Guide rail type unmanned aerial vehicle detection system and method for highway tunnel

Abstract

The invention discloses a guide rail type unmanned aerial vehicle detection system and method for a highway tunnel, and relates to the field of tunnel monitoring, and the system comprises an unmanned aerial vehicle and a guide rail arranged along the top of the tunnel. A guide rail manipulator is arranged on the unmanned aerial vehicle, two parallel active driving rollers are arranged at the tail end of the guide rail manipulator, and the two active driving rollers are used for making contact with an upper flange and a lower flange of a guide rail correspondingly and achieving sliding motion; negative electrode flexible conductive strips are arranged on two inclined guide surfaces of a lower flange of the guide rail, an elastic conductive slip ring is integrated in the active driving roller in contact with the lower flange, and the elastic conductive slip ring is used for being in sliding contact with the guide rail in the rolling process to obtain electric energy. The safety of highway tunnel detection is greatly improved, the frequency of manually entering the tunnel for detection is reduced by using the guide rail type unmanned aerial vehicle, and the operation risk of detection personnel in a complex and dangerous environment is reduced.

Description

Technical Field

[0001] This invention relates to the field of tunnel inspection, and more specifically to a rail-guided unmanned aerial vehicle (UAV) inspection system and method for highway tunnels. Background Technology

[0002] With the rapid development of my country's transportation infrastructure, the number of highway tunnels is increasing daily. As a crucial node in the transportation network, the structural safety of highway tunnels directly affects traffic safety and the stable development of the social economy. However, during long-term use, highway tunnels are susceptible to various factors such as geological conditions, environmental factors, and traffic loads, making them prone to defects such as lining cracks, water leakage, and structural deformation. Timely and accurate detection of tunnel defects is crucial for ensuring the safe operation of tunnels.

[0003] Traditional highway tunnel inspections primarily rely on manual inspections and vehicle-mounted inspection equipment. Manual inspections suffer from low efficiency, high labor intensity, and significant susceptibility to human factors. Furthermore, in hazardous areas such as high altitudes and confined spaces, manual inspections are difficult to implement, posing substantial safety risks. While vehicle-mounted inspection equipment can improve efficiency, its effectiveness is limited by installation and operating conditions, making it less effective at inspecting complex structures and concealed areas within tunnels.

[0004] In recent years, drone technology has developed rapidly. Drones have advantages such as flexibility, efficiency, and the ability to operate in complex environments, and have broad application prospects in the field of tunnel inspection.

[0005] However, when ordinary drones fly in tunnels, GPS signals are blocked, and relying on SLAM is prone to drift; the battery life is short, making it difficult to complete the inspection of the entire tunnel; at the same time, the airflow disturbance in the tunnel is large, resulting in poor flight stability; secondly, existing drones can only acquire surface visual information and cannot detect internal defects in the lining.

[0006] Therefore, existing UAV tunnel inspection technologies are affected by factors such as tunnel space limitations, traffic flow, wind speed, equipment pressure, and signal interference, resulting in poor flight stability and safety. They are unable to meet the high-precision requirements of tunnel inspection and urgently need a tunnel inspection system that combines high endurance, high precision, strong adaptability, and deep detection capabilities. Summary of the Invention

[0007] One objective of this invention is to provide a rail-mounted unmanned aerial vehicle (UAV) inspection system and method for highway tunnels. This invention solves the problem of limited battery life of traditional UAVs by dynamically supplying power to the rail.

[0008] The objective is achieved using the following technical solution: a rail-guided unmanned aerial vehicle (UAV) inspection system and method for highway tunnels, comprising a UAV and a rail laid along the top of the tunnel; the UAV is equipped with a rail-guided manipulator, and the end of the rail-guided manipulator is equipped with two parallel actively driven rollers, which are respectively used to contact the upper and lower flanges of the rail and achieve sliding motion.

[0009] The outer surfaces of the upper and lower flanges of the guide rail are provided with two inclined guide surfaces, and the active drive roller is provided with a V-shaped groove. The two inner walls of the V-shaped groove are respectively in contact with the two inclined guide surfaces of the guide rail.

[0010] Both inclined guide surfaces of the lower flange of the guide rail are provided with negative electrode flexible conductive strips. The active drive roller that contacts the lower flange integrates an elastic conductive slip ring. The elastic conductive slip ring is used to slide in contact with the guide rail during the rolling process to obtain electrical energy.

[0011] The preferred inclination angle of the two inclined guide surfaces is 15-30°; correspondingly, the included angle of the V-groove of the active drive roller is designed to be 60°, and it is formed by symmetrical splicing of two metal rollers with a cone angle of 30°. This allows the two inner walls of the V-groove to fully fit against the inclined surfaces on both sides of the guide rail flange, forming surface contact rather than point contact. This complementary angle design maximizes the contact area, which not only improves the stability of engagement but also reduces local pressure, avoiding structural wear caused by long-term sliding.

[0012] The inclined guide surface of the guide rail can be fully embedded in the V-shaped groove. A 2mm gap is reserved at the bottom of the V-shaped groove to avoid rigid collision between the top of the flange and the bottom of the groove, while also reserving space for displacement compensation during elastic pre-tightening. In addition, the diameter of the active drive roller is preferably 80mm. The diameter of the active drive roller is precisely matched with the installation height of the guide rail and the stroke of the UAV manipulator to ensure that the center of the active drive roller and the center of the guide rail flange are on the same horizontal line when engaged, avoiding unilateral force.

[0013] When the drone approaches the guide rail, it calculates the precise position of the guide rail flange using visual recognition and UWB positioning data. The robotic arm first completes the lifting and positioning based on the position data, and then corrects the horizontal deviation through the left and right fine adjustment mechanism to ensure the alignment accuracy of the V-groove and the flange.

[0014] The guide rail robot has a built-in micro servo motor. After alignment, the servo motor drives the active drive roller to translate in the direction of the guide rail flange until the inner wall of the V-groove is completely in contact with the flange slope. At the same time, the locking mechanism of the robot moves synchronously to fix the position of the roller, preventing lateral displacement after engagement, thus completing the engagement process. The response time of the entire engagement process is ≤0.5s.

[0015] The UAV is equipped with a dual-mode drive unit, which can switch between rail gliding mode and autonomous rotor flight mode. When the UAV receives an obstacle avoidance or derailment command, it controls the rail manipulator to release the rail and switch to autonomous rotor flight mode. After the UAV completes the obstacle avoidance or derailment command, it performs an automatic re-tracking operation.

[0016] The detection system also includes a multi-sensor fusion detection module, which is used to collect data on tunnel structure and environmental conditions.

[0017] The drone is coupled to the guide rail at the top of the tunnel via an active drive roller at the end of the guide rail manipulator. The V-shaped groove of the active drive roller matches the shape of the guide rail flange. Utilizing the automatic centering characteristics of the V-shaped structure, the drone is ensured to glide stably along the guide rail. At the same time, the active drive unit provides power for the glide, enabling controllable movement speed and direction.

[0018] The negative electrode flexible conductive strip set on the guide rail flange forms a sliding contact structure with the elastic conductive slip ring integrated inside the active drive roller. The elastic conductive slip ring has elastic preload, which can ensure continuous contact between the roller and the conductive strip during the rolling process, thereby building a stable power transmission channel and providing continuous power supply for the drone.

[0019] The dual-mode drive unit on the drone includes a rail gliding drive module and an autonomous rotor flight drive module. It receives instructions and switches between working modules through a central controller. When obstacle avoidance or off-rail conditions are triggered, the controller sends a signal to control the rail manipulator to unlock and disconnect from the rail. At the same time, the rotor drive module is activated to achieve mode switching. After completing the task, the positioning and recognition module guides the manipulator to re-grab the rail and resume the rail gliding mode.

[0020] Existing traditional rotary-wing drones rely on batteries, with a single flight time typically ranging from 30 to 60 minutes, which cannot meet the continuous inspection requirements of long tunnels. This system, powered dynamically by a guide rail, enables 24-hour uninterrupted operation, improving inspection efficiency by 5-10 times. Existing drones are prone to attitude deviations due to airflow disturbances within tunnels, leading to blurred or missed inspection data. This system, constrained by the guide rail, improves attitude stability by over 90%, achieving millimeter-level repeatability accuracy in inspection data. However, existing fixed-rail inspection equipment cannot handle rail obstacles, while ordinary drones have limited endurance. This system seamlessly switches between dual-mode drive modes, retaining the high efficiency of rail inspection while possessing autonomous obstacle avoidance capabilities, effectively improving scene adaptability. Furthermore, the gliding mode is suitable for long-distance, large-area routine inspections, while the flight mode can bypass obstacles or conduct off-track inspections of special areas, demonstrating high scene adaptability. The mode switching response is fast, avoiding operation interruptions due to obstacles. Routine inspections using the gliding mode consume less energy than the flight mode, further extending endurance.

[0021] Therefore, this system utilizes dynamic power supply via the guide rail, eliminating the reliance on built-in batteries found in traditional drones. This enables continuous, long-duration inspections without frequent recharging, significantly improving inspection efficiency. Furthermore, the automatic centering characteristics of the guide rail constraint and the actively driven rollers effectively counteract the impact of airflow disturbances within the tunnel on the drone's attitude, ensuring stable drone position during inspection and enhancing the accuracy of inspection data. Simultaneously, the dual-mode drive combines the efficiency of guide rail gliding with the flexibility of autonomous flight, making it suitable for both long-distance, wide-area routine inspections and the need to address guide rail obstacles or special areas. The multi-sensor fusion module can simultaneously cover tunnel structural defects and environmental safety status detection, eliminating the need for separate deployment of multiple inspection devices and reducing inspection costs and operational complexity.

[0022] The UAV is equipped with landing gear. In the rail taxiing mode, the rollers of the landing gear contact the inner wall of the rail, and the landing gear and the active drive rollers form a triangular support structure. An ultrasonic guided wave probe is installed on the rollers of the landing gear. The ultrasonic guided wave probe is coupled to the tunnel lining through the rollers of the landing gear, emits guided waves and receives reflected signals, and is used to detect voids or debonding defects inside the lining.

[0023] Some existing rail-guided UAVs only contact the rail via top rollers, resulting in a simple support structure that is susceptible to swaying due to interference. This system, when the UAV is in rail-guided taxiing mode, extends the landing gear to a preset position, ensuring close contact between the landing gear rollers and the inner wall of the rail. At this point, the active drive rollers of the rail-guided manipulator and the landing gear rollers form a triangular support structure. Utilizing the geometric stability of a triangle, the UAV's weight and inertial forces during taxiing are evenly distributed across three contact points, counteracting any potential overturning moments. The triangular support structure effectively suppresses lateral swaying and vertical bouncing of the UAV while taxiing along the rail, maintaining stable fuselage attitude even with slight installation deviations or undulations in the rail. The triangular support also evenly distributes the load, reducing pressure at individual contact points, minimizing wear on the active drive rollers and the rail, and extending the equipment's lifespan. Furthermore, this system better resists the impact of lateral airflow within tunnels, preventing the UAV from shifting its attitude or detaching from the rail due to airflow disturbances, thus improving operational safety.

[0024] Furthermore, the ultrasonic guided wave probe emits low-frequency guided waves into the tunnel lining through a roller. As the guided waves propagate inside the lining, they will be reflected and refracted when they encounter defects such as voids or debonding. After receiving the reflected signals, the probe analyzes the amplitude, phase, and propagation time of the reflected waves through signal processing algorithms, thereby determining the location, size, and type of the defects.

[0025] Compared to existing systems, this system eliminates the need for destructive operations such as drilling and chiseling through the tunnel lining to detect internal voids and debonding defects, thus protecting the structural integrity of the tunnel. The ultrasonic guided waves can propagate a considerable distance along the lining, and combined with the gliding motion of the drone, continuous detection can be achieved without stopping at each point, effectively improving detection efficiency.

[0026] Furthermore, this system utilizes the natural contact pressure between the landing gear rollers and the lining to achieve coupling, eliminating the need for additional coupling agent application, adapting to the complex environment of tunnels, and reducing operational complexity.

[0027] Furthermore, a bidirectional power transmission module is installed on the guide rail, which enables multiple drones to share power through the guide rail. Drones with power levels greater than a first threshold indirectly supply power to drones with power levels less than a second threshold.

[0028] The bidirectional power transmission module includes a DC-DC converter, a current detection unit, a communication unit, and a control unit. When multiple drones are operating, the battery SOC status is uploaded to the tunnel edge server in real time through the communication unit. The edge server sets a first threshold and a second threshold based on the SOC data and location information of each drone. When it detects that the SOC of a drone is lower than the second threshold, it schedules drones with an SOC higher than the first threshold within its preset range to move to the same guide rail section. At this time, the bidirectional power transmission module constructs a conductive loop with the guide rail as the carrier, and drones with sufficient power transmit power to drones with insufficient power through the guide rail, realizing indirect power supply.

[0029] Existing detection systems require individual drones to return to base when their battery is depleted, impacting overall efficiency. This system achieves multi-drone battery life sharing through power sharing, improving collaborative efficiency. Furthermore, this system eliminates the need for individual charging stations for each drone, enabling power sharing via rails and reducing equipment investment and maintenance costs. Even if some drones experience abnormal battery levels, power sharing allows for rapid resumption of operations, mitigating the risk of mission failure.

[0030] Preferably, the guide rail is provided with QR code markers and RFID tags at intervals to provide absolute position reference and calibration parameters for the UAV. The QR code markers store the absolute position coordinates of the UAV, and the RFID tags store the calibration parameters of the guide rail segment. The UAV is equipped with a vision camera and an RFID reader. During gliding or flight, the vision camera identifies the QR code markers in real time to obtain the absolute position reference; the RFID reader reads the calibration parameters in the tags and corrects the UAV's positioning data. Through the integrated application of both, the positioning accuracy of the UAV in tunnel environments without GPS is improved.

[0031] Preferably, the multi-sensor fusion detection module includes a 4K visible light camera, an infrared thermal imager, a 16-line LiDAR, and an electrochemical gas sensor. The 4K visible light camera captures defects such as cracks and spalling on the tunnel lining surface, achieving high-resolution image acquisition; the infrared thermal imager identifies potential hazards such as leakage and water accumulation by detecting temperature differences on the lining surface; the 16-line LiDAR quickly scans the internal structure of the tunnel to construct a 3D model for detecting lining deformation and clearance changes; and the electrochemical gas sensor monitors CO and other gases in the tunnel in real time. The system detects the concentration of harmful gases such as VOCs; data from each sensor is transmitted to the central processing unit, where noise is eliminated through fusion algorithms such as Kalman filtering and Bayesian estimation, resulting in a unified and accurate detection output.

[0032] On the other hand, the present invention also provides a rail-mounted unmanned aerial vehicle (UAV) detection method for highway tunnels, the UAV detection method comprising the following steps:

[0033] S1, the drone is connected to the guide rail via an active drive roller. The drone slides along the guide rail via the active drive roller and obtains power by contacting the negative electrode flexible conductive strip through the active drive roller. At the same time, the multi-sensor fusion detection module collects tunnel structure and environmental status data.

[0034] S2 monitors the road conditions ahead and the status of the guide rail in real time. When it receives a command to bypass an obstacle or derail, it controls the guide rail manipulator to release the guide rail and switches to autonomous rotor flight mode.

[0035] S3: After the UAV completes the obstacle avoidance or off-track command, it performs an automatic re-tracking operation through visual recognition and UWB positioning module.

[0036] S4. When several drones are working together, each drone uploads its battery SOC status in real time through the tunnel edge server. Based on the dynamic SOC status and drone location information, the system enables drones with power levels greater than a first threshold to indirectly supply power to drones with power levels less than a second threshold.

[0037] The automatic retracking operation in step S3 specifically includes the following steps:

[0038] S31, the drone hovers 1.5m below the preset guide rail section;

[0039] S32, activate the structured light emitting module to scan the guide rail area to identify the guide rail edge;

[0040] S33, combine the UWB anchor points deployed on the tunnel wall to calculate the pose information of the UAV relative to the guide rail;

[0041] S34, plan the guide rail manipulator's rail gripping trajectory based on the pose information;

[0042] S35 controls the guide rail robot to perform rail gripping actions and detects contact force in real time;

[0043] S36, when the contact force is detected to be >50N, the rail re-tracking is deemed successful and the system switches back to the guide rail sliding mode.

[0044] In step S2, the road conditions ahead and the status of the guide rail are monitored in real time. When an obstacle avoidance or off-rail command is received, the guide rail manipulator is controlled to release the guide rail, switch to autonomous rotor flight mode, and enable the drone battery to power the drone.

[0045] In step S4, each drone uploads its SOC status to the edge server in real time. When the drone's SOC is less than the second threshold, the server schedules drones within the preset range whose SOC is greater than the first threshold to the same guide rail segment, forming a conductive loop through the guide rail until the drone's SOC is greater than the safety threshold.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] This invention discloses a rail-guided unmanned aerial vehicle (UAV) inspection system and method for highway tunnels. This invention significantly improves the safety of highway tunnel inspection by using a rail-guided UAV, reducing the frequency of manual entry into the tunnel for inspection and lowering the operational risks for inspection personnel in complex and dangerous environments.

[0048] Meanwhile, the landing gear and the active drive roller form a triangular support structure. The geometric structure of the triangle has high stability, and the relationship between the three sides can remain relatively stable without deformation. Therefore, the triangular guide rail can provide reliable support and fixation, enabling the system to withstand a certain load and maintain accurate positioning without generating errors or vibrations.

[0049] This invention enables continuous charging of drones during movement via a guide rail, overcoming the limitations of traditional wireless charging in terms of distance and location, and significantly improving charging flexibility and efficiency. As the drone moves along the guide rail, the system can detect its position in real time and automatically activate the charging device in the corresponding section, providing a stable power supply. This process requires no manual intervention; the drone can charge while moving, greatly improving work efficiency and ease of use. This invention is the first to simultaneously use the guide rail as a guiding and power supply carrier, integrating ultrasonic guided wave detection with the landing gear support structure, achieving synergistic optimization of multiple technical modules. Addressing the endurance bottleneck in long tunnel inspections, this invention solves the problem of traditional drone range limitations through dynamic power supply via the guide rail. Attached Figure Description

[0050] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0051] Figure 1 This is a schematic diagram of the structure of the drone in the embodiment;

[0052] Figure 2 This is a schematic diagram of the guide rail structure in the embodiment.

[0053] The attached diagram shows the markings and corresponding component names:

[0054] 1-Guide rail, 2-UAV, 3-Guide rail manipulator, 4-Active drive roller, 5-Roller, 6-Negative electrode flexible conductive strip. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0056] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0057] Example 1

[0058] The system includes a drone 2 and a guide rail 1 fixedly installed along the top of the tunnel. The guide rail 1 is made of 6061-T6 aluminum alloy profile and the surface is anodized. The linear expansion coefficient is matched with the tunnel concrete lining. An expansion joint is set every 30m to allow ±10mm thermal expansion and contraction displacement and avoid stress concentration.

[0059] The UAV 2 is bolted with a guide rail manipulator 3. At the end of the guide rail manipulator 3 are two parallel actively driven rollers 4, each 80mm in diameter and with a 60° V-shaped groove circumferentially formed. The inclined guide surfaces on the outer surfaces of the upper and lower flanges of the guide rail 1 have an angle of 20°, and the inner walls of the V-shaped grooves fit snugly against the inclined guide surfaces. A silver-graphene composite film negative electrode flexible conductive strip 6 is fixed to the inclined guide surface of the lower flange of the guide rail 1. An elastic conductive slip ring is integrated inside the actively driven rollers 4, with a 35N preload provided by a phosphor bronze spring. A 48V DC regulated power supply is installed on the tunnel sidewall and connected to the positive electrode flexible conductive strip embedded in the web of the guide rail 1 via a cable, forming a bipolar sliding contact power supply system.

[0060] The UAV 2 is equipped with a retractable landing gear. In taxiing mode, the landing gear extends and the landing gear rollers 5 contact the inner wall of the guide rail, forming a triangular support structure with the active drive rollers 4. An ultrasonic waveguide probe is embedded inside the landing gear rollers 5, and three micro-hole water injection channels are provided on the outer surface, which are connected to the airborne KNF NF30 micro water pump.

[0061] The UAV 2 is equipped with a multi-sensor fusion detection module, including a Sony IMX586 4K visible light camera, a FLIRVue Pro R 640 infrared thermal imager, a Velodyne Puck Lite 16-line lidar, and an Alphasense B-series electrochemical gas sensor; each sensor is electrically connected to the onboard central processing unit, and the data is processed by the Kalman filter algorithm and then transmitted to the edge server.

[0062] When in use, the guide rail 1 is fixedly installed along the top of the tunnel and equipped with QR code markings and RFID tags; the drone 2 completes the engagement with the guide rail 1 through the guide rail robot 3, starts the 48V power supply, and the drone self-tests normally.

[0063] The drone switches to gliding mode and moves at a constant speed of 1 m / s along the guide rail; multiple sensors work simultaneously: a 4K camera captures images of the lining surface, an infrared thermal imager collects temperature data, a lidar scans the 3D point cloud, and a gas sensor monitors... , Concentration; an ultrasonic guided wave probe emits 50kHz guided waves to detect internal defects; a miniature water pump sprays deionized water as a coupling fluid at a flow rate of 1mL / min.

[0064] The vision camera identifies the QR code every 0.5 seconds to obtain the absolute position coordinates; the RFID reader reads the calibration parameters of the guide rail section; combined with UWB anchor point ranging data, the EKF algorithm is used to achieve a positioning accuracy of ±3mm, ensuring accurate recording of defect locations.

[0065] Data from each sensor is transmitted to the edge server in real time. The server performs image stitching, point cloud preprocessing, data classification and storage, generates a tunnel inspection report, and marks the location, type and size of defects.

[0066] The power supply circuit constructed by this system achieves a continuous, stable, and low-loss power supply for the UAV as it glides along the guide rail at the top of the tunnel through a complete and closed current conduction path. An external 48V DC regulated power supply is connected to the guide rail structure via a power cable laid on the tunnel sidewall. The guide rail is equipped with mutually insulated positive and negative conductive structures. The positive conductive structure is preferably a copper alloy conductive strip embedded inside the web of the guide rail, with a wear-resistant coating on its surface to improve its service life; the negative conductive structure uses a silver-graphene composite flexible conductive strip, which is attached to the two outer inclined guide surfaces of the lower flange of the guide rail and continuously laid along the length of the guide rail.

[0067] The drone's active drive roller is made of conductive metal. During gliding, its outer shell forms a sliding electrical contact with the positive conductive structure of the guide rail, serving as the positive terminal for the power supply circuit. An elastic conductive slip ring is integrated inside the roller, supported by a phosphor bronze spring sheet, and fitted with a silver-graphite composite brush contact at its end. Under a preset elastic preload of 30 to 40 Newtons, the slip ring maintains a tight fit with the negative flexible conductive strip on the lower flange. Even with minor undulations, vibrations, or thermal deformation of the guide rail, it maintains stable sliding electrical contact, effectively preventing contact interruption, arcing, or drastic fluctuations in contact resistance.

[0068] The electrical energy drawn from the active drive roller is transmitted to the power management module inside the UAV via an onboard shielded cable. The preferred shielded cable model is RVVP 2×0.75 mm², featuring a double-layer electromagnetic shielding structure with an inner aluminum foil layer and an outer braided copper mesh layer. This significantly suppresses electromagnetic interference generated by lighting systems, ventilation equipment, and wireless communication devices in tunnel environments, ensuring that the power supply voltage ripple is controlled within ±1%, thereby guaranteeing the normal operation of the flight control system, multi-sensor fusion detection module, and other sensitive electronic units.

[0069] After receiving DC power from the guide rail, the power management module provides stable power to various electrical components of the drone, including the central controller, 4K visible light camera, infrared thermal imager, lidar, electrochemical gas sensor, ultrasonic guided wave probe, and drive motor. Simultaneously, it intelligently manages the onboard lithium battery, enabling simultaneous inspection and charging in taxiing mode. The current flows through the electrical load, from the negative output terminal of the power management module into the elastic conductive slip ring, and then returns to the negative terminal of the external power supply via the sliding contact between the slip ring and the negative flexible conductive strip, ultimately completing the entire power supply circuit.

[0070] The silver-graphene composite conductive strip, with its extremely low surface resistivity, significantly reduces ohmic losses and temperature rise during sliding contact; the constant preload provided by the phosphor bronze spring sheet ensures contact reliability during long-term operation; and the high-shielding connection cable effectively isolates the impact of external electromagnetic noise on power supply quality.

[0071] The UAV is equipped with a dual-mode drive unit, which can switch between rail gliding mode and autonomous rotor flight mode. When the UAV receives an obstacle avoidance or derailment command, it controls the rail manipulator to release the rail and switch to autonomous rotor flight mode. After the UAV completes the obstacle avoidance or derailment command, it performs an automatic re-tracking operation.

[0072] The detection system also includes a multi-sensor fusion detection module, which is used to collect data on the tunnel structure and environmental conditions. The multi-sensor fusion detection module includes a 4K visible light camera, an infrared thermal imager, a 16-line lidar, and an electrochemical gas sensor.

[0073] In some embodiments, the UAV is equipped with landing gear. In the rail taxiing mode, the rollers of the landing gear contact the inner wall of the rail, and the landing gear and the active drive rollers form a triangular support structure. An ultrasonic guided wave probe is installed on the landing gear roller 5. The landing gear roller is covered with polyurethane, and the ultrasonic guided wave probe is embedded inside. The outer surface of the roller has microporous water injection channels. Before detection, a coupling fluid (such as water or glycerin) is sprayed by a micro water pump to achieve dynamic wet coupling and ensure that the guided wave effectively penetrates the lining.

[0074] The ultrasonic guided wave probe is coupled to the tunnel lining through the landing gear roller 5, emits guided waves and receives reflected signals, and is used to detect voids or debonding defects inside the lining.

[0075] In some embodiments, the guide rail is provided with QR code markers and RFID tags at intervals to provide absolute position reference and calibration parameters for the UAV.

[0076] When in use, the drone 2 starts the gliding mode of the guide rail 1 and glides at a constant speed along the guide rail 1; by actively driving the elastic conductive slip ring inside the roller 4 to slide into contact with the flexible conductive strip on the guide rail flange, it obtains continuous power and uploads the power supply status to the server in real time.

[0077] A 4K visible light camera continuously captures images of the tunnel lining surface to detect defects such as cracks and spalling; an infrared thermal imager collects the temperature distribution of the lining surface to identify leaks and water accumulation; a 16-line lidar scans the tunnel interior to generate point cloud data to detect lining deformation and clearance changes; and an electrochemical gas sensor monitors the tunnel in real time. , To detect the concentration of harmful gases, the ultrasonic guided wave probe emits a 50kHz low-frequency guided wave and receives the reflected signal, which is used to detect internal voids and debonding in the lining.

[0078] Data collected by each sensor is transmitted to the edge server in real time via a wireless local area network. The server performs noise reduction, image stitching, point cloud preprocessing, and format conversion on the data to generate structured data and classify and store it, while monitoring data integrity in real time.

[0079] A negative flexible conductive strip 6 is attached to the flange surface of the guide rail 1 as the negative pole of the power supply circuit. It can be adapted to be laid along the entire length of the guide rail or at intervals. The guide rail 1 serves as the positive pole of the power supply circuit. It is connected to a 48V DC regulated power supply through a cable laid on the tunnel sidewall. An overload protection switch and a leakage current protector are connected in series at the power supply end to ensure power supply safety.

[0080] The active drive roller 4 at the end of the drone guide rail manipulator in this system is a key power source. The active drive roller 4 integrates an elastic conductive slip ring. The active drive roller is geometrically matched with the guide rail flange. The elastic conductive slip ring is tightly attached to the negative conductive strip on the lower flange of the guide rail. At the same time, the triangular support structure formed by the active drive roller and the landing gear roller ensures the stability of the drone's attitude during gliding and avoids poor contact or arcing during sliding contact.

[0081] In rail-gliding mode only, the drone makes contact with the positive conductive area of ​​the rail via the metal shell of the actively driven roller, while the elastic slip ring makes contact with the negative conductive strip, forming a complete power supply circuit. In flight mode, the power supply circuit is disconnected, and the drone is powered independently by the onboard battery.

[0082] The negative electrode flexible conductive strip is in close contact with the outer conical surface of the active drive roller, and electrical energy is transferred from the negative electrode flexible conductive strip to the active drive roller; the active drive roller makes contact with the elastic contact finger of the elastic conductive slip ring through the inner wall of the hole, and transfers electrical energy to the elastic conductive slip ring; the elastic conductive slip ring is connected to the insulated terminal at the end of the wheel axle through a wire, and the terminal is then connected to the UAV's onboard power management module through a shielded cable (model: RVVP 2×0.75) to achieve continuous power supply during gliding; the positive terminal of the power supply circuit is achieved through the contact between the main body of the UAV guide rail manipulator and the guide rail body, finally forming a complete power supply circuit.

[0083] Among them, the resistivity of the silver-graphene composite conductive strip is only This significantly reduces sliding contact resistance and power loss; the elastic preload of the phosphor bronze spring sheet can adapt to the slight undulations on the guide rail surface, ensuring stable contact pressure during sliding and avoiding contact interruption caused by vibration.

[0084] As the drone of this system glides on the guide rail, the vision camera identifies the QR code mark next to the guide rail in real time to obtain the absolute position reference. The RFID reader reads the guide rail section calibration parameters in the RFID tag. Combined with the ranging data of the UWB anchor point, the positioning deviation is corrected by the Kalman filter algorithm, and finally high-precision positioning of ≤5mm is achieved to ensure accurate recording of defect positions.

[0085] Specifically, for QR code recognition: the visual camera recognizes the QR code next to the guide rail every 0.5 seconds to obtain its absolute coordinates. ;

[0086] RFID reading: Synchronously reads the calibration parameters of this section of the guide rail;

[0087] UWB ranging: The distance di to the UAV is measured from 4 UWB anchor points (coordinates known), and the relative pose Puwb is calculated. Puwb is the result of UWB trilateration.

[0088] Gaussian filtering is applied to the UWB ranging data to remove outliers that exceed the average distance, ensuring ranging accuracy.

[0089] Using the QR code recognition time as the time reference, timestamps are aligned between UWB ranging data and RFID correction data to avoid fusion deviations caused by asynchronous data.

[0090] Calculate the fused observation vector , as the observation input for EKF.

[0091] Kalman gain =

[0092] , ,

[0093] In some embodiments, the drone glides to a section of guide rail where there is a QR code marker; its true absolute coordinates are... ;

[0094] UWB solution location: ;

[0095] QR code recognition result: ;

[0096] RFID provides local offset correction: ;

[0097] Will

[0098] After one Kalman update, the estimated location is: ;

[0099] Deviation from the true value:

[0100] .

[0101] Example 2

[0102] Based on the above embodiment, a bidirectional power transmission module is installed on the guide rail. This module enables multiple drones to share power via the guide rail, with drones having a power level greater than a first threshold indirectly supplying power to drones with a power level less than a second threshold. When two drones are located on the same guide rail section, each is connected to the negative terminal of the common guide rail via an elastic slip ring and to the positive terminal via a metal roller / conductive brush, forming a DC bus connected in parallel to the guide rail. Drones with high battery power boost their battery energy to 48V via a DC-DC converter and inject it into the bus, while drones with low battery power draw power from the bus and charge their batteries via a DC-DC converter.

[0103] A rail-mounted unmanned aerial vehicle (UAV) inspection method for highway tunnels, the UAV inspection method comprising the following steps:

[0104] S1, the drone is connected to the guide rail via an active drive roller. The drone slides along the guide rail via the active drive roller and obtains power by contacting the negative electrode flexible conductive strip through the active drive roller. At the same time, the multi-sensor fusion detection module collects tunnel structure and environmental status data.

[0105] S2 monitors the road conditions ahead and the status of the guide rail in real time. When it receives a command to bypass an obstacle or derail, it controls the guide rail manipulator to release the guide rail and switches to autonomous rotor flight mode.

[0106] S3: After the UAV completes the obstacle avoidance or off-track command, it performs an automatic re-tracking operation through visual recognition and UWB positioning module.

[0107] In step S4, when several drones are operating collaboratively, each drone uploads its battery SOC status in real time to the tunnel edge server. Based on the dynamic SOC status and drone location information, the system indirectly supplies power to drones with battery levels above a first threshold that have battery levels below a second threshold. In step S4, each drone uploads its SOC status to the edge server in real time. When a drone's SOC is below the second threshold, the server schedules drones within a preset range with SOCs above the first threshold to the same guide rail segment, forming a conductive loop through the guide rail until the drone's SOC exceeds a safety threshold.

[0108] During use, each drone uploads its SOCi data to the edge server every 3 seconds; the server maintains the drone location list {pi} and battery status.

[0109] If SOCj < θlow, the search satisfies SOCi > θhigh and drone i

[0110] Schedule UAV i to move to the guide rail section where UAV j is located; the two form a loop through the guide rail, and UAV i supplies power to UAV j until SOCj≥SOCsafe.

[0111] θlow is the second threshold, i.e., the low battery threshold, which is preferably 0.18.

[0112] θhigh is the first threshold, i.e., the low battery threshold, preferably 0.82.

[0113] SOCsafe is the safety threshold, preferably 0.3.

[0114] After the high-battery drone i and the low-battery drone j arrive at the same guide rail section, they both activate the onboard bidirectional DC-DC converter (model TI LM5175), which has the function of switching between power supply and power receiving modes.

[0115] Circuit formation: When the high-capacity UAV i switches to power supply mode, its onboard power management module outputs its own battery voltage (converted to 48V via DC-DC converter to match the rail power supply voltage) to the elastic conductive slip ring built into the active drive roller, which is then transmitted to the negative conductive strip of the rail. At the same time, the rail body (positive pole) contacts the metal substrate of the active drive roller of UAV i, forming a local power supply circuit consisting of UAV i battery, bidirectional DC-DC converter (power supply mode), elastic conductive slip ring, negative conductive strip of rail, rail body (positive pole), UAV i metal substrate, and UAV i battery. At this time, the rail becomes a temporary power supply carrier for the high-capacity UAV i.

[0116] When the low-battery drone j receives energy, it switches to power-receiving mode and obtains 48V power from the negative conductive strip of the guide rail through the elastic conductive slip ring of its own actively driven roller. After being stepped down to the battery's matching voltage by the onboard bidirectional DC-DC converter, it charges its own battery, forming a charging circuit consisting of the negative conductive strip of the guide rail, the elastic conductive slip ring of drone j, the bidirectional DC-DC converter (power-receiving mode), the battery of drone j, the metal substrate of drone j, the guide rail body (positive pole), and the negative conductive strip of the guide rail.

[0117] In some embodiments, three drones work together, each equipped with a bidirectional power transmission module containing a TI LM5175 DC-DC converter and a 5G industrial communication module; the tunnel edge server deploys a collaborative scheduling algorithm to receive the SOC status and location information of each drone in real time.

[0118] During the testing process, drone A (SOC=0.15) detects that its battery level is below the second threshold, preferably 0.18, and sends a charging request to the edge server. The server then dispatches drone B (SOC=0.85) within a 30m radius to the rail section where drone A is located. After the two drones arrive, they form a conductive circuit through the rail: drone B switches to power supply mode, and the DC-DC converter converts the battery voltage to 48V and injects it into the rail; drone A switches to power receiving mode, and the DC-DC converter steps down the 48V voltage to 12.6V to charge the battery. During the charging process, the current detection unit monitors the transmission current in real time to ensure charging safety. When drone A's SOC rises to the safety threshold, preferably 0.3, charging is complete, and both drones resume their respective testing tasks.

[0119] Example 3

[0120] Based on the above embodiments, when the UAV receives an obstacle avoidance or derailment command, it controls the guide rail manipulator to release the guide rail, switches to autonomous rotor flight mode, activates the onboard lithium battery, and performs automatic re-tracking after completing the obstacle avoidance. The specific steps are as follows:

[0121] S31, the drone hovers 1.5m below the preset guide rail section;

[0122] S32, activate the structured light emission module to scan the guide rail area to identify the guide rail edge and obtain the guide rail point cloud;

[0123] The structured light emission module is activated to project an infrared stripe pattern onto the guide rail area, and the global shutter camera is simultaneously triggered to acquire images. The three-dimensional point cloud of the guide rail is reconstructed through triangulation.

[0124] The point cloud is preprocessed to remove outliers. Principal component analysis (PCA) is used to extract the web orientation vector uweb, and then the vertical direction of the inner flange is calculated. Assume the guide rail flange width w = 120mm;

[0125] The center point of the guide rail is estimated as follows: ,

[0126] S33, combine the UWB anchor points deployed on the tunnel wall to calculate the pose information of the UAV relative to the guide rail;

[0127] Let the coordinates of the four UWB anchor points be... (i=1,2,3,4), the measured distance is di.

[0128] Apply Gaussian filtering to di to remove those that satisfy the condition. outliers, among which, and These represent the mean and standard deviation, respectively. The optimized least squares method is used to calculate the UAV's position. ;

[0129] ;

[0130] in,

[0131] , ;

[0132] Assume the extrinsic parameters of the structured light camera are calibrated as the rotation matrix Rc and the translation vector. The target tracking position of the drone is:

[0133] = ;

[0134] S34, plan the guide rail manipulator's rail gripping trajectory based on the pose information;

[0135] Based on the current position of the robotic arm's end effector Starting from, The goal is to create a smooth track-grabbing trajectory with a planned time T of 2.5 seconds, ending at the target point.

[0136] A fifth-degree polynomial is applied independently for each coordinate axis:

[0137] + , ;

[0138] The boundary conditions are that the starting and ending positions, velocities, and accelerations are all zero.

[0139] , , p0 is the starting position. Target location.

[0140] The trajectory ensures that the motion process is free from impact and jitter, and the maximum acceleration is ≤ 0.8 m / s².

[0141] S35 controls the guide rail robot to perform rail gripping actions and detects contact force in real time;

[0142] The central controller drives the robotic arm to move along the planned trajectory, while simultaneously reading the normal contact force output by the six-dimensional force sensor in real time, with a sampling frequency of 200 Hz.

[0143] S36, when a contact force > 50N is detected, it is determined that the active drive roller has been fully embedded in the guide rail flange, the track re-entry is successful, and the system immediately switches back to the guide rail sliding mode and re-establishes the sliding electrical contact power supply. If the first attempt fails, i.e., when a contact force less than or equal to 50N is detected, fine-tuning is performed within ±10 mm around the target position, with a maximum of 3 retries; if it still fails, a track re-entry anomaly is reported and manual intervention is requested. Preferably, when a contact force > 50N is detected and the duration is ≥ 0.3s, and the elastic slip ring output voltage is stable at 47-49V, it is determined that the active drive roller has been fully embedded in the guide rail flange, and the track re-entry is successful.

[0144] In some embodiments, the drone hovering position Target position of guide rail center , ;

[0145] Trajectory planning (z-axis): ;

[0146] , =-0.576,

[0147] The robotic arm smoothly arrived at the target position, and the reading of the six-dimensional force sensor stabilized at 53.2N. Since 53.2 > 50, the system determined that the re-tracking was successful, switched to the gliding mode within 0.2 seconds, restored power, and continued the detection task.

[0148] The terms "first," "second," and "third" used in this document are merely for clarity of description and are not intended to restrict any order or emphasize importance. Furthermore, the term "connection" used in this document, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

[0149] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels, characterized in that, It includes a drone and a guide rail laid along the top of the tunnel; the drone is equipped with a guide rail manipulator, and the end of the guide rail manipulator is equipped with two parallel active drive rollers. The two active drive rollers are used to contact the upper and lower flanges of the guide rail and realize the sliding motion. The outer surfaces of the upper and lower flanges of the guide rail are provided with two inclined guide surfaces, and the active drive roller is provided with a V-shaped groove. The two inner walls of the V-shaped groove are respectively in contact with the two inclined guide surfaces of the guide rail. Both inclined guide surfaces of the lower flange of the guide rail are provided with negative electrode flexible conductive strips. The active drive roller that contacts the lower flange integrates an elastic conductive slip ring. The elastic conductive slip ring is used to slide in contact with the guide rail during the rolling process to obtain electrical energy. The UAV is equipped with a dual-mode drive unit, which can switch between rail gliding mode and autonomous rotor flight mode. When the UAV receives an obstacle avoidance or derailment command, it controls the rail manipulator to release the rail and switch to autonomous rotor flight mode. After the UAV completes the obstacle avoidance or derailment command, it performs an automatic re-tracking operation. The detection system also includes a multi-sensor fusion detection module, which is used to collect data on tunnel structure and environmental conditions.

2. The rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels according to claim 1, characterized in that, The UAV is equipped with landing gear. In the rail taxiing mode, the rollers of the landing gear are in contact with the inner wall of the rail, and the landing gear and the active drive rollers form a triangular support structure.

3. A rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels according to claim 2, characterized in that, An ultrasonic guided wave probe is installed on the landing gear rollers. The ultrasonic guided wave probe is coupled to the tunnel lining through the landing gear rollers, emits guided waves and receives reflected signals, and is used to detect voids or debonding defects inside the lining.

4. The rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels according to claim 1, characterized in that, The guide rail is equipped with a bidirectional power transmission module, which enables multiple drones to share power through the guide rail. Drones with power levels greater than a first threshold indirectly supply power to drones with power levels less than a second threshold.

5. A rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels according to claim 1, characterized in that, The guide rail is spaced apart with QR code markers and RFID tags to provide absolute position reference and calibration parameters for the UAV.

6. A rail-guided unmanned aerial vehicle (UAV) inspection system for highway tunnels according to claim 1, characterized in that, The multi-sensor fusion detection module includes a 4K visible light camera, an infrared thermal imager, a 16-line lidar, and an electrochemical gas sensor.

7. A rail-mounted unmanned aerial vehicle (UAV) inspection method for highway tunnels, characterized in that, The drone detection system according to any one of claims 1-6, the drone detection method includes the following steps: S1, the drone is connected to the guide rail via an active drive roller. The drone slides along the guide rail via the active drive roller and obtains power by contacting the negative electrode flexible conductive strip through the active drive roller. At the same time, the multi-sensor fusion detection module collects tunnel structure and environmental status data. S2 monitors the road conditions ahead and the status of the guide rail in real time. When it receives a command to bypass an obstacle or derail, it controls the guide rail manipulator to release the guide rail and switches to autonomous rotor flight mode. S3: After the UAV completes the obstacle avoidance or off-track command, it performs an automatic re-tracking operation through visual recognition and UWB positioning module. S4. When several drones are working together, each drone uploads its battery SOC status in real time through the tunnel edge server. Based on the dynamic SOC status and drone location information, the system enables drones with power levels greater than a first threshold to indirectly supply power to drones with power levels less than a second threshold.

8. A rail-mounted unmanned aerial vehicle (UAV) inspection method for highway tunnels according to claim 7, characterized in that, The automatic retracking operation in step S3 specifically includes the following steps: S31, the drone hovers 1.5m below the preset guide rail section; S32, activate the structured light emitting module to scan the guide rail area to identify the guide rail edge; S33, combine the UWB anchor points deployed on the tunnel wall to calculate the pose information of the UAV relative to the guide rail; S34, plan the guide rail manipulator's rail gripping trajectory based on the pose information; S35 controls the guide rail robot to perform rail gripping actions and detects contact force in real time; S36, when the contact force is detected to be >50N, the rail re-tracking is deemed successful and the system switches back to the guide rail sliding mode.

9. A rail-guided UAV inspection method for highway tunnels according to claim 1, characterized in that, In step S2, the road conditions ahead and the status of the guide rail are monitored in real time. When an obstacle avoidance or off-rail command is received, the guide rail manipulator is controlled to release the guide rail, switch to autonomous rotor flight mode, and enable the drone battery to power the drone.

10. A rail-guided UAV detection method for highway tunnels according to claim 1, characterized in that, In step S4, each drone uploads its SOC status to the edge server in real time. When the drone's SOC is less than the second threshold, the server schedules drones within the preset range whose SOC is greater than the first threshold to the same guide rail segment, forming a conductive loop through the guide rail until the drone's SOC is greater than the safety threshold.

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