Underwater robot fiber-optic follow-up positioning system and method for tunnel detection

Abstract

The application discloses an underwater robot optical fiber following laying and collecting positioning system and method for tunnel detection, and belongs to the technical field of ship and underwater engineering equipment. The system comprises a shore-based monitoring unit, a main detection robot, an optical fiber laying and collecting robot and a micro optical fiber cable; the optical fiber laying and collecting robot is internally provided with a cable winding drum, which is configured to release the micro optical fiber cable in the downstream synchronous manner with the main detection robot during a detection stage and lay the micro optical fiber cable on the bottom of the tunnel, and recover the optical fiber in the downstream manner during a recovery stage; the two robots are connected through parallel zero-resistance thin steel cables and communication cables, the force of the steel cables is monitored in real time by a tension sensing device, and the communication cables are kept in a relaxed and force-free state. The shore-based monitoring unit calculates the optical fiber laying and collecting length through the number of winding drum rotations and the current average effective diameter, and realizes accurate positioning of the robot position. The application takes the physical length of the optical fiber as the positioning reference, has no cumulative error, fills the gap of the positioning technology in the tunnel, and realizes real-time communication, accurate positioning and efficient and safe recovery.

Description

Technical Field

[0001] This invention relates to the field of ship and underwater engineering equipment technology, specifically to an underwater robot fiber optic follow-up deployment and positioning system and method for tunnel inspection. It is applicable to the inspection of long-distance, multi-curve pressurized water conveyance tunnels and belongs to the cross-application field of submersible auxiliary inspection equipment and in-pipe inspection robots. Background Technology

[0002] Long-distance water conveyance tunnels are critical infrastructure for ensuring the lifeline of urban water supply and hydropower generation, typically ranging from 1km to 40km in length. Due to their long-term operation in a high-pressure, high-flow-velocity environment, they are prone to defects such as lining spalling, cracks, deformation, and leakage, thus requiring regular inspection. However, traditional methods of shutting down water supply and manually inspecting these tunnels are costly, disrupt water supply, and pose safety risks.

[0003] Although underwater robot detection technology has become the mainstream approach, existing technologies still face multiple challenges: First, signal transmission in pressurized tunnels is difficult. Water strongly absorbs and attenuates electromagnetic waves, and there is currently no high-bandwidth wireless transmission technology for long-distance, highly enclosed water areas. In pressurized tunnels spanning several kilometers or even tens of kilometers, wireless signals can hardly penetrate the water to achieve stable communication, which fundamentally restricts the real-time remote control and data transmission capabilities of underwater robots.

[0004] Secondly, cabled underwater robots face difficulties in laying cables in long-distance pressurized tunnels with bends. Traditional ROVs connect to the shore via umbilical cables, but in long-distance inspections, the conventional towing method of cable laying encounters a sharp increase in resistance at bends. As the cable passes through bends, it experiences continuous friction with the tunnel walls, and the tension accumulates exponentially along the bend, easily leading to cable breakage. Current technology can only detect tunnels with straight sections of 1km to 2km; there is still no effective solution for detecting long-distance, multi-bend pressurized tunnels ranging from 2km to 40km.

[0005] Third, cable recovery remains a significant challenge. While patent CN121224952A discloses an airborne, follow-up cable deployment solution that addresses the issue of cable entanglement at the robot's tail, this solution only considers the deployment process and does not address how to recover the optical fiber after inspection. In long-distance tunnels, the reverse recovery method for 5km to 40km of already laid optical fiber would pose a significant challenge to power consumption, and currently, there is no effective solution.

[0006] Fourth, there is a lack of feasible positioning technology within tunnels. In underwater tunnel environments without GPS or BeiDou signals, inertial navigation or acoustic positioning suffers from cumulative errors. Currently, there is no feasible method for precise positioning within pressurized tunnels in long-distance, highly enclosed waters, making it difficult to accurately correlate detected cracks and defects with specific tunnel mileage markers.

[0007] Further research revealed several improved solutions in the existing technology: for example, patent CN109436255B uses a self-powered fuselage and a self-suspended cable, but it does not solve the real-time communication and positioning problems; patent CN110281251A uses climbing wheels and stabilizing wings to enhance its resistance to currents, but cable deployment and retrieval still rely on a single shore-based winch; and patent CN110576953A uses a "mother-daughter" mounting architecture, with a mobile sub-inspection robot carried on the back of a crawling mother inspection robot, and the cable passively towed by a shore-based winch. The existing technologies for cable laying, particularly in curved sections, suffer from exponential tension buildup due to friction between the cable and the tunnel wall, severely limiting detection distance. Furthermore, the retrieval method involves reverse retraction along the original path, and positioning relies on the integrated calculation of the winch speed sensor, which introduces cumulative errors. For example, patent CN110588925A presents a single robot system integrating detection, crawling, and cable laying functions. The robot rigidly drags the cable, bearing the dual burden of detection and cable dragging. Curve resistance easily leads to cable breakage, limiting its application to short-distance detection. Positioning also relies on the integrated calculation of the winch speed sensor. None of these existing technologies solve the problem of efficient fiber optic cable retrieval after long-distance detection.

[0008] Therefore, there is an urgent need for a new type of underwater robot fiber optic follow-up deployment and positioning system that can simultaneously solve four major problems: long-distance real-time communication, fiber optic resistance accumulation, efficient fiber optic retrieval, and real-time accurate positioning of the robot inside the cave. Summary of the Invention

[0009] This invention aims to provide an underwater robot fiber optic follow-up positioning system and method for tunnel inspection, in order to solve the following technical problems existing in the inspection of long-distance, multi-curve water conveyance tunnels ranging from 1km to 40km by existing tethered underwater robots: First, the challenge of long-distance real-time communication in pressurized tunnels; Second, the problem of high cable resistance and easy cable breakage in long-distance pressurized curved tunnels; Third, the lack of feasible and accurate positioning technology in the underwater tunnel environment; Fourth, the difficulty of fiber optic retrieval after inspection.

[0010] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: An underwater robot fiber optic follow-up deployment and retrieval positioning system for tunnel inspection includes a shore-based monitoring unit, a main inspection robot, a fiber optic deployment and retrieval robot, a micro fiber optic cable, a communication cable, and a zero-resistance thin steel cable. The shore-based monitoring unit is connected to the fiber optic cable delivery and retrieval robot via a micro-fiber optic cable. The micro-fiber optic cable is wound and stored in the cable drum built into the fiber optic cable delivery and retrieval robot, and the cable drum is driven to rotate by the built-in cable delivery and retrieval actuator to perform cable delivery or retrieval actions. The fiber optic deployment and retrieval robot is connected to the main detection robot via a communication cable. The fiber optic deployment and retrieval robot and the main detection robot are also connected by a zero-resistance thin steel cable. The zero-resistance thin steel cable is equipped with a tension sensing device to monitor the tension of the steel cable in real time and to keep the two robots at a fixed distance during navigation. The fiber optic cable deployment and retrieval robot is configured to: dynamically release the micro-fiber optic cable according to the main inspection robot's navigation speed during downstream inspection, so that the micro-fiber optic cable is laid loosely and straight in the middle of the tunnel bottom; and during the retrieval phase, it moves downstream along the tunnel and retrieves the micro-fiber optic cable that has been laid at the bottom of the tunnel. The shore-based monitoring unit acquires the length of the micro-fiber cable released or retrieved by the fiber optic cable release or retrieval robot, and tracks the position of the fiber optic cable release and retrieval robot and the main detection robot in real time to achieve positioning.

[0011] Preferably, the shore-based monitoring unit has a three-dimensional real-time screen display function, which can display the dynamic position of the main inspection robot and the fiber optic deployment and retrieval robot in real time. It can control the navigation direction, speed, position, and detailed photo capture function of the main inspection robot and the fiber optic deployment and retrieval robot in real time. It can display the spatial position relationship diagram of the tunnel, the upstream branch tunnel and the downstream branch tunnel, and observe the inspection video photos and sonar situation in the tunnel in real time. Any abnormal problems are recorded and saved in a timely manner.

[0012] Preferably, the main inspection robot can be positioned according to the control of the shore-based monitoring unit, or it can be preset to an automatic inspection mode that is close to the wall at a certain distance. The main inspection robot can take pictures and inspect the inner wall and the entire cross section of the tunnel, and transmit the inspection video photos and sonar data inside the tunnel to the shore-based monitoring unit in real time. When necessary, the shore-based monitoring unit can control the main inspection robot to perform attitude adjustment, strengthen the shooting and inspection, and exit the tunnel.

[0013] Preferably, the long-distance pressure tunnels to which this invention is applicable range from 1 km to 40 km in length.

[0014] Preferably, the fiber optic deployment and retrieval robot retrieves the micro-fiber cable downstream during the fiber optic retrieval stage. At the same time, when necessary, the shore-based monitoring unit can control the fiber optic deployment and retrieval robot to perform attitude adjustment, supplementary shooting, and exiting the cave tasks.

[0015] Furthermore, the communication cable and the zero-resistance thin steel cable are connected in parallel by loop binding with plastic strips at regular intervals to ensure their integrity and smoothness; and the length of the communication cable is slightly longer than the length of the zero-resistance thin steel cable so that the communication cable is in a relaxed and stress-free state.

[0016] Furthermore, the main detection robot includes a main robot spatial intelligent perception and control device, as well as a main robot multi-dimensional power drive device, a main robot intelligent shooting and monitoring device, a main robot power supply and a main robot lighting device, which are respectively connected to it in communication. The shore-based monitoring unit is connected to the main robot spatial intelligent perception and control device in communication via a micro-fiber cable, a fiber optic deployment and retrieval robot and a communication cable. The main robot spatial intelligent perception and control device is used to perceive the robot's spatial position and attitude and control its navigation. The main robot's multi-dimensional power drive device provides propulsion for forward movement, turning, and attitude adjustment; the main robot's intelligent shooting and monitoring device is used for high-definition shooting and defect detection of the tunnel's inner wall and full cross-section; the main robot's power supply provides power to all devices; and the main robot's lighting device is used for supplementary lighting during shooting. The fiber optic deployment and retrieval robot includes a deployment and retrieval robot spatial intelligent sensing and control device, as well as a deployment and retrieval robot multi-dimensional power drive device, a deployment and retrieval robot intelligent imaging device, a deployment and retrieval robot fiber optic storage intelligent deployment and retrieval device, a deployment and retrieval robot power supply, and a deployment and retrieval robot lighting device, all of which are respectively connected to the deployment and retrieval robot in communication. The shore-based monitoring unit is connected to the deployment and retrieval robot spatial intelligent sensing and control device via a micro-fiber optic cable. The micro-fiber optic cable is led out from the shore-based monitoring unit, wound around the deployment and retrieval robot fiber optic storage intelligent deployment and retrieval device, and then introduced and connected to the deployment and retrieval robot spatial intelligent sensing and control device. The deployment and retrieval robot spatial intelligent sensing and control device is used to sense the robot's spatial position and attitude and control navigation and deployment and retrieval operations. The multi-dimensional power drive device of the fiber optic deployment and retrieval robot provides propulsion, enabling the robot to move downstream in the center of the lower part of the tunnel. The intelligent imaging device of the deployment and retrieval robot is used to photograph and detect defects in the bottom and lower sidewalls of the tunnel. The intelligent fiber optic storage deployment and retrieval device of the deployment and retrieval robot dynamically lays microfiber cables according to the travel speed of the main inspection robot during the downstream detection phase, ensuring that the microfiber cables are laid loosely and straight in the middle of the bottom of the tunnel. During the fiber optic retrieval phase, it retrieves the microfiber cables already laid at the bottom of the tunnel and can obtain the length of the deployed and retrieved microfiber cables in real time. The power supply of the deployment and retrieval robot powers all the devices, and the lighting device of the deployment and retrieval robot is used for supplementary lighting for photography and deployment and retrieval operations.

[0017] Furthermore, the fiber optic storage intelligent deployment and retrieval device of the deployment and retrieval robot includes a cable drum, a deployment and retrieval execution device, a cable laying device, and a cable retrieval device. The cable drum is used to wind and store the microfiber cable. The deployment and retrieval execution device is used to drive the cable drum to rotate to perform cable deployment or retrieval actions. The cable laying device is used to dynamically deploy and retrieve the microfiber cable according to the travel speed of the main detection robot and lay it neatly at the bottom of the tunnel. The cable retrieval device is used to guide the microfiber cable to be neatly retrieved to the cable drum during cable retrieval. By establishing a correspondence between the number of rotations of the cable drum and the deployment and retrieval length of the microfiber cable, the length of the released or retrieved microfiber cable can be estimated by the shore-based monitoring unit based on the current average effective diameter and number of rotations of the cable drum.

[0018] Preferably, the diameter of the microfiber cable is 0.5~0.75mm; the diameter of the cable swivel is 0.3~0.4m and the length is 0.4m, which can accommodate microfiber cables up to 40km in length.

[0019] Preferably, the length of the zero-resistance thin steel cable is 10 to 50 meters, and more preferably 20 meters.

[0020] Preferably, the length of the communication cable is slightly longer than the length of the zero-resistance thin steel cable by 5% to 15%.

[0021] A fiber optic cable deployment and retrieval positioning method for an underwater robot used in tunnel inspection includes the following steps: S1, System Deployment The shore-based monitoring unit is placed on the bank at the entrance of the upstream branch tunnel. The main inspection robot and the fiber optic cable deployment robot are deployed one after the other at the entrance of the upstream branch tunnel on the upstream side of the tunnel. Communication cables and zero-resistance thin steel cables are laid in parallel between the main inspection robot and the fiber optic cable deployment robot. Micro-fiber optic cables are laid between the fiber optic cable deployment robot and the shore-based monitoring unit. The main body of the micro-fiber optic cable is stored in the cable drum of the fiber optic cable deployment robot. S2, Downstream Detection The main inspection robot enters the main tunnel from the upstream branch entrance, flows downstream along the water flow direction, and navigates and inspects according to a preset position or control line; the fiber optic cable release and recovery robot follows the main inspection robot and moves forward downstream, maintaining a fixed distance from the main inspection robot through a zero-resistance thin steel cable. The fiber optic cable release and recovery robot can automatically and dynamically match the release of the micro-fiber optic cable according to the navigation speed of the main inspection robot, so as to ensure that the micro-fiber optic cable is laid loosely and straight in the middle position of the bottom of the tunnel. Based on the real-time acquisition of the micro-fiber cable release length, the shore-based monitoring unit controls and tracks the position of the fiber optic cable release and recovery robot and the main inspection robot in real time, thereby locating the main tunnel inspection and defect location in real time, and transmitting relevant inspection information back to the shore-based monitoring unit in real time. When the main inspection robot and the fiber optic cable deployment and recovery robot approach the downstream branch entrance on the downstream side of the tunnel, the shore-based monitoring unit gives advance instructions to control the course and speed of the two robots and ensures that the two robots exit the tunnel smoothly. S3, Equipment Status Transition After the main inspection robot and the fiber optic deployment and retrieval robot emerged from the cave and surfaced, they assisted each other on the shore. The main inspection robot and the fiber optic deployment and retrieval robot then detached from the zero-resistance thin steel cable, communication cable and fiber optic connection. The shore-based monitoring unit is transported to the downstream branch tunnel entrance by means of transportation, and the fiber optic cable delivery robot is transported from the downstream back to the upstream branch tunnel entrance by means of transportation. At this time, control is transferred to the downstream. The upstream end of the micro-fiber cable is connected to the fiber optic cable delivery robot, and the downstream end is connected to the shore-based monitoring unit. S4, Fiber Optic Recycling The fiber optic cable deployment and retrieval robot enters the main tunnel from the upstream branch tunnel entrance and flows downstream along the route where the micro-fiber optic cable is laid. At the same time, it actively retrieves the micro-fiber optic cable laid at the bottom of the tunnel. The shore-based monitoring unit controls and tracks the position of the fiber optic cable deployment and retrieval robot in real time based on the real-time acquisition of the retrieved micro-fiber optic cable length. This allows for real-time location of the main tunnel to supplement the shooting position, and the relevant shooting information is transmitted back to the shore-based monitoring unit in real time until all the micro-fiber optic cable is retrieved and the robot reaches the downstream branch tunnel entrance to complete the inspection operation.

[0022] Furthermore, the shore-based monitoring unit establishes a correspondence between the number of rotations of the cable drum and the length of the micro-fiber cable being released or retrieved. By using the current average effective diameter and number of rotations of the cable drum, the length of the released or retrieved micro-fiber cable can be estimated, thereby calculating and tracking the position of the fiber optic release and retrieval robot in the main tunnel in real time, and the defects in the main tunnel can be correlated with the navigation mileage.

[0023] Compared with the prior art, the present invention has the following advantages: (1) Solved the problem of real-time communication in long-distance pressurized tunnels: A wired real-time communication link was established from the shore-based monitoring unit to the main detection robot and the fiber optic deployment and retrieval robot through a micro-fiber cable, overcoming the problem of strong attenuation of wireless signals by water in pressurized tunnels, and realizing high-bandwidth real-time data transmission for the first time in a 40km long-distance, strongly enclosed water area.

[0024] (2) Completely solves the problem of cable laying resistance in long-distance curved tunnels: The “optical fiber release and retrieval robot actively follows the cable laying” mode is adopted to replace the traditional “shore-based drag cable laying” mode. The release and retrieval robot actively and synchronously follows the release of optical fiber. The optical fiber does not bear the drag force of the robot at all, which completely solves the problem of exponential accumulation of frictional resistance between optical fiber and tunnel wall at curves, and completely solves the risk of cable breakage and signal interruption.

[0025] (3) First-ever efficient and safe fiber optic recovery: The fiber optic recovery strategy of "following the cable release and recovering it downstream" is adopted. The fiber optic release and recovery robot recovers the fiber downstream, which helps to save power consumption and completely avoids the problems of bend jamming and fiber breakage caused by reverse recovery.

[0026] (4) For the first time, precise positioning of robots in tunnels was achieved: For the first time, a correspondence between the number of rotations of the cable drum and the length of fiber optic cable release and recovery was established, and the length of released or recovered fiber optic cable was calculated based on the current average effective diameter and number of rotations of the cable drum. Positioning was performed based on the physical length of the fiber optic cable, and there was no cumulative error, filling the gap in the current lack of feasible positioning technology in tunnels.

[0027] (5) Three-dimensional real-time monitoring: The shore-based monitoring unit has a three-dimensional real-time screen display function, which can intuitively display the spatial relationship of the tunnel and the dynamic position of the robot, observe the detection video and sonar data in real time, promptly prompt and record abnormalities, and match them with the real-time positioning station data. The robot can be remotely controlled in real time, which greatly improves the detection efficiency and ease of operation. In addition, the main detection robot can navigate and detect according to the set position or controlled route, or it can be manually remotely controlled by the shore-based monitoring unit to adapt to different tunnel environments and detection needs. During the recovery phase, it can also be controlled by the shore-based monitoring unit to reshoot when necessary, which improves the targeting and efficiency of shooting.

[0028] (6) The exit control is safe and reliable: Before the main detection robot and the fiber optic cable release and recovery robot turn to exit the downstream branch tunnel, the shore-based monitoring unit will provide advance warning and manual assistance to control the robot's course and speed, ensuring a safe and smooth exit process. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the method of the present invention; Figure 2 This is a schematic diagram of the system deployment plan for step S1 of the method of the present invention; Figure 3 This is a schematic diagram of the downstream detection plane in step S2 of the method of the present invention; Figure 4 This is a schematic diagram of the device state transition plane in step S3 of the method of the present invention; Figure 5 This is a schematic diagram (a) of the optical fiber recovery plane in step S4 of the method of the present invention. Figure 6 This is a schematic diagram (II) of the optical fiber recovery plane in step S4 of the method of the present invention. Figure 7 This is a schematic diagram of the downstream detection cross-section in step S2 of the method of the present invention; Figure 8 This is a schematic cross-sectional view of the optical fiber recovery in step S4 of the method of the present invention; Figure 9 This is a schematic diagram of the structural connection between the main detection robot and the optical fiber deployment and recovery robot in the system of this invention.

[0030] Attached reference numerals: 10-Main hydraulic tunnel; 11-Tunnel inner wall; 12-Tunnel bottom; 13-Water flow direction; 20-Upstream branch tunnel entrance; 21-Downstream branch tunnel entrance; 100-Shore-based monitoring unit; 200-Main inspection robot; 210-Main robot spatial intelligent perception and control device; 220-Main robot multi-dimensional power drive device; 230-Main robot intelligent shooting and monitoring device; 240-Main robot power supply; 250-Main robot lighting device; 300-Fiber optic cable deployment and retrieval robot; 310-Deployment and retrieval robot air... Intelligent sensing and control device; 320-Multi-dimensional power drive device for the release and retrieval robot; 330-Intelligent shooting device for the release and retrieval robot; 340-Intelligent release and retrieval device with fiber optic storage for the release and retrieval robot; 341-Cable swivel drum; 342-Release and retrieval execution device; 343-Cable laying device; 344-Cable retrieval device; 350-Power supply for the release and retrieval robot; 360-Lighting device for the release and retrieval robot; 400-Micro fiber optic cable; 410-Communication cable; 420-Zero-resistance thin steel cable; 421-Tension sensing device; 500-Bend section. Detailed Implementation

[0031] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0032] I. Overview of the Detection Scenarios (refer to) Figure 1 , Figure 2 ) like Figure 2 As shown, the main hydraulic tunnel 10 to be inspected is a long-distance pressurized water conveyance tunnel, ranging in length from 1km to 40km, with the water flow direction 13 from left to right (upstream to downstream). The main hydraulic tunnel 10 has an inclined upstream branch tunnel 20 (construction and maintenance tunnel) on its upstream side and another inclined downstream branch tunnel 21 on its downstream side, including several curved sections 500 along the route. The inspection work must be completed without interrupting the water flow.

[0033] II. System Composition (Refer to) Figure 2 , Figure 9 ) This system mainly includes: shore-based monitoring unit 100, main detection robot 200, fiber optic cable deployment and recovery robot 300, communication cable 410, zero-resistance thin steel cable 420, and micro-fiber optic cable 400.

[0034] The shore-based monitoring unit 100 is positioned near the upstream branch tunnel entrance 20 before the inspection begins. Operators can manually remotely control the main inspection robot 200 via the shore-based monitoring unit 100, or set the main inspection robot 200 to enter an automatic patrol mode at a certain distance from the wall. The shore-based monitoring unit 100 has a real-time fiber optic length monitoring function. By receiving data on the current average effective diameter and number of rotations of the cable drum 341 uploaded by the fiber optic deployment and recovery robot 300, it calculates the length of released fiber optic cable and tracks the current position of the fiber optic deployment and recovery robot 300 in real time. During the equipment state transition phase, the shore-based monitoring unit 100 is transported to the downstream branch tunnel entrance 21 by vehicle or drone, transferring control downstream. At this time, the shore-based monitoring unit 100 connects to the downstream end of the micro-fiber optic cable 400 and communicates with the fiber optic deployment and recovery robot 300 through the micro-fiber optic cable 400. The shore-based monitoring unit 100 has a three-dimensional real-time screen display function, which can display the spatial relationship diagram of the tunnel, upstream branch tunnel and downstream branch tunnel, and display the dynamic position of the main detection robot 200 and the fiber optic deployment and retrieval robot 300 in real time. It can observe the detection video photos and sonar conditions in the tunnel in real time, promptly prompt, record and save abnormal problems such as cracks, and can control the underwater robot's navigation direction, speed, position and detailed photography in real time.

[0035] The main inspection robot 200 adopts an underwater floating configuration and can navigate and inspect according to preset positions or control routes. The main inspection robot 200 includes a main robot spatial intelligent perception and control device 210, a main robot multi-dimensional power drive device 220, a main robot intelligent imaging and monitoring device 230, a main robot power supply 240, and a main robot lighting device 250. The main robot spatial intelligent perception and control device 210 is used to perceive the robot's spatial position and attitude and control its navigation; the main robot multi-dimensional power drive device 220 is used to provide propulsion for forward movement, turning, and attitude adjustment; the main robot intelligent imaging and monitoring device 230 is used for high-definition imaging and defect detection of the tunnel inner wall 11 and the entire cross-section; the main robot power supply 240 is a high-capacity lithium-ion battery pack, with the battery capacity optimized according to the tunnel inspection length requirements; and the main robot lighting device 250 is used for supplementary lighting for imaging.

[0036] The fiber optic deployment and retrieval robot 300 adopts an underwater submersible configuration and navigates in a central position at the bottom of the tunnel. The fiber optic deployment and retrieval robot 300 includes a deployment and retrieval robot spatial intelligent sensing and control device 310, a deployment and retrieval robot multi-dimensional power drive device 320, a deployment and retrieval robot intelligent imaging device 330, a deployment and retrieval robot fiber optic storage intelligent deployment and retrieval device 340, a deployment and retrieval robot power supply 350, and a deployment and retrieval robot lighting device 360. The spatial intelligent sensing and control device 310 of the release and retrieval robot is used to sense the robot's spatial position and attitude and control its navigation and release and retrieval operations. The multi-dimensional power drive device 320 of the release and retrieval robot is used to provide propulsion, enabling the fiber optic release and retrieval robot 300 to move forward with the current in the center position at the bottom of the tunnel. The intelligent shooting device 330 of the release and retrieval robot is used to shoot and detect defects in the bottom 12 and lower sidewall of the tunnel. The fiber optic storage intelligent release and retrieval device 340 of the release and retrieval robot is used to release the cable according to the navigation speed of the main inspection robot 200 and control the retrieval according to the shore-based monitoring unit 100. The power supply 350 of the release and retrieval robot is a large-capacity lithium-ion battery pack, and the battery capacity design is optimized according to the tunnel inspection length requirements. The lighting device 360 ​​of the release and retrieval robot is used for supplementary lighting for shooting and release and retrieval operations. The fiber optic storage intelligent deployment and retrieval device 340 includes a cable drum 341, a deployment and retrieval execution device 342, a cable laying device 343, and a cable retrieval device 344. The cable drum 341 is used to wind and store the microfiber cable 400. The deployment and retrieval execution device 342 is used to drive the cable drum 341 to rotate to perform cable deployment or retrieval actions. The cable laying device 343 is used to lay the microfiber cable 400 according to the travel speed of the main detection robot 200 and lay it neatly and smoothly in the middle position of the tunnel bottom 12. The cable retrieval device 344 is used to guide the fiber optic cable to be neatly retrieved to the cable drum 341 when retrieving the cable.

[0037] Communication cable 410 is used for data transmission between the two robots, with one end connected to the main inspection robot 200 and the other end connected to the fiber optic deployment / retraction robot 300. Communication cable 410 and zero-resistance thin steel cable 420 are bundled and connected in parallel at regular intervals to ensure their integrity and smoothness. The zero-resistance thin steel cable 420 is approximately 20m long, allowing the two robots to maintain a fixed distance during inspection navigation. A tension sensor 421 is installed on the zero-resistance thin steel cable 420 to monitor the cable's tension in real time and coordinate the control of the two robots' navigation speeds to maintain basic synchronization through force feedback. The communication cable 410 is slightly longer than the zero-resistance thin steel cable 420 (approximately 22m to 23m), keeping the communication cable 410 in a relaxed, stress-free state to ensure its safety.

[0038] The microfiber cable 400 has a diameter of 0.5mm to 0.75mm and adopts a zero-buoyancy design. Before the inspection operation begins, the main body of the microfiber cable 400 is wound and stored on the cable drum 341 of the fiber optic cable deployment and retrieval robot 300. The cable drum 341 of the fiber optic storage intelligent deployment and retrieval device 340 of the deployment and retrieval robot has a diameter of 0.3m to 0.4m and a length of 0.4m, and can accommodate microfiber cables 400 up to 40km in length, meeting the inspection needs of long-distance tunnels from 1km to 40km, with sufficient redundancy. One end of the microfiber cable 400 is connected to the shore-based monitoring unit 100, and the other end is connected to the fiber optic cable deployment and retrieval robot 300.

[0039] III. Work Flow (Refer to) Figures 1 to 8 ) Step S1, System Deployment (refer to...) Figure 2 ) Both the main inspection robot 200 and the fiber optic deployment and recovery robot 300 are deployed at the upstream branch tunnel entrance 20. Communication cables 410 and zero-resistance thin steel cables 420 are bundled and connected in parallel at regular intervals to link the two robots. The shore-based monitoring unit 100 establishes communication with the fiber optic deployment and recovery robot 300 via the micro-fiber optic cable 400, and further establishes indirect communication with the main inspection robot 200 via the communication cable 410.

[0040] Step S2, Downstream Detection (refer to...) Figure 3 , Figure 7 , Figure 9 ) The main inspection robot 200 enters the main hydraulic tunnel 10 and moves downstream along the water flow direction 13. It can navigate and inspect according to preset positions or control routes, and can be manually remotely controlled or automatically patrolled along the tunnel wall as needed. The main robot's intelligent shooting and monitoring device 230 shoots and inspects the tunnel wall 11 and the entire cross-section, and the data is transmitted back in real time through the communication cable 410 and the micro-fiber optic cable 400.

[0041] The fiber optic cable deployment and retrieval robot 300 is positioned centrally at the bottom of the tunnel, propelled downstream by its multi-dimensional power drive device 320, following the main inspection robot 200 throughout the journey. A tension sensor 421 on the zero-resistance thin steel cable 420 monitors the force in real time, coordinating the two robots' speeds to maintain near-synchronous movement through force feedback. The fiber optic cable storage intelligent deployment and retrieval device 340 automatically adjusts the cable deployment speed based on the main inspection robot 200's speed and attitude, ensuring the zero-resistance thin steel cable 420 remains under zero tension, while the communication cable 410, being slightly longer than the steel cable, remains slack and unstressed.

[0042] The shore-based monitoring unit 100 establishes a correspondence between the number of rotations of the cable drum 341 and the length of fiber optic cable release / retrieval. Using the current average effective diameter and number of rotations of the cable drum 341, it calculates the length L of the released fiber optic cable. With the upstream branch tunnel entrance 20 as the zero point, it determines the current position of the main inspection robot 200 as L in real time, accurately mapping detected defects to tunnel mileage markers. When the main inspection robot 200 and the fiber optic cable release / retrieval robot 300 approach the downstream branch tunnel entrance 21, the shore-based monitoring unit 100 provides advance warning and manual assistance to control the robots' course and speed, ensuring smooth exit from the tunnel.

[0043] Step S3, Equipment Status Transition (refer to) Figure 4 ) After the two robots emerged from the cave and surfaced, they were assisted by humans to go ashore. The two robots were then disconnected from the communication cable 410, the zero-resistance thin steel cable 420, and the micro-fiber cable 400.

[0044] The shore-based monitoring unit 100 is transported to the downstream branch tunnel entrance 21 by means of transportation or drone, and connected to the downstream end of the micro-fiber cable 400, thus transferring control downstream.

[0045] The fiber optic cable release and recovery robot 300 is transported from downstream to the original starting position of the upstream branch tunnel 20 via a vehicle or drone, and connected to the starting end of the micro-fiber cable 400 to enter the fiber optic cable recovery process in step S4).

[0046] Step S4, Fiber optic cable recycling (refer to...) Figure 5 , Figure 6 , Figure 8 ) The fiber optic cable deployment and retrieval robot 300 re-enters the main hydraulic tunnel 10 from the upstream branch tunnel entrance 20, and descends along the fiber optic cable laying route in the direction of water flow 13 at the central position in the lower part of the tunnel. The intelligent deployment and retrieval device 340 of the deployment and retrieval robot actively retrieves the micro-fiber cable 400 laid at the bottom 12 of the tunnel. The fiber optic cable deployment and retrieval robot 300's retrieval navigation direction is consistent with the water flow direction 13 to save power consumption, and the retrieval direction is completely consistent with the laying direction, avoiding the problem of getting stuck in bends during reverse retrieval.

[0047] During the retrieval process, the intelligent imaging device 330 of the retrieval robot, when necessary, uses manual control of the shore-based monitoring unit 100 to supplement the imaging of the tunnel bottom 12 and the lower part of the sidewalls. The captured images are transmitted in real time to the shore-based monitoring unit 100 located downstream via a micro-fiber cable 400. The shore-based monitoring unit 100 establishes a correspondence between the number of rotations of the cable drum 341 and the length of the fiber optic cable. It calculates the length of the retrieved fiber optic cable based on the current average effective diameter and number of rotations of the cable drum 341, tracks its current position in real time, and correlates it with the tunnel mileage. This process continues until all fiber optic cables are retrieved and the downstream branch tunnel entrance 21 is reached, completing all inspection work.

[0048] IV. Principle of Fiber Optic Real-Time Positioning (Refer to...) Figure 3 , Figure 5 , Figure 7 , Figure 8 , Figure 9 ) This invention utilizes the physical length of the microfiber cable 400 as a positioning reference to achieve precise positioning of the robot in an underwater environment without GPS. Its core lies in establishing the correspondence between the number of rotations of the cable drum 341 during deployment and retrieval and the length of the deployed or retrieved fiber. The length of the deployed or retrieved microfiber cable 400 is calculated based on the current average effective diameter and number of rotations of the cable drum 341.

[0049] The cable swivel 341 has a diameter of 0.3m to 0.4m, and its circumference varies with the number of fiber winding layers. The fiber storage intelligent deployment and recovery device 340 of the deployment and recovery robot records the current average effective diameter and number of rotations of the cable swivel 341. The fiber deployment and recovery length L is calculated according to the following relationship: ,in The average effective diameter of the cable swivel 341 is given (including the roll of released microfiber cable 400 during the detection phase and the roll of retrieved microfiber cable 400 during the retrieval phase), and N is the number of rotations. The shore-based monitoring unit 100 receives this calculated data in real time to obtain the length of released or retrieved optical fibers.

[0050] During the downstream inspection phase, the distance between the main inspection robot 200 and the upstream branch tunnel opening 20 is the length L of the released optical fiber. Based on this, the shore-based monitoring unit 100 determines the position of the main inspection robot in real time and records the detected defects at the corresponding mileage marker L.

[0051] During the fiber optic cable retrieval phase, the shore-based monitoring unit 100 tracks the current position of the retrieved fiber optic cable and the travel distance of the fiber optic cable release and retrieval robot 300 in real time, ensuring that the mileage for supplementing the shooting defects is accurately matched.

[0052] This positioning method uses the physical length of the optical fiber as a reference, has no cumulative error, and is unaffected by environmental factors such as water flow, water quality, and tunnel shape. Its positioning accuracy can reach the meter level in tunnels ranging from 1km to 40km in length. The cable swivel 341 can accommodate micro-fiber cables up to 40km long, meeting the needs of ultra-long-distance detection.

[0053] V. Preferred Implementation Method Variations Variant 1: The length of the zero-resistance thin steel cable 420 can be adjusted from 10 meters to 50 meters according to the tunnel cross-section and curve curvature, and the length of the communication cable 410 is adjusted accordingly to 1.05 to 1.15 times the length of the steel cable. The communication cable 410 and the zero-resistance thin steel cable 420 are bundled and connected in parallel at regular intervals.

[0054] Variant 2: The Fiber Optic Retracting Robot 300 can be transported by means of transport, backup vehicles, or drones, depending on the site conditions.

[0055] Variant 3: The diameter of the micro-fiber cable 400 can be selected from 0.5mm to 0.75mm, and the diameter of the cable swivel 341 can be selected from 0.3m to 0.4m to adapt to different detection distance requirements. The fiber optic storage intelligent deployment and retrieval device 340 of the deployment and retrieval robot can be customized according to the tunnel length.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An underwater robot fiber optic follow-up deployment and positioning system for tunnel inspection, characterized in that: This includes shore-based monitoring units, main inspection robots, fiber optic deployment and recovery robots, micro-fiber optic cables, communication cables, and zero-resistance thin steel cables; The shore-based monitoring unit is connected to the fiber optic cable delivery and retrieval robot via a micro-fiber optic cable. The micro-fiber optic cable is wound and stored in the cable drum built into the fiber optic cable delivery and retrieval robot, and the cable drum is driven to rotate by the built-in cable delivery and retrieval actuator to perform cable delivery or retrieval actions. The fiber optic deployment and retrieval robot is connected to the main detection robot via a communication cable. The fiber optic deployment and retrieval robot and the main detection robot are also connected by a zero-resistance thin steel cable. The zero-resistance thin steel cable is equipped with a tension sensing device to monitor the tension of the steel cable in real time and to keep the two robots at a fixed distance during navigation. The fiber optic cable deployment and retrieval robot is configured to: dynamically release the micro-fiber optic cable according to the main inspection robot's navigation speed during downstream inspection, so that the micro-fiber optic cable is laid loosely and straight in the middle of the tunnel bottom; and during the retrieval phase, it moves downstream along the tunnel and retrieves the micro-fiber optic cable that has been laid at the bottom of the tunnel. The shore-based monitoring unit acquires the length of the micro-fiber cable released or retrieved by the fiber optic cable release or retrieval robot, and tracks the positions of the fiber optic cable release and retrieval robot and the main detection robot in real time to achieve positioning.

2. The underwater robot fiber optic follow-up positioning system for tunnel inspection according to claim 1, characterized in that: The communication cable is tied and connected in parallel with the zero-resistance thin steel cable at equal intervals; the length of the communication cable is longer than the length of the zero-resistance thin steel cable, so that the communication cable is in a relaxed and stress-free state.

3. The underwater robot fiber optic follow-up deployment and positioning system for tunnel inspection according to claim 1, characterized in that: The main detection robot includes a main robot spatial intelligent perception and control device, as well as a main robot multi-dimensional power drive device, a main robot intelligent shooting and monitoring device, a main robot power supply and a main robot lighting device, which are respectively connected to the main robot in communication. The shore-based monitoring unit is connected to the main robot spatial intelligent perception and control device in communication through a micro-fiber cable, a fiber optic launch and recovery robot and a communication cable. The fiber optic deployment and retrieval robot includes a spatial intelligent sensing and control device for the deployment and retrieval robot, as well as a multi-dimensional power drive device, an intelligent imaging device, a fiber optic storage intelligent deployment and retrieval device, a power supply, and a lighting device for the deployment and retrieval robot, all of which are communicatively connected to the device. The shore-based monitoring unit is communicatively connected to the spatial intelligent sensing and control device for the deployment and retrieval robot via a micro-fiber optic cable. The micro-fiber optic cable is led out from the shore-based monitoring unit, wound around the fiber optic storage intelligent deployment and retrieval device, and then introduced to the spatial intelligent sensing and control device for the deployment and retrieval robot. The fiber optic storage intelligent deployment and retrieval device of the deployment and retrieval robot includes a cable drum, a deployment and retrieval execution device, a cable laying device, and a cable retrieval device. The cable drum is used to wind and store micro-fiber optic cables. The deployment and retrieval execution device is used to drive the cable drum to rotate to perform cable deployment or retrieval actions. The cable laying device is used to dynamically release the micro-fiber optic cables to the bottom of the tunnel according to the travel speed of the main detection robot. The cable retrieval device is used to guide the micro-fiber optic cables back to the cable drum during cable retrieval.

4. The underwater robot fiber optic follow-up deployment and positioning system for tunnel inspection according to claim 3, characterized in that: The shore-based monitoring unit has a three-dimensional real-time screen display function, which can display the dynamic position of the main inspection robot and the fiber optic deployment and retrieval robot in real time, observe the inspection video and photos inside the tunnel in real time, and control the navigation direction, speed, position and shooting function of the main inspection robot and the fiber optic deployment and retrieval robot in real time.

5. A fiber optic cable follow-up deployment and retrieval positioning method for underwater robots used in tunnel inspection, applied to the fiber optic cable follow-up deployment and retrieval positioning system for underwater robots used in tunnel inspection as described in any one of claims 1 to 4, characterized in that, The steps include the following: S1. System Deployment: The shore-based monitoring unit is deployed on the bank at the entrance of the upstream branch tunnel. The main inspection robot is deployed in front of the fiber optic deployment robot and together they are deployed at the entrance of the upstream branch tunnel on the upstream side of the tunnel. Communication cables and zero-resistance thin steel cables are laid in parallel between the main inspection robot and the fiber optic deployment robot. Micro-fiber optic cables are laid between the fiber optic deployment robot and the shore-based monitoring unit. The main body of the micro-fiber optic cable is stored in the cable drum of the fiber optic deployment robot. S2. Downstream Inspection: The main inspection robot enters the main tunnel from the upstream branch entrance, moves downstream along the water flow direction, and navigates for inspection according to a preset position or control line. The fiber optic cable deployment robot follows the main inspection robot downstream, maintaining a fixed distance from the main inspection robot through a zero-resistance thin steel cable. The fiber optic cable deployment robot automatically and dynamically matches and releases the micro-fiber optic cable according to the main inspection robot's navigation speed to ensure that the micro-fiber optic cable is laid loosely and straight in the middle of the tunnel bottom. The shore-based monitoring unit controls and tracks the positions of the fiber optic cable deployment robot and the main inspection robot in real time based on the real-time acquisition of the micro-fiber optic cable release length, thereby locating the main tunnel inspection and defect location in real time. The relevant inspection information is transmitted back to the shore-based monitoring unit in real time. S3. Equipment Status Transition: After the main inspection robot and the fiber optic deployment and retrieval robot emerge from the tunnel and surface, the main inspection robot and the fiber optic deployment and retrieval robot detach from the zero-resistance thin steel cable, communication cable, and fiber optic connection; the shore-based monitoring unit is transferred to the downstream branch tunnel entrance, and the fiber optic deployment and retrieval robot is transferred from the downstream back to the upstream branch tunnel entrance, transferring control to the downstream. The upstream end of the micro-fiber optic cable is connected to the fiber optic deployment and retrieval robot, and the downstream end is connected to the shore-based monitoring unit. S4. Fiber Optic Retrieval: The fiber optic cable deployment and retrieval robot enters the main tunnel from the upstream branch tunnel entrance and flows downstream along the route of the micro-fiber optic cable. At the same time, it actively retrieves the micro-fiber optic cable laid at the bottom of the tunnel. The shore-based monitoring unit controls and tracks the position of the fiber optic cable deployment and retrieval robot in real time based on the real-time acquired length of the micro-fiber optic cable retrieved. This allows for real-time location of the main tunnel to supplement the shooting position. The relevant shooting information is transmitted back to the shore-based monitoring unit in real time until all the micro-fiber optic cables are retrieved and the robot reaches the downstream branch tunnel entrance to complete the inspection operation.

6. The underwater robot fiber optic cable deployment and retrieval positioning method for tunnel inspection according to claim 5, characterized in that: The shore-based monitoring unit establishes a correspondence between the number of rotations of the cable drum and the length of the microfiber cable released or retrieved. Using the current average effective diameter and number of rotations of the cable drum, the unit calculates the length L of the released or retrieved microfiber cable. The calculation formula is as follows: in: The current average effective diameter of the cable swivel is in meters; N is the number of rotations.

7. The underwater robot fiber optic cable deployment and retrieval positioning method for tunnel inspection according to claim 5, characterized in that: In step S3, after the main detection robot and the fiber optic deployment and retrieval robot emerge from the tunnel and surface, the zero-resistance thin steel cable, communication cable and fiber optic connection between them are disconnected; the shore-based monitoring unit is transferred to the downstream branch entrance of the tunnel, the fiber optic deployment and retrieval robot is transferred back to the upstream branch entrance, and the two ends of the micro-fiber optic cable are re-established with the fiber optic deployment and retrieval robot and the shore-based monitoring unit respectively.

8. The underwater robot fiber optic cable deployment and retrieval positioning method for tunnel inspection according to claim 5, characterized in that: In step S2, the shore-based monitoring unit monitors the release length of the micro-fiber cable in real time, and associates and matches the detected tunnel defect location with the corresponding micro-fiber cable release length to achieve precise location of the defect.

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