Dynamic response test method for underwater model of deep sea oil delivery hose

Abstract

The invention relates to the technical field of dynamic response testing, in particular to a dynamic response testing method for an underwater model of a deep sea oil delivery hose. The method comprises the following steps: designing an experimental model of the deep sea oil delivery hose according to a similarity rate, calculating seabed boundary constraint conditions of the bottom end of the hose in an experiment, and equivalently representing the supporting effect of a vertical pipe on the hose in the horizontal direction and the vertical direction by adopting a spring stiffness model; based on technical parameters and sea conditions of the FPSO, hydrodynamic software is adopted to calculate and generate a six-degree-of-freedom movement time history of the robot; the six-degree-of-freedom movement process of the robot platform is input into a robot control system for loading testing; a camera is used for collecting images used for recording all the whole shooting and testing processes. According to the invention, the motion mode of the semi-submersible FPSO can be accurately loaded and reasonably simulated, and the high accuracy of the test result is ensured by optimizing the boundary condition of the hose model.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic impact treatment technology for pipelines, and more specifically, to a method for testing the dynamic response of an underwater model of a deep-sea oil pipeline hose. Background Technology

[0002] When oil pipeline hoses operate at sea, they are subjected to the effects of waves and currents underwater, and the upper part is excited by the motion of the FPSO. Under the combined action of these two factors, what are the magnitudes of the hose's motion, acceleration, and tension? Will the tension become excessive, exceeding the hose's allowable stress and causing damage and breakage? These are crucial for safe oil transportation. Obtaining the hose's motion acceleration and tension is a key technology. Since the hose is located at a deep underwater position, conducting actual measurements is extremely difficult and impossible. Therefore, this paper provides a method for testing the dynamic response of an underwater model of a deep-sea oil pipeline hose. Summary of the Invention

[0003] The purpose of this invention is to provide a dynamic response testing method for underwater models of deep-sea oil pipeline hoses, in order to solve the problem mentioned in the background art of how to accurately obtain the motion, acceleration and tension response of deep-sea hoses in complex marine environments and evaluate their structural safety and reliability.

[0004] To achieve the above objectives, the present invention aims to provide a method for testing the dynamic response of an underwater model of a deep-sea oil pipeline hose, comprising the following steps:

[0005] S1. Design an experimental model of a deep-sea oil pipeline hose based on the similarity rate, and calculate the seabed boundary constraint conditions at the bottom of the hose in the experiment. Use a spring stiffness model to equivalently represent the support effect of the riser on the hose in the horizontal and vertical directions.

[0006] S2. Based on the technical parameters of the FPSO and the sea conditions, hydrodynamic software is used to calculate and generate the robot's six-degree-of-freedom motion time history.

[0007] S3. Input the six-degree-of-freedom motion history of the robot platform into the robot control system for loading test;

[0008] S4. Use a camera to collect images to record the entire shooting test process, and use an image processing program written in MATLAB to process the images and extract the time history data of hose displacement, velocity, and acceleration.

[0009] As a further improvement to this technical solution, in step S1, the seabed boundary constraint conditions at the bottom of the hose in the experiment are calculated, and a spring stiffness model is used to equivalently represent the supporting effect of the riser on the hose in the horizontal and vertical directions, including the following steps:

[0010] S1.1 Determine the similarity parameters and the similarity rate of each similarity parameter;

[0011] S1.2 Calculate the dimensions of the model riser and hose according to the similarity rate;

[0012] S1.3. Spring stiffness is used to represent the effect of the riser on the hose;

[0013] S1.4 Apply the calculated spring stiffness to the cut-off position of the riser in the experimental model.

[0014] As a further improvement to this technical solution, in step S1.3, spring stiffness is used to represent the effect of the riser on the hose, including the following steps:

[0015] S1.31. Based on the actual parameters of the riser and the buoy, as well as the marine environmental conditions, calculate the deformation of the riser under the action of the buoy using the principle of statics.

[0016] S1.32. Divide the riser into several units;

[0017] S1.33. For each riser unit, calculate the relationship between the deformation and internal forces of the unit based on the external forces acting on it.

[0018] S1.34. Through the above calculations, the stiffness matrix of the riser in the two main directions is obtained;

[0019] S1.35. Based on the stiffness matrix results of the riser unit, select the spring stiffness value to simulate the effect of the riser on the hose;

[0020] S1.36. Apply the selected spring stiffness to the design of the riser cut-off position in the experimental model.

[0021] As a further improvement to this technical solution, in step S2, based on the technical parameters of the FPSO and the sea state, hydrodynamic software is used to calculate and generate the robot's six-degree-of-freedom motion time history, including the following steps:

[0022] S2.1 Collect FPSO technical parameters, obtain sea state data, and preprocess the FPSO technical parameters and sea state data;

[0023] S2.2 Select hydrodynamic analysis software and create a three-dimensional model of the FPSO in the collected FPSO technical parameters.

[0024] S2.3 Input the collected wave and water flow parameters into the software and set the simulation time period;

[0025] S2.4 Perform hydrodynamic analysis and calculate the motion response of the FPSO in six degrees of freedom under a given sea state;

[0026] S2.5 Extract the data on the changes of each degree of freedom of the FPSO over time from the analysis results to form the motion time history curves of the six degrees of freedom of the FPSO.

[0027] S2.6. Convert the motion time history of the six degrees of freedom of the FPSO into robot motion control instructions.

[0028] As a further improvement to this technical solution, in step S2.6, the motion time history of the six degrees of freedom of the FPSO is converted into robot motion control instructions, including the following steps:

[0029] S2.61. Use a scaling factor to convert the motion time history of the prototype system into the corresponding value at the model scale;

[0030] S2.62 Determine the positional relationship between the robot platform and the top of the hose;

[0031] S2.63. Establish the inverse kinematics mapping relationship of rigid body motion based on rigid body kinematics, and solve for the motion control commands required by the robot platform;

[0032] S2.64. Based on the solved sequence of motion control instructions for the robot platform, generate specific control signals.

[0033] As a further improvement to this technical solution, in step S2.63, the inverse kinematics mapping relationship of rigid body motion is established based on rigid body kinematics, and the motion control commands required by the robot platform are solved, including the following steps:

[0034] S2.631. Define the position and orientation vectors of the robot platform in the global coordinate system;

[0035] S2.632. Use a rotation matrix to transform the relative position vector from the local coordinate system to the global coordinate system;

[0036] S2.633. The position of the top of the hose is obtained by adding the position of the robot platform to the relative position vector;

[0037] S2.634. Set the motion of the hose tip to be equal to the motion of the FPSO suspension point. Solve the motion control commands required by the robot platform using numerical methods, and generate the relationship between the hose tip and the FPSO suspension point, the relationship between the robot motion and the hose tip, and the relationship between the robot motion and the FPSO suspension point.

[0038] As a further improvement to this technical solution, in S2.633, the numerical method for solving the motion control commands required by the robot platform is as follows:

[0039] X FPSO =X robot +R(θ robot )·rL ;

[0040] In the formula, X FPSO X represents the position vector of the FPSO suspension point; robot R(θ) represents the position vector of the robot platform. robot ) represents the rotation matrix, θ robot r represents the rotation angle of the robot platform about its own axis. L This represents the vector from the robot platform to the tip of the hose;

[0041] To address the additional disturbance caused by waves, an external disturbance term is introduced during the numerical solution process:

[0042] X FPSO1 =X robot +R(θ robot )·r L +d;

[0043] In the formula, d represents the external disturbance term, and X FPSO1 This represents the position vector of the FPSO suspension point after optimization.

[0044] As a further improvement to this technical solution, in S2.634, the relationship between the hose tip and the FPSO suspension point, the relationship between the robot's motion and the hose tip, and the relationship between the robot's motion and the FPSO suspension point are as follows:

[0045] Relationship between the hose tip and the FPSO suspension point:

[0046] Z 软管顶端 =T1·Z FPSO悬挂点 ;

[0047] The relationship between robot movement and the tip of the hose:

[0048] Z 机器人运动 =T2·Z 软管顶端 ;

[0049] Relationship between robot motion and FPSO suspension point:

[0050] Z 机器人运动 =T1·T2·Z FPSO悬挂点 ;

[0051] In the formula, T1 represents the transformation matrix containing translation and rotation information from the tip of the hose to the robot platform, and Z... 软管顶端 T2 represents the time history of the movement at the tip of the hose model, T2 represents the transformation matrix containing translation and rotation information from the tip of the hose to the robot platform, and Z represents the time history of the movement at the tip of the hose model. 机器人运动 Z represents the robot's motion time history after considering the distance between the robot and the top of the hose. FPSO悬挂点 This indicates the time history of the FPSO suspension point movement.

[0052] As a further improvement to this technical solution, in step S3, the six-degree-of-freedom motion history of the robot platform is input into the robot control system for loading and testing, including the following steps:

[0053] S3.1 Configure the robot control system parameters, including control mode, control cycle, etc.

[0054] S3.2 Import the trajectory data of the six-degree-of-freedom robot into the robot control system via the interface;

[0055] S3.3. Use linear interpolation to smooth the trajectory data;

[0056] S3.4. Perform trajectory scheduling and loading according to the timestamp of each data point.

[0057] As a further improvement to this technical solution, in step S4, an image processing program written in MATLAB is used to process the image and extract the time history data of the hose displacement, velocity, and acceleration, including the following steps:

[0058] S4.1 Read the underwater hose motion image data captured in the experiment and preprocess the image data;

[0059] S4.2. Use the Harris corner detection method to identify and determine the feature target points on the hose in the image;

[0060] S4.3 After determining the feature point, use the feature point tracking method to track its position in consecutive image frames and record the pixel coordinates of the point in each frame.

[0061] S4.4. Convert the obtained pixel coordinate sequence into the actual physical position, and use the numerical differentiation method to calculate the velocity and acceleration, and obtain the time history of the velocity and acceleration.

[0062] S4.5. Visualize and save the extracted displacement, velocity, and acceleration data.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] This method for testing the dynamic response of underwater models of deep-sea oil pipeline hoses encompasses everything from model building and loading device design to the development of a complete testing system, with a particular emphasis on the application of innovative waterproofing technology. This technology can accurately load and reasonably simulate the motion modes of a semi-submersible FPSO, ensuring high accuracy of test results by optimizing the boundary conditions of the hose model. The designed instrument testing system not only accurately measures axial and bending strain, but the waterproofing technology effectively protects the test sensors, guaranteeing the reliability and effectiveness of the entire testing system. This invention is particularly suitable for offshore oil and gas transportation environments, providing solid technical support for improving hose transportation safety by simulating hose motion and internal force analysis under actual sea conditions. Most importantly, this technology solves key technical challenges in the dynamic testing of underwater hose models, making such testing possible and significantly advancing the safety and reliability of offshore oil and gas transportation hoses. Attached Figure Description

[0065] Figure 1 This is a flowchart illustrating the overall method of the present invention;

[0066] Figure 2 This is a diagram showing the connection arrangement between the robot and the test model in this embodiment. Detailed Implementation

[0067] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0068] Example: Please refer to Figure 1-2 As shown, this embodiment provides a method for testing the dynamic response of an underwater model of a deep-sea oil pipeline hose, including the following steps:

[0069] S1. Design an experimental model of a deep-sea oil pipeline hose based on the similarity rate, and calculate the seabed boundary constraint conditions at the bottom end of the hose (the cut-off position of the riser) in the experiment. Use a spring stiffness model to equivalently represent the supporting effect of the riser on the hose in the horizontal and vertical directions.

[0070] In this embodiment, the laboratory modeling method for the deep-water hose system is as follows: considering the geometry, weight, stiffness, and modeling method of the hose and its cut-off with the riser; considering the interaction between the free-standing riser, pontoon, and hose; calculating the cut-off at the bottom of the hose; designing the boundary conditions at the cut-off position with the riser; using spring stiffness to represent the effect of the riser on the hose at the cut-off position; the stiffness of the riser under the pontoon is calculated based on the static equivalence principle; different forces are applied at the upper end of the pontoon; the riser is divided into several units; the deformation of the riser under the combined action of the pontoon and external forces is calculated; the relationship curve between displacement and internal force is obtained; and the stiffness of the riser in two directions is determined accordingly.

[0071] The following steps are used to calculate the seabed boundary constraints at the bottom of the hose (the cut-off point of the riser) in the experiment, employing a spring stiffness model to equivalently represent the support effect of the riser on the hose in the horizontal and vertical directions:

[0072] S1.1 Determine similarity parameters, including length scale, time scale, force scale, etc., and determine the similarity rate of each similarity parameter;

[0073] S1.2 Calculate the dimensions of the model riser and hose according to the similarity rate. This includes not only the length and diameter of the hose, but also the dimensions of other components such as the riser and float.

[0074] S1.3. Spring stiffness is used to represent the effect of the riser on the hose;

[0075] The action of the riser on the flexible hose is represented by spring stiffness, and includes the following steps:

[0076] S1.31. Based on the actual parameters of the riser and pontoon (including length, diameter, material properties, etc.) and marine environmental conditions (including water flow velocity, wave height, etc.), calculate the deformation of the riser under the action of the pontoon using the principle of statics.

[0077] S1.32. Divide the riser into several units to facilitate subsequent calculations;

[0078] S1.33. For each riser unit, calculate the relationship between the deformation and internal forces of the unit based on the external forces it experiences (including the support force provided by the float, the force of the water flow, etc.).

[0079] S1.34. Through the above calculations, the stiffness matrix of the riser in the two main directions is obtained (the stiffness values ​​in the horizontal / vertical directions are obtained through static calculations). This step is to quantify the response characteristics of the riser under different stress states.

[0080] S1.35. Based on the stiffness matrix results of the riser unit, select the spring stiffness value to simulate the effect of the riser on the hose. The spring stiffness here can accurately reflect the support capacity of the riser on the bottom connection point (i.e. the bottom end of the hose) under actual working conditions.

[0081] S1.36. Apply the selected spring stiffness to the design of the riser cut-off position in the experimental model;

[0082] S1.4 Apply the calculated spring stiffness to the riser cut-off position of the experimental model as part of the seabed boundary constraint conditions. This step aims to ensure that the experimental model can accurately reflect the influence of the riser on the riser in the prototype system.

[0083] S2. Based on the technical parameters and sea conditions of FPSO (large-scale oil storage and offloading unit), hydrodynamic software is used to calculate and generate the robot's six-degree-of-freedom motion time history.

[0084] The robot's movement applies motion conditions to the upper end of the test hose. The robot's motion platform (including the static platform, S-joint, electric cylinder, P-joint, and moving platform) is at a distance L from the upper end of the test hose (see...). Figure 2 To ensure that the motion of the upper end of the test hose is similar to that of the FPSO, it is necessary to establish a relationship between the motion of the robot platform and the motion of the upper end of the test hose. This embodiment invents a technique for converting the platform motion into the motion boundary of the upper end of the test hose. This ensures that the motion excitation of the upper end of the test hose is similar to the motion conditions of the FPSO; the core is based on the theory of rigid body dynamics, establishing... Figure 2 The conversion relationship between the motion of point A and the motion of point B was established, and a response algorithm was established, which can quickly derive the time history of the robot's six degrees of freedom motion; the key point of this invention is to establish a conversion algorithm between the motion of the robot and the upper end of the test hose model.

[0085] The robot platform is connected to the test hose. The dimensions L and connection method of the connecting components (including connecting parts 1 and 2) are determined to ensure the effective transmission of robot motion. The motion of the top of the hose model meets the similarity requirement. The strain test system is arranged, and the strain test pipeline is attached to the hose to ensure that the fiber optic strain sensors are in a straight line.

[0086] Based on the technical parameters of FPSO (Floating Production Storage and Offloading) and sea conditions, hydrodynamic software was used to calculate and generate the robot's six-degree-of-freedom motion time history, including the following steps:

[0087] S2.1 Collect FPSO technical parameters, including but not limited to information such as the mass, size, center of gravity position, and moment of inertia of the FPSO. These parameters are crucial for accurately simulating its behavior in the marine environment. Obtain sea state data, including wave height, period, direction, and current speed and direction. These data are obtained from field measurements or standard sea state databases. Preprocess the FPSO technical parameters and sea state data.

[0088] S2.2 Select hydrodynamic analysis software (AQWA) and create a three-dimensional model of the FPSO in the hydrodynamic analysis software based on the collected FPSO technical parameters;

[0089] S2.3 Input the collected wave and water flow parameters into the software and set the simulation time period (determine the length of time to be simulated, and how many complete wave cycles need to be covered in order to capture dynamic response characteristics);

[0090] S2.4 Perform hydrodynamic analysis and calculate the motion response of the FPSO in six degrees of freedom (sway, pitch, heave, roll, pitch, and bow) under a given sea state;

[0091] S2.5 Extract the data on the changes of each degree of freedom of the FPSO over time from the analysis results to form the motion time history curves of the six degrees of freedom of the FPSO.

[0092] S2.6. Convert the motion time history of the six degrees of freedom of the FPSO into robot motion control instructions;

[0093] Furthermore, the motion time history of the FPSO's six degrees of freedom is converted into robot motion control instructions, including the following steps:

[0094] S2.61. Use a scaling factor to convert the motion time history of the prototype system into the corresponding value at the model scale;

[0095] S2.62 Determine the positional relationship between the robot platform and the top of the hose;

[0096] S2.63. Establish the inverse kinematics mapping relationship of rigid body motion based on rigid body kinematics, and solve for the motion control commands required by the robot platform;

[0097] Furthermore, based on rigid body kinematics, an inverse kinematics mapping relationship for rigid body motion is established, and the motion control commands required by the robot platform are solved, including the following steps:

[0098] S2.631. Define the position and orientation vectors of the robot platform in the global coordinate system;

[0099] S2.632. Use a rotation matrix to transform the relative position vector from the local coordinate system to the global coordinate system;

[0100] S2.633. The position of the top of the hose is obtained by adding the position of the robot platform to the relative position vector;

[0101] S2.634. Set the motion of the hose tip to be equal to the motion of the FPSO suspension point, solve the motion control commands required by the robot platform through numerical methods, and generate the relationship between the hose tip and the FPSO suspension point, the relationship between the robot motion and the hose tip, and the relationship between the robot motion and the FPSO suspension point.

[0102] The numerical method is used to solve for the motion control commands required by the robot platform.

[0103] X FPSO =X robot +R(θ robot )·r L ;

[0104] In the formula, X FPSO This represents the position vector of the hose suspension point on the FPSO (Floating Production Storage and Offloading System). This vector describes the position and orientation of the hose suspension point on the FPSO in the global coordinate system, typically including six degrees of freedom (3 translational displacements and 3 rotational angles); X robot R(θ) represents the position vector of the robot platform. robot θ represents a rotation matrix, which is used to transform a vector from a local coordinate system to a global coordinate system. robot The angle of rotation (i.e., roll, pitch, yaw) of the robot platform about its own axis is represented by r. L This represents the vector from the robot platform to the tip of the hose, indicating the position from the center of the robot platform to the connection point at the tip of the hose;

[0105] To address the additional disturbances caused by waves, an external disturbance term is introduced during the numerical solution process. (Wave forces are an unavoidable factor in the marine environment, especially for floating production storage and offloading (FPSO) units and their connecting hoses. Introducing an external disturbance term to simulate the impact of these wave forces makes the model more realistic, thereby improving the accuracy and reliability of the simulation results. In practical applications, robotic platforms need to be able to adapt to constantly changing marine conditions. By considering wave-induced disturbances, the design of the control system can be evaluated and improved to enhance its anti-interference capabilities. Simulating diverse scenarios by adjusting the specific form and parameters of the external disturbance term not only facilitates a deeper understanding of the system's dynamic behavior under various conditions but also provides the possibility for developing countermeasures.)

[0106] X FPSO1 =X robot +R(θ robot )·r L +d;

[0107] In the formula, d represents the external disturbance term (wave force disturbance vector, which is displacement disturbance), used to simulate the unmodeled dynamic effects, and X FPSO1 This represents the position vector of the suspension point of the optimized FPSO (large oil storage and offloading unit).

[0108] S2.64. Based on the solved sequence of motion control instructions for the robot platform, generate specific control signals suitable for the robot control system.

[0109] The relationships between the hose tip and the FPSO suspension point, the robot's motion and the hose tip, and the robot's motion and the FPSO suspension point are as follows:

[0110] Relationship between the hose tip and the FPSO suspension point:

[0111] Z 软管顶端 =T1·Z FPSO悬挂点 ;

[0112] The relationship between robot movement and the tip of the hose:

[0113] Z 机器人运动 =T2·Z 软管顶端 ;

[0114] Relationship between robot motion and FPSO suspension point:

[0115] Z 机器人运动 =T1·T2·Z FPSO悬挂点 ;

[0116] In the formula, T1 represents the transformation matrix (including translation vector and rotation angle) containing translation and rotation information from the tip of the hose to the robot platform, and Z... 软管顶端 T2 represents the time history of the movement at the tip of the hose model, T2 represents the transformation matrix containing translation and rotation information from the tip of the hose to the robot platform, and Z represents the time history of the movement at the tip of the hose model. 机器人运动 Z represents the robot's motion time history after considering the distance between the robot and the top of the hose. FPSO悬挂点 This indicates the time history of the FPSO suspension point movement.

[0117] S3. Input the six-degree-of-freedom motion history of the robot platform into the robot control system for loading test (input the determined six-degree-of-freedom motion history of the robot platform into the robot control system, check whether the motion of the upper end of the hose is consistent with the motion calculated in step 1. If they are consistent, start the loading test).

[0118] In this embodiment, the six-degree-of-freedom motion history of the robot platform is input into the robot control system for loading and testing, including the following steps:

[0119] S3.1 Configure the robot control system parameters, including control mode, control cycle, etc.

[0120] S3.2 Import the trajectory data of the six-degree-of-freedom robot into the robot control system via the interface;

[0121] S3.3. Use linear interpolation to smooth the trajectory data;

[0122] S3.4. Perform trajectory scheduling and loading according to the timestamp of each data point.

[0123] S4. Use a camera to collect images to record the entire shooting test process (set up a high-definition camera with an angle within 45°, and ensure that the height of the camera is within the range of the model's movement to avoid exceeding the lens and causing image signal loss. It is best to fix the camera on an underwater support, and the support needs to be fixed to the bottom of the pool to prevent it from tipping over). Use an image processing program written in MATLAB to process the images and extract the time history data of the hose displacement, velocity, and acceleration.

[0124] In this embodiment, the hose is subjected to the combined effects of FPSO excitation and wave current underwater, resulting in a wide range of motion. It exhibits large deflection and deformation, with a large range of motion. This embodiment proposes an optical testing method to address the motion of a hose model made of nonlinear materials with large deformation. High-resolution lenses are used to capture the motion of the hose model, and an image processing method is developed. Based on the MATLAB language platform, a corresponding computer program is developed to process the underwater images, obtaining the hose model's velocity, acceleration, displacement time history, and motion trajectory.

[0125] During the testing of the hose model, significant deformation occurred. Traditional underwater waterproofing techniques often result in the sealing membrane easily breaking during this deformation. This invention proposes a novel waterproofing technology. The key features of this technology are: firstly, the sealing membrane can be removed for sensor inspection; and secondly, the resulting waterproof membrane possesses strong toughness and is not easily broken. The invention focuses on the waterproofing material used, the tools employed to form the waterproof membrane, and the manufacturing process. The waterproofing material is placed above the sensor, smoothed, and then heated to a certain temperature using a heater. The material melts and forms a waterproof membrane. During the significant deformation of the hose model, this waterproof membrane effectively protects the sensor and the solder joints between the signal lines and the sensor.

[0126] Using a MATLAB-based image processing program to process images and extract time history data of hose displacement, velocity, and acceleration, the following steps are included:

[0127] S4.1 Read the underwater hose motion image data captured in the experiment and preprocess the image data;

[0128] S4.2. Use the Harris corner detection method to identify and determine the feature target points on the hose in the image (the principle of Harris corner detection is to calculate the covariance matrix of the gray-level changes of local windows in the image and determine the positions with significant gray-level changes in both the horizontal and vertical directions as corner points).

[0129] S4.3 After determining the feature points, use the feature point tracking method to track their positions in consecutive image frames and record the pixel coordinates of the point in each frame (the principle of feature point tracking is based on the local grayscale or texture similarity in adjacent image frames to estimate the optimal matching position of the feature point between consecutive frames, thereby continuously obtaining its pixel-level trajectory).

[0130] S4.4. Convert the obtained pixel coordinate sequence into the real physical position (complete the spatial calibration of the camera in advance, determine the correspondence between pixels and actual length, and after the conversion, obtain the trajectory of the displacement of the feature point in the real physical space as time changes), and use the numerical differentiation method to calculate the velocity and acceleration, and obtain the time history of velocity and acceleration.

[0131] S4.5. Visualize and save the extracted displacement, velocity, and acceleration data.

[0132] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for testing the dynamic response of a deep-sea oil transfer hose underwater model, characterized in that, It comprises the following steps: S1, according to the similarity rate, the experimental model of deep sea oil hose is designed, and the seabed boundary constraint condition of the bottom end of the hose in the experiment is calculated, and the spring stiffness model is used to equivalent represent the support effect of the riser on the hose in the horizontal direction and the vertical direction; S2, based on the technical parameters and sea conditions of FPSO, the six degree of freedom motion time history of the robot is calculated by using the hydrodynamic software; S3, the six degree of freedom motion time history of the robot platform is input into the robot control system for loading test; S4, the image used to record the whole process of shooting test is collected by using the camera, and the image processing program written by MATLAB is used to process the image, and the time history data of the displacement, velocity and acceleration of the hose are extracted.

2. The method of claim 1, wherein: In the S1, the seabed boundary constraint condition of the bottom end of the hose in the experiment is calculated, and the spring stiffness model is used to equivalent represent the support effect of the riser on the hose in the horizontal direction and the vertical direction, which comprises the following steps: S1.1, the similarity parameters are determined, and the similarity rate of each similarity parameter is determined; S1.2, according to the similarity rate, the size of the model riser and the hose is calculated; S1.3, the spring stiffness is used to represent the effect of the riser on the hose; S1.4, the calculated spring stiffness is applied to the riser truncation position of the experimental model.

3. The method of claim 2, wherein: In the S1.3, the spring stiffness is used to represent the effect of the riser on the hose, which comprises the following steps: S1.31, based on the actual parameters of the riser and the buoy, as well as the marine environmental conditions, the deformation of the riser under the action of the buoy is calculated by using the statics principle; S1.32, the riser is divided into several units; S1.33, for each riser unit, the deformation and internal force relationship of the unit is calculated according to the external force it receives; S1.34, through the above calculation, the stiffness matrix of the riser in two main directions is obtained; S1.35, based on the stiffness matrix result of the riser unit, the spring stiffness value is selected to simulate the effect of the riser on the hose; S1.36, the selected spring stiffness is applied to the design of the riser truncation position in the experimental model.

4. The method of claim 1, wherein: In the S2, based on the technical parameters and sea conditions of FPSO, the six degree of freedom motion time history of the robot is calculated by using the hydrodynamic software, which comprises the following steps: S2.1, collect the technical parameters of FPSO, obtain the sea condition data, and pretreat the technical parameters of FPSO and the sea condition data; S2.2, select the hydrodynamic analysis software, create the three-dimensional model of FPSO in the hydrodynamic analysis software according to the collected technical parameters of FPSO; S2.3, input the specific parameters of wave and current into the software and set the simulation time period; S2.4, perform hydrodynamic analysis to calculate the six degree of freedom motion response of FPSO under the given sea conditions; S2.5, extract the data of each degree of freedom of FPSO changing with time from the analysis result to form the motion time history curve of the six degrees of freedom of FPSO; S2.6, convert the motion time history of the six degrees of freedom of FPSO into robot motion control instructions.

5. The method of claim 4, wherein: In the S2.6, the motion time history of the six degrees of freedom of FPSO is converted into robot motion control instructions, which comprises the following steps: S2.61, converting the motion time history of the prototype system into corresponding values in the model scale using a scale factor; S2.62, determining the position relationship between the robot platform and the hose top end; S2.63, establishing an inverse mapping relationship of rigid body motion according to rigid body kinematics, and solving the motion control instructions required by the robot platform; S2.64, generating specific control signals based on the sequence of motion control instructions of the robot platform solved.

6. The method of claim 5, wherein: In S2.63, the inverse mapping relationship of rigid body motion is established according to rigid body kinematics, and the motion control instructions required by the robot platform are solved, including the following steps: S2.631, defining the position and attitude vector of the robot platform in the global coordinate system; S2.632, converting the relative position vector from the local coordinate system to the global coordinate system using a rotation matrix; S2.633, obtaining the position of the hose top end by adding the relative position vector to the position of the robot platform; S2.634, setting the motion of the hose top end equal to the motion of the FPSO suspension point, solving the motion control instructions required by the robot platform by numerical method, and generating the relationship between the hose top end and the FPSO suspension point, the relationship between the robot motion and the hose top end, and the relationship between the robot motion and the FPSO suspension point.

7. The method of claim 6, wherein: In S2.633, the numerical method for solving the motion control instructions required by the robot platform is: X FPSO = X robot + R(θ robot ) · r L ; where X FPSO represents the position vector of the FPSO suspension point; X robot represents the position vector of the robot platform, R(θ robot ) represents the rotation matrix, θ robot represents the rotation angle of the robot platform around its own axis, r L represents the vector from the robot platform to the top of the hose; For the additional disturbance force caused by waves, an external disturbance term is introduced in the process of using numerical method to solve: X FPSO1 = X robot + R(θ robot ) · r L + d; where d represents an external disturbance term, X FPSO1 represents the position vector of the optimized FPSO hang-off point.

8. The method of claim 6, wherein: In S2.634, the relationship between the hose top end and the FPSO suspension point, the relationship between the robot motion and the hose top end, and the relationship between the robot motion and the FPSO suspension point are: Relationship between the hose top end and the FPSO suspension point: Z 软管顶端 = T1 · Z FPSO悬挂点 ; Relationship between the robot motion and the hose top end: Z 机器人运动 = T2 · Z 软管顶端 ; Relationship between the robot motion and the FPSO suspension point: Z 机器人运动 = T1-T2-Z FPSO悬挂点 ; where T1 represents a transformation matrix containing translation and rotation information from the hose top end to the robot platform, Z 软管顶端 represents the hose model top end motion time history, T2 represents a transformation matrix containing translation and rotation information from the hose top end to the robot platform, Z 机器人运动 represents the robot motion time history considering the distance of the robot from the hose top end, Z FPSO悬挂点 represents the FPSO hang-off point motion time history.

9. The method of claim 1, wherein: In S3, the six-degree-of-freedom motion history of the robot platform is input into the robot control system for loading test, including the following steps: S3.1, configuring the robot control system parameters, including control mode, control period, etc.; S3.2, importing the trajectory data of the six-degree-of-freedom robot into the robot control system through the interface; S3.3, smoothing the trajectory data by linear interpolation; S3.4, scheduling and loading the trajectory according to the time stamp of each data point.

10. The method of claim 1, wherein: In S4, the image processing program written by MATLAB is used to process the image and extract the time history data of the hose displacement, velocity and acceleration, including the following steps: S4.1, reading the underwater hose motion image data taken in the experiment, and pre-processing the image data; S4.2, identifying and determining the feature target point on the hose in the image using the Harris corner point detection method; S4.3, after determining the feature point, tracking its position in consecutive image frames using the feature point tracking method, and recording the pixel coordinates of the point in each frame; S4.4, converting the obtained pixel coordinate sequence into real physical position, and calculating the velocity and acceleration by numerical differentiation method to obtain the time history of velocity and acceleration; S4.5, visualizing and saving output of the extracted displacement, velocity and acceleration data.

Images