A biomimetic octopus-inspired underwater pipe welding robot

Abstract

This invention provides a biomimetic octopus-inspired underwater pipeline welding robot, belonging to the field of robotics technology. The main structure adopts a semi-elliptical spherical pressure-resistant shell, with an internal reinforced support frame and a pneumatic bistable device. The pneumatic bistable device drives a water jet propulsion unit, enabling the robot's multi-degree-of-freedom movement. The robotic arm system includes multi-joint robotic arms evenly arranged around the main structure. Each multi-joint robotic arm includes multiple joints, a flexible telescopic rod, and a biomimetic vacuum suction cup. The joints are connected non-linearly. The end of the multi-joint robotic arm is equipped with a biomimetic vacuum suction cup. An SMA actuator is installed within the flexible telescopic rod. The contraction of the SMA actuator generates an eccentric driving force, enabling vertical position control and spatial bending motion of the biomimetic vacuum suction cup. The end of the multi-joint robotic arm can be modularly replaced with a welding module for performing underwater pipeline welding operations.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to a biomimetic octopus-inspired underwater pipeline welding robot. Background Technology

[0002] Common methods for repairing subsea pipelines include pipe fitting compensation kits, water curtain-type local dry welding, and movable gas chamber welding. Pipe fitting compensation kits can quickly cover damaged pipe fittings, but are not economical for repairing small damages. Water curtain-type local welding creates a stable local gas phase cavity within the water curtain, but requires precise welding positioning and automation. Movable gas chambers create a gas cavity underwater, offering high welding quality but are susceptible to welding fumes. Commonly used pipeline welding methods in China include high-pressure dry welding and pipeline lifting. High-pressure dry welding offers high welding quality but is expensive and has a complex preparation process. Pipeline lifting can raise the pipeline above the water surface for repairs, but requires high pipeline flexibility and is greatly affected by water depth.

[0003] While underwater pipeline welding technology has made significant progress, the focus remains primarily on research into welding methods and operational processes. The application of robotic automation and artificial intelligence is not widespread. Current pipeline maintenance and subsea pipeline welding repair still rely heavily on manual labor. The mainstream approach involves using high-pressure chambers to enclose the work area, using high pressure to expel water and create a high-pressure space underwater where welders perform their work. However, this equipment is extremely expensive, requires regular pressure chamber replacements, and has a long installation time. Therefore, in emergency situations, underwater welding operators must work directly in seawater, posing significant risks and increasing the risk of electric shock, explosions, burns, drowning, crush injuries, decompression sickness, or suffocation. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a biomimetic octopus-inspired underwater pipe welding robot, comprising: a main structure and a robotic arm system;

[0005] The main structure adopts a semi-elliptical spherical pressure-resistant shell, with an internal reinforced support frame and a pneumatic bistable device. The pneumatic bistable device is used to drive the water jet propulsion unit to realize the robot's multi-degree-of-freedom movement.

[0006] The robotic arm system includes multi-joint robotic arms, which are evenly arranged around the main structure. Each multi-joint robotic arm includes multiple joints, a flexible telescopic rod, and a bionic vacuum suction cup. The joints are connected by a non-linear connection. The bionic vacuum suction cup is located at the end of the multi-joint robotic arm. The flexible telescopic rod contains an SMA actuator. The flexible telescopic rod generates an eccentric driving force through the contraction of the SMA actuator, realizing the vertical position control and spatial bending motion of the bionic vacuum suction cup.

[0007] The multi-joint robotic arm has a modularly replaceable welding module at its end, which is used to perform subsea pipeline welding operations.

[0008] Furthermore, by controlling the contraction of the SMA filament through electrical heating, the SMA actuator is parallel to but not coincident with the central axis of the flexible telescopic rod, and the flexible deformation of the flexible telescopic rod is achieved through the SMA brake.

[0009] 3. The biomimetic octopus underwater pipeline welding robot according to claim 2, characterized in that multiple sets of SMA wires are placed in the flexible telescopic rod structure and arranged around the central axis, and the three sets of SMA wires embedded in each set of suction cup telescopic rod structure are evenly and symmetrically arranged about the central axis, and the angle between the line connecting every two sets of SMA wires and the central axis is 120 degrees.

[0010] Furthermore, the dynamic equations of the nonlinear two-segment robotic arm system are established:

[0011]

[0012] m1 and m2 are the masses of robotic arm 1 and robotic arm 2, respectively; l1 and l2 are the lengths of robotic arm 1 and robotic arm 2, respectively; θ1 and θ2 are the generalized coordinates of robotic arm 1 and robotic arm 2; g is the acceleration due to gravity; c1 and c2 are coefficients related to the motion damping of robotic arm 1 and robotic arm 2; F1 is the amplitude of the external force acting on robotic arm 1; ω1 and ω2 are the angular frequencies of the external forces F1 and F2, respectively.

[0013] The electrical control of the upper joints by the main body is remotely fed back to the terminal computer to obtain the motion demonstration trajectory of the robotic arm's end effector.

[0014] Furthermore, binocular stereo vision correction technology is used to image a point P(x,y,z) in the weld. During imaging, the image passes through a coordinate system (X... W Y W Z W ), camera coordinate system (X) C Y C Z C Multiple transformations are performed between the image physical coordinate system (O-xy) and the image pixel coordinate system (u, v). After the transformation, the following is obtained:

[0015]

[0016] Where: m x f x The equivalent focal length of the camera in the u direction, m y f y The equivalent focal length of the camera in the v direction; M1 is the intrinsic parameter matrix of the camera, M2 is the extrinsic parameter matrix of the camera, the rotation matrix is ​​R, and the translation vector is T.

[0017] Furthermore, by varying the positions of the tentacles, different flow shapes are obtained, which, in conjunction with the lateral thrust, enable multi-degree-of-freedom movement. The optimal navigation attitude is then determined through ANSYS finite element analysis.

[0018] Furthermore, when the bionic vacuum suction cup adsorbs an object, the muscle tissue of the bionic vacuum suction cup wall begins to contract, and the wrinkles at the edge gradually unfold, causing the bionic vacuum suction cup to gradually extend and open from its original natural state, adhering to the surface of the object. By increasing the perimeter of the edge, the area of ​​adhesion between the suction cup and the object is increased, and it is completely adhered to the surface of the object.

[0019] Furthermore, the outer shell is made using a T700CF / epoxy resin composite material reinforced with activated carbon nanotubes.

[0020] Furthermore, the robotic arm joints are supported by lightweight thin-walled bearings with a central hole inside. The wiring channels inside the robotic arm pass directly through the central hole inside the thin-walled bearing, and the drive and control circuits of the robotic arm pass through the central hole inside the thin-walled bearing.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. A four-segment high-degree-of-freedom vacuum suction cup robotic arm based on the movement of octopus tentacles and the fixation mechanism of suction cups was designed. By using an elastic telescopic suction cup device made of muscle material, the fixation problem on multi-curvature surfaces was solved. The tentacles have four segments. Based on the principle that octopuses use muscle contraction to expel water from the suction cup, creating a pressure difference between the inside and outside of the suction cup to generate suction, the relative position of the suction cup can be controlled by changing the structure of the muscle material to adapt to different curved surfaces under different working conditions and achieve underwater fixation.

[0023] 2. An octopus-inspired water jet propulsion device based on a pneumatic bistable device was proposed, which successfully solved the problem of insufficient propulsion capacity. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the robot system structure;

[0025] Figure 2Finite element analysis using Abaqus;

[0026] Figure 3 It is a two-bar linkage robotic arm;

[0027] Figure 4 This is a structural model of the robotic arm system;

[0028] Figure 5 DH model diagram of a multi-joint robotic arm;

[0029] Figure 6 This is a side view of the robotic arm's suction cup.

[0030] Figure 7 This is a model diagram of a wrinkled suction cup;

[0031] Figure 8 ANSYS finite element analysis of the head structure;

[0032] Figure 9 Comparison of streamlines at different mechanical tentacle positions;

[0033] Figure 10 This is a side view;

[0034] Figure 11 This is a picture of the actual product.

[0035] Figure 12 The distribution of SMA wires inside the flexible telescopic rod SMA actuator. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0037] Example 1

[0038] System design principles and structural design

[0039] The robot system design is divided into two main modules: the design of the main body module and the design of the robotic arm system, including the overall navigation performance and propulsion principle. In the main body module design phase, the shape and pressure resistance of the main body will be analyzed, and its materials, forming methods, and connection methods will be designed. In the robotic arm design phase, the control system, structure, suction cup design, welding principle design, and image information recognition system will be designed. For the overall design, finite element method (FEM) software will be used to analyze the streamline morphology under different postures. The overall structure is as follows: Figure 1 As shown.

[0040] The robot is equipped with a reinforced support frame and a pneumatic bistable device, which drives the water jet propulsion system to enable the robot to move with multiple degrees of freedom.

[0041] The propulsion principle of an octopus is actually a recoil motion, a phenomenon where, under the influence of internal forces, when the momentum of one part of the system changes in a certain direction, the momentum of the remaining part changes by the same magnitude in the opposite direction. If the system consists of two parts, and the total momentum is zero before the interaction, the octopus draws water into its mantle, breathes, and then expels the water through a short, funnel-shaped tube. The powerful jet of water propels it rapidly in the opposite direction.

[0042] The principle of water jet propulsion driven by a pneumatic bistable device is as follows: First, a bistable drive device is fabricated. This device jumps with the periodic on and off of gas, causing the water-repellent film to reciprocate, resulting in changes in the robot's internal volume. Second, by adjusting the drive frequency of the bistable device, the robot can rapidly spray water and slowly absorb water, creating a momentum difference that propels the robot forward. An elastic substrate with a certain bending stiffness is bent and deformed by external structural compression to position one, accumulating potential energy due to its own bending. When an external force is applied to the pre-bent elastic substrate, reaching a critical value that the substrate can withstand, the substrate will jump to position two.

[0043] In a preferred embodiment, the image information recognition system employs binocular stereo vision correction. Binocular stereo vision correction technology uses two cameras to capture images of the object under test from different poses, then calculates the disparity of corresponding pixels in the images captured by the two cameras, finally converting the image information from two-dimensional space to three-dimensional space. Simultaneously capturing weld seam images from different angles and measuring weld seam depth and other information features, the binocular camera is calibrated using Matlab to obtain camera parameters, and stereo correction is achieved through the Bouguet algorithm to improve the accuracy of weld seam recognition and measurement. When using binocular stereo vision correction technology, it is necessary to image a point P(x,y,z) in the weld seam. Image formation requires traversing a coordinate system (X,y,z) from the world coordinate system (X,y,z). W ,Y W Z W ), camera coordinate system (X) C ,Y C Z C Multiple transformations are performed between the image physical coordinate system (O-xy) and the image pixel coordinate system (u,v). The result after transformation is:

[0044]

[0045] Where: m x f x The equivalent focal length of the camera in the u direction, my f y The equivalent focal length of the camera in the v direction; the intrinsic parameter matrix of camera M1; and the extrinsic parameter matrix of camera M2. During the above transformation process, the lens focal length f and image center position (u0, v0) in the camera's intrinsic parameter matrix M1, as well as the rotation matrix R and translation vector T in the extrinsic parameter matrix M2, all affect the accuracy of the image. Two factors have the greatest impact: 1. Radial distortion caused by irregular changes in the radial curvature of the lens; 2. Tangential distortion caused by the misalignment between the geometric center and optical center of the lens. Therefore, it is necessary to use the camera's distortion coefficients and calculation formulas to correct image distortion.

[0046] Based on the pressure-resistant principle of octopuses, a semi-ellipsoidal shell was designed, and reinforcing materials were used to create partitions within the shell. The design was modeled using Abaqus finite element analysis software to simulate its compressive deformation under 100 atmospheres of pressure. Figure 2 As shown, the simulation results with a supporting frame (right) are compared with those without a supporting frame (left). The results show that after the supporting frame material is installed, the deformation of the main body under pressure is significantly reduced, the usable area is significantly increased, and the displacement of the outer shell anchor point is significantly reduced.

[0047] Activated carbon nanotubes can significantly reduce the surface tension of epoxy resin and improve its wettability on T700 carbon fibers, while having little effect on viscosity. The surface energy of the resin gradually decreases with increasing temperature. This is because surface energy is essentially an intermolecular interaction, and intermolecular interactions weaken with increasing temperature; therefore, the surface energy of a liquid generally decreases with rising temperature. Thus, the wettability of the resin on the fiber increases with increasing temperature. However, since increasing temperature may lead to a decrease in the resin's pot life and a reduction in resin content, a suitable processing temperature is determined by considering all three factors. It can also be seen that adding 0.5% (by mass) of activated carbon nanotubes significantly reduces the surface energy of the resin. The high rigidity of the carbon nanotubes prevents crack propagation when they encounter cracks, and the addition of activated carbon nanotubes significantly improves the wettability of the epoxy resin on the carbon fibers, thus significantly improving the interlaminar shear properties of the composite material.

[0048] Using a T700CF / epoxy resin composite material reinforced with activated carbon nanotubes to make the outer shell can better improve the shell's pressure resistance and prevent implosion and cracking problems.

[0049] Because the pressure hull needs to operate in deep water, it must have excellent sealing properties to prevent water from entering and damaging the items placed inside. Therefore, appropriate joining techniques are required to connect the composite materials and metal components into a single unit. Joining techniques include mechanical joining, adhesive joining, and hybrid joining methods.

[0050] Example 2

[0051] Robotic arm control and functional system

[0052] (1) Kinematic analysis of underwater multi-joint robotic arm

[0053] The overall robotic arm system comprises eight multi-joint robotic arms, each connected by a non-linear four-joint mechanism. Since the multi-joint underwater robotic arms require connecting adjacent links via joints, a two-linkage robotic arm is used as a demonstration model for kinematic analysis of its degrees of freedom. The mechanical model is as follows: Figure 3 As shown, the connecting rod is a uniform straight rod with a constant cross-section, m1 and m2 are the masses of robotic arm 1 and robotic arm 2, respectively, l1 and l2 are the lengths of the two robotic arms, θ1 and θ2 are generalized coordinates, and g is the acceleration due to gravity.

[0054] Using the Lagrange method to establish its motion differential equations, the dynamic model of the robotic arm system can be expressed as:

[0055]

[0056] In the above formula, Q1 and Q z For generalized forces, which include external loads and system damping forces, the fourth-order nonlinear term and the third-order nonlinear term in the gravity term are omitted here for ease of calculation. Thus, the dynamic equations of this nonlinear two-section robotic arm system are obtained as follows:

[0057]

[0058] Comparing the analytical and numerical solutions obtained by the multi-scale method, the two solutions show high agreement accuracy. It is also revealed that the multi-joint robotic arm system is affected by external excitation, damping, and nonlinear terms during operation. According to linear vibration theory, when the external excitation induces principal resonance in the robotic arm system, the system's motion amplitude will change abruptly with variations in excitation amplitude and frequency. Under low-frequency resonance, the system amplitude is larger and less prone to instability. Therefore, the interlocking connections between the multi-joint robotic arms can ensure degrees of freedom, and under low-frequency resonance, the required functions can be achieved while maintaining stability.

[0059] By solving the inverse kinematics model of the multi-joint underwater manipulator using reference coordinate system transformation and matrix array calculations, it can be seen that the position of the end joint of the underwater manipulator changes through the rotation angle of other joints. Therefore, when the vehicle is operating underwater, the electrical control of the upper end joints by the main body can be remotely fed back to the terminal computer to obtain the motion demonstration trajectory of the manipulator's end, thus enabling the end to meet the functional requirements of cutting, welding, etc.

[0060] like Figure 4 As shown, the design of the robotic arm's mechanical system needs to meet a series of requirements, including compact structure, light weight, and decoupling within its own structure. In the robotic arm system structure designed for the aircraft, the main body serves as the power source for the robotic arm's base joints, directly driving the joints of robotic arm 1 and robotic arm 2 to achieve rotation and adsorption functions. The overall robotic arm joints are supported by lightweight thin-walled bearings. The thin-walled bearings have a large central hole inside, allowing the wiring channels inside the robotic arm to pass directly through the central hole. The drive and control circuits of the robotic arm pass through the central hole inside the thin-walled bearings, ensuring both safe operation of the robotic arm and a lightweight and aesthetically pleasing overall design.

[0061] Example 3

[0062] Suction Cup System Principle

[0063] (1) Bionic principle of suction cup telescopic rod

[0064] The spacecraft is modeled after an octopus, and the design of the suction cup telescopic rod on the robotic arm is based on the muscular tissue structure of the octopus's arm—a muscular hydrostatic skeleton. A significant feature of the muscular hydrostatic skeleton is that its internal structure is almost entirely composed of tightly packed muscle tissue. This dense array of muscle fibers is also incompressible, meaning it has volume invariance.

[0065] Octopus arms can achieve flexible bending and deformation movements in space, mainly due to three important biological characteristics: ① The longitudinal muscle fibers of the octopus arm must be parallel but not coincident with the geometric central axis of the octopus arm; ② The longitudinal muscle fibers of the octopus arm can contract freely to generate driving force; ③ The other muscle tissues of the octopus arm cooperate with each other to maintain the volume stability of the octopus arm.

[0066] The intelligent material SMA exhibits a characteristic of actively contracting when heated, similar to the muscle fibers of an octopus's arm. When used in biomimetic fabrication, it can achieve flexible deformation of a telescopic rod by cooperating with an SMA actuator. The SMA actuator is a novel intelligent material actuator that integrates driving, sensing, and energy storage. When embedded inside a flexible telescopic rod, it can simulate the longitudinal muscle fibers distributed inside the muscle body of an octopus's arm. Its advantages are: ① The controller in the main body can control its extension and contraction by transmitting current; ② It has extremely high restoring stress, which can provide sufficient driving force for the deformation movement of the flexible telescopic rod.

[0067] (2) Internal materials and design of the suction cup telescopic rod

[0068] Inside each section of the flexible suction cup telescopic rod, the SMA actuator is parallel to but not coincident with the central axis of the flexible telescopic rod base. When the SMA actuator contracts, it simulates the contraction of the longitudinal muscles of an octopus's arm, generating an eccentric driving force. Because the point of application of this driving force is offset from the central axis, it produces a bending moment on the flexible suction cup telescopic rod. This allows the flexible telescopic rod to achieve vertical position control of the suction cup, facilitating suction cup adhesion on curved surfaces, and also to exhibit a bending motion in space, increasing the translational range of motion of the suction cup. Figure 9 As shown.

[0069] Meanwhile, to achieve the goal of bending in any direction in space, the flexible telescopic rod structure contains multiple sets of SMA wires arranged around the central axis, such as... Figure 12 As shown, the three sets of SMA wires embedded in each suction cup-telescopic rod structure are evenly and symmetrically arranged about the central axis, and the angle between the line connecting each pair of SMA wires and the central axis is 120 degrees.

[0070] Silicone rubber is selected as the flexible telescopic rod because it has a long storage life, is resistant to seawater corrosion, can maintain its performance in low-temperature environments, has a compressive strength of 2.5MPa-4MPa, is not easily compressed, and has flexibility, which can ensure the volume stability and bending requirements of the SMA filaments inside the flexible telescopic rod.

[0071] Underwater suction cup biomimicry and its adsorption principle

[0072] When an octopus's suckers adhere to an object, the muscle tissue of the sucker wall contracts, and the wrinkles at the edge of the sucker gradually unfold, causing the sucker to extend and open from its natural state, attaching itself to the object's surface. The increased perimeter of the edges increases the area of ​​contact with the object. Under the pressure of the sucker's arms, the extended sucker deforms according to the shape of the glass surface under the gradually increasing squeezing force. The combined effect of the suction force from the outer wall of the sucker and the pressure from the arms causes the wrinkles on the sucker's surface to expand, completely adhering to the object's surface, such as... Figure 12 As shown.

[0073] Silicone rubber is used as the material for the suction cups. When the silicone rubber suction cups are used for underwater adsorption, the adsorption position is first determined by a flexible telescopic rod, then the suction cup is pressed down, squeezing out seawater from inside the cup. Residual seawater and cavitation are then removed by a negative pressure vacuum gun at the top of the suction cup, creating a vacuum zone. The suction cups are continuously adhered until they are completely adsorbed onto the object's surface. Figure 7 As shown.

[0074] Example 4

[0075] navigation attitude control principle

[0076] Different flow profiles are achieved by varying the positions of the tentacles, which, in conjunction with the lateral thrusters, enable multi-degree-of-freedom movement. ANSYS finite element analysis demonstrates the excellent navigation performance of the nose structure. Figure 8 The top left image is the fluid velocity vector diagram, and the top right image is the head pressure diagram.

[0077] Regarding the attitude problem of mechanical tentacle structures during navigation, such as Figure 9 The analysis using ANSYS shows a fluid simulation of the robot with its legs spread out on the left. Clearly, significant turbulence is generated behind the legs, increasing drag. The right image shows the legs retracted, indicating a substantial reduction in turbulence and drag. This demonstrates that a smaller gradient at the outer edge of the structure's flow path results in smoother streamlines and lower drag. Therefore, during navigation, the optimal placement of the mechanical tentacle structure is based on a flow path (elliptical shape).

[0078] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A biomimetic octopus-inspired underwater pipe welding robot, characterized in that, include: Main structure and robotic arm system; The main structure adopts a semi-elliptical spherical pressure-resistant shell, with an internal reinforced support frame and a pneumatic bistable device. The pneumatic bistable device is used to drive the water jet propulsion unit to realize the robot's multi-degree-of-freedom movement. The robotic arm system includes multi-joint robotic arms, which are evenly arranged around the main structure. Each multi-joint robotic arm includes multiple joints, a flexible telescopic rod, and a bionic vacuum suction cup. The joints are connected by a non-linear connection. The bionic vacuum suction cup is located at the end of the multi-joint robotic arm. The flexible telescopic rod contains an SMA actuator. The flexible telescopic rod generates an eccentric driving force through the contraction of the SMA actuator, realizing the vertical position control and spatial bending motion of the bionic vacuum suction cup. The end effector of the multi-joint robotic arm can be modularly replaced with a welding module for performing subsea pipeline welding operations; Using binocular stereo vision correction technology, an image is formed of a point P(x, y, z) in the weld. During the imaging process, the image passes through a coordinate system (X... W Y W Z W ), camera coordinate system (X) C Y C Z C Multiple transformations are performed between the image physical coordinate system (O - xy) and the image pixel coordinate system (u, v). After the transformation, the following is obtained: ； Where: m x f x The equivalent focal length of the camera in the u direction, m y f y The equivalent focal length of the camera in the v direction; Let be the intrinsic parameter matrix of the camera. Let R be the extrinsic parameter matrix of the camera, R be the rotation matrix, and T be the translation vector. Establish the dynamic equations of the nonlinear two-segment robotic arm system: ； ； and The masses of robotic arm 1 and robotic arm 2 are respectively. and These are the lengths of robotic arm 1 and robotic arm 2, respectively. and Let g be the generalized coordinates of robotic arm 1 and robotic arm 2; g is the acceleration due to gravity. The coefficient is related to the motion damping of robotic arm 1 and robotic arm 2; F1 is the amplitude of the external force acting on robotic arm 1. Let F1 and F2 be the angular frequencies of the external forces. The electrical control of the upper joints by the main body is remotely fed back to the terminal computer to obtain the motion demonstration trajectory of the robotic arm end effector.

2. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 1, characterized in that, The contraction of the SMA wire is controlled by heating with electricity. The SMA actuator is parallel to but not coincident with the central axis of the flexible telescopic rod. The flexible deformation of the flexible telescopic rod is achieved by the SMA brake.

3. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 2, characterized in that, The flexible telescopic rod structure contains multiple sets of SMA wires arranged around the central axis. The three sets of SMA wires embedded in each suction cup telescopic rod structure are evenly and symmetrically arranged about the central axis, and the angle between the line connecting every two sets of SMA wires and the central axis is 120 degrees.

4. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 1, characterized in that, Different flow shapes are obtained by varying the positions of the tentacles, which, in conjunction with the lateral thrust, enable multi-degree-of-freedom movement. The optimal navigation attitude is then obtained through ANSYS finite element analysis.

5. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 1, characterized in that, When the bionic vacuum suction cup adsorbs an object, the muscle tissue of the suction cup wall begins to contract, and the wrinkles at the edge gradually unfold, causing the bionic vacuum suction cup to gradually extend and open from its original natural state, adhering to the object's surface. By increasing the perimeter of the edge, the area of ​​adhesion between the suction cup and the object is increased, allowing it to completely adhere to the object's surface.

6. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 1, characterized in that, The outer shell is made of T700CF / epoxy resin composite material reinforced with activated carbon nanotubes.

7. The biomimetic octopus-inspired underwater pipeline welding robot according to claim 1, characterized in that, The robotic arm joints are supported by lightweight thin-walled bearings. The thin-walled bearings have a central hole inside, and the wiring channels inside the robotic arm pass directly through the central hole inside the thin-walled bearings. The drive lines and control lines of the robotic arm pass through the central hole inside the thin-walled bearings.

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