Dynamic submarine cable three-dimensional reconstruction method and device, electronic equipment and storage medium

Abstract

The invention discloses a dynamic submarine cable three-dimensional reconstruction method and device, electronic equipment and a storage medium, which are used for solving the technical problem of failure of three-dimensional reconstruction of a dynamic cable caused by low shape sensing accuracy and stability of the dynamic submarine cable in the prior art. The method comprises the following steps: firstly, calculating a strain value of each fiber core in the multi-core optical fiber based on spectral drift, and performing characteristic curvature vector inverse solution by combining the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set; respectively carrying out discrete fitting on the discrete bending direction set and the discrete curvature set until the bending direction and the optical fiber curvature at each position in the multi-core optical fiber are fitted; the optical fiber torsion is solved according to the bending direction, a space curve is solved based on the optical fiber curvature and the optical fiber torsion, and the space curve corresponds to the axis track of the multi-core optical fiber; and finally, performing three-dimensional reconstruction on the submarine cable according to the axis track to obtain the three-dimensional shape of the submarine cable.

Description

Technical Field

[0001] The present invention relates to the technical field of submarine cable monitoring, and in particular to a method, device, electronic equipment and storage medium for dynamic submarine cable three-dimensional reconstruction. Background Art

[0002] Dynamic submarine cables, characterized by low stiffness, minimal damping, and low resonant frequency, are primarily used to supply cables and transmit communications signals to floating platforms. These cables are typically suspended from the bottom of the platform, partially exposed to the air. They are docked between the floating platform and a fixed subsea structure, allowing them to move with the floating structure. Buoyancy allows them to maintain a defined linear profile in the water, allowing them to accommodate the wide excursions of offshore floating structures while mitigating the load on the dynamic cable itself.

[0003] Dynamic submarine cables, subject to the disturbances of tidal currents and the motion of floating structures, are prone to sustained structural changes and significant low-frequency vibrations. Torsion during use leads to the accumulation of distortion in the fixed end equipment. Local bending radii and stresses are likely to exceed design values, causing mechanical damage to various parts. Furthermore, fatigue failure is prone to occur under loads such as currents and waves, with intermittent vortex-induced vibrations caused by currents being the primary cause of fatigue failure.

[0004] Fiber optic sensing offers advantages such as resistance to electromagnetic interference, small size, light weight, and ease of multiplexing. These characteristics make fiber optic sensors suitable for a wider range of applications, such as aircraft wings and medical surgical navigation. In multi-core optical fibers, the distance between the cores is typically very small. Due to their close arrangement, when the optical fiber is subjected to external torsion or bending, the displacement differences between the individual cores are minimal, resulting in insignificant strain changes. The small core spacing also means that even if the optical fiber as a whole experiences significant torsion, the geometric changes between the individual cores may not be sufficient to generate sufficient strain for detection.

[0005] When using structures like Fiber Bragg Gratings (FBGs) to detect strain in optical fibers, sufficient strain is required to produce a detectable wavelength shift. When the core spacing is small, these shifts can fall below the sensor's detection threshold, resulting in suboptimal sensing. This small core spacing creates minimal strain states, making torsion measurement difficult using multi-core optical fibers. This can lead to a loss of accuracy and stability in shape sensing, and ultimately, failure in 3D reconstruction of dynamic cables. Summary of the Invention

[0006] The present invention provides a method, device, electronic device and storage medium for dynamic submarine cable three-dimensional reconstruction, which are used to solve or partially solve the technical problem in the existing related technology that the accuracy and stability of dynamic submarine cable shape sensing are low, resulting in the failure of dynamic cable three-dimensional reconstruction.

[0007] The present invention provides a method for three-dimensional reconstruction of a dynamic submarine cable, wherein a spiral spoiler is arranged on the outer surface of the submarine cable, wherein the spiral spoiler is formed by at least one plate belt with plate teeth spirally rising and winding around the surface of the submarine cable, wherein the plate teeth are provided with spiral holes and grooves, and a multi-core optical fiber sensor is arranged in the spiral holes and grooves; the method comprises:

[0008] Calculating the strain value of each fiber core in the multi-core optical fiber based on the spectral drift, and performing an inverse solution of the characteristic curvature vector in combination with the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set;

[0009] performing discrete fitting on the discrete bending direction set and the discrete curvature set respectively until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted;

[0010] Solving the optical fiber torsion according to the bending direction, and solving a spatial curve based on the optical fiber curvature and the optical fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber;

[0011] The submarine cable is three-dimensionally reconstructed according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

[0012] Optionally, calculating the strain value of each core in the multi-core optical fiber based on the spectral drift includes:

[0013] When the optical fiber is subjected to strain, obtaining central wavelength data measured by the multi-core optical fiber sensor;

[0014] The strain value of each core in the multi-core optical fiber is calculated according to the central wavelength data.

[0015] Optionally, the multi-core optical fiber sensor is provided with a plurality of grating detection points along the multi-core optical fiber, each of the grating detection points being used to perform optical fiber bending and twisting strain detection on each core at a specific position of the multi-core optical fiber, and the characteristic curvature vector is inversely solved in combination with the strain value of each core to obtain a discrete bending direction set and a discrete curvature set, including:

[0016] For each of the grating detection points, the superposition vector sum of the curvature vectors of the fiber cores is calculated in combination with the strain value of each fiber core and an inverse solution is performed to obtain a discrete curvature value and a discrete bending direction value of the grating detection point;

[0017] The discrete bending direction values are integrated into a discrete bending direction set corresponding to the plurality of grating detection points, and the discrete curvature values are integrated into a discrete curvature set corresponding to the plurality of grating detection points.

[0018] Optionally, calculating the superposition vector sum of the curvature vectors of the fiber cores in combination with the strain values of the fiber cores and performing inverse solution to obtain the discrete curvature values and discrete bending direction values of the grating detection points includes:

[0019] Calculating the superposition vector sum of the curvature vectors of the fiber cores in combination with the strain values of the fiber cores, and performing an inverse solution on the superposition vector sum to obtain the discrete curvature value of the grating detection point;

[0020] A secondary inverse solution is performed based on the discrete curvature values in combination with the strain value of any of the fiber cores to obtain the discrete bending direction values of the grating detection points.

[0021] Optionally, discretely fitting the discrete bending direction set and the discrete curvature set until the bending direction and the fiber curvature at each position in the multi-core optical fiber are fitted comprises:

[0022] Based on the calculation method of spline interpolation point coefficients and functions, discrete fitting is performed on each of the discrete bending direction values, and discrete fitting is performed on each of the discrete curvature values;

[0023] When the discrete fitting is completed, determining whether the bending direction and fiber curvature at each position in the multi-core optical fiber are successfully fitted;

[0024] If yes, output the bending direction and fiber curvature at each position in the multi-core optical fiber;

[0025] If not, repeat the discrete fitting until the fitting is successful.

[0026] Optionally, solving the optical fiber torsion according to the bending direction, and solving the spatial curve based on the optical fiber curvature and the optical fiber torsion, includes:

[0027] Calculating an original bending angle corresponding to the bending direction, and obtaining an initial spiral angle at the same position as the original bending angle;

[0028] Subtracting the initial helix angle from the original bending angle to perform torsion angle compensation to obtain a target bending angle;

[0029] Solving a corrected bending direction according to the target bending angle, performing first-order and second-order derivatives on the corrected bending direction, and calculating the optical fiber torsion by combining the first-order and second-order derivative results;

[0030] According to the optical fiber curvature, the optical fiber torsion and the given initial conditions, the spatial curve is obtained by first solving the Frenet-Serret equation and then combining it with numerical integration to solve it.

[0031] Optionally, the axis trajectory includes the shape trajectory of the multi-core optical fiber and the spatial position of the multi-core optical fiber sensor, and the three-dimensional reconstruction of the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable includes:

[0032] First, the multi-core optical fiber is three-dimensionally reconstructed based on the shape trajectory, and then the coordinate transformation is performed in combination with the spatial position of the multi-core optical fiber sensor to indirectly reconstruct the current position of the submarine cable in space and restore the three-dimensional shape of the submarine cable in space.

[0033] The present invention also provides a dynamic submarine cable three-dimensional reconstruction device, which includes a spiral spoiler arranged on the outer surface of the submarine cable, wherein the spiral spoiler is formed by at least one plate with plate teeth spirally rising and winding around the surface of the submarine cable, the plate teeth being provided with spiral holes, and a multi-core optical fiber sensor being arranged in the spiral holes; the device comprises:

[0034] A characteristic curvature vector inverse solution module is used to calculate the strain value of each fiber core in the multi-core optical fiber based on the spectral drift, and perform characteristic curvature vector inverse solution based on the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set;

[0035] A discrete fitting module, configured to perform discrete fitting on the discrete bending direction set and the discrete curvature set, respectively, until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted;

[0036] A spatial curve solving module, configured to solve the optical fiber torsion according to the bending direction, and solve a spatial curve based on the optical fiber curvature and the optical fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber;

[0037] A three-dimensional reconstruction module is used to perform three-dimensional reconstruction on the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

[0038] The present invention further provides an electronic device, comprising a processor and a memory:

[0039] The memory is used to store program code and transmit the program code to the processor;

[0040] The processor is configured to execute any one of the above methods for dynamic submarine cable three-dimensional reconstruction according to instructions in the program code.

[0041] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the dynamic submarine cable three-dimensional reconstruction method as described in any one of the above items.

[0042] It can be seen from the above technical solutions that the present invention has the following advantages:

[0043] A method for three-dimensional reconstruction of dynamic submarine cables based on multi-core optical fibers is provided. A spiral spoiler is arranged on the outer surface of the submarine cable. The spiral spoiler is formed by at least one plate with plate teeth spirally rising and winding around the cable surface. The plate teeth are provided with spiral holes, and multi-core optical fiber sensors are arranged in the spiral holes. Dynamic submarine cable posture monitoring is thus improved based on the spiral spoiler to resolve distortion information, suppressing vortex-induced motion while achieving three-dimensional reconstruction. For the three-dimensional reconstruction of dynamic submarine cables, the strain value of each core in the multi-core optical fiber is first calculated based on spectral drift. The characteristic curvature vector is then inversely solved based on the strain value of each core to obtain a discrete bending direction set and a discrete curvature set. Discrete fitting is then performed on the discrete bending direction set and the discrete curvature set until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted. The fiber torsion is then resolved based on the bending direction, and a spatial curve is resolved based on the fiber curvature and fiber torsion. The spatial curve corresponds to the axial trajectory of the multi-core optical fiber. Finally, the submarine cable is reconstructed in three dimensions based on the axial trajectory to obtain the three-dimensional shape of the submarine cable. Therefore, by constructing a three-dimensional inversion of a dynamic submarine cable, not only can the accuracy and stability of dynamic submarine cable shape sensing be improved, but also the purposes of attitude monitoring, vortex-induced vibration suppression, and vibration measurability can be achieved simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 Schematic diagram of the structure of a spiral spoiler;

[0046] Figure 2 This is a schematic diagram of the structure of a single plate strip in a spiral spoiler;

[0047] Figure 3 A flowchart of a method for three-dimensional reconstruction of a dynamic submarine cable;

[0048] Figure 4 A schematic diagram of the coordinate axes of the bending angle and bending direction of a multi-core optical fiber;

[0049] Figure 5 Schematic diagram of the overall process of a dynamic submarine cable 3D reconstruction method;

[0050] Figure 6 The figure is a structural block diagram of a dynamic submarine cable 3D reconstruction device.

[0051] Description of reference numerals:

[0052] 1-submarine cable; 2-spiral spoiler; 3-single plate belt; 4-plate teeth; 5-spiral hole groove; 6-plate belt piece. DETAILED DESCRIPTION

[0053] Embodiments of the present invention provide a method, device, electronic device, and storage medium for dynamic submarine cable three-dimensional reconstruction, which are used to solve or partially solve the technical problem in the existing related technology that the accuracy and stability of dynamic submarine cable shape sensing are low, resulting in the failure of dynamic cable three-dimensional reconstruction.

[0054] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] As an example, real-time monitoring of dynamic submarine cables is currently mainly achieved through fiber optic sensing. Fiber optic sensing has the advantages of being resistant to electromagnetic interference, small in size, lightweight, and easy to multiplex. These characteristics give fiber optic sensors a wider range of applications, such as aircraft wings and medical surgical navigation. In multi-core optical fibers, the distance between the cores is usually very small. Due to the close arrangement, when the optical fiber is subjected to external torsion or bending, the displacement difference between the cores is very small, resulting in insignificant strain changes. The smaller core spacing also means that even if the optical fiber as a whole undergoes significant torsion, the geometric changes between the individual cores may not be sufficient to generate a large enough strain for detection.

[0056] When using structures like fiber Bragg gratings to detect strain in optical fibers, sufficient strain is required to produce a detectable wavelength shift. When the core spacing is small, these shifts can fall below the sensor's detection threshold, resulting in suboptimal sensing. This small core spacing creates minimal strain states, making torsion measurement difficult using multi-core optical fibers. This can lead to a loss of accuracy and stability in shape sensing, and ultimately, failure in 3D reconstruction of dynamic cables.

[0057] Through further analysis, the present invention believes that local distortion is an important source of error in optical fiber shape sensors. Among them, distortion refers to the local circumferential angular deviation of the optical fiber or fiber core away from the neutral axis in the optical fiber shape sensor during the deformation of the sensor. Therefore, in actual calculations, it is necessary to measure the distortion information and compensate for it in the reconstruction algorithm. In order to solve the distortion information, a spiral structure can be designed and used in multi-core optical fibers and single-mode optical fiber shape sensors with external substrates. The spiral structure is to pre-apply an equal amount of distortion with a certain period to each optical fiber or fiber core away from the neutral axis in the optical fiber shape sensor during the sensor manufacturing process. The spiral outer core will produce a common mode response after being bent. Through the spiral core design, axial strain, bending-induced strain and twisting-induced strain can be separated.

[0058] Therefore, one of the core inventive aspects of the present invention is to address the shortcomings of existing technologies by providing a method for 3D reconstruction of dynamic submarine cables using multi-core optical fibers. On one hand, a spiral spoiler is deployed on the outer surface of the submarine cable. The spiral spoiler is composed of at least one plate with teeth, which spirally wraps around the cable surface. The teeth are provided with spiral grooves, and multi-core optical fiber sensors are deployed within the spiral grooves. This spiral spoiler improves dynamic submarine cable posture monitoring by extracting distortion information, achieving 3D reconstruction while suppressing vortex-induced motion. On the other hand, for the three-dimensional reconstruction of dynamic submarine cables, the strain values of each fiber core in the multi-core optical fiber are first calculated based on spectral drift. The characteristic curvature vector is then inverted based on the strain values of each fiber core to obtain a discrete bending direction set and a discrete curvature set. The discrete bending direction set and the discrete curvature set are then discretely fitted until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted. The fiber torsion is then solved based on the bending direction, and a spatial curve is solved based on the fiber curvature and fiber torsion. The spatial curve corresponds to the axis trajectory of the multi-core optical fiber. Finally, the submarine cable is reconstructed in three dimensions based on the axis trajectory to obtain the three-dimensional shape of the submarine cable. By constructing a three-dimensional inversion of dynamic submarine cables, the accuracy and stability of dynamic cable shape sensing can be improved, while also achieving the goals of attitude monitoring, vortex-induced vibration suppression, and vibration measurability.

[0059] The harsh marine environment, complex cable ancillary structures, and large flexible deformations make dynamic submarine cable marine engineering design extremely challenging. Sensors are used to determine the spatial position, orientation, and other overall information of the operating cable in the operating environment to build a three-dimensional cable model. This provides accurate, real-time, stable, and reliable cable measurement information for various cable-related operations. This provides important guidance for submarine cable design, service status assessment, installation, construction, and operation and maintenance.

[0060] Based on this, an embodiment of the present invention first provides a dynamic submarine cable posture monitoring device based on multi-core optical fiber. Specifically, a distributed four-core optical fiber 3D shape sensing system is constructed. By integrating multiple fiber Bragg grating devices and multiple Bragg grating arrays on a multi-core optical fiber, and leveraging the spatial distribution of the four cores within the same fiber, a large-scale optical device micro-integration system is formed. This allows for the deformation differences of the Bragg gratings at different spatial locations to be determined, enabling 3D shape reconstruction of the multi-core optical fiber and, indirectly, the dynamic submarine cable.

[0061] In a specific implementation, a spiral spoiler is arranged on the outer surface of the submarine cable. The spiral spoiler is formed by at least one plate with plate teeth that spirally rises and wraps around the surface of the submarine cable. The plate teeth are provided with spiral holes, and multi-core fiber Bragg grating sensors (hereinafter referred to as multi-core fiber sensors) are arranged in the spiral holes. For example, taking three plates as an example to form a spiral spoiler, Figure 1 A schematic structural diagram of a spiral spoiler provided by an embodiment of the present invention is shown.

[0062] It should be noted that the spiral spoiler does not necessarily have to consist of three strips. In practice, a single strip can generally meet measurement requirements, but using three strips can improve measurement accuracy. Therefore, if layout conditions permit, a spiral spoiler can be formed by using three strips to achieve higher measurement accuracy. It should be understood that this is not a limitation of the present invention.

[0063] Combine Figure 1 A spiral spoiler 2 is arranged on the outer surface of the dynamic submarine cable 1. The spiral spoiler 2 is composed of three plates 3 spirally rising around the surface of the submarine cable 1, and the plates 6 are interlocked to form a cylindrical sleeve coaxial with the submarine cable 1.

[0064] A raised tooth 4 is axially arranged in the center of the strip 3, and the teeth 4 corresponding to the three strips 3 are spirally symmetrical. This symmetrical spiral structure changes the current separation angle along the longitudinal direction of the tube, thereby disrupting the spatial correlation of the vortex, dispersing it, and thus weakening its strength and reducing lift.

[0065] At the same time, the spiral spoiler 2 adopts polyether polyurethane elastomer, which has strong seawater resistance, tear resistance, impact resistance and high rebound properties, and is added with a water-repellent agent with water absorption effect.

[0066] Furthermore, a spiral hole 5 is provided in the plate teeth 4. For example, the structural diagram of the single plate strip 3 in the spiral spoiler 2 is as follows: Figure 2 shown.

[0067] A multi-core fiber sensor is positioned within the spiral groove 5. This sensor detects fiber bending and torsional strain using multiple optical fibers. Multiple gratings are inscribed within the sensor, forming a Bragg grating array. This arrayed fiber Bragg grating exhibits randomly distributed characteristic parameters. Furthermore, the center wavelength of the arrayed fiber Bragg gratings and the spacing between adjacent fiber Bragg gratings are randomized within a certain range, thereby suppressing grating crosstalk and increasing the array's multiplexing capacity.

[0068] The multi-core fiber sensor is coupled to a multi-core fiber fan-in / fan-out device. The multiple sensor signal channels generated by the device are connected to a fiber Bragg grating (FBG) interrogator. When 3D reconstruction is required, the center wavelength data of the fiber Bragg grating (FBG) in each channel is transmitted to a host computer. A visualization program, built on the host computer using LabVIEW (a commonly used graphical programming language), collects and stores the FBG wavelength data and feeds it into a 3D configuration (spatial position + shape) reconstruction algorithm to complete real-time 3D shape reconstruction. Technicians can observe the 3D reconstruction results in real time through the host computer.

[0069] When an optical fiber undergoes pure bending, Kirchhof's elastic rod theory dictates that the strain experienced by the fiber core is linearly related to the product of its curvature and the core spacing. Generally speaking, in a helical outer core configuration, methods for improving torsion measurement sensitivity primarily include reducing the pitch and increasing the distance from the outer core to the center. In currently available helical multi-core optical fibers, the centerline of the helical fibers serves as the central axis of the fiber sensor. This structural characteristic results in a small core spacing and minimal strain, making torsion measurement applications with multi-core optical fibers difficult.

[0070] The multi-core optical fiber in the embodiment of the present invention is a four-core optical fiber, which is mainly composed of a central fiber core located at the center of the cladding and three outer fiber cores arranged in the form of an equilateral triangle. The three outer optical fibers are arranged in parallel. The centerline of the fiber cluster is located outside the centerline of the cable and is tightly connected to the catheter. The multi-core optical fiber sensor will be stretched together with the surrounding material. The neutral plane of the multi-core optical fiber sensor when it is deformed is the centerline of the cable. The torsional strain of the fiber cluster is positively correlated with the eccentric distance between the center of the cable and the center of the fiber cluster. Based on the spiral structure, the multi-core optical fiber can be pre-twisted to increase the twisting feeling and at the same time increase the distance from the outer core to the center. The larger the eccentric distance, the larger the relative rotation radius of the fiber cluster, and when subjected to torsion, it will experience greater linear displacement and angular change (equivalent to amplifying the torsional strain). The amplification of torsional strain can, in some cases, improve the detection sensitivity of torsion. This is different from the existing multi-core optical fiber, in which the centerline of the optical fiber sensor is the central axis when it is deformed.

[0071] For some shape sensors with long measurement lengths and that use internal scattered signals of optical fibers to measure strain, it is necessary to ensure the packaging consistency at all positions along the optical fiber. And it is necessary to calibrate one by one on cross sections with smaller spacing. The shape sensor composed of multi-core optical fibers provided by the embodiment of the present invention is not only compact in configuration, but also has each fiber core being basically isotropic. Therefore, there is no need to calibrate the optical fibers and gratings one by one. The use of multi-core optical fiber sensors can significantly reduce the complexity of the layout, and the distortion information of the flexible structure can also be reflected in the recovery results of the multi-core optical fiber sensor.

[0072] Furthermore, the continuous unidirectional torsion of the spiral spoiler 2 in the embodiments of the present invention allows for differentiation between clockwise and counterclockwise rotation of the optical fiber along its length. This makes the spiral multi-core optical fiber sensor more sensitive to torsional strain. Furthermore, during monitoring, the direction of optical fiber deformation can be determined based on the different directions of central wavelength shift caused by clockwise and counterclockwise strain on the fiber core.

[0073] In particular, the spiral spoiler 2 in the embodiment of the present invention is essentially a spiral strake. Spiral strakes are an effective device for suppressing vortex-induced vibrations. In practical applications, the spiral strakes can change the current separation angle along the longitudinal direction of the pipe, thereby disrupting the spatial correlation of vortices, dispersing them, and thereby weakening their strength and reducing lift. The use of the spiral spoiler 2 can improve underwater flow diversion efficiency and prevent fatigue failure during the service life of offshore platform risers.

[0074] Similar to static cables, dynamic cables also require waterproofing. This waterproof barrier is typically achieved by extruding a lead sheath onto the cable. However, since it cannot flex with dynamic wave motion, it is not suitable for floating wind farms. This embodiment of the present invention employs spiral spoilers 2 on the outer surface of the dynamic submarine cable 1, achieving both high mechanical strength and waterproofing requirements.

[0075] Combined with the above-mentioned introduction of the spiral spoiler, in order to enable those skilled in the art to better understand the technical solution of the present invention, refer to Figure 3 , shows a flowchart of a method for dynamic 3D reconstruction of a submarine cable provided by an embodiment of the present invention, which may specifically include the following steps:

[0076] Step 301: Calculate the strain value of each core in the multi-core optical fiber based on the spectral drift, and perform an inverse solution of the characteristic curvature vector in combination with the strain value of each core to obtain a discrete bending direction set and a discrete curvature set;

[0077] In an embodiment of the present invention, the strain value of each fiber core is first calculated through spectral drift, and then the Kirchhof elastic rod theory is used to establish a three-dimensional deformation measurement torsion angle compensation method for the helical fiber core structure, thereby realizing three-dimensional reconstruction of multi-core optical fibers and further realizing three-dimensional reconstruction of dynamic submarine cables.

[0078] In a specific implementation, the strain value of each core in a multi-core optical fiber is calculated based on spectral drift. The method is as follows: when the optical fiber is subjected to strain, the central wavelength data measured by the multi-core optical fiber sensor is obtained; and then the strain value of each core in the multi-core optical fiber is calculated based on the central wavelength data.

[0079] In combination with the contents in the aforementioned spiral spoiler embodiment, based on the Bragg grating array characteristics of the sensor, the multi-core optical fiber sensor can be regarded as having multiple grating detection points along the multi-core optical fiber, and each grating detection point is used to perform optical fiber bending and torsional strain detection on each core at a specific position of the multi-core optical fiber.

[0080] For multi-core optical fibers, the positions of the cores in the fiber cross section are defined by the core center distance r and the angular spacing of 120°. Indicates the relationship between the fiber core i and the y-axis ( ). According to the geometric relationship of the cross section, no matter how the fiber cores are distributed on the cross section, the strain value of the fiber core can be expressed as follows:

[0081]

[0082] in, is the strain magnitude of the fiber core i; k is the curvature magnitude of the current grating detection point; The above equation is valid for any number of fiber cores and any fiber core distribution.

[0083] In actual calculations, in order to use information from all fiber cores to calculate the curvature and reduce the sensitivity to errors in single strain measurements, a curvature vector (also called curvature vector) can be defined first. , the vector direction of the curvature vector is the direction from the center of the cross section to the i-th fiber core. Further, the direction can be decomposed into the direction on the y-axis and the z-axis, and the corresponding curvature vector components are 、 . Specifically, It can be expressed as:

[0084]

[0085] In the formula, the unit vector and Aligned with the y-axis and z-axis in the detection point coordinate system respectively.

[0086] For M cores in a multi-core fiber, the sum of the superposition vectors of the curvature vectors can be calculated and inversely solved. When the cores are symmetrically distributed, the curvature value of the current grating detection point can be calculated:

[0087]

[0088] The bending angle is then calculated by determining the angle of the curvature vector relative to the y-axis of the cross-sectional coordinate system is (in this case, if the bending angle is zero, it means the bending direction is along the y-axis):

[0089]

[0090] When the curvature value k and the angle between the fiber core i and the y-axis are calculated This can then be substituted into the previous core strain value In the calculation formula, the angle between the bending direction of the current grating detection point and the y-axis is obtained by inverse solution. , further calculations show Corresponding bending direction value The coordinate axis diagram of the bending angle and bending direction of a multi-core optical fiber (the multi-core optical fiber in the embodiment of the present invention is a structure with a central core and three outer cores) is as follows: Figure 4 shown.

[0091] Repeat the above steps for each grating detection point along the multi-core fiber to achieve the grating detection point along a specific position Generate discrete curvature sets and bending direction set By further fitting these two discrete data sets, we can get the curvature and bending direction A function of arc length s. Where, the curvature The function represents the curvature of the fiber at each position in the multi-core fiber, the bending direction The function represents the bending direction at each position in the corresponding multi-core optical fiber.

[0092] According to the above introduction, in a specific implementation, the characteristic curvature vector is inversely solved in combination with the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set. This can be done as follows: for each grating detection point, the superposition vector sum of the curvature vectors of each fiber core is calculated in combination with the strain value of each fiber core and inversely solved to obtain the discrete curvature value and discrete bending direction value of the grating detection point; each discrete bending direction value is integrated into a discrete bending direction set corresponding to multiple grating detection points, and each discrete curvature value is integrated into a discrete curvature set corresponding to multiple grating detection points.

[0093] Furthermore, the superposition vector sum of the curvature vectors of each fiber core is calculated in combination with the strain value of each fiber core and an inverse solution is performed to obtain the discrete curvature value and discrete bending direction value of the grating detection point. Specifically, the superposition vector sum of the curvature vectors of each fiber core is calculated in combination with the strain value of each fiber core, and the superposition vector sum is inversely solved once to obtain the discrete curvature value of the grating detection point; then, based on the discrete curvature value, a second inverse solution is performed in combination with the strain value of any fiber core to obtain the discrete bending direction value of the grating detection point.

[0094] Step 302: performing discrete fitting on the discrete bending direction set and the discrete curvature set respectively, until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted;

[0095] Specifically, discrete fitting is performed on the discrete bending direction set and the discrete curvature set respectively until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted, which can be:

[0096] Based on the calculation method of spline interpolation point coefficients and functions, discrete fitting is performed on each discrete bending direction value, and discrete fitting is performed on each discrete curvature value at the same time;

[0097] When the discrete fitting is completed, it is determined whether the bending direction and fiber curvature at each position in the multi-core optical fiber are successfully fitted;

[0098] If yes, output the bending direction and fiber curvature at each position in the multi-core optical fiber;

[0099] If not, repeat the discrete fitting until the fitting is successful.

[0100] Step 303, solving the fiber torsion according to the bending direction, and solving a spatial curve based on the fiber curvature and the fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber;

[0101] In practice, the initial optical fiber is already helically wound on the surface of the submarine cable, giving it a pre-existing helical angle. This means that every position in a multi-core optical fiber actually has an initial helical angle.

[0102] Due to the special structure of the helical multi-core optical fiber, the pre-twist value of the helical fiber (also known as the initial helix angle) must be subtracted when the bending angle is actually used for subsequent calculations. :

[0103]

[0104] Where h is the thread pitch.

[0105] In a multi-core optical fiber, the wavelength of the central core is only affected by temperature and axial strain, so the central core is insensitive to torsion. It is affected by temperature, axial strain, bending, and torsion at the same time. As for bending strain, due to the particularity of the core distribution of multi-core optical fiber, the sum of the bending strains of the three outer fibers is always 0, so the bending strain can be offset by summing up first. Then, the strains of the other fiber cores except the central fiber core affected by torsion, axial strain and temperature are calculated by averaging, and the strain of the central fiber core is calculated. The torsional strain can be decoupled by making a difference :

[0106]

[0107] The very small distance between the fiber cores allows them to remain effectively isothermal. Consequently, the central reference grating sees exactly the same thermal impact as the outer sensing gratings and experiences the same longitudinal extension or compression. This effect can be easily canceled out using the compensation described above.

[0108] In a specific implementation, the optical fiber torsion is solved according to the bending direction. The steps are as follows: calculating the original bending angle corresponding to the bending direction, and obtaining the initial spiral angle at the same position as the original bending angle; subtracting the initial spiral angle from the original bending angle to compensate for the torsion angle, and obtaining the target bending angle; solving the corrected bending direction according to the target bending angle, performing first-order and second-order derivatives on the corrected bending direction, and combining the first-order and second-order derivative results to calculate the optical fiber torsion.

[0109] Based on the calculated fiber curvature and fiber torsion, the Frenet-Serret formulas (also known as the Frenet-Serret equations) between the tangent, normal, and binormal directions of the curve in three-dimensional space can then be used to solve the strain value (fiber tangent vector) at each position in the multi-core optical fiber through distributed sensing. The differential equation is then solved numerically (integrating the fiber tangent vector) to obtain the position of the multi-core optical fiber in three-dimensional space and ultimately obtain a spatial curve. It can be understood that if the spiral spoiler is composed of multiple interlocking plates (such as three plates) with plate teeth, and a corresponding number of multi-core optical fiber sensors are provided, the position of multiple multi-core optical fibers in three-dimensional space can be obtained.

[0110] The Frenet-Serret equations are a set of important formulas for describing the geometric properties of space curves. They primarily characterize the local geometric properties of space curves by describing the rate of change of parameters such as fiber curvature and fiber torsion with the arc length parameter (s).

[0111] Curvature represents the rate of change of the tangent vector, describing the degree of curvature of a space curve at a certain point. Torsion, on the other hand, represents the rate of change of the binormal vector, describing how quickly the direction of the tangent vector changes when the space curve is curved.

[0112] The spatial curve is solved based on the fiber curvature and fiber torsion. Specifically, according to the fiber curvature, fiber torsion and given initial conditions (the initial conditions can be understood as solving the initial values at the starting point of the fiber), the Frenet-Serret equation is first solved, and then combined with numerical integration to solve the spatial curve.

[0113] Step 304: perform three-dimensional reconstruction on the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

[0114] It can be understood that the actual object to be measured in the embodiment of the present invention is a dynamic submarine cable. A spiral spoiler is provided on the outside of the dynamic submarine cable as a sleeve. The sleeve is surrounded by three interlocking plates. Plate teeth are provided on the plate, and a multi-core fiber optic sensor is placed in the spiral hole groove in the plate teeth. Based on the characteristics of the spiral structure, the multi-core fiber optic sensor itself and the central axis of the object to be measured do not coincide. When the multi-core optical fiber is fixed on the outer busbar of the catheter, the shape and spatial position restored by the multi-core optical fiber sensor are actually the trajectory of the multi-core optical fiber axis. In other words, the axis trajectory of the multi-core optical fiber can mainly include the shape trajectory of the multi-core optical fiber and the spatial position of the multi-core optical fiber sensor, and is not the center of the dynamic submarine cable. Therefore, when the three-dimensional shape of the multi-core optical fiber is obtained by three-dimensional reconstruction, it is necessary to solve the three-dimensional shape of the dynamic submarine cable in space by the spatial position of the multi-core optical fiber sensor based on the relevant theory of coordinate transformation.

[0115] In a specific implementation, the three-dimensional reconstruction of the submarine cable is performed according to the axis trajectory to obtain the three-dimensional shape of the submarine cable. This can be done by: firstly reconstructing the multi-core optical fiber in three dimensions based on the shape trajectory, and then performing coordinate transformation in combination with the spatial position of the multi-core optical fiber sensor to indirectly reconstruct the current position of the submarine cable in space and restore the three-dimensional shape of the submarine cable in space.

[0116] In an embodiment of the present invention, a three-dimensional reconstruction method based on a multi-core optical fiber is provided for the three-dimensional reconstruction of a dynamic submarine cable. First, the strain value of each fiber core in the multi-core optical fiber is calculated based on the spectral drift, and the characteristic curvature vector is inversely solved in combination with the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set; then, the discrete bending direction set and the discrete curvature set are discretely fitted respectively until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted; then, the fiber torsion is solved according to the bending direction, and the spatial curve is solved based on the fiber curvature and the fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber; finally, the submarine cable is three-dimensionally reconstructed according to the axis trajectory to obtain the three-dimensional shape of the submarine cable. Therefore, by constructing a three-dimensional inversion of a dynamic submarine cable, not only the accuracy and stability of dynamic submarine cable shape sensing can be improved, but also the purposes of attitude monitoring, vortex-induced vibration suppression, and vibration measurability can be achieved simultaneously.

[0117] For better explanation, refer to Figure 5 , which shows a schematic diagram of the overall process of a method for dynamic submarine cable 3D reconstruction provided by an embodiment of the present invention. It should be noted that this embodiment only briefly describes the general process of dynamic submarine cable 3D reconstruction. The specific implementation of each step can be understood by referring to the relevant content in the previous embodiments. A detailed description is omitted here. It is understood that the present invention is not limited to this.

[0118] Step 1: Calculate the strain value of each core in the multi-core optical fiber based on the spectral drift;

[0119] Step 2: For each grating detection point, the superposition vector sum of the curvature vectors of each fiber core is calculated in combination with the strain value of each fiber core, and the discrete curvature value and discrete bending direction value of the grating detection point are obtained by inverse solution;

[0120] Step 3: Obtain the discrete bending direction set and discrete curvature set through data integration;

[0121] Step 4: Based on the calculation of the spline interpolation point coefficients and the function method, discrete fitting is performed on the discrete bending direction set and the discrete curvature set respectively. When the discrete fitting is completed, it is determined whether the bending direction (bending direction function) and fiber curvature (fiber curvature function) at each position in the multi-core optical fiber are successfully fitted. If so, jump to step 5; if not, repeat step 4 until the fitting is successful.

[0122] Step 5: Combine torsion angle compensation to solve the fiber torsion according to the bending direction;

[0123] Step 6: Based on the fiber curvature, fiber torsion, and given initial conditions, the Frenet-Serret equation is first solved and then numerically integrated to obtain a spatial curve, where the spatial curve corresponds to the axis trajectory of the multi-core fiber.

[0124] Step 7: First, perform three-dimensional reconstruction of the multi-core optical fiber based on the axis trajectory, and then combine it with coordinate transformation to indirectly restore the three-dimensional shape of the submarine cable in space.

[0125] Reference Figure 6 , showing a block diagram of a dynamic submarine cable 3D reconstruction device provided by an embodiment of the present invention. First, a spiral spoiler is arranged on the outer surface of the submarine cable. The spiral spoiler is formed by at least one plate with plate teeth spirally rising and winding around the surface of the submarine cable. The plate teeth are provided with spiral holes, and multi-core optical fiber sensors are arranged in the spiral holes. The device may specifically include:

[0126] Characteristic curvature vector inverse solution module 601, used to calculate the strain value of each fiber core in the multi-core optical fiber based on the spectral drift, and perform characteristic curvature vector inverse solution based on the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set;

[0127] A discrete fitting module 602 is configured to perform discrete fitting on the discrete bending direction set and the discrete curvature set, respectively, until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted;

[0128] A spatial curve solving module 603 is configured to solve the optical fiber torsion according to the bending direction, and solve a spatial curve based on the optical fiber curvature and the optical fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber;

[0129] The three-dimensional reconstruction module 604 is configured to perform three-dimensional reconstruction on the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

[0130] In an optional embodiment, the characteristic curvature vector inverse solution module 601 includes:

[0131] a central wavelength data acquisition module, configured to acquire central wavelength data measured by the multi-core optical fiber sensor when the optical fiber is subjected to strain;

[0132] The strain value calculation module is used to calculate the strain value of each core in the multi-core optical fiber according to the central wavelength data.

[0133] In an optional embodiment, the multi-core optical fiber sensor is provided with a plurality of grating detection points along the multi-core optical fiber, each of the grating detection points being used to perform optical fiber bending and torsional strain detection on each core at a specific position of the multi-core optical fiber, and the characteristic curvature vector inverse solution module 601 includes:

[0134] a superposition vector sum inverse solution module, which calculates the superposition vector sum of the curvature vectors of each fiber core in combination with the strain value of each fiber core for each grating detection point and performs inverse solution to obtain the discrete curvature value and discrete bending direction value of the grating detection point;

[0135] The data set integration module is used to integrate the discrete bending direction values into a discrete bending direction set corresponding to the multiple grating detection points, and integrate the discrete curvature values into a discrete curvature set corresponding to the multiple grating detection points.

[0136] In an optional embodiment, the superposition vector and inverse solution module includes:

[0137] a discrete curvature value solving module, configured to calculate the superposition vector sum of the curvature vectors of each fiber core in combination with the strain value of each fiber core, and perform an inverse solution on the superposition vector sum to obtain the discrete curvature value of the grating detection point;

[0138] The discrete bending direction value solving module is used to perform a secondary inverse solution based on the discrete curvature value in combination with the strain value of any of the fiber cores to obtain the discrete bending direction value of the grating detection point.

[0139] In an optional embodiment, the discrete fitting module 602 includes:

[0140] A discrete fitting submodule, configured to perform discrete fitting on each of the discrete bending direction values and discrete fitting on each of the discrete curvature values based on a method of calculating spline interpolation point coefficients and functions;

[0141] A fitting result judgment module is used to judge whether the bending direction and fiber curvature at each position in the multi-core optical fiber are successfully fitted when the discrete fitting is completed;

[0142] A data output module, configured to output the bending direction and fiber curvature at each position in the multi-core optical fiber;

[0143] The repeated fitting module is used to re-perform discrete fitting until the fitting is successful.

[0144] In an optional embodiment, the space curve solving module 603 includes:

[0145] a bending angle calculation module, configured to calculate an original bending angle corresponding to the bending direction, and obtain an initial spiral angle at the same position as the original bending angle;

[0146] a torsion angle compensation module, configured to perform torsion angle compensation by subtracting the initial helix angle from the original bending angle to obtain a target bending angle;

[0147] an optical fiber torsion solving module, configured to solve a corrected bending direction according to the target bending angle, perform first-order and second-order derivatives on the corrected bending direction, and calculate the optical fiber torsion by combining the first-order and second-order derivative results;

[0148] The space curve solving submodule is used to obtain the space curve by first solving the Frenet-Serret equation according to the optical fiber curvature, the optical fiber torsion and the given initial conditions, and then combining the numerical integration solution.

[0149] In an optional embodiment, the axis trajectory includes the shape trajectory of the multi-core optical fiber and the spatial position of the multi-core optical fiber sensor, and the three-dimensional reconstruction module 604 is specifically configured to:

[0150] First, the multi-core optical fiber is three-dimensionally reconstructed based on the shape trajectory, and then the coordinate transformation is performed in combination with the spatial position of the multi-core optical fiber sensor to indirectly reconstruct the current position of the submarine cable in space and restore the three-dimensional shape of the submarine cable in space.

[0151] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the aforementioned method embodiment.

[0152] An embodiment of the present invention further provides an electronic device, the device including a processor and a memory:

[0153] The memory is used to store program codes and transmit the program codes to the processor;

[0154] The processor is configured to execute the dynamic submarine cable three-dimensional reconstruction method of any embodiment of the present invention according to the instructions in the program code.

[0155] An embodiment of the present invention further provides a computer-readable storage medium, which is used to store program code, and the program code is used to execute the dynamic submarine cable three-dimensional reconstruction method of any embodiment of the present invention.

[0156] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0157] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0158] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0159] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0160] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0161] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for 3D reconstruction of a dynamic submarine cable, characterized in that: A spiral spoiler is arranged on the outer surface of a submarine cable, wherein the spiral spoiler is formed by at least one plate with plate teeth spirally rising and winding around the surface of the submarine cable, wherein the plate teeth are provided with spiral holes and grooves, and a multi-core optical fiber sensor is arranged in the spiral holes and grooves; the method comprises: Calculating the strain value of each fiber core in the multi-core optical fiber based on the spectral drift, and performing an inverse solution of the characteristic curvature vector in combination with the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set; performing discrete fitting on the discrete bending direction set and the discrete curvature set respectively until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted; Solving the optical fiber torsion according to the bending direction, and solving a spatial curve based on the optical fiber curvature and the optical fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber; The submarine cable is three-dimensionally reconstructed according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

2. The method for dynamic submarine cable 3D reconstruction according to claim 1, characterized in that: The calculating the strain value of each core in the multi-core optical fiber based on the spectral drift includes: When the optical fiber is subjected to strain, obtaining central wavelength data measured by the multi-core optical fiber sensor; The strain value of each core in the multi-core optical fiber is calculated according to the central wavelength data.

3. The method for 3D reconstruction of a dynamic submarine cable according to claim 1, wherein: The multi-core optical fiber sensor is provided with a plurality of grating detection points along the multi-core optical fiber, each of the grating detection points being used to perform optical fiber bending and twisting strain detection on each core at a specific position of the multi-core optical fiber, and the characteristic curvature vector is inversely solved in combination with the strain value of each core to obtain a discrete bending direction set and a discrete curvature set, including: For each of the grating detection points, the superposition vector sum of the curvature vectors of the fiber cores is calculated in combination with the strain value of each fiber core and an inverse solution is performed to obtain a discrete curvature value and a discrete bending direction value of the grating detection point; The discrete bending direction values are integrated into a discrete bending direction set corresponding to the plurality of grating detection points, and the discrete curvature values are integrated into a discrete curvature set corresponding to the plurality of grating detection points.

4. The method for dynamic submarine cable 3D reconstruction according to claim 3, characterized in that: The calculating the superposition vector sum of the curvature vectors of the fiber cores in combination with the strain values of the fiber cores and performing inverse solution to obtain the discrete curvature value and the discrete bending direction value of the grating detection point includes: Calculating the superposition vector sum of the curvature vectors of the fiber cores in combination with the strain values of the fiber cores, and performing an inverse solution on the superposition vector sum to obtain the discrete curvature value of the grating detection point; A secondary inverse solution is performed based on the discrete curvature values in combination with the strain value of any of the fiber cores to obtain the discrete bending direction values of the grating detection points.

5. The method for 3D reconstruction of a dynamic submarine cable according to claim 3 or 4, characterized in that: The discrete fitting is performed on the discrete bending direction set and the discrete curvature set respectively until the bending direction and the fiber curvature at each position in the multi-core optical fiber are fitted, including: Based on the calculation method of spline interpolation point coefficients and functions, discrete fitting is performed on each of the discrete bending direction values, and discrete fitting is performed on each of the discrete curvature values; When the discrete fitting is completed, determining whether the bending direction and fiber curvature at each position in the multi-core optical fiber are successfully fitted; If yes, output the bending direction and fiber curvature at each position in the multi-core optical fiber; If not, repeat the discrete fitting until the fitting is successful.

6. The method for dynamic submarine cable 3D reconstruction according to claim 1, characterized in that: Solving the optical fiber torsion according to the bending direction, and solving the spatial curve based on the optical fiber curvature and the optical fiber torsion, includes: Calculating an original bending angle corresponding to the bending direction, and obtaining an initial spiral angle at the same position as the original bending angle; Subtracting the initial helix angle from the original bending angle to perform torsion angle compensation to obtain a target bending angle; Solving a corrected bending direction according to the target bending angle, performing first-order and second-order derivatives on the corrected bending direction, and calculating the optical fiber torsion by combining the first-order and second-order derivative results; According to the optical fiber curvature, the optical fiber torsion and the given initial conditions, the spatial curve is obtained by first solving the Frenet-Serret equation and then combining it with numerical integration to solve it.

7. The method for 3D reconstruction of a dynamic submarine cable according to claim 1, wherein: The axis trajectory includes the shape trajectory of the multi-core optical fiber and the spatial position of the multi-core optical fiber sensor, and the three-dimensional reconstruction of the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable includes: First, the multi-core optical fiber is three-dimensionally reconstructed based on the shape trajectory, and then the coordinate transformation is performed in combination with the spatial position of the multi-core optical fiber sensor to indirectly reconstruct the current position of the submarine cable in space and restore the three-dimensional shape of the submarine cable in space.

8. A dynamic submarine cable 3D reconstruction device, characterized in that: A spiral spoiler is arranged on the outer surface of the submarine cable, wherein the spiral spoiler is formed by at least one plate with plate teeth spirally rising and winding around the surface of the submarine cable, wherein the plate teeth are provided with spiral holes and grooves, and a multi-core optical fiber sensor is arranged in the spiral holes and grooves; the device comprises: A characteristic curvature vector inverse solution module is used to calculate the strain value of each fiber core in the multi-core optical fiber based on the spectral drift, and perform characteristic curvature vector inverse solution based on the strain value of each fiber core to obtain a discrete bending direction set and a discrete curvature set; A discrete fitting module, configured to perform discrete fitting on the discrete bending direction set and the discrete curvature set, respectively, until the bending direction and fiber curvature at each position in the multi-core optical fiber are fitted; A spatial curve solving module, configured to solve the optical fiber torsion according to the bending direction, and solve a spatial curve based on the optical fiber curvature and the optical fiber torsion, wherein the spatial curve corresponds to the axis trajectory of the multi-core optical fiber; A three-dimensional reconstruction module is used to perform three-dimensional reconstruction on the submarine cable according to the axis trajectory to obtain the three-dimensional shape of the submarine cable.

9. An electronic device, characterized in that: The device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the dynamic submarine cable three-dimensional reconstruction method according to any one of claims 1 to 7 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store program code, and the program code is used to execute the dynamic submarine cable three-dimensional reconstruction method according to any one of claims 1 to 7.

Images