Underwater robot applied to hull crack monitoring

Abstract

The underwater robot applied to hull crack monitoring comprises bionic tension legs, a trunk body and a fixing mechanism, the four sets of bionic tension legs are arranged on the two sides of the trunk body, each bionic tension leg is composed of a main supporting leg and an auxiliary supporting leg in a hinged mode, and the auxiliary supporting legs are connected with rolling wheels in the trunk body through tension inhaul cables; synchronous alternate movement of the adjacent bionic tension legs is achieved in a special roller combination mode, the fixing mechanism is connected with a spherical limiting stopper at the bottom of the trunk body through a spherical clamping block, ejection of an ejector pin is controlled through a wedge-shaped sliding block and a magnetic sliding block, and then the spherical clamping block is locked; the underwater robot is subjected to lightweight design through the bionic principle, the structure of the bionic tension leg is simplified through the tension structure, the weight and control difficulty of the underwater robot are greatly reduced, the leg is controlled and integrated to the trunk body through the tension inhaul cable, and the underwater robot has extremely high leakproofness and is suitable for various soft and complex terrains underwater.

Description

Technical Field

[0001] The invention relates to the field of marine equipment, in particular to an underwater robot used for monitoring cracks in a hull. Background Art

[0002] At present, during the navigation of ships, due to the influence of sea conditions and other environmental factors, cracks often appear on the surface of the hull, especially the bottom of the ship is more likely to expand, resulting in cracks on the bottom of the ship. The monitoring of cracks also requires the ship to enter the dock for systematic inspection. On the one hand, this causes a lot of time to be spent on maintenance and inspection when the ship enters and leaves the dock, resulting in a significant increase in maintenance costs. On the other hand, under the condition that docks are relatively scarce, smaller cracks often require regular monitoring and attention outside the dock to achieve ship condition monitoring, and often do not require docking for maintenance, wasting limited resources.

[0003] In the related art, in order to be able to detect cracks on the surface of the hull near the dock from time to time, especially to monitor cracks on the bottom of the ship, the underwater robots in the prior art are not convenient to walk in the water or on the soft seabed below the water surface due to their complex structure, and the underwater robots require multiple motors to drive each joint, which greatly increases the weight and complexity of the robot, making it difficult to continuously monitor the bottom surface of the ship, and increases the failure rate of the complex robotic arms exposed in the complex underwater environment. In addition, due to the poor endurance of the underwater robot, it is difficult to monitor cracks on ships at a long distance by its own power.

[0004] Therefore, in order to better monitor the hull, especially the cracks on the bottom of the ship, in case of an accident on the ship on the sea or in distant sea areas, it is necessary to provide an underwater robot for monitoring the cracks in the hull. Summary of the invention

[0005] The purpose of the present invention is to provide an underwater robot used for hull crack monitoring. The bionic principle is adopted to reduce the number of control motors through a tension structure that imitates the principle of spider legs, greatly reducing the weight and control difficulty of the robot. The control structure is integrated into the trunk body through tension cables to improve the airtightness of the device. Combined with bionic airbags, the robot can walk in water and on soft terrain at the bottom of the water.

[0006] In order to achieve the above-mentioned purpose, the present invention provides an underwater robot for hull crack monitoring, comprising a bionic tension leg and a trunk body, the bionic tension leg comprising a main support leg and a secondary support leg, one end of the main support leg is hinged to the secondary support leg, and the other end of the main support leg is hinged to the trunk body; the bionic tension leg provides outward tension through an elastic support rod and provides inward pulling force through a tension cable; the trunk body comprises a steering gear and a power supply, the steering gear synchronously controls four rollers, the rollers are connected to the tension cables, the steering gear retracts and releases the length of the tension cables to control the movement of the bionic tension leg, the power supply is installed on the bottom plate in the middle of the trunk body, the power supply is connected to the receiver through an electric regulator, the receiver is respectively connected to the steering gear, the gas generation device and the environment detection module, and the crack detection module is arranged on the side and top of the trunk body.

[0007] There are four groups of bionic tension legs, each group of bionic tension legs is located at both sides of the trunk body, the bionic tension legs in the same group move in the same direction, and the adjacent bionic tension legs on the same side move in opposite directions.

[0008] The main support leg and the auxiliary support leg are arc-shaped, and the main support leg and the auxiliary support leg are hollow inside. A spherical walking foot is installed at the end of the auxiliary support leg. The middle part of the auxiliary support leg is hinged to one end of the elastic support rod, and the other end of the elastic support rod is fixed to the trunk body. One end of the tension cable is connected to the end of the auxiliary support leg, and the other end of the tension cable passes through the trunk body and is connected to the roller.

[0009] An environmental detection module is installed at the front end of the trunk body, and an airbag is installed at the rear end of the trunk body. The airbag is connected to the trunk body through a cylindrical fixing nut. The airbag passes through the inside of the fixing nut through a ventilation tube and is connected to a gas generating device. The gas generating device is installed on the inner wall of the rear side of the trunk body, the power supply is fixed to the middle of the inner bottom plate of the trunk body, the electric regulator and the receiver are fixed above the power supply, and the servos are installed on both sides of the power supply.

[0010] The servo is provided with a gear 1 on the side close to the environment detection module, and the gear 1 is meshed with rollers 1 and 2 on both sides, and the roller 1 winds up the tension cable on the left side from the top, and the roller 2 winds up the tension cable on the right side from the top; the servo is provided with a gear 2 on the side close to the airbag, and the gear 2 is meshed with rollers 3 and 4 on both sides, and the gear 2 winds up the tension cable on the left side from the bottom, and the roller 3 winds up the tension cable on the right side from the bottom.

[0011] A spherical stopper is installed at the center of the bottom surface of the trunk body of the underwater robot. The spherical stopper is hollow inside and has a circular opening. A conical top block is installed at the center of the inner circle of the spherical stopper. A thimble is installed on the top of the conical top block. A slideway for the thimble to slide is provided inside the conical top block. The bottom of the thimble is elastically connected to the bottom of the conical top block. The fixing mechanism includes a fixed base, which is fixed to the side of the hull. The fixed base is cylindrical and hollow inside. A spring 1 is installed on the side of the fixed base close to the trunk body. A slide tube is installed inside the spring 1. One end of the slide tube is fixed to the inner bottom of the fixed base, and the other end of the slide tube is fixed to the inner bottom of the fixed base. The sliding tube extends in the direction of the trunk body, the interior of the sliding tube is hollow, the portion of the sliding tube located inside the fixed base is provided with a cross-shaped opening, a magnetic slider is installed inside the sliding tube, the end of the magnetic slider close to the side of the hull is a sloped surface, a spring 2 is installed at the end of the magnetic slider, the spring 2 passes through the openings on the left and right sides of the sliding tube and is fixed to the bottom of the fixed base, the wedge-shaped slider passes through the upper and lower sides of the sliding tube and cooperates with the magnetic slider, a spring 3 is installed on the top of the wedge-shaped slider, the top of the spring 3 is fixed to the inner wall of the fixed base, the pull ring passes through the fixed base and is connected to the top of the wedge-shaped slider, the protruding end of the sliding tube is hinged to the spherical block, and the spherical block is provided with a sloped surface near the opening of the conical top block.

[0012] A detection method of an underwater robot applied to hull crack monitoring comprises the following steps: Step a, align the opening of the spherical stopper at the bottom of the underwater robot with the spherical block, and use the trunk body to compress the spring, so that the conical top block pushes the spherical block open under the pressure and slides along the spherical stopper. When the spherical block is opened to the maximum angle, the ejector pin is sucked out by the magnetic slider and the two spherical blocks are clamped, and the hull carries the underwater robot to the designated sea area; Step b, after reaching the designated sea area, pull the pull ring upwards and slide the wedge-shaped slider upwards. Under the action of spring 2, the magnetic slider slides along the slide tube to the bottom of the fixed base. The ejector pin loses the magnetic attraction of the magnetic slider and retracts into the conical ejector block. Under the action of spring 1, the spherical block escapes from the spherical stopper and the underwater robot is ejected into the water. Step c, after the underwater robot falls into the water, the bionic tension leg is controlled to move by the steering gear, when gear one and gear two rotate clockwise, roller one rotates counterclockwise and releases the tension cable, under the action of the elastic strut, the bionic tension leg connected to roller one extends, roller two rotates counterclockwise and retracts the tension cable, so that the bionic tension leg connected to roller two is retracted, gear three rotates counterclockwise and retracts the tension cable, so that the bionic tension leg connected to gear three is retracted, roller four rotates counterclockwise and releases the tension cable, so that the bionic tension leg connected to roller four extends, so that the four groups of bionic tension legs perform reciprocating motion synchronously; Step d, when the underwater robot moves to the vicinity of the bottom of the hull, the crack detection module is controlled by the receiver to detect the bottom of the ship. After the data is collected, the gas generating device generates nitrogen and inflates the airbag, which inflates and brings the underwater robot back to the surface.

[0013] Compared with the related art, the present invention has the following beneficial effects: (1) By lightweighting the robot, elastic struts and tension cables were used to simulate the movement principle of the jumping spider’s legs, which reduced the weight of the underwater robot and the complexity of the bionic tension leg. (2) The control of the leg joints is integrated into the trunk through tension cables, which avoids short circuit and disconnection failure of the bionic tension leg due to humid or dusty environments and improves the air tightness of the control equipment; (3) The steering gear of the present invention realizes the synchronous operation of the bionic tension legs through different combinations of rollers and four tension cables, thereby reducing the control difficulty of the underwater robot; (4) The fixing mechanism of the present invention can quickly disassemble the spherical stopper and the spherical block through the cooperation of the magnetic slider and the ejector pin, and eject the device through the spring, thereby realizing the convenient carrying and deployment of the underwater robot; (5) The underwater robot of the present invention adopts a spider-like shape. When the designated exploration work is completed, the airbag is inflated, and the airbag at the tail is inflated to make the robot float to the surface, so that it can be recycled and reused; (6) The underwater robot of the present invention is carried by a mother ship with one or more robots to a designated water area, and the underwater robot is used to monitor the cracks on the bottom of the ship, especially in a relatively soft water bottom. Conventional bionic robots tend to sink to the bottom of the water and cannot move freely due to their complex structure and heavy weight. In addition, the crack detection module at the top is used to perform real-time monitoring, which greatly improves the monitoring efficiency of the bottom of the ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A three-dimensional schematic diagram of an underwater robot used for monitoring hull cracks in the present invention; Figure 2 is a three-dimensional schematic diagram of the bionic tension leg of the present invention; Figure 3 A three-dimensional schematic diagram of the internal structure of the trunk body of the present invention; Figure 4 This is a schematic diagram of an underwater robot underwater exploration system for monitoring hull cracks according to the present invention; Figure 5 A three-dimensional schematic diagram of a fixing method of an underwater robot used for hull crack monitoring according to the present invention; Figure 6 is a three-dimensional cross-sectional view of the fixing mechanism of the present invention; Figure 7 A two-dimensional cross-sectional view of the connection mode of the fixing mechanism of the present invention; Figure 8 A three-dimensional schematic diagram of another embodiment of the bionic tension leg of the present invention; The following are marked in the figure: 1-bionic tension leg, 2-trunk body, 3-fixing mechanism, 4-hull, 101-main support leg, 102-secondary support leg, 103-elastic support rod, 104-tension cable, 105-spherical walking foot, 201-gas generating device, 202-ventilation pipe, 203-fixing nut, 204-gear three, 205-roller four, 206-gear two, 207-servo, 208-roller one, 209-gear one, 2 10-roller 2, 211-power supply, 212-electric adjustment, 213-receiver, 214-spherical limiter, 215-conical top block, 216-thimble, 217-crack detection module, 218-airbag, 301-fixed base, 302-pull ring, 303-spring 1, 304-spring 3, 305-spring 2, 306-sliding tube, 307-wedge slider, 308-magnetic slider, 309-spherical block. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0016] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0017] like Figure 1-2As shown, an underwater robot used for hull crack monitoring includes a bionic tension leg 1 and a trunk body 2, the bionic tension leg 1 includes a main support leg 101 and a secondary support leg 102, one end of the main support leg 101 is hinged to the secondary support leg 102, and the other end of the main support leg 101 is hinged to the trunk body 2, the bionic tension leg 1 provides outward tension through an elastic support rod 103, and provides inward tension through a tension cable 104, the trunk body 2 includes a steering gear 207 and a power supply 211, the steering gear 207 synchronously controls four rollers, the rollers are connected to the tension cable 104, the steering gear 207 retracts and releases the length of the tension cable 104 to control the movement of the bionic tension leg 1, the power supply 211 is installed on the bottom plate in the middle of the trunk body 2, the power supply 211 is connected to the receiver 213 through the electric adjustment 212, and the receiver 213 is respectively connected to the steering gear 207 and the gas generation device The device 201 is connected to the crack detection module 217, there are four groups of bionic tension legs 1, each group of bionic tension legs 1 is located on both sides of the trunk body 2, the movement directions of the bionic tension legs 1 in the same group are the same, and the adjacent bionic tension legs 1 on the same side move in opposite directions, the main support leg 101 and the auxiliary support leg 102 are arc-shaped, the main support leg 101 and the auxiliary support leg 102 are hollow inside, and a spherical walking foot 105 is installed at the end of the auxiliary support leg 102, the middle part of the auxiliary support leg 102 is hinged to one end of the elastic support rod 103, and the other end of the elastic support rod 103 is fixed to the trunk body 2, one end of the tension cable 104 is connected to the end of the auxiliary support leg 102, and the other end of the tension cable 104 passes through the trunk body 2 and is connected to the roller; the crack detection module 217 is arranged on the side and top of the trunk body 2, and is used for crack monitoring of the side and bottom of the hull. In addition, the underwater robot of the present invention is provided with an air bag inside. When walking in water or underwater, the buoyancy is controlled by controlling the size of the air bag as a common means in the prior art. There is no need to describe the structure in detail in this application. In addition, the posture adjustment of the underwater robot in water should also be a means frequently used in the prior art, such as driving by setting a movable water jet pump so that the underwater robot can move freely in the water. The main inventive point of the present invention lies in the bionic structure and the improvement of the monitoring of cracks on the bottom of the ship when walking on soft underwater terrain. In addition, the structure of the crack detection module located at the top of the trunk body is the same as the detection module located at the side end of the trunk body, which will not be described in detail here.

[0018] like Figure 3As shown, a crack detection module 217 is installed at the front end of the trunk body 2, and an airbag 218 is installed at the rear end of the trunk body 2. The airbag 218 is connected to the trunk body 2 through a cylindrical fixing nut 203. The airbag 218 passes through the interior of the fixing nut 203 through a ventilation tube 202 and is connected to the gas generating device 201. The gas generating device 201 is installed on the inner wall of the rear side of the trunk body 2, the power supply 211 is fixed to the middle part of the inner bottom plate of the trunk body 2, the electric regulator 212 and the receiver 213 are fixed above the power supply 211, and the servo 207 is installed on both sides of the power supply 211. A gear 1 209 is installed on the side of the servo 207 close to the crack detection module 217, and rollers 1 208 and rollers 2 210 are meshed on both sides of the gear 1 209. Roller 1 208 winds up the tension cable 104 on the left side from the top, and roller 2 210 winds up the tension cable 104 on the right side from the top. A gear 2 206 is installed on the side of the servo 207 close to the airbag 218, and rollers 3 204 and rollers 4 205 are meshed on both sides of the gear 206. Gear 2 206 winds up the tension cable 104 on the left side from the bottom, and rollers 3 204 winds up the tension cable 104 on the right side from the bottom.

[0019] like Figure 4 As shown, the underwater robot includes a bionic tension leg 1, a trunk body 2, a fixing mechanism 3 and a hull 4. A spherical stopper 214 is installed at the center of the bottom surface of the trunk body 2. The spherical stopper 214 is hollow inside and has a circular opening. A conical top block 215 is installed at the center of the inner circle of the spherical stopper 214. A top pin 216 is installed on the top of the conical top block 215. A slideway is provided inside the conical top block 215 for the top pin 216 to slide. The bottom of the top pin 216 is elastically connected to the bottom of the conical top block 215.

[0020] like Figure 5-7As shown, the fixed base 301 is fixed to the side of the hull 4, the fixed base 301 is columnar, the fixed base 301 is hollow inside, a spring 303 is installed on the side of the fixed base 301 close to the trunk body 2, a slide tube 306 is installed inside the spring 303, one end of the slide tube 306 is fixed to the inner bottom of the fixed base 301, and the other end of the slide tube 306 extends toward the trunk body 2, the slide tube 306 is hollow inside, and the part of the slide tube 306 located inside the fixed base 301 is provided with a cross-shaped opening, a magnetic slider 308 is installed inside the slide tube 306, and the end of the magnetic slider 308 close to the side of the hull 4 is The end of the magnetic slider 308 is provided with a spring 2 305, which passes through the openings on the left and right sides of the slide tube 306 and is fixed to the bottom of the fixed base 301. The wedge-shaped slider 307 passes through the upper and lower sides of the slide tube 306 and cooperates with the magnetic slider 308. The top of the wedge-shaped slider 307 is provided with a spring 304, and the top of the spring 304 is fixed to the inner wall of the fixed base 301. The pull ring 302 passes through the fixed base 301 and is connected to the top of the wedge-shaped slider 307. The protruding end of the slide tube 306 is hinged to the spherical block 309, and the spherical block 309 is provided with a slope surface near the opening of the conical top block 215.

[0021] In this embodiment, by means of lightweight processing, elastic struts 103 and tension cables 104 are used to simulate the leg movement principle of jumping spiders, thereby reducing the weight of the bionic exploration robot and reducing the complexity of the bionic tension leg; the control of the leg joints is integrated into the trunk body 2 through the tension cable 104, thereby avoiding short circuit and disconnection failure of the bionic tension leg 1 due to a humid or dusty environment, and improving the air tightness of the control device; the servo 207 controls the bionic tension leg 1 to operate synchronously through different combinations of rollers and four tension cables 104, thereby reducing the control difficulty of the bionic exploration robot; the fixing mechanism 3 can quickly disassemble the spherical limiter 214 and the spherical block 309 through the cooperation of the magnetic slider 308 and the ejector pin 216, and the device can be ejected through the spring, thereby realizing convenient carrying and deployment of the bionic robot; the bionic exploration robot adopts a spider-like appearance, and when the specified exploration work is completed, the airbag 218 is inflated, and the robot is floated to the surface through the inflated airbag 218 at the tail, so as to realize repeated recycling.

[0022] As another embodiment of the present invention, Figure 8As shown, the elastic support rod 103 is replaced by a circular spring 106, which is installed at the hinge of the main support leg 101 and the auxiliary support leg 102 to provide outward tension for the bionic tension leg 1. The main support leg 101 and the trunk body 2 are set to be fixed, one end of the tension cable 104 is connected to the middle of the auxiliary support leg 102, and the other end of the tension cable 104 passes through the connection point in the middle of the main support leg 101 and is connected to the corresponding roller inside the trunk body. The tension cable 104 and the main support leg 101 connection point are connected to achieve free sliding through the pulley. The movement of the auxiliary support leg 102 is controlled by the balance of the two forces of the tension cable 104 and the circular spring 106. When the roller retracts the tension cable 104, the tension cable 104 pulls the middle of the auxiliary support leg 102, thereby realizing the movement of the bionic tension leg 1.

[0023] In this embodiment, the elastic support rod 103 is replaced by a circular spring 106, and the tension cable 104 is brought closer to the main support leg 101 and the auxiliary support leg 102, thereby increasing the space of the inner curved part of the bionic tension leg and improving the ability of the bionic tension leg 1 to cross obstacles in complex environments.

[0024] A detection method of an underwater robot used for hull crack monitoring Figure 1-7 As shown, the following steps are included: Step a, align the opening of the spherical stopper 214 at the bottom of the underwater robot with the spherical block 309, and use the trunk body 2 to press the spring 1 303. Under the pressure, the conical top block 215 pushes the spherical block 309 open and slides along the spherical stopper 214. When the spherical block 309 opens to the maximum angle, the ejector pin 216 is sucked out by the magnetic slider 308 and the two spherical blocks 309 are clamped. The hull 4 carries the underwater robot to the designated sea area. Step b, after reaching the designated sea area, pull the pull ring 302 upwards and slide the wedge-shaped slider 307 upwards. Under the action of the second spring 305, the magnetic slider 308 slides along the slide tube 306 to the bottom of the fixed base 301. The ejector pin 216 loses the magnetic attraction of the magnetic slider 308 and retracts into the conical ejector block 215. Under the action of the first spring 303, the spherical block 309 escapes from the spherical stopper 214, and the underwater robot is ejected into the water. Step c, after the underwater robot falls into the water, the bionic tension leg 1 is controlled to move by the steering gear 207. When the gear 1 209 and the gear 2 206 rotate clockwise, the roller 1 208 rotates counterclockwise and releases the tension cable 104. Under the action of the elastic strut 103, the bionic tension leg 1 connected to the roller 1 208 extends out, the roller 2 210 rotates counterclockwise and retracts the tension cable 104, so that the bionic tension leg 1 connected to the roller 2 210 is retracted, the gear 3 204 rotates counterclockwise and retracts the tension cable 104, so that the bionic tension leg 1 connected to the gear 3 204 is retracted, the roller 4 205 rotates counterclockwise and releases the tension cable 104, so that the bionic tension leg 1 connected to the roller 4 205 extends out, so that the four groups of bionic tension legs 1 perform reciprocating motion synchronously; Step d, when the underwater robot moves to the designated area, the crack detection module is controlled by the receiver to detect the bottom of the ship. After data collection is completed, the gas generating device 201 generates nitrogen and inflates the airbag 218. The airbag 218 expands and brings the underwater robot back to the surface.

[0025] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the above description is only for explaining the principles of the present invention, and that various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and these changes and improvements all fall within the scope of the present invention claimed for protection.

[0026] The protection scope of the present invention is defined by the following claims and their equivalents.

Claims

1. An underwater robot used for hull crack monitoring, Features: The bionic tension leg (1) comprises a bionic tension leg (1) and a trunk body (2), wherein the bionic tension leg (1) comprises a main support leg (101) and a secondary support leg (102), wherein one end of the main support leg (101) is hinged to the secondary support leg (102), and the other end of the main support leg (101) is hinged to the trunk body (2), and the bionic tension leg (1) provides outward tension through an elastic support rod (103) and provides inward pulling force through a tension cable (104); The trunk body (2) comprises a steering gear (207) and a power supply (211), the steering gear (207) synchronously controlling four rollers, the rollers being connected to the tension cable (104), the steering gear (207) retracting and releasing the length of the tension cable (104) to control the movement of the bionic tension leg (1), the power supply (211) being installed inside the trunk body (2), the power supply (211) being connected to a receiver (213) via an electric regulator (212), the receiver (213) being connected to the steering gear (207), the gas generating device (201) and the crack detection module (217) respectively, and the crack detection module (217) being arranged at the front end and the top end of the trunk body (2).

2. An underwater robot for monitoring hull cracks as claimed in claim 1, Features: There are four groups of bionic tension legs (1), each group of bionic tension legs (1) is located on both sides of the trunk body (2), the bionic tension legs (1) in the same group move in the same direction, and the adjacent bionic tension legs (1) on the same side move in opposite directions.

3. An underwater robot for monitoring hull cracks as claimed in claim 2, Features: The main support leg (101) and the auxiliary support leg (102) are arc-shaped, the main support leg (101) and the auxiliary support leg (102) are hollow inside, a spherical walking foot (105) is installed at the end of the auxiliary support leg (102), the middle part of the auxiliary support leg (102) is hinged to one end of an elastic support rod (103), the other end of the elastic support rod (103) is fixed to the trunk body (2), one end of the tension cable (104) is connected to the end of the auxiliary support leg (102), and the other end of the tension cable (104) passes through the trunk body (2) and is connected to a roller.

4. An underwater robot for monitoring hull cracks as claimed in claim 3, Features: The front end and top end of the trunk body (2) are equipped with a crack detection module (217), the rear end of the trunk body (2) is equipped with an air bag (218), the air bag (218) is connected to the trunk body (2) via a cylindrical fixing nut (203), the air bag (218) passes through the inside of the fixing nut (203) via a ventilation tube (202) and is connected to a gas generating device (201), the gas generating device (201) is installed on the inner wall of the rear side of the trunk body (2), the power supply (211) is fixed to the middle part of the inner bottom plate of the trunk body (2), the electric regulator (212) and the receiver (213) are fixed above the power supply (211), and the steering gear (207) is installed on both sides of the power supply (211).

5. An underwater robot for monitoring hull cracks as claimed in claim 4, Features: The steering gear (207) is provided with a gear 1 (209) on one side close to the crack detection module (217), and the gear 1 (209) is meshed with roller 1 (208) and roller 2 (210) on both sides, and the roller 1 (208) winds up the tension cable (104) on the left side from the top, and the roller 2 (210) winds up the tension cable (104) on the right side from the top, and the steering gear (207) is provided with a gear 2 (206) on one side close to the airbag (218), and the gear 2 (206) is meshed with roller 3 (204) and roller 4 (205) on both sides, and the gear 2 (206) winds up the tension cable (104) on the left side from the bottom, and the roller 3 (204) winds up the tension cable (104) on the right side from the bottom.

6. An underwater robot for monitoring hull cracks as claimed in claim 5, Features: A spherical stopper (214) is installed at the center of the bottom surface of the trunk body (2); the spherical stopper (214) is hollow inside and has a circular opening; a conical top block (215) is installed at the center of the inner circle of the spherical stopper (214); a top pin (216) is installed at the top of the conical top block (215); a slideway is provided inside the conical top block (215) for the top pin (216) to slide; and the bottom of the top pin (216) is elastically connected to the bottom of the conical top block (215); The fixing mechanism (3) comprises a fixing base (301), wherein the fixing base (301) is fixed to the side of the hull (4), the fixing base (301) is columnar, the fixing base (301) is hollow inside, a spring 1 (303) is installed on a side of the fixing base (301) close to the trunk body (2), a sliding tube (306) is installed inside the spring 1 (303), one end of the sliding tube (306) is fixed to the inner bottom of the fixing base (301), the other end of the sliding tube (306) extends toward the trunk body (2), the sliding tube (306) is hollow inside, the part of the sliding tube (306) located inside the fixing base (301) is provided with a cross-shaped opening, a magnetic slider (308) is installed inside the sliding tube (306), and the magnetic slider (3 08) The end of the side close to the hull (4) is a sloped surface, and the end of the magnetic slider (308) is installed with a spring 2 (305), and the spring 2 (305) passes through the openings on the left and right sides of the slide tube (306) and is fixed to the bottom of the fixed base (301). The wedge-shaped slider (307) passes through the upper and lower sides of the slide tube (306) and cooperates with the magnetic slider (308). The top of the wedge-shaped slider (307) is installed with a spring 3 (304), and the top of the spring 3 (304) is fixed to the inner wall of the fixed base (301). The pull ring (302) passes through the fixed base (301) and is connected to the top of the wedge-shaped slider (307). The protruding end of the slide tube (306) is hinged to the spherical block (309), and the spherical block (309) is provided with a sloped surface near the opening of the conical top block (215).

7. An underwater robot detection method for hull crack monitoring, using an underwater robot for hull crack monitoring according to any one of claims 1 to 6, The following steps are involved: Step a, aligning the opening of the spherical stopper (214) at the bottom of the bionic exploration robot with the spherical clamping block (309), pressing the spring 1 (303) with the trunk body (2), and under the action of pressure, the conical top block (215) pushes the spherical clamping block (309) open and slides along the spherical stopper (214), when the spherical clamping block (309) is opened to the maximum angle, the top pin (216) is sucked out by the magnetic slider (308) and the two spherical clamping blocks (309) are clamped, and the hull (4) carries the underwater robot to the sea area of ​​the hull to be monitored; Step b, after arriving at the designated sea area, the pull ring (302) is pulled up and the wedge-shaped slider (307) is slid upward, and under the action of the second spring (305), the magnetic slider (308) slides along the slide tube (306) toward the bottom of the fixed base (301), and the ejector pin (216) retracts into the conical ejector block (215) after losing the magnetic attraction of the magnetic slider (308), and under the action of the first spring (303), the spherical clamping block (309) escapes from the spherical stopper (214), and the underwater robot is ejected into the water; Step c, after the underwater robot falls into the water, the bionic tension leg (1) is controlled to move by the steering gear (207). When the gear 1 (209) and the gear 2 (206) rotate clockwise, the roller 1 (208) rotates counterclockwise and releases the tension cable (104). Under the action of the elastic support rod (103), the bionic tension leg (1) connected to the roller 1 (208) extends, and the roller 2 (210) rotates counterclockwise and retracts the tension cable (104). 4), the bionic tension leg (1) connected to the second roller (210) is retracted, the gear three (204) rotates counterclockwise and retracts the tension cable (104), so that the bionic tension leg (1) connected to the third gear (204) is retracted, the roller four (205) rotates counterclockwise and releases the tension cable (104), so that the bionic tension leg (1) connected to the fourth roller (205) is extended, so that the four groups of bionic tension legs (1) perform reciprocating motion synchronously; Step d, when the underwater robot moves to the designated area, the receiver (213) controls the crack detection module (217) to perform environmental detection. After data collection is completed, the gas generation device (201) generates nitrogen and inflates the airbag (218). The airbag (218) expands and brings the underwater robot back to the surface.

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