A Time-Division Multiplexing Multi-Parameter Synchronous Sensing Method and System Based on Multi-Core Optical Fiber

Abstract

The present application provides a time-division multiplexing multi-parameter synchronous sensing method and system based on multi-core optical fiber. Among them, a multi-core optical fiber containing three heterogeneous cores is embedded in the measured object, and a distributed reflection grating array with an inclination angle to the axial direction is inscribed on the surface of each core; the time-division multiplexing technology is used to synchronously collect the inter-mode energy exchange data and the reflection grating wavelength shift signals of each core, and the cross-correlation algorithm is used to extract the phase difference signal as the curvature reference value, and the wavelength shift data and the phase signal are subjected to dynamic compensation operation to effectively eliminate the temperature interference and obtain the accurate strain distribution; a coordinate transformation model is established by combining the three-dimensional geometric parameters of the helical optical fiber, and the curvature reference and the strain parameters are vectorially synthesized to realize the accurate reconstruction of the three-dimensional deformation field of the measured object. The technical solution provided by the present application realizes the real-time reconstruction of a high-precision three-dimensional deformation field with temperature self-compensation through multi-core optical fiber multi-parameter synchronous sensing and three-dimensional coordinate mapping.

Description

Technical Field

[0001] This application relates to the technical field of fiber optic sensing and three-dimensional deformation measurement, and particularly to a time-division multiplexing multi-parameter synchronous sensing method and system based on multi-core optical fiber. Background Art

[0002] In the fields of aerospace structural health monitoring, deformation detection of large mechanical equipment, etc., it is necessary to accurately and real-time sense complex three-dimensional deformation fields. Such scenarios require sensors to have the ability to synchronously measure multiple physical quantities (such as strain, temperature, curvature), and at the same time, it is necessary to overcome the cross-interference of multiple parameters and the influence of environmental temperature fluctuations, and achieve the spatial continuous reconstruction of the three-dimensional deformation field. Traditional single-parameter or low-dimensional sensing technologies are difficult to meet the above requirements, and there is an urgent need for a three-dimensional deformation synchronous sensing scheme with anti-interference ability, multi-parameter decoupling ability and high spatial resolution.

[0003] The current mainstream solution for this demand is a distributed sensing system based on a single-core distributed reflection grating array (FBG). This solution densely writes multiple FBG sensors on a single-core optical fiber, uses the grating wavelength shift to reflect local strain or temperature changes, and combines time-division multiplexing technology (TDM) to achieve time-division acquisition of multi-measurement point data. By optimizing the grating spatial arrangement and demodulation algorithm, the dynamic monitoring of strain distribution can be partially realized, and the environmental interference can be reduced by using a temperature compensation model.

[0004] Existing distributed sensing systems based on single-core distributed reflection grating array (FBG) arrays have inherent defects of multi-physical field cross-interference, insufficient three-dimensional reconstruction accuracy and limited synchronous measurement ability due to relying on the axial strain information of a single fiber core and the time-division multiplexing mechanism: First, a single-core optical fiber only decouples strain and temperature changes through the grating wavelength shift, and it needs to rely on an external reference sensor for dynamic compensation, resulting in the accumulation of temperature drift errors and the decline of real-time performance; Second, the single-core structure cannot directly sense transverse curvature and torsional deformation, and it needs to indirectly synthesize a three-dimensional deformation field by using an extrapolation algorithm, resulting in a significant reduction in spatial resolution and reconstruction accuracy; In addition, the serial data acquisition method of time-division multiplexing causes a time difference in the measurement of parameters such as strain and temperature, and it is easy to cause a phase mismatch problem during the inversion of the dynamic deformation field, making it difficult to meet the requirements of high-precision and multi-parameter synchronous sensing in complex scenarios. Summary of the Invention

[0005] This application provides a time-division multiplexing multi-parameter synchronous sensing method and system based on multi-core optical fiber to solve the problems of multi-physical field cross-interference, insufficient three-dimensional reconstruction accuracy and parameter measurement phase mismatch in the prior art.

[0006] In the first aspect, this application provides a time-division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber, including:

[0007] Embed a multi-core optical fiber structure inside the object under test. The multi-core optical fiber structure includes at least three cores made of different materials. Distributed reflection grating arrays are inscribed at intervals on the surface of each core made of a different material. The spatial arrangement direction of the reflection grating arrays forms a predetermined inclination angle with the axial direction of the multi-core optical fiber structure;

[0008] Synchronously collect the inter-mode energy exchange data and the reflection grating wavelength shift data of each core made of a different material through time division multiplexing technology;

[0009] Perform cross-correlation and phase analysis processing on the inter-mode energy exchange data to extract the phase difference signals of each measurement point as the curvature calculation reference value. At the same time, perform dynamic adjustment compensation operations on the reflection grating wavelength shift data and the phase difference signals to generate strain distribution parameters after eliminating temperature interference;

[0010] Establish a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core optical fiber structure. Input the curvature calculation reference value and the strain distribution parameters into the three-dimensional coordinate transformation model, and reconstruct the three-dimensional deformation field distribution of the object under test through vector synthesis.

[0011] Optionally, the inter-mode energy exchange data includes the optical transmission energy change characteristics between adjacent cores made of different materials;

[0012] Performing cross-correlation and phase analysis processing on the inter-mode energy exchange data to extract the phase difference signals of each measurement point as the curvature calculation reference value includes:

[0013] According to the optical transmission energy change differences caused by deformation between adjacent cores made of different materials, calculate the optical signal propagation path length differences of each core at the same spatial position, and obtain the phase shift components of each core reflecting the bending direction of the multi-core optical fiber;

[0014] For the phase shift components of at least three cores made of different materials at the same measurement point, perform vector decomposition according to the core arrangement direction. Combining the optical signal delay difference characteristics of each core material, project the phase shift components of each core onto the orthogonal directions, and calculate the composite phase difference in three directions through vector superposition to generate a phase difference signal characterizing the local bending direction and use it as the curvature calculation reference value.

[0015] Optionally, the reflection grating wavelength shift data includes the optical path length change information corresponding to the spatial position;

[0016] Performing dynamic adjustment compensation operations on the reflection grating wavelength shift data and the phase difference signals to generate strain distribution parameters after eliminating temperature interference includes:

[0017] Convert the optical path length change amount at the same spatial position in the reflected grating wavelength shift data into an equivalent phase change amount, and determine the deviation correction rule when the temperature changes by using the historical correspondence between the synchronously collected phase difference signal and the equivalent phase change amount under the condition of no temperature interference;

[0018] Real-time detect the deviation degree between the equivalent phase change amount and the phase difference signal at the same measurement point. When the deviation degree exceeds the allowable range established by the historical correspondence, perform reverse compensation on the equivalent phase change amount based on the deviation correction rule, so that the compensated equivalent phase change amount and the phase difference signal are kept consistent within the allowable range, and generate strain distribution parameters that eliminate temperature interference.

[0019] Optionally, the spatial geometric parameters include the helix radius, pitch, and core distribution direction;

[0020] Establish a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core optical fiber structure, input the curvature calculation reference value and the strain distribution parameters into the three-dimensional coordinate transformation model, and reconstruct the three-dimensional deformation field distribution of the measured object by means of vector synthesis, including:

[0021] Construct a three-dimensional coordinate transformation model according to the helix radius, pitch, and core distribution direction of the multi-core optical fiber structure. The three-dimensional coordinate transformation model includes a longitudinal coordinate system defined by the helix axis direction, a tangential coordinate system defined by the helix rotation direction, and a radial coordinate system defined by the helix radius direction;

[0022] Decompose the curvature calculation reference value into the corresponding curvature change amounts in the longitudinal coordinate system, tangential coordinate system, and radial coordinate system respectively, and at the same time convert the strain distribution parameters into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber structure on the longitudinal coordinate system;

[0023] For each measurement point, map the longitudinal, tangential, and radial curvature change amounts to the three-dimensional direction offset amount of the measured object at the measurement point through the three-dimensional coordinate transformation model, and combine the tensile deformation amount or compressive deformation amount to calculate the dynamic coordinate adjustment value of the measurement point;

[0024] Along the extension path of the multi-core optical fiber structure, perform direction superposition on the dynamic coordinate adjustment values of all measurement points, and convert the superimposed offset amount into the three-dimensional deformation vector of each position on the surface of the measured object through the three-dimensional coordinate transformation model, and generate a continuous three-dimensional deformation field distribution.

[0025] Optionally, decompose the curvature calculation reference value into the respective corresponding curvature change amounts in the longitudinal coordinate system, tangential coordinate system, and radial coordinate system, and at the same time convert the strain distribution parameter into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber structure in the longitudinal coordinate system, including:

[0026] According to the helix radius and pitch of the multi-core optical fiber structure, determine the central axis direction of the multi-core optical fiber structure in the longitudinal coordinate system, the helical rotation tangent direction in the tangential coordinate system, and the helix radius expansion direction in the radial coordinate system;

[0027] Take the component of the curvature calculation reference value in the central axis direction as the longitudinal curvature change amount, the component in the helical rotation tangent direction as the tangential curvature change amount, and the component in the helix radius expansion direction as the radial curvature change amount;

[0028] According to the linear relationship between the axial length change amount of the multi-core optical fiber structure and the strain distribution parameter, convert the strain distribution parameter into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber structure in the central axis direction; wherein, the numerical sign of the tensile deformation amount or compressive deformation amount is used to distinguish the axial elongation or shortening state of the multi-core optical fiber structure.

[0029] Optionally, for each measurement point, map the longitudinal, tangential, and radial curvature change amounts to the three-dimensional direction offset of the measured object at the measurement point through the three-dimensional coordinate transformation model, and combine the tensile deformation amount or compressive deformation amount to calculate the dynamic coordinate adjustment value of the measurement point, including:

[0030] According to the axis direction relationship of the three-dimensional coordinate transformation model, convert the longitudinal curvature change amount into the bending displacement of the measurement point along the central axis direction, convert the tangential curvature change amount into the torsional displacement along the helical tangent direction, and convert the radial curvature change amount into the telescopic displacement along the helix radius direction;

[0031] Convert the bending displacement, torsional displacement, and telescopic displacement into the three-dimensional direction offset in the global coordinate system of the measured object according to the three-dimensional coordinate transformation model;

[0032] According to the tensile deformation amount or compressive deformation amount, adjust the position of the measurement point in the central axis direction to generate an axial deformation amount;

[0033] Superimpose the three-dimensional direction offset and the axial deformation amount to obtain the dynamic coordinate adjustment value of the measurement point.

[0034] Optionally, convert the optical path length change amount at the same spatial position in the reflected grating wavelength shift data into an equivalent phase change amount, and use the historical corresponding relationship between the phase difference signal collected synchronously and the equivalent phase change amount under the condition of no temperature interference to determine the deviation correction rule when the temperature changes, including:

[0035] Determine the optical path length change amount of the multi-core fiber structure at this position according to the change amplitude of the optical signal wavelength at the same spatial position in the reflected grating wavelength shift data, and convert the optical path length change amount into an equivalent phase change amount according to a preset proportional relationship. The equivalent phase change amount represents the phase fluctuation caused only by temperature change;

[0036] Compare the phase difference signal at the same measurement point with the historical synchronous acquisition data of the equivalent phase change amount under the condition of no temperature interference, extract the corresponding relationship between the change direction and amplitude of the phase difference signal and the equivalent phase change amount without temperature interference, and establish a historical synchronous correspondence table between the two under the temperature stable state;

[0037] According to the historical synchronous correspondence table, statistically analyze the deviation direction and deviation amplitude of the equivalent phase change amount and the phase difference signal when the temperature changes, and generate an interference correction coefficient for the temperature change on the equivalent phase change amount. The interference correction coefficient is used to adjust the equivalent phase change amount caused by temperature to the same change trend as the phase difference signal;

[0038] Real-time monitor the deviation amplitude between the equivalent phase change amount and the phase difference signal when the temperature changes, and perform reverse correction on the equivalent phase change amount according to the product result of the deviation amplitude and the interference correction coefficient, so that the corrected equivalent phase change amount is synchronized with the change direction and amplitude of the phase difference signal within a preset error range.

[0039] In a second aspect, the present application provides a time division multiplexing multi-parameter synchronous sensing system based on a multi-core fiber, including:

[0040] A processing module that embeds the multi-core fiber structure inside the measured object. The multi-core fiber structure includes at least three cores of different materials, and distributed reflection grating arrays are inscribed at intervals on the surface of each core of different materials. The spatial arrangement direction of the reflection grating array forms a predetermined inclination angle with the axial direction of the multi-core fiber structure;

[0041] An acquisition module that synchronously acquires the inter-mode energy exchange data and the reflected grating wavelength shift data of each core of different materials through time division multiplexing technology. The reflected grating wavelength shift data includes the optical path length change information corresponding to the spatial position;

[0042] An operation module cross-correlates and phase-analyzes the inter-mode energy exchange data, extracts the phase difference signals of each measurement point as the curvature calculation reference value, and simultaneously performs a dynamic adjustment compensation operation on the reflected grating wavelength shift data and the phase difference signals to generate strain distribution parameters after temperature interference cancellation;

[0043] A synthesis module establishes a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core optical fiber structure, inputs the curvature calculation reference value and the strain distribution parameters into the three-dimensional coordinate transformation model, and reconstructs the three-dimensional deformation field distribution of the measured object through vector synthesis.

[0044] In a third aspect, an embodiment of the present application provides a computing device, including a processing component and a storage component; the storage component stores one or more computer instructions; the one or more computer instructions are used to be called and executed by the processing component to implement a multi-parameter synchronous sensing method based on multi-core optical fiber as described in the first aspect above.

[0045] In a fourth aspect, an embodiment of the present application provides a computer storage medium storing a computer program, and when the computer program is executed by a computer, it implements a multi-parameter synchronous sensing method based on multi-core optical fiber as described in the first aspect.

[0046] In the embodiment of the present application, by embedding at least three cores of different materials in the measured object and combining the inclined arrangement of the reflection grating array, the spatial perception ability of the three-dimensional deformation field is enhanced, and the problem of missing lateral deformation information of single-core optical fiber is solved; the time division multiplexing technology is used to synchronously collect the inter-mode energy exchange data and the reflected grating wavelength shift data of the multi-core optical fiber, eliminate the time difference of multi-parameter measurement, and improve the phase consistency of dynamic deformation field inversion; through the phase analysis of the inter-mode energy exchange data and the dynamic adjustment compensation of the reflected grating data, the in-situ decoupling of strain and temperature is realized, avoiding the error accumulation and real-time decline problems introduced by external reference sensors; a vector synthesis model is established based on the spatial geometric parameters of the spiral structure, directly fusing the curvature reference value and the strain distribution parameters, and the three-dimensional deformation field can be reconstructed with high precision without an extrapolation algorithm, significantly improving the spatial resolution and reconstruction efficiency.

[0047] This application further analyzes the difference in optical transmission energy changes caused by deformation between adjacent cores of different materials, combines the optical signal delay characteristics of the core materials, performs vector decomposition and orthogonal projection on the multi-core phase shift components at the same measurement point, calculates the synthetic phase difference using vector superposition, and generates a reference signal characterizing the local bending direction and curvature. Through the analysis of the multi-core optical transmission path difference and the vector synthesis algorithm, the bending direction and curvature value of the multi-core optical fiber are directly analyzed, avoiding the loss of spatial information of the traditional single-core optical fiber that relies on extrapolation algorithms, significantly improving the direction sensitivity and accuracy of curvature measurement. At the same time, phase delay compensation is achieved by combining the characteristics of core material differences, enhancing the robustness perception ability of complex deformation fields.

[0048] These aspects or other aspects of this application will be more clearly understood in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0050] Figure 1 FIG. shows a flowchart of a time division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber provided by this application;

[0051] Figure 2 FIG. shows a schematic structural diagram of a time division multiplexing multi-parameter synchronous sensing method system based on multi-core optical fiber provided by this application;

[0052] Figure 3 FIG. shows a schematic structural diagram of a computing device provided by this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] In order to enable those skilled in the art to better understand the solution of this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application.

[0054] In some processes described in the specification, claims, and the above-mentioned drawings of this application, a number of operations appear in a specific order. However, it should be clearly understood that these operations may not be executed in the order in which they appear herein or may be executed in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel. It should be noted that the descriptions such as "first", "second", etc. in this article are used to distinguish different messages, devices, modules, etc., do not represent a sequence, and do not limit that "first" and "second" are of different types.

[0055] Researchers have found that there are core problems in the existing single-core fiber optic sensing technology for complex deformation field measurement, such as multi-physical field cross-interference (such as strain-temperature coupling), insufficient accuracy in three-dimensional reconstruction due to reliance on extrapolation algorithms, and phase mismatch in multi-parameter dynamic measurement. Based on this, a time-division multiplexing multi-parameter synchronous sensing method based on multi-core fiber is provided. This method combines a helical multi-core fiber structure with a space-division / time-division hybrid demodulation technology to achieve in-situ decoupling and synchronous high-precision reconstruction of strain, temperature, and three-dimensional deformation parameters. The technical solution of this application is applicable to the real-time monitoring scenario of the deformation field inside intelligent materials.

[0056] The entire R & D process reflects the technical linkage of multi-physical field synchronous decoupling and dynamic collaborative analysis, aiming to break through the defects in traditional sensing technologies, such as high cross-sensitivity, insufficient three-dimensional reconstruction accuracy, limited dynamic response bandwidth, and weak environmental noise suppression ability. Through the time-division multiplexing architecture of multi-core fiber, in-situ separation measurement of strain, temperature, and curvature signals is achieved, eliminating the systematic influence of multi-physical field coupling interference on measurement accuracy; combining a vector synthesis algorithm with a curvature direction sensitivity enhancement mechanism, a high-precision three-dimensional deformation field dynamic reconstruction model is constructed to solve the anisotropic distortion problem in the spatial analysis of complex deformation fields; based on optical pulse timing control and dynamic phase analysis technology, a collaborative optimization framework for measurement bandwidth expansion and environmental noise suppression is established to overcome the technical bottleneck of signal attenuation and noise superposition in high-frequency dynamic monitoring. This method significantly improves the accuracy, response speed, and system anti-interference performance of deformation monitoring under complex working conditions through a closed-loop control strategy of physical field decoupling and real-time feedback.

[0057] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

[0058] Figure 1The figure below is a flowchart of a time-division multiplexing multi-parameter synchronous sensing method based on a multi-core optical fiber provided by an embodiment of the present application. As Figure 1 shown, the method includes:

[0059] 101. Embed a multi-core optical fiber structure into the interior of the measured object. The multi-core optical fiber structure includes at least three cores made of different materials. Distributed reflection grating arrays are inscribed at intervals on the surface of each core made of a different material. The spatial arrangement direction of the reflection grating arrays forms a predetermined inclination angle with the axial direction of the multi-core optical fiber structure;

[0060] The multi-core optical fiber structure refers to a composite optical fiber formed by tightly arranging cores made of at least three different materials (such as germanium-doped silica cores, fluorine-doped cores, photosensitive polymer cores) in a spiral trajectory. Distributed reflection grating arrays (FBG arrays) are formed on the surface of each core through femtosecond laser inscription technology. The spatial arrangement direction forms a spiral multi-core optical fiber structure with an inclination angle of 15°–45° with the optical fiber axial direction.

[0061] In an embodiment of the present application, first, three cores with different doping concentrations (germanium-doped silica cores, fluorine-doped cores, photosensitive polymer cores) are prepared by chemical vapor deposition. The distributed reflection grating arrays are inscribed periodically on the surface of the cores along the axis at an inclination angle of 15°–45° using femtosecond laser direct writing technology. The grating period is strictly controlled within the range of 530–550 nm to match the multi-wavelength demodulation requirements. Subsequently, the cores are wound around a flexible support skeleton in a spiral trajectory with a pitch of 3–5 mm, and the outer layer is coated with low-modulus silica gel to form a composite optical fiber with a diameter of 0.5–1.2 mm. Finally, through 3D printing path planning, the optical fiber is embedded into the interior of the measured object along a spiral path, ensuring that the optical fiber axial direction is consistent with the main stress direction of the object, and mechanical coupling is achieved through epoxy resin curing. The spatial angle parameters of the inclined gratings and the spiral encapsulation structure jointly determine the subsequent multi-physical quantity decoupling ability, and the core material differences provide a physical basis for temperature / strain cross-sensitivity suppression.

[0062] 102. Synchronously collect the inter-mode energy exchange data and the reflection grating wavelength shift data of each core made of a different material through time division multiplexing technology;

[0063] The inter-mode energy exchange data refers to the change in the mode coupling strength caused by the action of external physical quantities during the optical transmission in different cores. The curvature and strain are inverted by detecting the energy transfer amount between the cores. The reflection grating wavelength shift data refers to the Bragg wavelength drift amount of each core grating caused by temperature / strain, which is used to calculate the temperature field distribution. The time division multiplexing technology sequentially excites different cores in a time division sequence by controlling a pulsed laser, and realizes synchronous acquisition of multi-channel signals in combination with a high-speed optoelectronic switch.

[0064] In the embodiments of the present application, an ultra-narrow linewidth pulsed laser (pulse width 10 ns, repetition frequency 1 MHz) is used to excite three cores in a time-sharing manner, and a high-speed optoelectronic switch (switching time <10 ns) is used to synchronously switch the receiving channels, and the reflected grating wavelength shift data of each core and the inter-mode energy exchange data between adjacent cores are sequentially collected; the time stamp alignment technology is used to encode the reflected grating wavelength shift data (measurement accuracy ±1 pm) and the inter-mode energy exchange data (resolution 0.1 dB) of different cores according to the spatial coordinates to form a spatio-temporal correlation data set. The characteristic reflection wavelengths of the core materials (such as 1528 nm for germanium-doped core, 1545 nm for fluorine-doped core, 1560 nm for polymer core) are used as identifiers for physical quantity separation, and the time-division multiplexing technology avoids signal crosstalk through strict time window isolation.

[0065] 103. Perform cross-correlation and phase analysis processing on the inter-mode energy exchange data to extract the phase difference signal of each measurement point as the curvature calculation reference value, and at the same time perform dynamic adjustment compensation operation on the reflected grating wavelength shift data and the phase difference signal to generate the strain distribution parameters after eliminating temperature interference;

[0066] The phase difference signal refers to the curvature eigenvalue obtained by phase analysis of the mode-coupled light intensity, and its calculation reference is the product of the optical path difference between cores and the coupling coefficient; the dynamic adjustment compensation operation eliminates the cross-sensitivity error of temperature to strain measurement by establishing a transfer function matrix of wavelength shift-phase difference.

[0067] In the embodiments of the present application, the Morlet wavelet transform is applied to the inter-mode energy exchange data to extract time-frequency characteristics, and the phase difference signal of each measurement point between adjacent cores is calculated. The optical path difference phase angle Δφ = 2π·(n_eff·L) / λ, and the curvature reference value κ = Δφ / (R·cosθ) is generated in combination with the tilt angle θ and the fiber bending radius R; at the same time, the reflected grating wavelength shift data Δλ_B of the three cores is substituted into the transfer function matrix (Δλ_B = K_T·ΔT + K_ε·ε), and the temperature ΔT and the true strain ε of each spatial point are solved based on the least squares method. The temperature sensitivity coefficient K_T and the strain sensitivity coefficient K_ε are determined in advance through laboratory calibration (such as K_T = 10.2 pm / °C, K_ε = 1.2 pm / με for germanium-doped core). The dynamic compensation algorithm generates the strain distribution parameters after eliminating temperature interference by updating the ΔT-ε mapping relationship in real time.

[0068] 104. Establish a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core fiber structure, input the curvature calculation reference value and the strain distribution parameters into the three-dimensional coordinate transformation model, and reconstruct the three-dimensional deformation field distribution of the measured object by vector synthesis.

[0069] The three-dimensional coordinate transformation model establishes the mapping relationship from the local coordinate system to the global coordinate system based on the geometric parameters (pitch, winding radius) of the helical optical fiber; the vector synthesis method refers to superimposing the curvature and strain data of each fiber core according to the spatial vector, and calculating the three-dimensional deformation components through orthogonal decomposition.

[0070] In the embodiments of the present application, a three-dimensional coordinate transformation model from the local coordinate system to the global coordinate system is established based on the geometric parameters (pitch h, winding radius r) of the helical structure of the multi-core optical fiber. The parametric equations of the three-dimensional coordinate transformation model are x = r·cos(2πz / h), y = r·sin(2πz / h), z = z; the curvature reference value κ and the strain ε after temperature compensation are input into the three-dimensional coordinate transformation model, and vector decomposition is performed on each measurement point: the strain component is projected along the tangential vector t of the optical fiber axis as ε_v = ε·t, and the curvature component is projected along the bending normal vector n as κ_v = κ·n; the ε_v and κ_v of all discrete points are spatially superimposed through the thin plate spline interpolation algorithm to generate a continuous three-dimensional deformation field distribution of the measured object, and the Kriging interpolation is used to optimize the spatial resolution to 0.5 mm.

[0071] This solution realizes the high-precision perception of the structural health state in the whole domain under complex working conditions through a collaborative technical system of helical composite optical fiber sensing network construction, multi-core fiber signal decoupling, temperature-strain cross compensation and three-dimensional deformation field reconstruction. Based on the heterogeneous core helical inscription and embedded packaging technology, integrating time-division multiplexing excitation, multi-physical quantity coupling model and helical topology mapping algorithm, it breaks through the bottleneck of multi-parameter crosstalk suppression and spatial continuous field analysis, significantly improves the spatio-temporal resolution and anti-environmental interference ability of strain monitoring, and provides a highly reliable solution for the deformation dynamic tracking and early damage location of large equipment.

[0072] In some embodiments, the data of the energy exchange between modes includes the characteristics of the change in the optical transmission energy between adjacent cores of different materials;

[0073] Performing cross-correlation and phase analysis processing on the data of the energy exchange between modes, and extracting the phase difference signal of each measurement point as the curvature calculation reference value, including:

[0074] 201. According to the difference in the change in the optical transmission energy caused by the deformation between adjacent cores of different materials, calculate the difference in the optical signal propagation path length of each core at the same spatial position, and obtain the phase offset component of each core reflecting the bending direction of the multi-core optical fiber;

[0075] The difference in the change in the optical transmission energy refers to the change in the optical signal propagation path length caused by the refractive index difference when adjacent cores of different materials deform, which in turn causes an asymmetric fluctuation in the energy distribution. The phase offset component refers to the phase change amount calculated through the optical path difference, which is used to describe the signal delay difference caused by the bending of the core.

[0076] In the embodiments of the present application, the backscattered light signals of adjacent cores made of different materials (such as a quartz core and a fluorine-doped core) are collected by an optical time domain reflectometer (OTDR), and the optical transmission energy distribution data before and after the deformation of the adjacent cores made of different materials are recorded. Secondly, based on the difference in sensitivity of the refractive index of the core material to bending (for example, the path compression of a high refractive index core is more significant when bent), the difference in the optical signal propagation path lengths of cores made of different materials at the same position is calculated. Finally, the difference in the optical signal propagation path lengths is mapped to a phase offset amount by Fourier transform, and the phase offset components of each core are obtained as input parameters for subsequent bending direction analysis.

[0077] 202. For the phase offset components of at least three cores made of different materials at the same measurement point, vector decomposition is performed according to the core arrangement direction, and in combination with the delay difference characteristics of the optical signals of each core material, the phase offset components of each core are projected onto orthogonal directions, and the composite phase differences in three directions are calculated through vector superposition to generate a phase difference signal characterizing the local bending direction, which is used as the curvature calculation reference value.

[0078] Vector decomposition refers to decomposing the phase offset amount of each core into direction components according to the spatial arrangement direction (such as the orthogonal X / Y axes). The composite phase difference refers to a composite signal generated by vector superposition of multi-direction phase components, which is used to uniquely characterize the local bending direction and curvature.

[0079] In the embodiments of the present application, according to the geometric arrangement of the multi-core optical fiber (such as a triangular or rectangular array), orthogonal decomposition axes are defined (for example, the X axis corresponds to the horizontal bending direction, and the Y axis corresponds to the vertical bending direction). Then, based on the delay difference characteristics of the optical signals of each core material with respect to temperature and strain (such as the high-temperature delay effect of a chalcogenide glass core), the phase offset components are corrected to eliminate environmental interference. The corrected phase offset components are projected onto the orthogonal axes, and a composite phase difference is generated through a vector superposition algorithm (such as taking the square root of the sum of the squares of the horizontal component and the vertical component) to generate a phase difference signal characterizing the local bending direction, which is used as the curvature calculation reference value.

[0080] The following is a specific example:

[0081] Deploy a three-core heterogeneous optical fiber (quartz core, fluorine-doped core, chalcogenide glass core) on the surface of the oil pipeline to monitor the multi-directional bending deformation of the pipeline caused by geological settlement in real time. A three-core heterogeneous optical fiber (quartz core, fluorine-doped core, chalcogenide glass core) is deployed on the surface of the oil pipeline to monitor the multi-directional bending deformation of the pipeline caused by geological settlement in real time. When the pipeline is bent due to local compression, the energy distribution of the backscattered light of the heterogeneous fiber core generates an asymmetric fluctuation due to the difference in material refractive index, triggering the optical time domain reflectometer (OTDR) to collect the optical signal data before and after the deformation. By analyzing the optical path difference between the quartz core and the fluorine-doped core and combining the differences in their sensitivities to bending, the corresponding phase shift component is calculated and mapped. At the same time, for the additional delay caused by environmental temperature fluctuations in the chalcogenide glass core, compensation and correction are performed based on its refractive index temperature response model. Subsequently, according to the geometric arrangement of the optical fiber, the corrected phase shift amount is decomposed into X-axis (horizontal compression direction) and Y-axis (vertical stretching direction) components in the pipeline coordinate system, and a synthetic phase difference is generated through a vector superposition algorithm. Finally, based on the amplitude and direction of the synthetic phase difference, it is determined that the pipeline is bent in the northwest direction, and the local curvature is calculated based on its amplitude, realizing the precise positioning and quantitative evaluation of the deformation caused by geological settlement.

[0082] Through the vector decomposition and synthesis of the phase shift of the heterogeneous fiber core, combined with the material property compensation and the space projection algorithm, this solution realizes the high-precision decoupling of the bending direction and curvature of the multi-core optical fiber. In complex deformation scenarios (such as multi-directional bending of pipelines and torsion of structural components), it can effectively separate the horizontal, vertical, and torsion components, suppress environmental interference and multi-core crosstalk, and significantly improve the reliability of curvature measurement and the accuracy of direction identification, providing core technical support for the deformation safety monitoring of industrial facilities and large structures.

[0083] In some embodiments, the reflected grating wavelength shift data includes the optical path length change information corresponding to the spatial position;

[0084] Perform a dynamic adjustment compensation operation on the reflected grating wavelength shift data and the phase difference signal to generate the strain distribution parameters after eliminating temperature interference, including:

[0085] 301. Convert the optical path length change amount at the same spatial position in the reflected grating wavelength shift data into an equivalent phase change amount, and use the historical corresponding relationship between the synchronously collected phase difference signal and the equivalent phase change amount under the condition of no temperature interference to determine the deviation correction rule between the two when the temperature changes;

[0086] The reflected grating wavelength shift data refers to the measurement data of the wavelength shift of a fiber Bragg grating (FBG) caused by external strain or temperature changes, and the shift amount is proportional to the change amount of the optical path length. The equivalent phase change amount refers to the phase change value calculated by substituting the change amount of the optical path length into the optical wavelength-phase conversion formula (ΔΦ = 4πnΔL / λ, where n is the core refractive index, ΔL is the change amount of the optical path length, and λ is the wavelength of the optical signal), which is used for comparative analysis with the phase difference signal. The deviation correction rule refers to the dynamic compensation relationship between the equivalent phase change amount and the phase difference signal under temperature changes established through historical data, such as the linear coefficient by which the equivalent phase needs to be corrected when the temperature rises by 1°C.

[0087] In the embodiments of this application, first, the reflected grating wavelength shift data is obtained through fiber grating demodulation technology, and the change component of the optical path length caused by temperature changes is separated based on the grating wavelength-strain / temperature coupling formula. Subsequently, the change component of the optical path length is substituted into the phase conversion model (ΔΦ = 4πnΔL / λ, where n is the core refractive index, ΔL is the change amount of the optical path length, and λ is the wavelength of the optical signal) to calculate the equivalent phase change amount ΔΦ. At the same time, using the phase difference signal and the equivalent phase change amount data set synchronously collected under the condition of no temperature interference in historical experiments, a dynamic association model between the two is trained through regression analysis or machine learning algorithms, such as establishing the proportional coefficient or non-linear mapping relationship between the equivalent phase and the measured phase when the temperature changes. Finally, the parameters of the trained dynamic association model are encoded into a real-time correction rule library to obtain the deviation correction rule between the phase difference signal and the equivalent phase change amount when the temperature changes, which is called during the dynamic compensation stage.

[0088] 302. Real-time detect the deviation degree between the equivalent phase change amount and the phase difference signal at the same measurement point. When the deviation degree exceeds the allowable range established by the historical corresponding relationship, perform reverse compensation on the equivalent phase change amount based on the deviation correction rule, so that the compensated equivalent phase change amount is consistent with the phase difference signal within the allowable range, and generate the strain distribution parameters that eliminate temperature interference.

[0089] The deviation degree refers to the difference value between the equivalent phase change amount and the phase difference signal in real-time measurement, which can be quantified by the root mean square error (RMSE) or the correlation coefficient. Reverse compensation means that when the deviation degree exceeds the preset threshold, an inverse adjustment is applied to the equivalent phase change amount according to the deviation correction rule to eliminate the influence of temperature interference on the strain phase.

[0090] In the embodiments of the present application, during the real-time monitoring stage, the wavelength shift data of the reflection grating and the phase difference signal are synchronously acquired, and the change in the optical path length is converted into an equivalent phase change. By calculating the real-time deviation degree between the equivalent phase change and the phase difference signal, and comparing it with the allowable deviation threshold (such as based on the standard deviation or confidence interval) obtained from historical data statistics. If the deviation degree exceeds the threshold, the deviation correction rule in the real-time correction rule library trained in step 301 is called to perform a reverse adjustment on the equivalent phase change. The specific adjustment methods include linear compensation (such as reducing the deviation by a proportional coefficient) or non-linear compensation (such as predicting the compensation amount through a neural network). After iterative correction, ensure that the dynamic deviation degree between the compensated equivalent phase change and the phase difference signal is stabilized within the allowable range, and output the strain distribution parameters after eliminating temperature interference.

[0091] The following is a specific example:

[0092] An optical fiber Bragg grating array and multi-core sensing optical fibers are simultaneously deployed at the critical load-bearing parts of the bridge to monitor the structural strain under the coupled action of vehicle loads and day-night temperature differences. When a heavy vehicle passes by, the distributed reflection grating array FBG detects the wavelength shift caused by local strain, calculates the change in the optical path length and converts it into an equivalent phase change; at the same time, the phase difference signal of the multi-core optical fiber reflects the phase fluctuation caused by the actual strain. The system has established a day-night temperature-phase correction model through historical experimental data. During real-time monitoring, it is found that there is a significant deviation between the equivalent phase change and the phase difference signal due to the rising temperature of sunlight, triggering the reverse compensation mechanism. According to the temperature rise-compensation coefficient relationship stored in the correction rule library, the equivalent phase change is dynamically adjusted to eliminate the phase drift caused by temperature. After continuous multi-round compensation, stable and reliable strain distribution parameters are output, accurately positioning the high-strain area of the bridge, providing a basis for structural safety warning.

[0093] This solution effectively decouples the cross-interference of temperature and strain on phase calculation by integrating the dynamic correlation characteristics of the reflection grating wavelength shift data and the phase difference signal, combining historical data modeling and real-time reverse compensation mechanism. In complex environmental monitoring scenarios, it can adaptively eliminate the measurement errors caused by temperature fluctuations, significantly improve the calculation accuracy and stability of strain distribution parameters, and provide core support for the reliable application of fiber optic sensing technology in fields such as civil engineering and energy pipelines.

[0094] In some embodiments, the spatial geometric parameters include the spiral radius, pitch, and core distribution direction;

[0095] Based on the spatial geometric parameters of the multi-core optical fiber structure, a three-dimensional coordinate transformation model is established. The curvature calculation reference value and the strain distribution parameters are input into the three-dimensional coordinate transformation model, and the three-dimensional deformation field distribution of the measured object is reconstructed through vector synthesis, including:

[0096] 401. Construct a three-dimensional coordinate transformation model according to the helix radius, pitch, and core distribution direction of the multi-core optical fiber structure. The three-dimensional coordinate transformation model includes a longitudinal coordinate system defined by the helix axis direction, a tangential coordinate system defined by the helix rotation direction, and a radial coordinate system defined by the helix radius direction.

[0097] The three-dimensional coordinate transformation model refers to the mathematical mapping framework between the local coordinate system and the global coordinate system established through the geometric characteristics of the helical optical fiber. The longitudinal coordinate system (Z-axis) is defined as the extension direction along the helix centerline, the tangential coordinate system (T-axis) is the tangent direction of the helical trajectory, and the radial coordinate system (R-axis) extends outward perpendicular to the helix axis.

[0098] In the embodiments of the present application, first, according to the helical structure parameters of the multi-core optical fiber (such as helix radius, pitch, and core distribution direction), use parametric equations to describe the spatial path of the optical fiber in the global coordinate system. Then, define the local coordinate system based on the helical geometric characteristics, including the longitudinal coordinate system defined by the helix axis direction, the tangential axis perpendicular to the axis and pointing to the rotation direction, and the radial axis along the helix radius direction. Finally, establish the differential mapping relationship between the local coordinate system and the global coordinate system by calculating the Jacobian matrix to obtain the constructed three-dimensional coordinate transformation model, ensuring that the subsequent spatial conversion of curvature and strain data can be accurately realized.

[0099] 402. Decompose the curvature calculation reference value into the respective corresponding curvature change amounts in the longitudinal coordinate system, tangential coordinate system, and radial coordinate system, and at the same time convert the strain distribution parameter into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber structure on the longitudinal coordinate system.

[0100] Curvature decomposition means projecting the measured curvature onto the three orthogonal directions of Z / T / R according to the helical geometric characteristics, and the tensile deformation amount converts the strain into axial deformation through Hooke's law.

[0101] In the embodiments of the present application, first, decompose the curvature calculation reference value of each measurement point according to the three orthogonal directions of the local coordinate system (the longitudinal coordinate system, the tangential coordinate system, and the radial coordinate system) to eliminate the coupling error between the components, and obtain the respective corresponding curvature change amounts in the longitudinal coordinate system, the tangential coordinate system, and the radial coordinate system. Subsequently, combine the material mechanics model to convert the strain distribution parameter into the tensile deformation amount or compressive deformation amount in the longitudinal direction, and consider the shrinkage amount caused by the transverse Poisson effect. Finally, integrate the decomposed curvature components and the strain deformation amounts into a structured data stream to provide input parameters for the reconstruction of the three-dimensional deformation field of the measured object.

[0102] 403. For each measurement point, map the longitudinal, tangential, and radial curvature change amounts to the three-dimensional direction offset amount of the measured object at the measurement point through the three-dimensional coordinate transformation model, and calculate the dynamic coordinate adjustment value of the measurement point in combination with the tensile deformation amount or compressive deformation amount;

[0103] The three-dimensional direction offset amount is a displacement vector generated by integrating the curvature components and superimposing the strains, and the dynamic coordinate adjustment value includes the position correction amounts in the X / Y / Z directions.

[0104] In the embodiment of the present application, the multi-core optical fiber is divided into multiple micro-element segments, and the longitudinal tensile / compressive deformation amounts (the strain conversion results from step 402) and three orthogonal components of the curvature (longitudinal bending, tangential torsion, radial compression) of each micro-element segment are extracted. According to the material mechanics model, the longitudinal deformation amount is directly converted into the displacement along the optical fiber axis, and the curvature components are converted into the transverse displacement (tangential torsion displacement) and the normal displacement (radial compression displacement) through differential geometry formulas. The longitudinal, tangential, and radial displacement components are superimposed according to the local coordinate system direction to form the local displacement vector of the micro-element segment. Using the three-dimensional coordinate transformation model generated in step 401, the local displacement vectors in the longitudinal, tangential, and radial directions in the local coordinate system are converted into the three-dimensional direction offset amounts of the measured object at the measurement point in the global coordinate system. The dynamic coordinate adjustment value of the measurement point is obtained by dynamically calculating the three-dimensional direction offset amount and the tensile deformation amount or compressive deformation amount to ensure the accurate reconstruction of the spatial position.

[0105] 404. Along the extension path of the multi-core optical fiber structure, perform direction superposition on the dynamic coordinate adjustment values of all measurement points, and convert the superimposed offset amount into the three-dimensional deformation vectors of each position on the surface of the measured object through the three-dimensional coordinate transformation model to generate a continuous three-dimensional deformation field distribution.

[0106] Direction superposition means integrating the displacement contributions of all measurement points along the optical fiber path and generating a continuous deformation field through an interpolation algorithm. The three-dimensional deformation vector refers to the deformation direction and amplitude of each position point on the surface of the measured object.

[0107] In the embodiments of the present application, based on the dynamic coordinate adjustment values of each measurement point generated in step 403, the longitudinal, tangential, and radial correction amounts of the measurement points are directionally superimposed along the extension path of the multi-core optical fiber structure, and the local cumulative offset is converted into a continuous three-dimensional deformation vector field in the global coordinate system of the measured object by using the three-dimensional coordinate transformation model. By combining the surface geometric topology relationship (such as the CAD mesh model) with the radial basis function interpolation, the discrete deformation data is extended into a smooth deformation field covering the entire domain of the object. At the same time, the constitutive model of material mechanics and the finite element iteration algorithm are introduced to eliminate non-physical distortions and ensure the physical rationality of the three-dimensional deformation field. Further, by fusing the redundant measurement data of the multi-core optical fiber and the collaborative verification of the external inertial sensor, the noise interference is reduced by the dynamic filtering algorithm, the three-dimensional deformation field is optimized and mapped to the digital twin model, the deformation direction and amplitude distribution are rendered in real time, and the deformation trend is predicted by combining the time series analysis to obtain the final three-dimensional deformation field distribution. When the deformation amount exceeds the preset threshold, hierarchical alarms are triggered and high-risk areas are located, realizing a full-process closed-loop feedback from dynamic monitoring to active early warning.

[0108] The following is a specific example:

[0109] Embed a spiral multi-core optical fiber inside the wind turbine blade to monitor the three-dimensional deformation distribution under the action of aerodynamic loads in real time. First, construct a three-dimensional coordinate transformation model according to the spiral parameters of the optical fiber and input the curvature and strain measurement data into the model. When the blade is loaded, the curvature of each measurement point of the optical fiber is decomposed into longitudinal, tangential, and radial components, and the axial deformation amount is obtained after the strain parameter is converted. Subsequently, calculate the local displacement of each microelement segment by the differential geometry method and map it to the global coordinate system to generate a discrete deformation point cloud. Finally, use the interpolation algorithm to reconstruct the continuous deformation field of the entire blade domain, accurately locate the high-strain area, and the verification results show that the error between the deformation field and the laser measurement data is less than 3%, meeting the engineering monitoring requirements.

[0110] This solution maps the linear measurement data of the multi-core optical fiber into a three-dimensional deformation field through spiral geometric modeling and coordinate transformation, solving the problem of insufficient spatial continuity in traditional methods. By combining the curvature-strain joint solution and the interpolation optimization algorithm, high-precision deformation reconstruction of complex structures (such as wind turbine blades and bridges) is realized, supporting millimeter-level deformation perception and global visualization, providing a reliable technical means for structural health monitoring.

[0111] In some embodiments, decomposing the curvature calculation reference value into the respective corresponding curvature change amounts in the longitudinal coordinate system, the tangential coordinate system, and the radial coordinate system, and at the same time converting the strain distribution parameter into the tensile deformation amount or the compressive deformation amount of the multi-core optical fiber structure on the longitudinal coordinate system, includes:

[0112] 501. Determine the central axis direction of the multi-core optical fiber structure in the longitudinal coordinate system, the spiral rotation tangent direction in the tangential coordinate system, and the spiral radius expansion direction in the radial coordinate system according to the spiral radius and pitch of the multi-core optical fiber structure;

[0113] The spiral radius refers to the radius of the spiral trajectory of the cores in the multi-core optical fiber around the central axis. The pitch refers to the axial length of one full rotation of the multi-core optical fiber spiral structure along the central axis direction. The central axis direction refers to the straight reference axis along the overall extension direction of the multi-core optical fiber, which is used to define the reference direction of the longitudinal coordinate system. The spiral rotation tangent direction refers to the tangential coordinate axis direction along the tangent direction of the spiral trajectory and forming a fixed angle with the central axis direction. The spiral radius expansion direction refers to the radial coordinate axis direction perpendicular to the spiral rotation tangent direction and pointing to the outside of the spiral radius.

[0114] In an embodiment of the present application, based on the spiral radius and pitch of the multi-core optical fiber structure, through parametric geometric modeling (for example, using the spiral equation in the cylindrical coordinate system to describe the three-dimensional spatial form), the mathematical expression of the spiral path of the multi-core optical fiber is accurately constructed. Subsequently, three orthogonal directions are determined through mathematical differentiation and vector operations: differentiating the parametric equation along the axis direction to obtain the unit vector of the longitudinal central axis; differentiating and normalizing the tangent direction of the spiral path to obtain the tangential unit vector that changes dynamically with the spiral; finally, generating the radial unit vector perpendicular to the spiral plane through the cross product of the longitudinal and tangential vectors. This process transforms the abstract spiral structure into a coordinate system that can be quantitatively analyzed, providing a direction reference for subsequent curvature decomposition.

[0115] 502. Use the component of the curvature calculation reference value in the central axis direction as the longitudinal curvature change amount, the component in the spiral rotation tangent direction as the tangential curvature change amount, and the component in the spiral radius expansion direction as the radial curvature change amount;

[0116] The longitudinal curvature change amount refers to the bending curvature component of the central axis of the multi-core optical fiber in the longitudinal (Z-axis) direction, reflecting the overall bending deformation degree. The tangential curvature change amount refers to the torsional curvature component of the multi-core optical fiber in the spiral rotation tangent direction (T-axis), characterizing the torsional deformation of the spiral structure. The radial curvature change amount refers to the curvature component of the multi-core optical fiber in the spiral radius expansion direction (R-axis), which is used to describe the radial compression or expansion deformation.

[0117] In the embodiments of the present application, the original curvature calculation reference value is decomposed into three orthogonal directions, namely the longitudinal direction, the tangential direction, and the radial direction defined in step 501, through the vector projection algorithm. Specifically, the curvature vectors of the curvature calculation reference value are respectively projected onto the spiral rotation tangent direction (tangential unit vector) and the spiral radius outward expansion direction (radial unit vector): the component in the tangential direction is defined as the tangential curvature change amount, which directly characterizes the local torsion degree of the spiral structure around the central axis; the component in the radial direction is defined as the radial curvature change amount, which reflects the expansion or contraction effect of the spiral radius due to deformation. At the same time, the longitudinal curvature component corresponds to the overall bending state of the central axis. The dynamic coordinate system correction mechanism runs synchronously: when the spiral parameters (such as the pitch or radius) change due to deformation, the tangential and radial unit vectors are updated in real time to ensure that the projection direction is consistent with the actual geometric shape of the spiral, thereby avoiding the curvature decoupling distortion caused by coordinate system offset.

[0118] 503. According to the linear relationship between the axial length change amount of the multi-core optical fiber structure and the strain distribution parameter, convert the strain distribution parameter into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber structure in the direction of the central axis; wherein, the numerical sign of the tensile deformation amount or compressive deformation amount is used to distinguish the axial elongation or shortening state of the multi-core optical fiber structure.

[0119] The axial length change amount refers to the absolute elongation or shortening amount of the multi-core optical fiber along the central axis direction (Z-axis), and the unit is millimeter (mm). The strain distribution parameter refers to the axial strain value calculated through the spectral shift of the multi-core fiber grating reflection spectrum, and the unit is microstrain (με). The numerical sign distinction means determining the deformation direction through the positive and negative signs of the strain value: a positive value is the tensile deformation amount (axial elongation), and a negative value is the compressive deformation amount (axial shortening).

[0120] In the embodiments of the present application, based on the linear relationship between the axial length change amount of the multi-core optical fiber structure and the strain distribution parameter, the strain distribution parameter is directly converted into the tensile deformation amount or compressive deformation amount of the multi-core optical fiber in the direction of the central axis. The axial elongation or shortening deformation state of the multi-core optical fiber structure is automatically distinguished by the positive and negative signs of the numerical values of the tensile deformation amount or compressive deformation amount, and the rationality of the linear hypothesis is verified by combining the material mechanics parameters. For the pitch change caused by the spiral structure deformation, the actual axial deformation amount is corrected through geometric ratio scaling, so as to eliminate the interference of the spiral path expansion and contraction on the axial deformation calculation and ensure the accuracy of the physical quantity conversion.

[0121] The following is a specific example:

[0122] Aiming at the composite deformation problem caused by the long-term wind and wave alternating loads on the blades of offshore wind turbines, this solution realizes dynamic monitoring through a multi-core optical fiber spiral embedding structure. First, a longitudinal, tangential, and radial orthogonal dynamic coordinate system is constructed based on the preset spiral parameters (initial pitch, radius) of the blade. When the blade deformation causes changes in the spiral parameters, the tangential and radial unit vectors are updated in real time to synchronize the actual geometric shape. The original curvature in the fiber optic sensing data is decoupled by a vector projection algorithm: the longitudinal component along the central axis direction reflects the overall bending of the blade (such as the tip deflection curvature of 0.15 m⁻¹), the tangential component in the direction of the spiral rotation tangent quantifies the local torsional strength (such as the circumferential shear deformation at the blade root), and the radial component in the direction of the outward expansion of the spiral radius captures the radius anomaly caused by structural damage (such as the continuous positive offset caused by segment delamination). Further, the strain-deformation conversion relationship is corrected by combining the real-time pitch parameter, suppressing the interference of spiral expansion and contraction, and verifying the elastic response of the material (the maximum tensile amount after correction is 1.2 mm). Finally, multi-dimensional indicators such as longitudinal bending warning, torque overload risk, and delamination damage location are output.

[0123] Based on the dynamic coordinate system adaptive calibration, multi-directional curvature decoupling algorithm, and strain-deformation linear correction mechanism, this solution breaks through the limitation of the traditional monitoring method for the aliasing of composite deformation signals: through the independent extraction of the longitudinal, tangential, and radial curvature components and the real-time correction of the dynamic projection direction, the high-precision separation of the coupling signals of the overall bending, local torsion, and internal damage of the blade is achieved, significantly reducing the risk of misjudgment; combined with the real-time pitch parameter feedback and the strain sign two-way verification mechanism, the interference of spiral expansion and contraction on the deformation inversion is effectively suppressed, improving the measurement reliability; further integrating the elastic modulus constraint and the fatigue life model, multi-dimensional quantitative indicators (such as tip displacement warning, torque overload threshold, delamination damage location) are output, providing accurate decision-making support for predictive maintenance and significantly extending the service life of key components. This solution is compatible with engineering scenarios with different spiral parameter configurations, and still maintains monitoring continuity under extreme working conditions such as sudden wind speed changes or wave load impacts, providing a new generation of solutions with both high precision and strong versatility for the structural health management of major equipment.

[0124] In some embodiments, for each measurement point, the changes in the longitudinal, tangential, and radial curvatures are mapped to the three-dimensional direction offset of the measured object at the measurement point through the three-dimensional coordinate transformation model, and combined with the tensile deformation amount or compressive deformation amount, the dynamic coordinate adjustment value of the measurement point is calculated, including:

[0125] 601. According to the axis direction relationship of the three-dimensional coordinate transformation model, the longitudinal curvature change amount is converted into the bending displacement of the measurement point along the central axis direction, the tangential curvature change amount is converted into the torsional displacement along the spiral tangent direction, and the radial curvature change amount is converted into the expansion and contraction displacement along the spiral radius direction;

[0126] The longitudinal curvature variation is a parameter that describes the change in the bending degree of the measured object (such as a blade) along the central axis direction; the tangential curvature variation is a quantity that characterizes the curvature change generated when the measured object twists around the axis; the radial curvature variation is a quantity that represents the telescopic deformation of the measured object along the spiral radius direction; the bending displacement is the deformation offset along the central axis direction derived from the longitudinal curvature variation; the torsional displacement is the rotational offset along the spiral tangent direction derived from the tangential curvature variation; the telescopic displacement is the telescopic offset along the spiral radius direction derived from the radial curvature variation.

[0127] In the embodiments of the present application, based on the axial projection relationship of the three-dimensional coordinate transformation model (such as a coordinate transformation matrix or a geometric projection algorithm), the longitudinal curvature variation is substituted into the curvature-displacement mapping formula to calculate the bending displacement along the central axis direction; then, using the geometric parameters in the spiral tangent direction (such as the pitch angle, spiral radius), combined with the tangential curvature variation, the torsional displacement along the spiral tangent direction is derived through a rotation transformation model (such as a rotation matrix or vector decomposition); at the same time, according to the physical relationship between the spiral radius and the radial curvature (such as Hooke's law or geometric strain formula), the radial curvature variation is converted into the telescopic displacement along the radius direction; finally, through coordinate system projection and geometric parameter iteration, the longitudinal curvature, tangential curvature, and radial curvature are synchronously converted into displacement components in the local coordinate system, providing basic data for global coordinate mapping.

[0128] 602. Convert the bending displacement, torsional displacement, and telescopic displacement into three-dimensional direction offsets in the global coordinate system of the measured object according to the three-dimensional coordinate transformation model;

[0129] The global coordinate system is a fixed reference coordinate system with the installation base point of the measured object as the origin, used to uniformly describe the spatial positions of all measurement points; the three-dimensional direction offset is the three-dimensional deformation offset of the measured object in the global coordinate system, including displacement components in the X / Y / Z axis directions.

[0130] In the embodiments of the present application, through the three-dimensional coordinate transformation model (such as Euler angle transformation or homogeneous coordinate transformation), the bending displacement, torsional displacement, and telescopic displacement in the local coordinate system are mapped to the global coordinate system; combined with the spiral geometric parameters of the measured object (such as pitch, spiral radius), according to the geometric superposition rule (such as vector addition or tensor synthesis), the local displacement components are converted into three-dimensional direction offsets in the X / Y / Z axes in the global coordinate system; and through matrix operation and dynamic calibration of geometric parameters, the spatial consistency between the local displacement and the global coordinates is ensured, providing input for subsequent axial deformation correction.

[0131] 603. Adjust the position of the measurement point in the central axis direction according to the tensile deformation amount or compressive deformation amount to generate an axial deformation amount;

[0132] The longitudinal tensile deformation or compressive deformation refers to the change in length caused by the axial force (such as tensile force, compressive force) on the measured object, which is directly measured by a strain sensor; the axial deformation refers to the correction value of the position in the direction of the central axis adjusted according to the longitudinal deformation, and is used to dynamically compensate for the coordinate deviation caused by the helical expansion and contraction.

[0133] In the embodiment of the present application, according to the tensile deformation or compressive deformation (directly measured by the strain sensor), a linear correction model (such as the linear relationship between strain and displacement or polynomial fitting) is used to adjust the position of the measurement point along the central axis direction; at the same time, combined with the real-time pitch parameter (such as the dynamic pitch change of the helical structure), the coupling interference of the helical expansion and contraction on the axial displacement is eliminated through a dynamic compensation algorithm, and finally an accurate axial deformation is generated to achieve independent correction and error isolation of the axial displacement.

[0134] 604. Superimpose the three-dimensional direction offset and the axial deformation to obtain the dynamic coordinate adjustment value of the measurement point.

[0135] The dynamic coordinate adjustment value refers to the three-dimensional position correction amount of the measured object in the global coordinate system finally synthesized, which is generated by superimposing the three-dimensional direction offset and the axial deformation, and is used to describe the actual deformation state of the current measurement point.

[0136] In the embodiment of the present application, the three-dimensional direction offset and the axial deformation in the global coordinate system are superimposed according to weights (such as Kalman filtering or weighted average algorithm), and the dynamic coordinate adjustment value is generated through a data fusion algorithm; at the same time, the two-way verification of the strain sign (such as the positive and negative strain consistency check) is used to exclude abnormal data to ensure the reliability of the synthesis result; finally, the three-dimensional position correction amount of the measured object in the global coordinate system is output, providing high-precision data support for real-time deformation monitoring and early warning.

[0137] The following is a specific example:

[0138] Taking the deformation monitoring of a wind turbine blade as an example, first (step 601), through the fiber optic strain sensors arranged on the blade surface, the longitudinal curvature change amount of a certain section of the blade is measured to be 0.12 、the tangential curvature change amount is 0.08 and the radial curvature change amount is 0.05 , based on the spiral geometric parameters (pitch angle 15°, spiral radius 2.3 m), the bending displacement of 8.7 mm, the torsional displacement of 4.2°, and the telescopic displacement of 3.5 mm are calculated respectively using the coordinate transformation matrix; subsequently (step 602), through homogeneous coordinate transformation, the local displacements are mapped to the global coordinate system, and the offsets in the X / Y / Z axis directions are obtained as +12.3 mm, -5.6 mm, and +9.8 mm respectively; meanwhile (step 603), according to the longitudinal tensile strain of 1.2‰ measured by the strain sensor, the axial position is dynamically compensated through a linear correction model to generate an axial strain correction value of +7.4 mm; finally (step 604), the three-dimensional offsets and the correction value are superimposed, and after Kalman filter fusion, the dynamic coordinate adjustment value (X+14.1 mm / Y-5.6 mm / Z+17.2 mm) is output, and it is verified by a laser tracker, with the error controlled within ±0.3 mm, effectively supporting the safety warning of the blade.

[0139] This solution realizes the high-precision decoupling of composite deformations and dynamic coordinate inversion through independent conversion of curvature components, local-global coordinate mapping, dynamic correction of axial deformations, and data fusion. Separating bending, torsional, and telescopic displacements avoids misjudgment caused by signal aliasing; global coordinate mapping combined with dynamic pitch compensation significantly improves the deformation positioning accuracy; fusing strain sign verification and weight superposition enhances the anti-interference ability.

[0140] In some embodiments, the optical path length change amount at the same spatial position in the reflected grating wavelength offset data is converted into an equivalent phase change amount, and using the historical correspondence relationship between the synchronously collected phase difference signal and the equivalent phase change amount under the condition of no temperature interference, the deviation correction rule between the two when the temperature changes is determined, including:

[0141] 701. Determine the optical path length change amount of the multi-core optical fiber structure at this position according to the optical signal wavelength change amplitude in the reflected grating wavelength offset data, and convert the optical path length change amount into an equivalent phase change amount according to a preset proportional relationship. The equivalent phase change amount represents the phase fluctuation caused only by temperature change;

[0142] The reflected grating wavelength offset data refers to the change amount of the reflected light wavelength (unit: pm) measured by the fiber grating sensor, including the wavelength offset caused by temperature or strain; the optical path length change amount refers to the physical length change value of the optical fiber (unit: μm) calculated according to the wavelength offset data through the photoelastic effect formula, and its calculation formula is ΔL = K·Δλ_temp (K is the material calibration coefficient); the equivalent phase change amount refers to the phase fluctuation amount (unit: rad) obtained by converting the optical path length change amount according to the formula Δφ = 4πΔL / λ. This quantity only characterizes the phase change caused by temperature.

[0143] In the embodiments of the present application, the reflected light wavelength shift Δλ is collected by a fiber Bragg grating sensor, and the temperature-related optical signal wavelength change amplitude Δλ_temp (eliminating the strain term βΔε) is separated in combination with the grating wavelength shift model Δλ = λ (αΔT + βΔε), and then the optical path length change amount ΔL of the optical fiber is calculated based on the photoelastic effect formula ΔL = K·Δλ_temp, where K is a pre-calibrated material proportionality coefficient; finally, the optical path length change amount ΔL is substituted into the phase conversion formula Δφ_temp = 4πΔL / λ_initial (λ_initial is the initial wavelength) to generate an equivalent phase change amount Δφ_temp caused only by temperature, which is used as the reference input for subsequent temperature interference correction.

[0144] 702. Compare the phase difference signal at the same measurement point with the historical synchronous acquisition data of the equivalent phase change amount under the condition of no temperature interference, extract the corresponding relationship between the change direction and amplitude of the phase difference signal and the equivalent phase change amount when there is no temperature interference, and establish a historical synchronous correspondence table between the two under the temperature stable state;

[0145] The phase difference signal refers to the strain difference amount (unit: rad) calculated by the phase difference between adjacent cores in a multi-core optical fiber, which is used to reflect the phase change caused by mechanical deformation; the historical synchronous correspondence table refers to a database of the direction and amplitude relationship between the phase difference signal and the equivalent phase change amount calibrated through experiments under the condition of no temperature interference, including the change direction (positive / negative), amplitude ratio, and confidence level parameters.

[0146] In the embodiments of the present application, in a calibration environment without temperature interference, the phase difference signal Δφ_strain (reflecting mechanical deformation) and the equivalent phase change amount Δφ_temp (the theoretical value approaches 0) are synchronously acquired, and the data groups with the equivalent phase change amount Δφ_temp fluctuation less than the threshold are screened; the amplitude ratio relationship (such as Δφ_strain = 0.95Δφ_temp + 0.1) and the direction consistency rule between the phase difference signal Δφ_strain and the equivalent phase change amount Δφ_temp are established through statistical analysis (such as linear regression), and the confidence level index (such as R²>0.95) is recorded. Finally, a historical synchronous correspondence table including the change direction, amplitude ratio, and confidence level is constructed for subsequent deviation detection when the temperature changes.

[0147] 703. According to the historical synchronous correspondence table, statistically analyze the deviation direction and deviation amplitude of the equivalent phase change amount and the phase difference signal when the temperature changes, and generate an interference correction coefficient for the temperature change to the equivalent phase change amount. The interference correction coefficient is used to adjust the equivalent phase change amount caused by temperature to the same change trend as the phase difference signal;

[0148] The deviation direction refers to the difference between the actual change direction of the equivalent phase change amount and the phase difference signal when the temperature changes (e.g., Δφ_temp is positive while Δφ_strain is negative); the interference correction coefficient refers to the temperature compensation parameters (such as the proportional coefficient γ and the offset θ) fitted based on historical deviation data, which are used to adjust the equivalent phase change amount to be synchronized with the phase difference signal.

[0149] In the embodiment of the present application, based on the historical synchronization correspondence table, the deviation direction and deviation amplitude of the equivalent phase change amount Δφ_temp and the phase difference signal Δφ_strain in the temperature change scenario are extracted. The deviation model Δφ_error = γΔφ_temp + θ (γ is the slope correction coefficient, θ is the intercept compensation term) is fitted by the least squares method. Through iterative optimization, the error between the corrected equivalent phase change amount Δφ'_temp = Δφ_temp - Δφ_error and the phase difference signal Δφ_strain is minimized (e.g., the mean square error < 0.1 rad²); finally, the interference correction coefficients γ and θ are generated and stored in the dynamic compensation parameter library to provide a rule basis for real-time correction.

[0150] 704. Monitor the deviation amplitude of the equivalent phase change amount and the phase difference signal in real time when the temperature changes. According to the product result of the deviation amplitude and the interference correction coefficient, perform a reverse correction on the equivalent phase change amount to make the corrected equivalent phase change amount synchronized with the phase difference signal in terms of the change direction and amplitude within a preset error range.

[0151] The reverse correction refers to an operation of subtracting or proportionally adjusting the equivalent phase change amount according to the deviation amplitude calculated in real time (Δφ_error = γ·Δφ_temp + θ), so that the corrected Δφ'_temp = Δφ_temp - Δφ_error has the same change trend as the phase difference signal.

[0152] In the embodiment of the present application, when the temperature changes during actual monitoring, the current equivalent phase change amount Δφ_temp and the phase difference signal Δφ_strain are obtained in real time. The deviation amplitude Δφ_error = γΔφ_temp + θ is calculated according to the pre-stored correction coefficients, and a reverse correction is performed on the equivalent phase change amount Δφ_temp to obtain the equivalent phase change amount Δφ'_temp = Δφ_temp - Δφ_error; the correction effectiveness is verified through threshold judgment (e.g., |Δφ'_temp - Δφ_strain| < 0.5 rad). If it exceeds the preset error range, online recalibration based on a sliding window is triggered (re-fitting γ and θ); finally, the corrected equivalent phase change amount Δφ'_temp synchronized with the phase difference signal is output to ensure that temperature interference is effectively suppressed and the true deformation signal is accurately extracted.

[0153] The following is a specific example:

[0154] In a bridge health monitoring scenario, the fiber Bragg grating sensor first measures the reflected light wavelength shift Δλ = 1200 pm (Δλ represents the wavelength shift), separates the temperature-related component Δλ_temp = 850 pm (Δλ_temp is the wavelength shift of the temperature term) through the grating wavelength shift model, calculates the change in the physical length of the optical fiber ΔL = K·Δλ_temp = 680 μm by combining the material proportionality coefficient K = 0.8 μm / pm, and based on the initial wavelength λ_initial = 1550 nm, derives the temperature equivalent phase change Δφ_temp = 4πΔL / λ_initial ≈ 5.5 rad; in the laboratory calibration stage, a synchronous correlation rule between the strain phase change Δφ_strain and Δφ_temp is established based on the data without temperature change interference (for example, when Δφ_temp = 5 rad, Δφ_strain = 5.2 rad, confidence level R² = 0.98); during actual monitoring, when Δφ_temp = 5.5 rad, Δφ_strain = 4.8 rad (amplitude deviation of 12%), calculates the phase deviation Δφ_error = γΔφ_temp + θ ≈ 1.125 rad through the fitting slope correction coefficient γ = 0.15 and the intercept compensation term θ = 0.3 rad, and performs a reverse correction on Δφ_temp to obtain the corrected phase change Δφ'_temp = Δφ_temp - Δφ_error = 4.375 rad, reducing the residual between it and Δφ_strain from 1.125 rad to 0.425 rad (error reduction of 65%); if the residual exceeds the limit (such as > 0.5 rad threshold), the dynamic recalibration mechanism is triggered to update γ and θ, and finally the high-precision deformation signal Δφ'_temp is output to verify the effectiveness of the temperature-strain decoupling technology.

[0155] This solution uses a collaborative mechanism of temperature-strain decoupling separation and dynamic compensation correction, separates the phase changes related to temperature and strain based on a physical model, constructs a quantitative correlation rule by combining calibration data, and suppresses the coupling interference of temperature on the deformation signal from the source; reduces the temperature residual error through a dynamic error compensation strategy, improves the amplitude and direction fidelity of the strain signal, and at the same time uses the sliding window recalibration mechanism triggered by the residual to continuously suppress the problems of environmental drift and model mismatch, ensuring the stability of long-term monitoring. The solution takes phase domain decoupling as the core, directly matches the sensitive dimension of the optical interference system, avoids the distortion risk of traditional demodulation methods, realizes the independent characterization and cross-interference quantification of multiple physical fields such as temperature and strain, and provides a generalization framework for the synchronous analysis of multiple types of deformations under complex working conditions. Through a full-process closed-loop design that integrates theoretical models and engineering experience, the robustness and real-time performance of the system in a strong temperature change and high-noise environment are significantly enhanced, and it is suitable for high-precision health monitoring of infrastructure such as bridges and pipelines.

[0156] Figure 2 FIG. 1 is a schematic structural diagram of a time-division multiplexing multi-parameter synchronous sensing system based on a multi-core optical fiber provided by an embodiment of the present application. As Figure 2 shown, the system includes:

[0157] A processing module 21, which embeds a multi-core optical fiber structure inside the measured object. The multi-core optical fiber structure includes at least three cores made of different materials. Distributed reflection grating arrays are inscribed at intervals on the surfaces of each core made of different materials. The spatial arrangement direction of the reflection grating arrays forms a predetermined inclination angle with the axial direction of the multi-core optical fiber structure;

[0158] An acquisition module 22, which synchronously acquires the inter-mode energy exchange data and the reflection grating wavelength shift data of each core made of different materials through time division multiplexing technology. The reflection grating wavelength shift data includes the optical path length change information corresponding to the spatial position;

[0159] An operation module 23, which performs cross-correlation and phase analysis processing on the inter-mode energy exchange data, extracts the phase difference signals at each measurement point as the curvature calculation reference value, and simultaneously performs dynamic adjustment compensation operations on the reflection grating wavelength shift data and the phase difference signals to generate strain distribution parameters after eliminating temperature interference;

[0160] A synthesis module 24, which establishes a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core optical fiber structure, inputs the curvature calculation reference value and the strain distribution parameters into the three-dimensional coordinate transformation model, and reconstructs the three-dimensional deformation field distribution of the measured object by means of vector synthesis.

[0161] Figure 2 The above-mentioned time-division multiplexing multi-parameter synchronous sensing system based on a multi-core optical fiber can execute Figure 1 the time-division multiplexing multi-parameter synchronous sensing method based on a multi-core optical fiber described in the embodiment shown in FIG. 2. The implementation principle and technical effects will not be elaborated here. For each module and unit in the above-mentioned time-division multiplexing multi-parameter synchronous sensing system based on a multi-core optical fiber, the specific manner of performing operations has been described in detail in the embodiment related to the method, and will not be elaborated here.

[0162] In a possible design, Figure 2 the time-division multiplexing multi-parameter synchronous sensing system based on a multi-core optical fiber described in the embodiment shown in FIG. 2 can be implemented as a computing device. As Figure 3 shown, the computing device may include a storage component 31 and a processing component 32;

[0163] The storage component 31 stores one or more computer instructions, and the one or more computer instructions are called and executed by the processing component 32.

[0164] The processing component 32 is used for the above Figure 1 A time-division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber in the above embodiment.

[0165] Among them, the processing component 32 may include one or more processors to execute computer instructions to complete all or part of the steps in the above method. Of course, the processing component may also be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components for executing the above method.

[0166] The storage component 31 is configured to store various types of data to support the operation of the terminal. The storage component can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0167] Of course, the computing device necessarily may also include other components, such as input / output interfaces, display components, communication components, etc.

[0168] The input / output interface provides an interface between the processing component and the peripheral interface module, and the above peripheral interface module may be an output device, an input device, etc.

[0169] The communication component is configured to facilitate communication between the computing device and other devices in a wired or wireless manner, etc.

[0170] Among them, the computing device may be a physical device or an elastic computing host provided by a cloud computing platform, etc. At this time, the computing device may refer to a cloud server, and the above processing component, storage component, etc. may be basic server resources leased or purchased from the cloud computing platform.

[0171] The embodiment of the present application also provides a computer storage medium storing a computer program, and when the computer program is executed by a computer, it can implement the above Figure 1 A time-division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber in the shown embodiment.

[0172] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0173] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units. That is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative labor.

[0174] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. And these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of this application.

Claims

1. A time-division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber, characterized in that: include: Embed a multi-core optical fiber structure into the object to be measured, wherein the multi-core optical fiber structure comprises at least three optical fiber cores of different materials, and a distributed reflection grating array is inscribed on the surface of each optical fiber core at intervals, wherein the spatial arrangement direction of the reflection grating array forms a predetermined tilt angle with the axial direction of the multi-core optical fiber structure; The inter-mode energy exchange data and reflection grating wavelength shift data of fiber cores of different materials are synchronously collected through time division multiplexing technology; Cross-correlation and phase analysis are performed on the inter-mode energy exchange data to extract the phase difference signal at each measurement point as a reference value for curvature calculation. Dynamic adjustment and compensation operations are simultaneously performed on the reflection grating wavelength offset data and the phase difference signal to generate strain distribution parameters after temperature interference is eliminated. A three-dimensional coordinate transformation model is established based on the spatial geometric parameters of the multi-core optical fiber structure, the curvature calculation reference value and the strain distribution parameter are input into the three-dimensional coordinate transformation model, and the three-dimensional deformation field distribution of the measured object is reconstructed by vector synthesis.

2. The method according to claim 1, characterized in that The inter-mode energy exchange data includes the light transmission energy variation characteristics between adjacent fiber cores of different materials; Cross-correlation and phase analysis processing are performed on the energy exchange data between the modes, and the phase difference signal of each measurement point is extracted as a reference value for curvature calculation, including: Based on the difference in light transmission energy change caused by deformation between adjacent fiber cores of different materials, the difference in the optical signal propagation path length of each fiber core at the same spatial position is calculated to obtain the phase offset component of each fiber core reflecting the bending direction of the multi-core optical fiber; The phase offset components of at least three fiber cores of different materials at the same measurement point are vector-decomposed according to the core arrangement direction. Combined with the delay difference characteristics of each core material for the optical signal, the phase offset components of each core are projected into orthogonal directions. The composite phase difference in the three directions is calculated by vector superposition to generate a phase difference signal that characterizes the local bending direction and serves as a reference value for curvature calculation.

3. The method according to claim 1, characterized in that The reflection grating wavelength offset data includes optical path length change information corresponding to the spatial position; Dynamically adjusting and compensating the reflection grating wavelength offset data and the phase difference signal to generate strain distribution parameters after temperature interference is eliminated, including: Convert the optical path length change at the same spatial position in the reflection grating wavelength offset data into an equivalent phase change, and use the historical correspondence between the synchronously collected phase difference signal and the equivalent phase change under temperature-free conditions to determine the deviation correction rule between the two when the temperature changes; The deviation degree between the equivalent phase change and the phase difference signal at the same measurement point is detected in real time. When the deviation degree exceeds the allowable range established by the historical correspondence, the equivalent phase change is reversely compensated based on the deviation correction rule, so that the compensated equivalent phase change and the phase difference signal remain consistent within the allowable range, thereby generating strain distribution parameters that eliminate temperature interference.

4. The method according to claim 1, wherein The spatial geometric parameters include spiral radius, pitch and core distribution direction; A three-dimensional coordinate transformation model is established based on the spatial geometric parameters of the multi-core optical fiber structure, the curvature calculation reference value and the strain distribution parameter are input into the three-dimensional coordinate transformation model, and the three-dimensional deformation field distribution of the object under test is reconstructed by vector synthesis, including: Constructing a three-dimensional coordinate transformation model based on the helical radius, helical pitch, and core distribution direction of the multi-core optical fiber structure, wherein the three-dimensional coordinate transformation model includes a longitudinal coordinate system defined by the helical axis direction, a tangential coordinate system defined by the helical rotation direction, and a radial coordinate system defined by the helical radius direction; Decomposing the curvature calculation reference value into corresponding curvature changes in the longitudinal coordinate system, the tangential coordinate system, and the radial coordinate system, and converting the strain distribution parameter into a tensile deformation variable or a compressive deformation variable of the multi-core optical fiber structure in the longitudinal coordinate system; For each measuring point, the longitudinal, tangential, and radial curvature changes are mapped into three-dimensional offsets of the measured object at the measuring point using the three-dimensional coordinate transformation model, and a dynamic coordinate adjustment value of the measuring point is calculated in combination with the tensile deformation or the compressive deformation; Along the extension path of the multi-core optical fiber structure, the dynamic coordinate adjustment values of all measurement points are directional superimposed, and the superimposed offsets are converted into three-dimensional deformation vectors at each position on the surface of the measured object through the three-dimensional coordinate transformation model to generate a continuous three-dimensional deformation field distribution.

5. The method according to claim 4, characterized in that Decomposing the curvature calculation reference value into corresponding curvature changes in the longitudinal coordinate system, the tangential coordinate system, and the radial coordinate system, and converting the strain distribution parameter into a tensile deformation variable or a compressive deformation variable of the multi-core optical fiber structure in the longitudinal coordinate system, including: Determining, according to the helical radius and pitch of the multi-core optical fiber structure, the central axis direction of the multi-core optical fiber structure in the longitudinal coordinate system, the helical rotation tangent direction in the tangential coordinate system, and the helical radius outward expansion direction in the radial coordinate system; The component of the curvature calculation reference value in the direction of the central axis is used as the longitudinal curvature change, the component in the direction of the spiral rotation tangent is used as the tangential curvature change, and the component in the direction of the spiral radius expansion is used as the radial curvature change; According to the linear relationship between the axial length change of the multi-core optical fiber structure and the strain distribution parameter, the strain distribution parameter is converted into a tensile deformation variable or a compressive deformation variable of the multi-core optical fiber structure in the direction of the central axis; wherein the numerical sign of the tensile deformation variable or the compressive deformation variable is used to distinguish the axial elongation or shortening state of the multi-core optical fiber structure.

6. The method according to claim 5, characterized in that For each measurement point, the longitudinal, tangential, and radial curvature changes are mapped into three-dimensional offsets of the object at the measurement point using the three-dimensional coordinate transformation model, and the dynamic coordinate adjustment value of the measurement point is calculated in combination with the tensile deformation or the compressive deformation, including: According to the axial direction relationship of the three-dimensional coordinate transformation model, the longitudinal curvature change is converted into a bending displacement of the measuring point along the central axis direction, the tangential curvature change is converted into a torsional displacement along the spiral tangent direction, and the radial curvature change is converted into a telescopic displacement along the spiral radius direction; Converting the bending displacement, torsional displacement and telescopic displacement into three-dimensional directional offsets in the global coordinate system of the object being measured according to the three-dimensional coordinate transformation model; According to the tensile deformation or the compressive deformation, the position of the measuring point in the direction of the central axis is adjusted to generate an axial deformation; The three-dimensional direction offset is superimposed on the axial deformation to obtain a dynamic coordinate adjustment value of the measuring point.

7. The method according to claim 2, characterized in that The optical path length change at the same spatial position in the reflection grating wavelength offset data is converted into an equivalent phase change. The historical correspondence between the synchronously collected phase difference signal and the equivalent phase change under temperature-free conditions is used to determine a deviation correction rule between the two when the temperature changes, including: Determining an optical path length change of the multi-core optical fiber structure at the same spatial position based on a wavelength change amplitude of an optical signal at the same spatial position in the reflection grating wavelength offset data, and converting the optical path length change into an equivalent phase change according to a preset proportional relationship, wherein the equivalent phase change represents a phase fluctuation caused only by temperature change; Compare the phase difference signal at the same measurement point with the historical synchronous acquisition data of the equivalent phase change under the condition of no temperature interference, extract the corresponding relationship between the change direction and amplitude of the phase difference signal and the equivalent phase change under the condition of no temperature interference, and establish a historical synchronous correspondence table between the two under the condition of stable temperature; According to the historical synchronization correspondence table, the deviation direction and deviation amplitude of the equivalent phase change and the phase difference signal when the temperature changes are calculated, and an interference correction coefficient of the temperature change on the equivalent phase change is generated. The interference correction coefficient is used to adjust the equivalent phase change caused by the temperature to a change trend consistent with the phase difference signal; The deviation amplitude of the equivalent phase change and the phase difference signal when the temperature changes is monitored in real time. The equivalent phase change is reversely corrected according to the product of the deviation amplitude and the interference correction coefficient, so that the change direction and amplitude of the corrected equivalent phase change and the phase difference signal are synchronized within a preset error range.

8. A time-division multiplexing multi-parameter synchronous sensing system based on multi-core optical fiber, characterized in that: include: A processing module is configured to embed a multi-core optical fiber structure into the object to be measured, wherein the multi-core optical fiber structure comprises at least three optical fiber cores of different materials, and a distributed reflection grating array is inscribed on the surface of each optical fiber core at intervals, wherein the spatial arrangement direction of the reflection grating array forms a predetermined tilt angle with the axial direction of the multi-core optical fiber structure; An acquisition module, which synchronously acquires inter-mode energy exchange data and reflection grating wavelength shift data of fiber cores of different materials through time division multiplexing technology. The reflection grating wavelength shift data includes optical path length change information at corresponding spatial positions; a calculation module that performs cross-correlation and phase analysis on the inter-mode energy exchange data, extracts the phase difference signal of each measurement point as a reference value for curvature calculation, and simultaneously performs dynamic adjustment and compensation calculation on the reflection grating wavelength offset data and the phase difference signal to generate strain distribution parameters after temperature interference is eliminated; A synthesis module establishes a three-dimensional coordinate transformation model based on the spatial geometric parameters of the multi-core optical fiber structure, inputs the curvature calculation reference value and the strain distribution parameter into the three-dimensional coordinate transformation model, and reconstructs the three-dimensional deformation field distribution of the object under test through vector synthesis.

9. A computing device, characterized in that It includes a processing component and a storage component; the storage component stores one or more computer instructions; the one or more computer instructions are used to be called and executed by the processing component to implement a time-division multiplexing multi-parameter synchronous sensing method based on multi-core optical fiber as described in any one of claims 1 to 7.

10. A computer storage medium, characterized in that A computer program is stored, and when the computer program is executed by a computer, a time-division multiplexing multi-parameter synchronous sensing method based on a multi-core optical fiber is implemented as described in any one of claims 1 to 7.

Images