, drone-mounted relay units, bridge structure information collection units, bridge surface disease information collection units, data storage units, and drone ground stations; The ground terminal is fixedly installed on the side of the bridge and continuously collects bridge vibration signals through a multi-sensor fusion module; the drone is equipped with a camera and a lidar to collect information on bridge surface damage; When the drone enters a signal-blocked area, the relay system automatically switches the communication mode: a) The ground terminal acts as a relay node, receiving drone data and forwarding it to the base station; b) In drone formation mode, the host drone acts as a relay node, receiving and forwarding data from slave drones; The ground terminal or base station uploads the collected data to the cloud platform, extracts key parameters of the bridge health status through modal analysis methods, and generates an assessment report; The relay system monitors the signal strength in real time. When all communication paths do not meet the requirements, the exception handling mechanism is triggered to temporarily store the data and re-upload it after the signal is restored.

2. The relay system for detecting the health status of bridges based on signals from unmanned aerial vehicles as claimed in claim 1, characterized in that: The ground terminal unit is the core control and communication relay node for bridge health monitoring, used for bridge vibration signal collection, UAV communication relay, and data management and transmission; When the UAV performs inspection tasks and in a signal-blocking environment, the ground terminal unit ensures the integrity and accuracy of data transmission through the relay function. The ground terminal switches between Wi-Fi, LoRa and public communication networks according to the actual communication environment. The ground terminal processes and temporarily stores the collected bridge vibration signals and inspection data to ensure the continuity and integrity of the data.

3. The relay system for detecting the health status of a bridge based on a signal obstruction of an unmanned aerial vehicle as claimed in claim 2, characterized in that: The unmanned aerial vehicle relay unit is used to provide a communication relay function during the bridge health monitoring process and ensure the continuity of data transmission when the signal is blocked or the communication link is interrupted; The drone-mounted relay unit achieves reliable communication with ground terminals or other drones by integrating 5GHz Wi-Fi and LoRa modules. During the inspection process, when the direct connection between the drone and the ground terminal is blocked, the relay unit can automatically switch to the host role and serve as a relay node to provide communication support for other drones.

4. The relay system for detecting the health status of a bridge based on a signal obstruction of an unmanned aerial vehicle as claimed in claim 3, characterized in that: The bridge structure information collection unit is used to collect dynamic characteristic data of the bridge structure during the bridge health monitoring process, mainly including the vibration signal, displacement, inclination angle and other structure-related physical parameters of the bridge. The bridge structure information collection unit integrates a variety of high-precision sensor modules and collects the structural status information of the bridge in real time to provide important data for the analysis and evaluation of the bridge health status.

5. The relay system for detecting the health status of bridges based on signals from unmanned aerial vehicles as claimed in claim 4, characterized in that: The bridge surface disease information collection unit is used to collect disease information on the bridge surface during the bridge health monitoring process, mainly including the detection and recording of disease characteristics such as cracks, corrosion, and peeling; the bridge surface disease information collection unit integrates imaging equipment such as high-definition cameras and infrared sensors, and can collect high-resolution images and other relevant data in complex bridge environments, providing basic data for the evaluation of bridge surface diseases.

6. The relay system for detecting the health status of a bridge based on signal obstruction by an unmanned aerial vehicle as claimed in claim 5, characterized in that: The data storage unit is used to store various data collected during the bridge health monitoring process, including vibration signals, displacement data, tilt angle information of the bridge structure, and image data of bridge surface diseases; the data storage unit can record data from the multi-sensor module in real time through a high-speed storage device; The UAV ground station is used as the command and control center in the UAV bridge health monitoring system, responsible for the flight control, data management, task scheduling and communication relay functions of the UAV; the ground station communicates with the UAV in real time through a wireless communication link, receives bridge detection data transmitted by the UAV, and sends control instructions to ensure the smooth completion of the inspection task.

7. The relay system for detecting the health status of a bridge based on signal obstruction by an unmanned aerial vehicle as claimed in claim 6, characterized in that: When the drone enters the signal blocking area, the relay system automatically switches the communication mode: When the drone inspection is not in progress, the ground terminal is fixedly installed on the side of the bridge to continuously collect the vibration signal of the bridge; the ground terminal transmits the vibration signal to a nearby base station through a multi-sensor fusion module, and the base station then uploads the data to the cloud platform. On the cloud data platform, the relay system analyzes the vibration characteristics of the bridge through the modal analysis method, extracts the parameters of the natural frequency and damping ratio, and evaluates the health status of the bridge: The specific process is as follows: The relay system monitors the vibration signals of the bridge in real time through the ground terminal, which is fixedly installed at the structural node of the bridge and collects the vibration signals through the integrated multi-sensor fusion module. The vibration data is preliminarily processed by the Linux controller, and the pre-processed vibration data is stored in the data storage module of the ground terminal; The ground terminal uploads the vibration signal to the cloud server through the LoRa wireless communication module for centralized storage and management; when the communication link between the ground terminal and the base station is disconnected, the relay system will automatically traverse other ground terminals around and establish connections through Wi-Fi or LoRa; the relay system transmits data to the cloud through the connectable ground terminal to ensure timely data upload; During data transmission, the relay system will distinguish the data of different nodes and mark which nodes have disconnected communication links, ensuring clear traceability records in subsequent data analysis and maintenance. At the same time, the relay system can dynamically adjust the communication path according to the node connection status to ensure the continuity of bridge health status monitoring. On the cloud platform, the data is deeply analyzed through modal analysis methods to extract key parameters such as the natural frequency and damping ratio of the bridge. Based on these parameters, the relay system generates a bridge health status assessment report and provides a reference for subsequent maintenance. The relay system is equipped with a real-time detection function for abnormal signals to promptly identify significant frequency changes or modal anomalies in vibration signals. When an abnormality occurs in the bridge vibration signal, the relay system will automatically trigger an early warning and notify relevant maintenance personnel to conduct inspections and maintenance to ensure the safety of the bridge.

8. The relay system for detecting the health status of a bridge based on signal obstruction by an unmanned aerial vehicle as claimed in claim 7, characterized in that: When the UAV enters a complex structure area such as the bottom of a bridge for inspection, the wireless communication link directly with the base station or ground terminal may be blocked due to the obstruction of the bottom structure of the bridge, including the ground terminal as a relay node and the UAV formation relay mode, as follows: The ground-based terminal is used as a relay node: When the drone is inspecting, the ground terminal automatically switches between the Wi-Fi module and the LoRa module according to the signal strength of the communication environment through an automatic switching mechanism. If the drone is blocked from communicating directly with the base station when inspecting the bottom of the bridge, the ground terminal will act as a relay node to receive the data transmitted by the drone and pass the data to the base station through the ground terminal to ensure that the bridge inspection data is real-time and complete; the specific process is as follows: When the drone begins to inspect the bottom of the bridge, it first establishes a communication connection with the ground terminal and the base station through the 5GHz Wi-Fi and LoRa communication modules. The communication link between the drone and the base station is used to receive the bridge disease image data collected by the drone, while the communication link between the drone and the ground terminal remains silent. During the drone inspection process, the relay system will monitor the communication signal strength with the base station in real time. When the drone enters a complex structure area such as the bottom of a bridge, the relay system will automatically detect that the communication signal between the drone and the base station is blocked due to obstruction or signal attenuation. When it is detected that the drone cannot communicate directly with the base station, the relay system automatically switches to the mode where the ground terminal acts as a relay node. At this time, the drone sends the collected bridge disease image data to the ground terminal via Wi-Fi or LoRa module; The ground terminal, as a relay node, is responsible for receiving the data transmitted by the drone, which includes information on bridge surface cracks, thread defects, and bridge corrosion images. The ground terminal performs preliminary preprocessing on the received data through its internal cache and data processing module.

9. The relay system for detecting the health status of a bridge based on signal obstruction by an unmanned aerial vehicle as claimed in claim 8, characterized in that: After receiving the data from the drone, the ground terminal will transmit the data to the base station through the LoRa communication link with the base station. When the wireless signal environment is poor, the ground terminal has the ability to automatically select the best signal to ensure stable data transmission; After the base station receives the data transmitted by the ground terminal, it uploads it to the cloud server for centralized processing and storage. At this time, the relay system conducts in-depth analysis of the data through the analysis platform and generates a bridge health status report.

10. The relay system for detecting the health status of bridges based on signals from unmanned aerial vehicles as claimed in claim 9, characterized in that: The drone formation relay mode: In some complex situations, the ground terminal may not be able to directly connect to the drone in the inspection, so the drone formation collaborative working mode is introduced; the drone formation is divided into a master drone and a slave drone; when the ground terminal cannot communicate directly with the drone, the drones in the system will automatically adjust to a master-slave structure: Host UAV as a relay node: The host UAV is responsible for maintaining connection with the ground terminal and transmitting the received inspection data back to the ground terminal or base station; Slave drone: A drone that cannot communicate directly with a ground terminal transmits data to a host drone that can connect to a ground terminal. The host drone acts as a relay and transmits this data back to the ground terminal or base station.

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