Robot for detecting surface defects of underwater structure

Abstract

A system comprises a positively buoyant remote operated vehicle (ROV) 1 for detecting surface defects of an underwater structure, the ROV comprises a shell 12 having side edges that fit into and conform with a frame 11. The system further comprises a buoy 101 comprising an upper anti-swing device which cooperates with an anti-swing base 16 arranged on the robot. The ROV further comprises a self-unhooking device 2 comprising a buoyancy feature, which is unlocked when the ROV is submerged. The self-unhooking device comprises a fixed part fixedly attached to a steel cable attached at a shore station, and a movable part that is fixedly attached to the robot. After deployment, the fixed part of the self-unhooking device is retracted to shore via the steel cable and for recovery the fixed part is fed to a buoy along an umbilical 100 to dock with the movable part.

Description

TECHNICAL FIELD The present invention belongs to the technical field of robots, and particularly relates to a robot for detecting surface defects of an underwater structure. BACKGROUND Due to long-term environmental erosion, material aging, and sustained loading, hydraulic structures suffer from defects such as cavitation, erosion, dissolution, and freezing thaw, leading to accumulation of structure damages and decreased resistance, and potentially catastrophic consequences. Various defects usually originate or manifest on surfaces of the structures, with cracks being one of the most serious issues. For example, cracks in a dam are obvious signs of structural danger in the dam. Therefore, dam inspection serves as an important means to discover and identify diseases and hazards of the dam, and is also essential for evaluating dam safety and determining reinforcement and remediation of the dam. Underwater operation environments of a hydroelectric power station has significant characteristics such as great working depths, wide distribution of defects, long maintenance time, complex turbulent flow, and poor water visibility. Divers face high risks, low efficiency, limited coverage, and restricted means of exploration. The application of remote operated vehicle (ROV) is gradually shifting from marine environment exploration to hydraulic inspection. At present, various types of remote operated vehicle are developed for ship hull inspections both domestically and internationally, those designed for dam inspections are relatively scarce. Engineering practice reveals that dam underwater inspections are subjected to such problems as complex flow velocity interference, identification of complex structure positioning, entanglement with underwater floating objects, disturbance from floating sludge, seasonal muddy water, special confined space, and stable operation in varying conditions, these problems need to be solved urgently. Therefore, it is necessary to develop a lightweight and highly stable remote operated vehicle adaptable to defect detection in diverse underwater conditions. SUMMARY To solve the problems existing in the prior art, the present invention provides a robot for detecting surface defects of an underwater structure In order to achieve the above objective, the present invention provides the following technical solution: a robot for detecting surface defects of an underwater structure, the robot is arranged by using positive buoyancy, and includes a shell, a bottom and side edges of the shell adopt a conformal design, and fit into a framework corresponding to an inner wall of the shell, a buoy, an antiswing device, and a self-unhooking device; the anti-swing device includes an upper anti-swing mechanism disposed at a lower portion of the buoy and an anti-swing base disposed at a top of the robot, and the anti-swing mechanism and the anti-swing base are disposed in a matching manner; the self-unhooking device includes a movable part and a fixed part that are matched with each other, and the fixed part releases the movable part under the action of buoyancy, such that the movable part is detached from the fixed part, and the fixed part can lock the movable part when no buoyancy exists; in the process of deploying and recovering the robot, an upper portion of the fixed part is connected to the other end of a load-bearing steel cable with one end fixed at a shore station and used for deploying and recovering the robot, and a lower portion of the movable part is fixedly connected to hangers disposed at the top of the robot; after the robot is successfully deployed, the fixed part of the self-unhooking device is retracted by the shore station through the load-bearing steel cable; and to recover the robot, the fixed part enters the buoy along an umbilical cable, upon docking with the movable part, and forms the entire self-unhooking device. Further, the self-unhooking device is a locking mechanism that automatically attaches and detaches for deploying and retrieving an underwater robot and a latch spring device in the operation method disclosed in the Chinese patent CN 109733985A., specifically: the fixed part of the self-unhooking device is sleeved on an outside of the movable part, the movable part is a hoisting and deployment head, a center of the hoisting and deployment head is configured as a through-hole for allowing the umbilical cable to pass through, and a lower portion of the hoisting and deployment head is fixedly connected to the robot; and when arriving at a deployment point, the hoisting and deployment head is detached from the fixed part and moves downwards a water bottom together with the robot. The fixed part of the self-unhooking device includes a hanging ring disposed on an upper portion thereof and connected to the load-bearing steel cable, a buoyancy ring disposed on a lower position of the hanging ring, a hoisting bracket disposed on a lower portion of the buoyancy ring, and a fixed clamping jaw disposed between the hoisting bracket and the buoyancy ring. The design and principle of the fixed clamping jaw are consistent with those of the Chinese patent CN 109733985 A, and will not be described in detail herein. Further, the self-unhooking device of the present invention is improved on the basis of the Chinese patent CN 109733985 A, specifically: a slotted plate of the hoisting bracket and a clasp are disposed on a side edge of the fixed part of the self-unhooking device, the hoisting bracket and the slotted plate are provided as entry and exit for taking out the umbilical cable from the fixed part, and placing the umbilical cable into the fixed part, and the clasp is configured to fixed the hoisting bracket and the slotted plate on the fixed part. The fixed clamping jaw of the self-unhooking device is connected to the buoyancy ring, the buoyancy ring is naturally pressed down when not submerged, and the fixed clamping jaw extends inwards to be stuck with the upper portion of the hoisting and deployment head placed inside the hoisting bracket, such that the hoisting and deployment head is fixedly connected to the hoisting bracket. When the robot gradually submerges in water, the buoyancy ring on the self-unhooking device gradually floats upwards, the fixed clamping jaw is accordingly driven to move outwards until the robot completely submerged, and the fixed clamping jaw is then detached from the hoisting and deployment head to complete the release of the robot. The anti-swing base is embedded in a buoyancy block at the top of the robot, and a root thereof is fixed by bolts. When the robot is hoisted to enter and exit from the water, swinging and swaying may occur solely from the contact between the hoisting bracket and the hangers , which will have an adverse effect on the equipment of the robot, therefore, the anti-swing base is matched with the upper anti-swing mechanism on the buoy in the present invention to reduce its own shaking and improve the safety performance of the equipment. Further, the buoy is used for assisting the deployment, recovery and positioning of the robot, and monitoring a water surface, where the buoy includes a buoy body and a floating ball, the buoy body is of a U-shaped opening structure, a bottom of the U-shaped opening structure is provided with a clamping groove matched with an appearance structure of the floating ball, a limiting portion is arranged on an upper part of the clamping groove, and the limiting portion is configured to preventing the floating ball from moving upwards or downwards to detach from a body of the floating ball, but the floating ball can move back and forth inside the buoy body, that is, the floating ball enters and exits from the body of the floating ball through the U-shaped opening; the body of the floating ball is connected to the floating ball through a cable; a center of the floating ball is of a through hole structure, an accommodating cavity for accommodating the self-unhooking device is formed in the through hole, and the through hole is further configured to allow the umbilical cable connecting a shore station and the robot to pass through. Further, the robot provided by the present invention further includes a detection module disposed outside the shell, an operation module disposed on a face of the robot, an emergency self-rescue module, as well as a power module and an electric control module disposed inside the shell; the detection module, the operation module, the power module and the emergency self-rescue module are respectively in communication connection with the electric control module, and the electric control module is in communication connection with the shore station through the umbilical cable, the detection module includes an acoustic detection device and an optical detection device, and is configured to detect an underwater environment and surface conditions of the underwater structure; the operation module includes a manipulator for carrying out operations; the power module includes thrusters for driving the movement of the robot; the emergency self-rescue module includes an emergency buoyancy device, an emergency ballast dumping device and an emergency self-rescue control container, and is configured to enable the robot to float to water surface by relying on the emergency self-rescue module after the robot experiences underwater malfunctions; and the electric control module includes a power distribution cabinet, a control cabinet and a power supply cabinet, and is configured to supply and distribute power for various operations of the robot, receive data transmitted from other modules, transmit the received data to the shore station, receive instructions from the shore station and control the operation of the other modules. Further, the framework includes a plurality of horizontally disposed horizontal frameworks and vertically disposed longitudinal frameworks. The horizontal framework includes an electric control layer horizontal framework, a first power layer horizontal framework, a second power layer horizontal framework and a detection layer horizontal framework disposed in sequence from bottom to top; and the longitudinal framework includes a back longitudinal framework disposed on a back of the robot, side longitudinal frameworks disposed on side edges of the robot and face longitudinal frameworks disposed on the face of the robot. Further, each layer of the horizontal frameworks is disposed in a cross shape with profiles of a certain width, five longitudinal frameworks are provided, one back longitudinal framework, two symmetrically disposed lateral longitudinal frameworks and two mirroring facial longitudinal frameworks. Preferably, the framework is made from I-shaped steel or T-shaped titanium alloy profiles. Further, an inner wall of the shell is fixedly connected to the framework in a threaded way. Further, the buoyancy block is further included, and the buoyancy block is disposed at the top of the robot. More further, the buoyancy block is disposed on an upper portion of the detection layer horizontal framework, a lower portion of the buoyancy block is in butt joint with an upper portion of the shell, and the buoyancy block is conformal with the shell. An interior of the buoyancy block is irregularly designed according to equipment layout, buoyancy distribution and other factors, so as to ensure that a buoyancy center is in a central position. Further, appearance of the robot is a bionic streamlined configuration, such as a seahorse, a creature that maintains vertical movement and good stability in the ocean, and the streamline configuration thereof is a reference configuration for configuration of the robot. Preferably, the shell material is titanium alloy. Further, the acoustic detection device includes a USBL beacon and an upper-scan sonar disposed at the top of the robot, a side-scan sonar disposed on a side edge of the robot, and a forwardlooking multi-beam sonar and a depth gauge disposed on the face of the robot; the buoy is equipped with an ultra-short baseline positioning system, the USBL beacon and the ultra-short baseline positioning system form a hydroacoustic positioning array for detecting distance and orientation of the robot relative to the buoy and the position of the buoy itself, such that the position of the robot is identified; the upper-scan sonar, the side-scan sonar and the forwardlooking multi-beam sonar are respectively configured to detect an upper environment, a side environment and a lower-middle environment of an operating surface of the robot; the depth gauge is configured to monitor a depth of the underwater position of the robot; and the USBL beacon, the upper-scan sonar, the side-scan sonar, the forward-looking multi-beam sonar, and the depth gauge are respectively in communication connection with the control cabinet, and are configured to transmit the detected data to the control cabinet. Further, the back of the robot is further equipped with an altimeter, the altimeter is in communication connection with the control cabinet for measuring distances between the robot and solid objects such as the underwater structure, such that the robot is at a safe distance so as to protect the robot. Further, the optical detection device includes a laser scanner disposed at the top of the robot, a plurality of pan-tilt-zoom (PTZ) cameras disposed on the back and the face of the robot, and a plurality of LED lamps disposed on an upper portion and a lower portion of the robot; the laser scanner is configured to quickly acquire visual three-dimensional data of a surface of the underwater structure, to achieve 3D imaging; the PTZ cameras are configured to photograph the underwater environment and objects to be measured; the LED lamps are configured to provide illumination for the robot; the laser scanner, the PTZ cameras and the LED lamps are separately connected to the power supply cabinet; and the laser scanner and the PTZ cameras are respectively in communication connection with the control cabinet and are configured to transmit the collected data to the control cabinet. Further, the PTZ cameras each is sleeved with a waterproof glass cover, and the PTZ cameras each is fixed inside the waterproof glass cover; and when the robot is close to a dam surface for near-distance detection, the glass cover can play a role of displacing water, thereby effectively solving the problem of low visibility in the water environment. Further, four PTZ cameras are provided, and each PTZ camera is disposed on upper and lower portions of the face and back of the robot. Further, the thrusters include horizontal thrusters, vertical thrusters, and side thrusters; the horizontal thrusters are disposed in a middle of the robot and configured to implement movement of the robot in a horizontal direction, the vertical thrusters are disposed on two sides of the robot and configured to implement movement of the robot in a vertical direction, and the side thrusters are disposed on two sides of the upper portion of the robot and configured to implement movement of the robot in the horizontal direction at a low jitter frequency. Further, the side thrusters includes a first side thruster and a second side thruster perpendicular to each other, the first side thruster configured to realize horizontal and longitudinal posture adjustments of the robot, and the second side thruster is configured to realize horizontal and transverse posture adjustments of the robot. Further, the side thrusters are micro-thrusters, and compared with the two main thrusters, that is, the horizontal thrusters and the vertical thrusters, the side surface thrusters are smaller in size and disturbance during operation, and configured to slightly adjust a movement direction of the robot during operation, providing smaller steering force to the robot, such that the posture adjustments of the robot can be realized, and the stability of the robot during operation is maintained. Working conditions of the side thrusters in the present invention are as follows: when the robot faces the dam surface to perform operation, the horizontal main thrusters are turned off, the robot is fixed on the dam surface through the adsorber, and the micro-thrusters are started to resist underwater turbulence near the dam surface to assist in adjusting the movement direction of the robot, such that posture adjustments of the robot are realized, movement disturbance is reduced, and the stability of the robot during operation is maintained. Further, four horizontal thrusters are disposed in a vector manner; and two vertical thrusters are provided and disposed vertically on both sides of the robot, respectively. Further, a vertical thruster protective cover is disposed on around each vertical thruster, and the vertical thruster protective cover is fixedly disposed on the shell for protecting the vertical thruster. Further, the horizontal thrusters are fixed on the framework through a hoop, and are connected by using bolts. Further, the manipulator includes a large arm with one end connected to the framework and a small arm connected to the other end of the large arm, two manipulators are provided and symmetrically disposed on the face of the robot, two channels are formed on the shell, and the large arm of the manipulator can be retracted into the channel of the shell, and the small arm of the manipulator is conformal with the shell. Further, the large arm of the manipulator is fixedly disposed on the electric control layer horizontal framework, and a maximum extension of the manipulator is up to 750 mm when the manipulator carries out the operation. Further, the electric control module is disposed at the lower portion of the robot, such that a metacentric height of the robot can be significantly improved; the power distribution cabinet is configured to distribute power according to the power supply requirements of each module; the power supply cabinet is configured to supply power to each module according to a power distribution scheme of the power distribution cabinet; and the control cabinet is configured to receive data transmitted from each module, transmit the received data to the shore station, and receive instructions from the shore station to control the operation of the other modules. Further, the electric control module further includes a drive container, and the drive container is configured to place drive controllers for controlling the operation of the motor of each thruster and the manipulator; the drive controllers are in communication connection with the motors of the thruster and the manipulator and the control cabinet for receiving instruction signals transmitted from the control cabinet of the robot, and transmitting the instruction signals to facilitate the operation of each driving device. The driving device includes a horizontal thruster, a vertical thruster, a side surface thruster, and a manipulator. Further, when performing a dam inspection operation, the robot may suffer failures such as entanglement, cable breakage, power supply and communication abnormalities due to a complex underwater environment, the emergency buoyancy device is disposed at the top of the robot, and includes an emergency buoy and a first release mechanism, and the emergency buoyancy device is configured to release the emergency buoy out of the robot body and quickly floating to the water surface after the robot experiences malfunctions, so as to guide operators to find and search the robot; the emergency ballast dumping device is disposed at the lower portion of the robot, and includes a ballast and a second release mechanism, and the emergency ballast dumping device is configured to automatically discard the ballast in the event of a malfunction, such that the robot can float to the water surface to rescue by relying on the buoyancy of the robot; and the emergency self-rescue control container includes a controller, the controller is in communication connection with the emergency buoyancy device and the emergency ballast dumping device, and the control is configured to receive active instructions or power supply, distribution information, communication connection signals and depth data transmitted by the control cabinet, to determine whether the robot has abnormalities of power supply interruption, communication signal interruption, long time delay, exceeding maximum pressure and maximum depth, to make an emergency decision according to the abnormalities, and to transmit an action instruction corresponding to the emergency decision to the emergency buoyancy device and / or the emergency ballast dumping device. The emergency decision is as follows: Default priority to activate the emergency ballast dumping device, and the ballast is released first to enable the robot to float; when the robot does not reach the water surface within the preset time, the emergency buoyancy device will be activated to release the emergency buoy, and the operators can search and rescue the robot through the position of the buoy and the umbilical cable. Further, the emergency buoy is disposed at the top of the emergency buoyancy device and is connected to the first release mechanism through a cable, the first release mechanism can restrain and release the cable, the emergency buoy floats to the water surface by releasing the cable, and the emergency buoy is fixed to the top of the buoyancy block by restraining the cable. Further, the first release mechanism includes a release motor, a gear driven by the release motor, a rack in meshing transmission with the gear, a connecting rod and a connecting ring; and one end of the connecting rod is fixedly connected to the rack, the other end thereof is a free end, the connecting rod and the connecting ring are disposed in a matched mode, the free end of the connecting rod is strung with the connecting ring, and a cable connected to the emergency buoy is wound on the connecting ring. When the emergency buoyancy device receives instructions for releasing the emergency buoy, the release motor is started, and the rotation of the gear drives the rack to move horizontally. For example, the rack horizontally moves rightwards to drive the connecting rod to horizontally move rightwards, the connecting ring strung on a left end of the connecting rod is detached from the connecting rod, the connecting ring disconnected from the connecting rod is in a free state in the emergency buoyancy device, the cable wound on the connecting ring is freely released due to the buoyancy generated from the emergency buoy and traction force from the cable, and the emergency buoy finally floats to the water surface. Further, the ballast is preset as particles such as lead sand or iron sand, which is stored in the second release mechanism, a release hole is formed on a bottom of the second release mechanism, and the release hole on the bottom thereof is driven to open and close in a gear meshing manner, such that the ballast is dumped through the release hole. When iron sand or lead sand is used as the ballast, dumping of the ballast will not have secondary impact on the dam structure at the water bottom. Further, in order to meet the task requirements of close observation and inspection of underwater dam of a large hydroelectric power station, an intelligent sub-machine with adsorption function is designed. The robot in the present invention further includes a sub-machine module disposed at a bottom of the robot, the sub-machine module is in communication connection with the electric control module, the sub-machine module includes a winch and an AUV sub-machine connected to the winch through a cable, the winch is disposed on the framework and is configured to retract the AUV sub-machine, and the AUV sub-machine serves as a sub-machine of the robot. During operation, the AUV sub-machine moves away from the robot and form a working mode of master-slave machine with the robot, such that collaborative operation of the robot and multiple machines in the complex underwater environment is realized. Further, the AUV sub-machine includes a sub-machine frame, a sub-machine shell disposed in the sub-machine frame, the PTZ camera and the adsorber disposed on a front portion, two submachine horizontal thrusters disposed on a rear portion, a sub-machine side thruster disposed inside the sub-machine frame and a sub-machine vertical thruster disposed on a top of the submachine shell, a waterproof connector and a sub-machine device box disposed on the top of the sub-machine shell, and the sub-machine device is configured to store the electric control device of the sub-machine; and the adsorber is configured to be adsorbed on a wall surface of the narrow groove, so as to facilitate short-distance detection of the AUV sub-machine. More further, the PTZ camera on the AUV sub-machine is sleeved with a sub-machine glass cover, and the sub-machine glass cover has the function same as that of the glass cover on the robot. Further, the present invention further includes a wheeled wall-surface crawling mechanism, the wheeled wall-surface crawling mechanism is a frame structure fitting in with a shape of the robot, and a bottom, a front side thereof, and a junction between the bottom and the front side are all equipped with wheels; and when in use, the robot is placed inside the wheeled wall-surface crawling mechanism. The detection robot provided by the present invention has the working mode of A and B surfaces, the A and B surfaces are front and back surfaces of the robot, the two surfaces are both working surfaces, the A surface is relatively narrow and suffers a small resistance when moving forwards, upwards and downwards, featuring a large scope of inspection and strong maneuverability, and the A surface is used when initial inspection of the dam surface is performed; and the B surface is blunt, and features better structural compatibility when being close to the dame surface, making it convenient for the manipulator to work at a short distance, and the B surface is used when precision inspection of the dam surface is performed. Compared with the prior art, the present invention provides a robot for detecting surface defects of an underwater structure, which has the following beneficial effects: (1) The robot provided by the present invention mainly aims at various working conditions and complex special space detection requirements, such as a horizontal plane, an upright surface, and a slope surface of an underwater dam of a large hydroelectric power station, and a lightweight and high-stability robot for detecting surface defects of an underwater structure capable of meeting various underwater working conditions is accordingly provided, which can resist flow disturbance rejection and realize refined detection of defects. (2) The robot provided by the present invention has the working mode of A and B surfaces, effectively improving the detection efficiency of the robot. (3) The robot provided by the present invention adopts a reconfigurable parallel vector propulsion mechanism, which can improve the hydrodynamic layout, optimize the hydrodynamic performance, propulsion power and multi-degree-of-freedom flow resistance of the robot, and also has the advantages of effective thrust with six degrees of freedom of full posture, low power consumption and low self-weight. In addition, the propulsion mode of main thruster micro-thruster combination is adopted, such that the water flow disturbance can be reduced as much as possible while the robot body is stabilized, floating of the sinking sludge is reduced, the organic glass cover design wrapping the PTZ cameras is used, the underwater visual capability is effectively improved, and fine detection under muddy water conditions is realized. (4) The robot provided by the present invention adopts the design of a modular mechanical structure to meet the requirements of rapid assembly and disassembly on site, such that the robot has the working capacity for different types of tasks; each unit module achieves lightweight design based on the functions required; and the layout of the mechanical structure is optimized, the metacentric height of the robot is increased, and the high-stability design of the robot body is realized. (5) The robot provided by the present invention is provided with the intelligent sub-machine with adsorption function, which meets the demand for underwater close observation of the dam body, and the collaborative operation mode of the robot and its sub-machine expands the underwater detection range of the robot and achieves full coverage of the underwater detection area. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a three-dimensional structure of a detection robot according to the present invention. FIG. 2 is a schematic diagram of a right view structure of a detection robot according to the present invention. FIG. 3 is a schematic diagram of a rear view structure of a detection robot according to the present invention. FIG. 4 is a schematic diagram of a front view structure of a detection robot according to the present invention. FIG. 5 is a schematic diagram of a top view structure of a detection robot according to the present invention. FIG. 6 is a schematic diagram of a bottom view structure of a detection robot according to the present invention. FIG. 7 is a structural schematic diagram of a self-unhooking device of a detection robot according to the present invention. FIG. 8 is a structural schematic diagram of an AUV sub-machine of a detection robot according to the present invention. FIG. 9 is a schematic diagram of an internal perspective structure of a detection robot according to the present invention. FIG. 10 is a schematic diagram of a skeleton structure of a detection robot according to the present invention. FIG. 11 is a schematic diagram of main thruster vector arrangement of a detection robot according to the present invention. FIG. 12 is a first schematic diagram of micro-thruster vector arrangement of a detection robot according to the present invention. FIG. 13 is a second schematic diagram of micro-thruster vector arrangement of a detection robot according to the present invention. FIG. 14 is a structural schematic diagram of a wheeled wall-surface crawling mechanism of a detection robot according to the present invention. FIG. 15 is a structural schematic diagram of a detachable adsorption mechanism of a detection robot according to the present invention. FIG. 16 is a schematic diagram of integrated hoisting and deployment of a detection robot and a dynamic buoy according to the present invention. FIG. 17 is a diagram of an integrated underwater detection operating mode of a detection robot and a dynamic buoy according to the present invention. Reference numerals in the accompanying drawings: 1. robot; 2. self-unhooking device; 3. laser scanner; 4. emergency buoyancy device; 5. upper scan sonar; 6. buoyancy block; 7. L'SBL beacon; 8. PTZ camera; 9. LED lamp; 10. vertical thruster; 11. framework; 111. electric control layer horizontal framework; 112. first power layer horizontal framework; 113. second power layer horizontal framework; 114. detection layer horizontal framework; 115. back longitudinal framework; 116. lateral longitudinal frameworks; 117. facial longitudinal framework; 12. shell; 13. altimeter; 14. side-scan sonar; 15. AUV submachine; 16. anti-swing base; 17. first side thruster; 18. vertical thruster protective cover; 19. glass cover; 20. second side thruster; 21. horizontal thruster; 22. supporting pillar; 23. manipulator; 24. forward-looking multi-beam sonar; 25. depth gauge; 26. emergency ballast dumping device; 27. hanging ring; 28. slotted plate; 29. buoyancy ring; 30. fixed clamping jaw; 31. hoisting and deployment head; 32. hoisting bracket; 33. hanger; 34. waterproof connector; 35. sub-machine shell; 36. sub-machine glass cover; 37. adsorber; 38. sub-machine vertical thruster; 39. sub-machine frame; 40. sub-machine device box; 41. sub-machine horizontal thruster; 42. sub-machine side thruster; 43. winch; 44. emergency self-rescue control tank; 45. power supply cabinet; 46. drive container; 47. control cabinet; 100. umbilical cable; 101. buoy; and 102. floating ball. DETAILED DESCRIPTION OF EMBODIMENTS The technical solutions of embodiments of the present invention will be described below clearly and comprehensively in conjunction with accompanying drawings of the embodiments of the present invention. Apparently, the embodiments described are merely some embodiments rather than all embodiments of the present invention. All the other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the scope of protection of the present invention. As shown in FIGs. 1-6, a robot for detecting surface defects of an underwater structure provided by the present invention, the robot 1 is arranged by using positive buoyancy, and includes a shell 12, a bottom and side edges of the shell 12 adopt a conformal design, and fit into a framework 11 corresponding to an inner wall of the shell 12, a buoy 101, an anti-swing device, and a selfunhooking device 2; the anti-swing device includes an upper anti-swing mechanism disposed at a lower portion of the buoy 101 and an anti-swing base 16 disposed at a top of the robot 1, and the anti-swing mechanism and the anti-swing base 16 are disposed in a matching manner; the selfunhooking device 2 includes a movable part and a fixed part that are matched with each other, and the fixed part releases the movable part under the action of buoyancy, such that the movable part is detached from the fixed part, and the fixed part can lock the movable part when no buoyancy exists; in the process of deploying and recovering the robot 1, an upper portion of the fixed part is the other end of a load-bearing steel cable with one end fixed at a shore station and used for deploying and recovering the robot 1, and a lower portion of the movable part is fixedly connected to hangers 33 disposed at the top of the robot 1; after the robot is successfully deployed, the fixed part of the self-unhooking device 2 is retracted by the shore station through the load-bearing steel cable; and to recover the robot, the fixed part enters the buoy 101 along an umbilical cable 100 and is in butt joint with the movable part to form the entire self-unhooking device 2. In one specific implementation of this embodiment, as shown in FIG. 7, the self-unhooking device 2 of the present invention is a locking mechanism that automatically attaches and detaches for deploying and retrieving an underwater robot 1 and a latch spring device in the operation method disclosed in the Chinese patent CN 109733985 A, specifically: the fixed part of the self-unhooking device 2 is sleeved on an outside of the movable part, the movable part is a hoisting and deployment head 31, a center of the hoisting and deployment head 31 is configured as a through-hole for allowing the umbilical cable 100 to pass through, and a lower portion of the hoisting and deployment head 31 is fixedly connected to the robot 1; and when arriving at a deployment point, the hoisting and deployment head 31 is detached from the fixed part and moves downwards a water bottom together with the robot 1. The fixed part of the self-unhooking device 2 includes a hanging ring 27 disposed on an upper portion thereof and connected to the load-bearing steel cable, a buoyancy ring 29 disposed on a lower position of the hanging ring 27, a hoisting bracket 32 disposed on a lower portion of the buoyancy ring 29, and a fixed clamping jaw 30 disposed between the hoisting bracket 32 and the buoyancy ring 29. The design and principle of the fixed clamping jaw 30 are consistent with those of the Chinese patent CN 109733985 A, and will not be described in detail herein. In one specific implementation of this embodiment, as shown in FIG. 7, the self-unhooking device 2 of the present invention is improved on the basis of the Chinese patent CN 109733985 A, specifically: a slotted plate 28 of the hoisting bracket 32 and a clasp are disposed on a side edge of the fixed part of the self-unhooking device, the hoisting bracket 32 and the slotted plate 28 are provided as entry and exit for taking out the umbilical cable 100 from the fixed part, and placing the umbilical cable 100 into the fixed part, and the clasp is configured to fixed the hoisting bracket 32 and the slotted plate 28 on the fixed part. The fixed clamping jaw 30 of the self-unhooking device 2 is connected to the buoyancy ring 29, the buoyancy ring 29 is naturally pressed down when not submerged, and the fixed clamping jaw 30 extends inwards to be stuck with the upper portion of the hoisting and deployment head 31 placed inside the hoisting bracket 32, such that the hoisting and deployment head 31 is fixedly connected to the hoisting bracket 32. When the robot 1 gradually submerges in water, the buoyancy ring 29 on the self-unhooking device 2 gradually floats upwards, the fixed clamping jaw 30 is accordingly driven to move outwards until the robot completely submerged, and the fixed clamping jaw 30 is then detached from the hoisting and deployment head 31 to complete the release of the robot 1. As shown in FIG. 2, the anti-swing base 16 is embedded in a buoyancy block 6 at the top of the robot 1, and a root thereof is fixed by bolts. When the robot 1 is hoisted to enter and exit from the water, swinging and swaying may occur solely from the contact between the hoisting bracket 32 and the hangers 33, which will have an adverse effect on the equipment of the robot 1, therefore, the anti-swing base 16 is matched with the upper anti-swing mechanism on the buoy 101 in the present invention to reduce its own shaking and improve the safety performance of the equipment. In one specific implementation of this embodiment, as shown in FIGs. 16-17, the buoy 101 is used for assisting the deployment, recovery and positioning of the robot 1, and monitoring a water surface, where the buoy includes a buoy 101 and a floating ball 102, buoy 101 is of a U-shaped opening structure, a bottom of the U-shaped opening structure is provided with a clamping groove matched with an appearance structure of the floating ball 102, a limiting portion is arranged on an upper part of the clamping groove, and the limiting portion is configured to preventing the floating ball 102 from moving upwards or downwards to detach from a body of the floating ball 102, but the floating ball 102 can move back and forth inside the buoy 101, that is, the floating ball enters and exits from the body of the floating ball 102 through the U-shaped opening; the body of the floating ball 102 is connected to the floating ball 102 through a cable; a center of the floating ball 102 is of a through hole structure, an accommodating cavity for accommodating the self-unhooking device 2 is formed in the through hole, and the through hole is further configured to allow the umbilical cable 100 connecting a shore station and the robot 1 to pass through. In one specific implementation of this embodiment, as shown in FIG. 9, the robot 1 of the present invention further includes a detection module disposed outside the shell 12, an operation module disposed on a face of the robot 1, an emergency self-rescue module, as well as a power module and an electric control module disposed inside the shell 12; the detection module, the operation module, the power module and the emergency self-rescue module are respectively in communication connection with the electric control module, and the electric control module is in communication connection with a shore station through the umbilical cable 100; the detection module includes an acoustic detection device and an optical detection device, and is configured to detect an underwater environment and surface conditions of the underwater structure; the operation module includes a manipulator 23 for carrying out operations; the power module includes thrusters for driving the movement of the robot 1; the emergency self-rescue module includes an emergency buoyancy device 4, an emergency ballast dumping device 26 and an emergency self-rescue control container 44, and is configured to enable the robot 1 to float to water surface by relying on the emergency self-rescue module after the robot 1 experiences underwater malfunctions; and the electric control module includes a power distribution cabinet, a control cabinet 47 and a power supply cabinet 45, and is configured to supply and distribute power for various operations of the robot 1, receive data transmitted from other modules, transmit the received data to the shore station, receive instructions from the shore station and control the operation of the other modules. In one specific implementation of this embodiment, as shown in FIG. 10, the framework 11 includes a plurality of horizontally disposed horizontal frameworks and vertically disposed longitudinal frameworks. The horizontal framework includes an electric control layer horizontal framework 111, a first power layer horizontal framework 112, a second power layer horizontal framework 113 and a detection layer horizontal framework 114 disposed in sequence from bottom to top; and the longitudinal framework 11 includes a back longitudinal framework 115 disposed on a back of the robot 1, side longitudinal frameworks 116 disposed on side edges of the robot 1 and face longitudinal frameworks 117 disposed on the face of the robot 1. In one specific implementation of this embodiment, each layer of the horizontal frameworks is disposed in a cross shape with profiles of a certain width, five longitudinal frameworks are provided, one back longitudinal framework 115, two symmetrically disposed lateral longitudinal frameworks 116 and two mirroring facial longitudinal frameworks 117. Preferably, the framework 11 is made from I-shaped steel or T-shaped titanium alloy profiles. In one specific implementation of this embodiment, since main thrusters of the robot are placed above the first power layer horizontal framework 112; and the robot provided by the present invention further includes a plurality of supporting pillars 22, and the plurality of supporting pillars 22 are uniformly distributed between the first power layer horizontal framework 112 and the second power layer horizontal framework 113 for improving rigidity and bearing capacity of the framework 11. In one specific implementation of this embodiment, an inner wall of the shell 12 is fixedly connected to the framework 11 in a threaded way. In one specific implementation of this embodiment, the buoyancy block 6 is further included, and the buoyancy block 6 is disposed at the top of the robot 1. In one specific implementation of this embodiment, the buoyancy block 6 is disposed on an upper portion of the detection layer horizontal framework 114, a lower portion of the buoyancy block 6 is in butt joint with an upper portion of the shell 12, and the buoyancy block 6 is conformal with the shell 12. An interior of the buoyancy block 6 is irregularly designed according to equipment layout, buoyancy distribution and other factors, so as to ensure that a buoyancy center is in a central position. In one specific implementation of this embodiment, appearance of the robot 1 is a bionic streamlined configuration, such as a seahorse, a creature that maintains vertical movement and good stability in the ocean, and the streamline configuration thereof is a reference configuration for configuration of the robot 1. Preferably, the shell 12 material is titanium alloy. In one specific implementation of this embodiment, the acoustic detection device includes a USBL beacon 7 and an upper-scan sonar 5 disposed at the top of the robot 1, a side-scan sonar 14 disposed on a side edge of the robot 1, and a forward-looking multi-beam sonar 24 and a depth gauge 25 disposed on the face of the robot 1; the buoy 101 is equipped with an ultra-short baseline positioning system, the USBL beacon 7 and the ultra-short baseline positioning system form a hydroacoustic positioning array for detecting distance and orientation of the robot 1 relative to the buoy 101 and the position of the buoy 101 itself, such that the position of the robot 1 is identified; the upper-scan sonar 5, the side-scan sonar 14 and the forward-looking multibeam sonar 24 are respectively configured to detect an upper environment, a side environment and a lower-middle environment of an operating surface of the robot 1; the depth gauge 25 is configured to monitor a depth of the underwater position of the robot 1; and the USBL beacon 7, the upper-scan sonar 5, the side-scan sonar 14, the forward-looking multi-beam sonar 24, and the depth gauge 25 are respectively in communication connection with the control cabinet 47, and are configured to transmit the detected data to the control cabinet 47. In one specific implementation of this embodiment, the back of the robot 1 is further equipped with an altimeter 13, the altimeter 13 is in communication connection with the control cabinet 47 for measuring distances between the robot 1 and solid objects such as the underwater structure, such that the robot 1 is at a safe distance so as to protect the robot. In one specific implementation of this embodiment, the optical detection device includes a laser scanner 3 disposed at the top of the robot 1, a plurality of pan-tilt-zoom (PTZ) cameras 8 disposed on the back and the face of the robot 1, and a plurality of LED lamps 9 disposed on an upper portion and a lower portion of the robot 1; the laser scanner 3 is configured to quickly acquire visual three-dimensional data of a surface of the underwater structure, to achieve 3D imaging; the PTZ cameras 8 are configured to photograph the underwater environment and objects to be measured; the LED lamps 9 are configured to provide illumination for the robot 1; the laser scanner 3, the PTZ cameras 8 and the LED lamps 9 are separately connected to the power supply cabinet 45; and the laser scanner 3 and the PTZ cameras 8 are respectively in communication connection with the control cabinet 47 and are configured to transmit the collected data to the control cabinet 47. In one specific implementation of this embodiment, the PTZ cameras 8 each is sleeved with a waterproof glass cover 19, and the PTZ cameras 8 each is fixed inside the waterproof glass cover 19; and when the robot 1 is close to a dam surface for near-distance detection, the glass cover 19 can play a role of displacing water, thereby effectively solving the problem of low visibility in the water environment. Preferably, four PTZ cameras 8 are provided, and each PTZ camera is disposed on upper and lower portions of the face and back of the robot 1. In one specific implementation of this embodiment, as shown in FIGs. 11-13, the thrusters include horizontal thrusters 21, vertical thrusters 10, and side surface thrusters; the horizontal thrusters 21 are disposed in a middle of the robot 1 and configured to implement movement of the robot 1 in a horizontal direction, the vertical thrusters 10 are disposed on two sides of the robot 1 and configured to implement movement of the robot 1 in a vertical direction, and the side thrusters are disposed on two sides of the upper portion of the robot 1 and configured to implement movement of the robot 1 in the horizontal direction at a low jitter frequency. In one specific implementation of this embodiment, the side thrusters includes a first side thruster 17 and a second side thruster 20 perpendicular to each other, the first side thruster 17 configured to realize horizontal and longitudinal posture adjustments of the robot 1, and the second side thruster 20 is configured to realize horizontal and transverse posture adjustments of the robot 1. In one specific implementation of this embodiment, the side thrusters are micro-thrusters, and compared with the two main thrusters, that is, the horizontal thrusters 21 and the vertical thrusters 10, the side surface thrusters are smaller in size and disturbance during operation, and configured to slightly adjust a movement direction of the robot 1 during operation, providing smaller steering force to the robot 1, such that the posture adjustments of the robot 1 can be realized, and the stability of the robot 1 during operation is maintained. Working conditions of the side thrusters in the present invention are as follows: when the robot 1 faces the dam surface to perform operation, the horizontal main thrusters are turned off, the robot 1 is fixed on the dam surface through the adsorber 37, and the micro-thrusters are started to resist underwater turbulence near the dam surface to assist in adjusting the movement direction of the robot I, such that posture adjustments of the robot 1 are realized, movement disturbance is reduced, and the stability of the robot 1 during operation is maintained. In one specific implementation of this embodiment, four horizontal thrusters 21 are disposed in a vector manner; and two vertical thrusters 10 are provided and disposed vertically on both sides of the robot 1, respectively. In one specific implementation of this embodiment, a vertical thruster protective cover 18 is disposed on around each vertical thruster 10, and the vertical thruster protective cover 18 is fixedly disposed on the shell 12 for protecting the vertical thruster 10. In one specific implementation of this embodiment, the horizontal thrusters 21 are fixed on the framework 11 through a hoop, and are connected by using bolts. In one specific implementation of this embodiment, the manipulator 23 includes a large arm with one end connected to the framework 11 and a small arm connected to the other end of the large arm, two manipulators 23 are provided and symmetrically disposed on the face of the robot 1, two channels are formed on the shell 12, and the large arm of the manipulator 23 can be retracted into the channel of the shell 12, and the small arm of the manipulator 23 is conformal with the shell 12. In one specific implementation of this embodiment, the large arm of the manipulator 23 is fixedly disposed on the electric control layer horizontal framework 111, and a maximum extension of the manipulator 23 is up to 750 mm when the manipulator carries out the operation. In one specific implementation of this embodiment, the electric control module is disposed at the lower portion of the robot 1, such that a metacentric height of the robot 1 can be significantly improved; the power distribution cabin is configured to distribute power according to the power supply requirements of each module; the power supply cabinet 45 is configured to supply power to each module according to a power distribution scheme of the power distribution cabinet; and the control cabinet 47 is configured to receive data transmitted from each module, transmit the received data to the shore station, and receive instructions from the shore station to control the operation of the other modules. In one specific implementation of this embodiment, the electric control module further includes a drive container 46, and the drive container 46 is configured to place drive controllers for controlling the operation of the motor of each thruster and the manipulator 23; the drive controllers are in communication connection with the motors of the thruster and the manipulator 23 and the control cabinet 47 for receiving instruction signals transmitted from the control cabinet 47 of the robot 1, and outputting the driving signals to facilitate the operation of each driving device. The driving device includes a horizontal thruster 21, a vertical thruster 10, a side surface thruster, and a manipulator 23. In one specific implementation of this embodiment, when performing a dam inspection operation, the robot 1 may suffer failures such as entanglement, cable breakage, power supply and communication abnormalities due to a complex underwater environment, the emergency buoyancy device 4 is disposed at the top of the robot 1, and includes an emergency buoy and a first release mechanism, and the emergency buoyancy device is configured to release the emergency buoy out of the robot 1 body and quickly floating to the water surface after the robot 1 experiences malfunctions, so as to guide operators to find and search the robot 1; the emergency ballast dumping device 26 is disposed at the lower portion of the robot 1, and includes a ballast and a second release mechanism, and the emergency ballast dumping device is configured to automatically discard the ballast when the robot 1 in the event of a malfunction, such that the robot 1 can float to the water surface to rescue by relying on the buoyancy of the robot 1; and the emergency self-rescue control container 44 includes a controller, the controller is in communication connection with the emergency buoyancy device 4 and the emergency ballast dumping device 26, and the control is configured to receive active instructions or power supply, distribution information, communication connection signals and depth data transmitted by the control cabinet 47, to determine whether the robot 1 has abnormalities of power supply interruption, communication signal interruption, long time delay, exceeding maximum pressure and maximum depth, to make an emergency decision according to the abnormalities, and to transmit an action instruction corresponding to the emergency decision to the emergency buoyancy device 4 and / or the emergency ballast dumping device 26. The emergency decision is as follows: Default priority to activate the emergency ballast dumping device, and the ballast is released first to enable the robot 1 to float; when the robot 1 does not reach the water surface within the preset time, the emergency buoyancy device 4 will be activated to release the emergency buoy, and the operators can search and rescue the robot 1 through the position of the buoy 101 and the umbilical cable 100. In one specific implementation of this embodiment, the emergency buoy is disposed at the top of the emergency buoyancy device 4 and is connected to the first release mechanism through a cable, the first release mechanism can restrain and release the cable, the emergency buoy floats to the water surface by releasing the cable, and the emergency buoy is fixed to the top of the buoyancy block 6 by restraining the cable. In one specific implementation of this embodiment, the first release mechanism includes a release motor, a gear driven by the release motor, a rack in meshing transmission with the gear, a connecting rod and a connecting ring; and one end of the connecting rod is fixedly connected to the rack, the other end thereof is a free end, the connecting rod and the connecting ring are disposed in a matched mode, the free end of the connecting rod is strung with the connecting ring, and a cable connected to the emergency buoy is wound on the connecting ring. When the emergency buoyancy device 4 receives an instruction for releasing the emergency buoy, the release motor is started, and the rotation of the gear drives the rack to move horizontally. For example, the rack horizontally moves rightwards to drive the connecting rod to horizontally move rightwards, the connecting ring strung on a left end of the connecting rod is detached from the connecting rod, the connecting ring disconnected from the connecting rod is in a free state in the emergency buoyancy device 4, the cable wound on the connecting ring is freely released due to the buoyancy generated from the emergency buoy and traction force from the cable, and the emergency buoy finally floats to the water surface. In one specific implementation of this embodiment, the ballast is preset as particles such as lead sand or iron sand, which is stored in the second release mechanism, a release hole is formed on a bottom of the second release mechanism, and the release hole on the bottom thereof is driven to open and close in a gear meshing manner, such that the ballast is dumped through the release hole. When iron sand or lead sand is used as the ballast, dumping of the ballast will not have secondary impact on the dam structure at the water bottom. In one specific implementation of this embodiment, as shown in FIGs. 1, 3, 8, and 15, in order to meet the task requirements of close observation and inspection of underwater dam of a large hydroelectric power station, an intelligent sub-machine with adsorption function is designed. The robot 1 in the present invention further includes a sub-machine module disposed at a bottom of the robot 1, the sub-machine module is in communication connection with the electric control module, the sub-machine module includes a winch 43 and an AUV sub-machine 15 connected to the winch 43 through a cable, the winch 43 is disposed on the framework 11 and is configured to retract the AUV sub-machine 15, and the AUV sub-machine 15 serves as a sub-machine of the robot 1. During operation, the AUV sub-machine moves away from the robot 1 and form a working mode of master-slave machine with the robot 1, such that collaborative operation of the robot 1 and multiple machines in the complex underwater environment is realized. In one specific implementation of this embodiment, as shown in FIGs. 8 and 15, the AUV submachine 15 includes a sub-machine frame 39, a sub-machine shell 35 disposed in the submachine frame 39, the PTZ camera 8 and the adsorber 37 disposed on a front portion, two submachine horizontal thrusters 41 disposed on a rear portion, a sub-machine side thruster 42 disposed inside the sub-machine frame 39 and a sub-machine vertical thruster 38 disposed on a top of the sub-machine shell 35, a waterproof connector 34 and a sub-machine device box 40 disposed on the top of the sub-machine shell 35, and the sub-machine device box 40 is configured to store the electric control device of the sub-machine; and the adsorber 37 is configured to be adsorbed on a wall surface of the narrow groove, so as to facilitate shortdistance detection of the AUV sub-machine 15. In one specific implementation of this embodiment, the PTZ camera 8 on the AUV sub-machine 15 is sleeved with a sub-machine glass cover 36, and the sub-machine glass cover has the function same as that of the glass cover 19 on the robot 1. The detection robot 1 of the present invention has the working mode of A and B surfaces, the A and B surfaces are front and back surfaces of the robot 1, the two surfaces are both working surfaces, the A surface is relatively narrow and suffers a small resistance when moving forwards, upwards and downwards, featuring a large scope of inspection and strong maneuverability, and the A surface is used when initial inspection of the dam surface is performed; and the B surface is blunt, and features better structural compatibility when being close to the dame surface, making it convenient for the manipulator 23 to work at a short distance, and the B surface is used when precision inspection of the dam surface is performed. In one specific implementation of this embodiment, as shown in FIG. 14, the present invention further includes a wheeled wall-surface crawling mechanism, the wheeled wall-surface crawling mechanism is a frame structure fitting in with a shape of the robot 1, and a bottom, a front side thereof, and a junction between the bottom and the front side are all equipped with wheels; and in the maintenance process of the robot 1, it can walk on the dam at the water bottom through the wheels mounted on the wheeled wall-surface crawling mechanism. When in use, the robot 1 is placed inside the wheeled wall-surface crawling mechanism, such that the collision can be prevented and the robot 1 can be protected; and three surfaces of the wheeled wall-surface crawling mechanism with the wheels (that is, the bottom, the front side and the connecting surface between the bottom and the front side) are in one-to-one contact with three wall surfaces of the dam, facilitating better detection of the wall surfaces of the dame. In one specific implementation of this embodiment, an included angle between three surfaces of the wheeled wall-surface crawling mechanism is adjustable, such that the wheeled wall-surface crawling mechanism can adapt to more wall surfaces of the dam. The deployment and recovery process of the present invention is as follows: as shown in FIGs. 7, 16 and 17, when the robot 1 is deployed, a hoisting and deployment device on the shore station establishes a connection with the self-unhooking device 2 placed in the floating ball 102 through the load-bearing steel cable, and meanwhile, the umbilical cable 100 passes through it; and the load-bearing steel cable hoists the buoy and the robot 1, and the buoy 101 is borne by the robot 1 body through the anti-swing device, in which case, the buoy, the floating ball and the robot form a trinity, such that the integrated hoisting and deployment are implemented. When the robot 1 enters water and meets floating conditions of the buoy body, as the robot 1 continues diving, the floating ball 102 meets its own buoyancy requirements; and since the movable part of self-unhooking device 2 in the floating ball 102 is detached from the fixed part due to the buoyancy, the robot 1 is accordingly detached from the floating ball 102, in which case, the floating ball 102 is pulled by the buoy winch of the buoy body through the cable. Subsequently, the shore station recovers the self-unhooking device 2 through the load-bearing steel cable, so as to prevent the umbilical cable 100 from being stuck and restricted in the selfunhooking device 2, and cause damage to the umbilical cable 100, adversely affecting the operation of the robot 1, during the operation of the robot 1. After the self-unhooking device 2 is recovered to the shore station, the operator unfastens the clasp (not indicated in FIG. 7) on the fixed part to remove the slotted plate 28, such that the umbilical cable 100 is detached from the fixed part of the self-unhooking device. When the robot 1 is diving, the umbilical cable 100 drives the floating ball 102 to move, such that the floating ball 102 and the robot 1 are always on the same plumb line, the buoy 101 is in connection with the floating ball 102 by retracting a cable on the buoy winch, the floating ball, and transmits the information of water surface positioning. When the robot is recovered, the operator in the shore station places the umbilical cable 100 into the fixed part of the self-unhooking device 2, closes the slotted plate 28, and fastens the clasp, and the fixed part of the self-unhooking device 2 carries the load-bearing steel cable to above the floating ball 102 along the umbilical cable 100; since the umbilical cable 100 is always in a tensioned state, the fixed part of the self-unhooking device 2 slides into the through hole of the floating ball 100 due to the gravity during the recovery process, waiting for the robot 1, buoy, and the floating ball to realize an integrated system; and the fixed part is in butt joint with the movable part, and the fixed part locks the movable part to achieve recovery. During recovery, the buoy 101 recovers the cable through its own buoy winch, and brings the floating ball 102 is into its U-shaped opening by its own power system until the buoy winch is tightened. At the same time, the shore station slides the fixed part of the self-unhooking device 2 having the load-bearing steel cable into the through hole of the floating ball 102 through the umbilical cable 100 of the robot 1, and in the process of slowly recovering the umbilical cable 100, the point-to-point bearing connection between the anti-swing base 16 on the robot and the upper anti-swing apparatus on the lower portion of the buoy body is implemented by cooperating with the position adjustment of the buoy 101, in which case, the buoy, floating ball and robot form a trinity , and the integrated recovery is implemented. It should be noted that: when the buoy, floating ball and robot form a trinity, the floating ball 102 is located inside the buoy body, the fixed part of the self-unhooking device 2 is in a state without buoyancy, and when the fixed part of the self-unhooking device 2 is aligned with upper and lower positions of the hoisting and deployment head 31 serving as the movable part, an upper portion of the hoisting and deployment head 31 pushes the fixed clamping jaw 30 open, and the fixed part locks the movable part to achieve recovery. It should be noted that the relation terms, for example, first, second, etc., are used herein merely for distinguishing one entity or operation from another entity or operation but do not necessarily require or imply that there exists any actual relation or sequence between these entities or operations. Furthermore, terms "comprising", "including" or any other variants thereof are intended to cover the non-exclusive including, thereby making that the process, method, object or apparatus comprising a series of elements comprise not only those elements but also other elements that are not listed explicitly or the inherent elements to the process, method, merchandise or apparatus. Without further limitations, an element limited by the phrase "comprising / including a" does not exclude that there exists another same element in the process, method, merchandise or apparatus comprising the element. Although the embodiments of the present invention have been illustrated and described, it should be understood that those of ordinary skill in the art may make various changes, modifications, replacements and variations to the above embodiments without departing from the principle and spirit of the present invention, and the scope of the present invention is limited by the appended claims and their legal equivalents.

Claims

1. A robot for detecting surface defects of an underwater structure, characterized by comprising a shell, a bottom and side edges of the shell adopt a conformal design, and fit into a framework corresponding to an inner wall of the housing, a buoy, an anti-swing device, and a self-unhooking device; the anti-swing device comprises an upper anti-swing mechanism disposed at a lower portion of the buoy and an anti-swing base disposed at a top of the robot, and the anti-swing mechanism and the anti-swing base are disposed in a matching manner; the selfunhooking device comprises a movable part and a fixed part that are matched with each other, and the fixed part releases the movable part under the action of buoyancy, such that the movable part is detached from the fixed part, and the fixed part can lock the movable part when no buoyancy exists; in the process of deploying and recovering the robot, an upper portion of the fixed part is connected to the other end of a load-bearing steel cable with one end fixed at a shore station and used for deploying and recovering the robot, and a lower portion of the movable part is fixedly connected to hangers disposed at the top of the robot; after the robot is successfully deployed, the fixed part of the self-unhooking device is retracted by the shore station through the load-bearing steel cable; and to recover the robot, the fixed part enters into the buoy along an umbilical cable, upon docking with the movable part, and forms the entire self-unhooking device.

2. The robot for detecting surface defects of an underwater structure according to claim 1, characterized in that the robot further comprises a detection module disposed outside the shell, an operation module disposed on a face of the robot, an emergency self-rescue module, as well as a power module and an electric control module disposed inside the shell; the detection module, the operation module, the power module and the emergency self-rescue module are respectively in communication connection with the electric control module, and the electric control module is in communication connection with the shore station through the umbilical cable; the detection module comprises an acoustic detection device and an optical detection device, and is configured to detect an underwater environment and surface conditions of the underwater structure; the operation module comprises a manipulator for carrying out operations; the power module comprises thrusters for driving the movement of the robot; the emergency self-rescue module comprises an emergency buoyancy device, an emergency ballast dumping device and an emergency self-rescue control container, and is configured to enable the robot to float to water surface by relying on the emergency self-rescue module after the robot experiences underwater malfunctions; and the electric control module comprises a power distribution cabinet, a control cabinet and a power supply cabinet, and is configured to supply and distribute power for various operations of the robot, receive data transmitted from other modules, transmit thereceived data to the shore station, receive instructions from the shore station and control the operation of the other modules.

3. The robot for detecting surface defects of an underwater structure according to claim 1, characterized in that the framework comprises a plurality of horizontally disposed horizontal frameworks and vertically disposed longitudinal frameworks.

4. The robot for detecting surface defects of an underwater structure according to claim 3, characterized in that the horizontal framework comprises an electric control layer horizontal framework, a first power layer horizontal framework, a second power layer horizontal framework and a detection layer horizontal framework disposed in sequence from bottom to top; and the longitudinal framework comprises a back longitudinal framework disposed on a back of the robot, side longitudinal frameworks disposed on side edges of the robot and face longitudinal frameworks disposed on the face of the robot.

5. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the acoustic detection device comprises a USBL beacon and an upper-scan sonar disposed at the top of the robot, a side-scan sonar disposed on a side edge of the robot, and a forward-looking multi-beam sonar and a depth gauge disposed on the face of the robot; the buoy is equipped with an ultra-short baseline positioning system, the USBL beacon and the ultrashort baseline positioning system form a hydroacoustic positioning array for detecting distance and orientation of the robot relative to the buoy and the position of the buoy itself, such that the position of the robot is identified; the upper-scan sonar, the side-scan sonar and the forwardlooking multi-beam sonar are respectively configured to detect an upper environment, a side environment and a lower-middle environment of an operating surface of the robot; the depth gauge is configured to monitor a depth of the underwater position of the robot; and the USBL beacon, the upper-scan sonar, the side-scan sonar, the forward-looking multi-beam sonar, and the depth gauge are respectively in communication connection with the control cabinet, and are configured to transmit the detected data to the control cabinet.

6. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the optical detection device comprises a laser scanner disposed at the top of the robot, a plurality of pan-tilt-zoom (PTZ) cameras disposed on the back and the face of the robot, and a plurality of LED lamps disposed on an upper portion and a lower portion of the robot; the laser scanner is configured to quickly acquire visual three-dimensional data of a surface of the underwater structure, to achieve 3D imaging; the PTZ cameras are configured to photograph the underwater environment and objects to be measured; the LED lamps are configured to provide illumination for the robot; the laser scanner, the PTZ cameras and the LED lamps are separately connected to the power supply cabinet; and the laser scanner and the PTZcameras are respectively in communication connection with the control cabin, and are configured to transmit the collected data to the control cabinet.

7. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the thrusters comprise horizontal thrusters, vertical thrusters, and side thrusters; the horizontal thrusters are disposed in a middle of the robot and configured to implement movement of the robot in a horizontal direction, the vertical thrusters are disposed on two sides of the robot and configured to implement movement of the robot in a vertical direction, and the side thrusters are disposed on two sides of the upper portion of the robot and configured to implement movement of the robot in the horizontal direction.

8. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the manipulator comprises a large arm with one end connected to the framework and a small arm connected to the other end of the large arm, two manipulators are provided and symmetrically disposed on the face of the robot, two channels are formed on the shell, and the large arm of the manipulator can be retracted into the channel of the shell, and the small arm of the manipulator is conformal with the shell.

9. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the emergency buoyancy device is disposed at the top of the robot for releasing the emergency buoy out of the robot body and quickly floating to the water surface after the robot experiences underwater malfunctions, so as to guide operators to find and search the robot; the emergency ballast dumping device is disposed at the lower portion of the robot, and the emergency ballast dumping device is configured to automatically discard the ballast in the event of a malfunction, such that the robot can float to the water surface to rescue by relying on the buoyancy of the robot; and the emergency self-rescue control container, which is in communication connection with the emergency buoyancy device and the emergency ballast dumping device, and the control is configured to receive active instructions or power supply, distribution information, communication connection signals and depth data transmitted by the control cabinet, to determine whether the robot has abnormalities of power supply interruption, communication signal interruption, long time delay, exceeding maximum pressure or maximum depth, to make an emergency decision according to the abnormalities, and to transmit an action instruction corresponding to the emergency decision to the emergency buoyancy device and / or the emergency ballast dumping device.

10. The robot for detecting surface defects of an underwater structure according to claim 2, characterized in that the robot further comprises a sub-machine module disposed at a bottom of the robot, the sub-machine module is in communication connection with the electric control module, the sub-machine module comprises a winch and an ALJV sub-machine connected to thewinch through a cable, the winch is disposed on the framework and is configured to retract the AUV sub-machine, and the AUV sub-machine serves as a sub-machine of the robot; and during operation, the AUV sub-machine moves away from the robot and form a working mode of master-slave machine with the robot.5 11. The robot for detecting surface defects of an underwater structure according to claim 1,characterized in that the robot further comprises a wheeled wall-surface crawling mechanism, the wheeled wall-surface crawling mechanism is a frame structure fitting in with a shape of the robot, and a bottom, a front side thereof, and a junction between the bottom and the front side are all equipped with wheels; and when in use, the robot is placed inside the wheeled wall-surface 10 crawling mechanism.

Images