An underwater target positioning method, system and terminal based on dynamic error suppression

Abstract

The application discloses a kind of underwater target positioning method, system and terminal based on dynamic error suppression, the method includes: the vibration signal of underwater target is obtained by distributed optical fiber acoustic wave sensing technology, the rough position of underwater target is obtained according to vibration signal, according to rough position, first time difference is obtained by sound field propagation phase compensation model, and the first accurate position is obtained by correcting the phase distortion of rough position according to first time difference;Strain data of optical fiber is collected, and the actual curvature radius of sound wave propagation path is obtained using strain data, second time difference is obtained according to actual curvature radius, and the optical cable deformation of first accurate position is corrected according to second time difference, to obtain second accurate position;According to second time difference, dynamic compensation is carried out on sound path difference, to obtain corrected sound path difference, and the final accurate position is obtained according to corrected sound path difference;The real coordinate is obtained by coordinate conversion to final accurate position.The precision of underwater target positioning is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of underwater navigation technology, and in particular to an underwater target positioning method, system, terminal, and computer-readable storage medium based on dynamic error suppression. Background Technology

[0002] Distributed Acoustic Sensing (DAS) is a technology that uses optical fibers as sensing elements to continuously and distributedly measure environmental parameters along the fiber path. DAS technology is based on the Rayleigh backscattering effect of optical fibers. By sending laser pulses into the fiber, lattice defects within the fiber scatter some of the light back to the demodulator. By analyzing this backscattered light, the longitudinal strain change over time along the fiber every few meters can be inferred, thus enabling real-time monitoring of external sound waves and vibrations.

[0003] DAS technology was initially applied to fields such as oil pipeline monitoring and perimeter security, but it faces technical bottlenecks in underwater target positioning, such as signal propagation model mismatch and environmental noise interference. The main problems it faces include insufficient environmental adaptability: acoustic or inertial navigation is limited by medium characteristics and cumulative errors, and cannot meet the requirements for long-term and high-precision operation. The DAS near-field model is also flawed: the coupling error problem between phase distortion and fiber deformation has not been solved.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] The main objective of this invention is to provide an underwater target positioning method, system, terminal, and computer-readable storage medium based on dynamic error suppression. This invention aims to solve the problem of insufficient underwater target positioning accuracy caused by acoustic or inertial navigation limitations due to medium characteristics and accumulated errors, as well as phase distortion and fiber deformation, when using DAS for underwater target positioning in the prior art.

[0006] To achieve the above objectives, the present invention provides an underwater target localization method based on dynamic error suppression, the underwater target localization method based on dynamic error suppression comprising the following steps:

[0007] Acquire the initial vibration signal of the underwater target, and preprocess the initial vibration signal to obtain the target vibration signal;

[0008] The target vibration signal is initially located to obtain a rough position of the underwater target relative to the optical fiber. A first time difference is obtained based on the rough position. The phase distortion of the rough position is corrected based on the first time difference to obtain the first precise position of the underwater target.

[0009] The strain data of the optical fiber is collected, the three-dimensional shape of the optical fiber is reconstructed using the strain data, and the three-dimensional shape is optimized by B-spline curve fitting to obtain the actual radius of curvature of the sound wave propagation path. The second time difference is obtained based on the actual radius of curvature, and the optical cable deformation at the first precise position is corrected based on the second time difference to obtain the second precise position of the underwater target.

[0010] The sound path difference is dynamically compensated based on the second time difference to obtain the corrected sound path difference, and the final precise position of the underwater target is obtained based on the corrected sound path difference.

[0011] The final precise location is mapped to a geographic coordinate system for coordinate transformation to obtain the true coordinates of the underwater target, and the true coordinates are then visualized.

[0012] Optionally, in the underwater target localization method based on dynamic error suppression, acquiring the initial vibration signal of the underwater target specifically includes:

[0013] A short pulse of coherent laser light is injected into an optical fiber, and scattered light generated when the coherent laser light propagates in the optical fiber is received, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber.

[0014] The phase change and intensity change of the scattered light are obtained, and the initial vibration signal of the underwater target is obtained based on the phase change and intensity change.

[0015] Optionally, in the underwater target localization method based on dynamic error suppression, the preprocessing of the initial vibration signal to obtain the target vibration signal specifically includes:

[0016] The initial vibration signal is subjected to bandpass filtering or wavelet transform to remove high-frequency noise and baseline drift, resulting in a filtered signal.

[0017] The filtered signal is divided into short-time windows to obtain a framed signal. Adaptive threshold detection is performed on the framed signal to obtain the target vibration signal, wherein the target vibration signal is an effective signal caused by vibration or sound waves along the optical fiber.

[0018] Optionally, the underwater target localization method based on dynamic error suppression, wherein the preliminary localization of the target vibration signal to obtain a coarse position of the underwater target relative to the optical fiber, obtaining a first time difference based on the coarse position, and correcting the phase distortion of the coarse position based on the first time difference to obtain a first precise position of the underwater target, specifically includes:

[0019] The initial time difference between the arrival of the target vibration signal on the adjacent fiber segment is calculated. Based on the initial time difference and the sound velocity profile (SVP) model, the approximate location of the underwater target is generated.

[0020] Based on the approximate position, the phase difference of the spherical wave is calculated using the sound field propagation phase compensation model. The phase distortion of the approximate position is then corrected based on the spherical wave phase difference to obtain the corrected first time difference.

[0021] Based on the first time difference and combined with the sound velocity profile (SVP) model, the position of the underwater target is iteratively optimized to obtain the first precise position of the underwater target.

[0022] Optionally, the underwater target localization method based on dynamic error suppression, wherein acquiring strain data of the optical fiber and using the strain data to reconstruct the three-dimensional morphology of the optical fiber specifically includes:

[0023] Strain data at various points on the optical fiber are acquired by phase-sensitive optical time-domain reflectometry. The strain data is then processed by moving average or wavelet filtering to obtain denoised strain data. The thermal expansion effect of the denoised strain data is then eliminated by temperature-strain decoupling algorithm to obtain the target strain data.

[0024] The curvature of each point of the optical fiber is calculated based on the target strain data. The curvature is converted into a tangent direction angle change value. The tangent direction angle change value is integrated in three-dimensional space to obtain the three-dimensional morphological coordinates of the optical fiber. The three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

[0025] Optionally, the underwater target localization method based on dynamic error suppression, wherein the step of performing B-spline curve fitting optimization on the three-dimensional shape to obtain the actual radius of curvature of the sound wave propagation path, obtaining the second time difference based on the actual radius of curvature, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain the second precise position of the underwater target, specifically includes:

[0026] An initial B-spline curve is generated based on the three-dimensional morphological coordinates, wherein the initial B-spline curve is composed of control points and node vectors;

[0027] With the goal of minimizing the curvature error, the control points and node vectors of the initial B-spline are adjusted, and iterative optimization is performed using the Levenberg-Marquardt algorithm until the curvature error is less than a preset threshold, thus obtaining the actual curvature of the sound wave propagation path.

[0028] The changed length of the optical fiber is calculated based on the radius of the actual curvature, the original length of the optical fiber, and the cross-sectional radius of the optical fiber. The second time difference is obtained based on the changed length.

[0029] Based on the second time difference and combined with the sound velocity profile (SVP) model, the optical cable deformation at the first precise location is iteratively optimized to obtain the second precise location of the underwater target.

[0030] Optionally, the underwater target localization method based on dynamic error suppression, wherein mapping the final precise location to a geographic coordinate system for coordinate transformation to obtain the true coordinates of the underwater target specifically includes:

[0031] During the laying of the optical fiber, key points are marked using GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-marked. The key points of the optical fiber include the starting point, the turning point, and the ending point of the optical fiber.

[0032] Based on the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed using linear interpolation and B-spline curve fitting.

[0033] The final precise location is mapped to the mapping model for coordinate transformation, and the true coordinates of the underwater target are output.

[0034] Furthermore, to achieve the above objectives, the present invention also provides an underwater target positioning system based on dynamic error suppression, wherein the underwater target positioning system based on dynamic error suppression includes:

[0035] The data acquisition and processing module is used to acquire the initial vibration signal of the underwater target, and to preprocess the initial vibration signal to obtain the target vibration signal;

[0036] A phase distortion correction module is used to perform preliminary positioning of the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtain a first time difference based on the rough position, and correct the phase distortion of the rough position based on the first time difference to obtain the first precise position of the underwater target.

[0037] The optical cable deformation correction module is used to collect strain data of the optical fiber, reconstruct the three-dimensional shape of the optical fiber using the strain data, optimize the three-dimensional shape by B-spline curve fitting, obtain the actual radius of curvature of the sound wave propagation path, obtain the second time difference based on the actual radius of curvature, and correct the optical cable deformation at the first precise position based on the second time difference to obtain the second precise position of the underwater target.

[0038] The dynamic sound path difference compensation module is used to dynamically compensate the sound path difference according to the second time difference to obtain the corrected sound path difference, and to obtain the final accurate position of the underwater target based on the corrected sound path difference.

[0039] The coordinate transformation and display module is used to map the final precise location to a geographic coordinate system to perform coordinate transformation, obtain the real coordinates of the underwater target, and visualize the real coordinates.

[0040] Furthermore, to achieve the above objectives, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and an underwater target localization program based on dynamic error suppression stored in the memory and executable on the processor, wherein when the underwater target localization program based on dynamic error suppression is executed by the processor, it implements the steps of the underwater target localization method based on dynamic error suppression as described above.

[0041] Furthermore, to achieve the above objectives, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores an underwater target localization program based on dynamic error suppression, and the underwater target localization program based on dynamic error suppression, when executed by a processor, implements the steps of the underwater target localization method based on dynamic error suppression as described above.

[0042] In this invention, vibration signals of underwater targets are obtained using distributed fiber optic acoustic sensing technology. A coarse position of the underwater target is obtained based on the vibration signals. A first time difference is obtained using a sound field propagation phase compensation model based on the coarse position. The phase distortion of the coarse position is corrected using the first time difference to obtain a first precise position. Strain data of the optical fiber is collected, and the actual radius of curvature of the sound wave propagation path is obtained using the strain data. A second time difference is obtained based on the actual radius of curvature. The fiber optic cable deformation at the first precise position is corrected using the second time difference to obtain a second precise position. The sound path difference is dynamically compensated based on the second time difference to obtain a corrected sound path difference. The final precise position is obtained based on the corrected sound path difference. The final precise position is then transformed to obtain the true coordinates. This invention significantly improves the accuracy of underwater target positioning. Attached Figure Description

[0043] Figure 1 This is a flowchart of a preferred embodiment of the underwater target localization method based on dynamic error suppression of the present invention;

[0044] Figure 2 This is a structural diagram of a preferred embodiment of the underwater target positioning system based on dynamic error suppression of the present invention;

[0045] Figure 3 This is a structural diagram of a preferred embodiment of the terminal of the present invention. Detailed Implementation

[0046] This application provides an underwater target localization method, system, and terminal based on dynamic error suppression. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description is provided with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0047] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0048] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0049] The underwater target localization method based on dynamic error suppression described in the preferred embodiment of the present invention, such as... Figure 1 As shown, the underwater target localization method based on dynamic error suppression includes the following steps:

[0050] Step S10: Obtain the initial vibration signal of the underwater target, and preprocess the initial vibration signal to obtain the target vibration signal.

[0051] The acquisition of the initial vibration signal of the underwater target specifically includes:

[0052] A short pulse of coherent laser light is injected into an optical fiber, and scattered light generated when the coherent laser light propagates in the optical fiber is received, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber.

[0053] The phase change and intensity change of the scattered light are obtained, and the initial vibration signal of the underwater target is obtained based on the phase change and intensity change.

[0054] Understandably, DAS (Distributed Acoustic Sensing) is based on optical time-domain reflectometry and combines Rayleigh scattering or coherent effect measurements. It mainly includes: Optical pulse emission: Injecting short pulses (typically nanosecond-level) of coherent laser light into the optical fiber. Scattered signal reception: As the optical pulse propagates in the fiber, Rayleigh scattering occurs due to the inhomogeneities in the fiber's microstructure. Some of the scattered light returns along its original path to the transmitting end. External disturbance detection: When acoustic waves or vibrations exist in the surrounding environment, they slightly alter the physical deformation (strain) of the fiber, causing changes in the phase or intensity of the scattered light. By monitoring these changes, the characteristics and location of the external disturbance can be deduced.

[0055] The DAS employs a narrow-linewidth (linewidth < 1kHz) high-coherence laser (1550nm wavelength) emitting laser pulses with a peak power > 10W. The pulse width is ≤ 100ns, supporting tunable pulse intervals (1-100μs) to meet different spatial resolution requirements (0.1-10m). Based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) technology, it captures Rayleigh scattering phase changes using a balanced detector and a high-speed acquisition card (sampling rate ≥ 250MS / s), with a dynamic range > 50dB. It supports multi-channel parallel processing (e.g., 4-channel synchronous acquisition), with a single-channel monitoring distance up to 100km and a total coverage of 400km. The acoustic-sensitive optical cable is a double-armored tensile-strength structure cable with a sound pressure sensitivity ≥ -150dB re 1rad / μPa and tensile strength > 100kN, suitable for ocean currents and mechanical stress environments. The acoustic-sensitive optical cable is laid in a serpentine pattern along the target area (such as a submarine pipeline or the target operation path) to ensure maximum acoustic coupling efficiency.

[0056] Further, the initial vibration signal is preprocessed to obtain the target vibration signal, specifically including:

[0057] The initial vibration signal is subjected to bandpass filtering or wavelet transform to remove high-frequency noise and baseline drift, resulting in a filtered signal.

[0058] The filtered signal is divided into short-time windows to obtain a framed signal. Adaptive threshold detection is performed on the framed signal to obtain the target vibration signal, wherein the target vibration signal is an effective signal caused by vibration or sound waves along the optical fiber.

[0059] Understandably, in distributed acoustic sensing (DAS), adaptive threshold detection is used to identify valid signals (such as intrusion, leakage, etc.) caused by vibration or sound waves along the fiber optic cable, while suppressing environmental noise (such as wind noise, electromagnetic interference). The specific process is as follows:

[0060] (1) Signal preprocessing:

[0061] Denoising filtering: High-frequency noise and baseline drift are removed by bandpass filtering or wavelet transform.

[0062] Frame processing: Divide the continuous signal into short time windows (such as one frame per second) to facilitate the calculation of local statistics.

[0063] (2) Dynamic threshold calculation:

[0064] Noise baseline estimation: Estimate the mean and standard deviation of noise during quiet periods when no events occur (e.g., by using statistical variance).

[0065] Threshold update: Adjust the threshold based on the statistical characteristics of the current window.

[0066] (3) Event detection and verification:

[0067] Over-threshold trigger: When the signal amplitude exceeds the current threshold, it is marked as a candidate event.

[0068] Multi-condition verification: Combine duration, frequency characteristics (such as the energy proportion of a specific frequency band) or spatial correlation (simultaneous triggering of nearby fiber optic points) to further confirm the authenticity of the event.

[0069] Step S20: Perform preliminary positioning on the target vibration signal to obtain the approximate position of the underwater target relative to the optical fiber. Obtain a first time difference based on the approximate position. Correct the phase distortion of the approximate position based on the first time difference to obtain the first precise position of the underwater target.

[0070] Specifically, the initial time difference between the arrival of the target vibration signal on the adjacent fiber segment is calculated, and based on the initial time difference and the sound velocity profile (SVP) model, the approximate location of the underwater target is generated.

[0071] It is understandable that if the signal emitted by the vibration source propagates at a speed of v to two detection points (A and B) on the optical fiber, their propagation times are t and t, respectively. A and t B Then the time difference Δt = t B -t A The corresponding distance difference Δd = v·Δt. By using multiple time difference and sound velocity models, a hyperbolic equation can be constructed to solve for the vibration source location. Assuming the vibration source is located at coordinates (x, y), and the coordinates of fiber optic detection points A and B are (xA, 0) and (xB, 0) respectively (assuming the fiber is laid along the x-axis), and the sound velocity is v, then: The solution (x, y) is the approximate location of the underwater target.

[0072] The sound velocity profile (SVP) model is used to correct for the influence of factors such as temperature and pressure on the propagation speed v of vibration signals in the medium (water). Calibration using high-precision temperature / pressure sensors or reference sources ensures that the sound velocity error is <0.5 m / s. For example, if Δt = 1 ms, a sound velocity error of 0.5 m / s will result in a distance error of 0.5 mm, which meets the requirements of most applications.

[0073] Furthermore, based on the approximate position, the spherical wave phase difference is calculated using a sound field propagation phase compensation model. The phase distortion at the approximate position is then corrected based on the spherical wave phase difference to obtain the corrected first time difference.

[0074] It is understandable that for two detection points (xa, 0) and (xb, 0), the phase difference is: in, For the phase delay at point b, r a For the phase delay at point b, r b Let r be the distance the sound wave travels from point b. a Let f be the sound wave propagation distance at point a, f be the sound wave frequency, and v be the speed of sound.

[0075] Furthermore, due to the near-field spherical wave's (r b -r a The nonlinearity necessitates the reconstruction of the true phase difference through a compensation model. This application's compensation method introduces a phase correction term into signal processing, converting the spherical wave phase into an equivalent plane wave phase. For example, for any detection point x... i The phase compensation amount is: Where, x c As a reference point, r c This is a reference distance (usually the perpendicular distance from the vibration source to the optical fiber).

[0076] Therefore, the process of calculating the spherical wave phase difference at each detection point based on the approximate location (x, y) using the sound field propagation phase compensation model is expressed as follows:

[0077]

[0078] Based on the phase difference of spherical waves, a compensation function is generated. The phase distortion at the coarse position is corrected according to the compensation function so that it approximates the phase difference under the plane wave assumption, and the corrected first time difference is obtained.

[0079] Furthermore, based on the first time difference and combined with the sound velocity profile (SVP) model, the position of the underwater target is iteratively optimized to obtain the first precise position of the underwater target.

[0080] Step S30: Collect strain data of the optical fiber, reconstruct the three-dimensional shape of the optical fiber using the strain data, perform B-spline curve fitting optimization on the three-dimensional shape to obtain the actual radius of curvature of the sound wave propagation path, obtain the second time difference based on the actual radius of curvature, correct the optical cable deformation at the first precise position based on the second time difference, and obtain the second precise position of the underwater target.

[0081] In this embodiment, the DAS system measures the strain distribution along the optical fiber with high spatial resolution, and the strain value at each measuring point reflects the local deformation at that location. By integrating the strain data, the three-dimensional morphology of the optical fiber (including bending, twisting, etc.) can be reconstructed segment by segment, thereby correcting the geometric model of the sound wave propagation path.

[0082] The process of acquiring strain data from the optical fiber and reconstructing its three-dimensional morphology using that data specifically includes:

[0083] Strain data at various points on the optical fiber are acquired by phase-sensitive optical time-domain reflectometry. The strain data is then processed by moving average or wavelet filtering to obtain denoised strain data. The thermal expansion effect of the denoised strain data is then eliminated by temperature-strain decoupling algorithm to obtain the target strain data.

[0084] The curvature of each point of the optical fiber is calculated based on the target strain data. The curvature is converted into a tangent direction angle change value. The tangent direction angle change value is integrated in three-dimensional space to obtain the three-dimensional morphological coordinates of the optical fiber. The three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

[0085] Understandably, physical deformations of optical fibers (such as bending and stretching) alter the actual length and curvature of the sound wave propagation path, leading to positioning errors. Reconstructing the three-dimensional morphology of the optical fiber using distributed strain data and calculating the radius of curvature of the sound wave propagation path using B-spline curve fitting can significantly improve positioning accuracy.

[0086] In this embodiment, the DAS system uses phase-sensitive optical time-domain reflectometry to acquire the strain ε(') at various points along the optical fiber with a preset resolution (e.g., 0.1 meters), where ' is the coordinate along the optical fiber. The strain data is then processed by moving average or wavelet filtering to obtain denoised strain data. Temperature compensation is performed using a temperature-strain decoupling algorithm to eliminate the thermal expansion effect of the denoised strain data, thus obtaining the target strain data.

[0087] Next, based on the strain-curvature relationship Calculate the curvature k(x') at each measuring point: Where r is the cross-sectional radius of the optical fiber, and R(x') is the radius of curvature along the coordinates of the optical fiber.

[0088] Assuming the optical fiber is a continuous elastic beam, the curvature k(x') is converted into the tangent direction angle change θ(x'). Furthermore, by integrating in three-dimensional space, the tangent direction angle is converted into the three-dimensional shape coordinates (X, Y, Z) of the optical fiber.

[0089] Further, the three-dimensional shape is optimized by B-spline curve fitting to obtain the actual radius of curvature of the sound wave propagation path. A second time difference is obtained based on the actual radius of curvature. The optical cable deformation at the first precise position is corrected based on the second time difference to obtain the second precise position of the underwater target. Specifically, this includes:

[0090] An initial B-spline curve is generated based on the three-dimensional morphological coordinates, wherein the initial B-spline curve is composed of control points and node vectors;

[0091] With the goal of minimizing the curvature error, the control points and node vectors of the initial B-spline are adjusted, and iterative optimization is performed using the Levenberg-Marquardt algorithm until the curvature error is less than a preset threshold, thus obtaining the actual curvature of the sound wave propagation path.

[0092] The changed length of the optical fiber is calculated based on the radius of the actual curvature, the original length of the optical fiber, and the cross-sectional radius of the optical fiber. The second time difference is obtained based on the changed length.

[0093] Based on the second time difference and combined with the sound velocity profile (SVP) model, the optical cable deformation at the first precise location is iteratively optimized to obtain the second precise location of the underwater target.

[0094] In this embodiment, the changed length ΔL of the optical fiber is calculated based on the radius R of the actual curvature, the original length L of the optical fiber, and the cross-sectional radius r of the optical fiber. The second time difference is then calculated based on the changed length and the speed of sound. The varying length ΔL of the optical fiber is obtained.

[0095] Step S40: Dynamically compensate the sound path difference according to the second time difference to obtain the corrected sound path difference, and obtain the final precise position of the underwater target according to the corrected sound path difference.

[0096] If the signal emitted by the vibration source propagates at a speed of v to two detection points (A and B) on the optical fiber, and their propagation times are t and t respectively, then... A and t B Then the time difference Δt = t B -t A The corresponding distance difference Δd = v·Δt can be used to construct a hyperbolic equation to solve for the location of the vibration source by using multiple time difference and sound speed models.

[0097] The second time difference is dynamically compensated to obtain the corrected sound path difference. The corrected sound path difference is then substituted into the above mathematical model as Δd = v·Δt: In the solution, (x, y) is obtained again, which is the final precise location of the underwater target.

[0098] Step S50: Map the final precise location to a geographic coordinate system to perform coordinate transformation, obtain the true coordinates of the underwater target, and visualize the true coordinates.

[0099] Specifically, during the laying of the optical fiber, key points are marked using GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-marked. The key points of the optical fiber include the starting point, the turning point, and the ending point of the optical fiber.

[0100] Based on the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed using linear interpolation and B-spline curve fitting.

[0101] The final precise location is mapped to the mapping model for coordinate transformation, and the true coordinates of the underwater target are output.

[0102] It is understood that the final precise location described in this invention is the location directly output by the DAS system, which is a relative coordinate along the fiber optic line (e.g., "1200 meters east of the starting point"). This has limitations due to the local coordinate system and lacks geographical reference significance. Therefore, in this embodiment, this relative coordinate needs to be mapped to WGS-84 (a globally universal latitude and longitude elevation coordinate system) for integration with geographic information platforms such as GIS maps and satellite imagery.

[0103] Specifically, the process begins with fiber optic geocalibration: during fiber optic laying, key points (such as starting points, turning points, and ending points) are calibrated using GPS or RTK technology, ensuring a reasonable density of calibration points (at least 3 GPS calibration points per kilometer) and guaranteeing a mapping error of <0.1 meters in WGS-84 coordinates. Next, a mapping model is constructed: a mapping model is built using linear interpolation (suitable for straight fiber segments, converting the distance along the fiber into latitude and longitude increments) and B-spline curve fitting (for curved fibers, combining calibration points to generate a continuous geographic coordinate function for the fiber). Finally, the final precise location is mapped onto the mapping model for coordinate transformation. Based on the local coordinate x of the vibration source (distance from the fiber starting point), its WGS-84 coordinates are calculated, and the true coordinates (i.e., WGS-84 coordinates) of the underwater target are output.

[0104] As can be seen, this invention addresses the core problems of existing underwater target positioning technologies, such as low positioning accuracy, poor environmental adaptability, and insufficient multi-target recognition capability, by proposing a real-time positioning method based on distributed optical fiber acoustic sensing (DAS). Through the synergistic optimization of phase compensation algorithm and optical fiber deformation self-calibration technology, combined with a multi-source signal fusion processing architecture, the near-field detection accuracy and robustness in complex marine environments are significantly improved.

[0105] Furthermore, such as Figure 2 As shown, based on the above-described underwater target localization method based on dynamic error suppression, the present invention also provides an underwater target localization system based on dynamic error suppression, wherein the underwater target localization system based on dynamic error suppression includes:

[0106] The data acquisition and processing module 51 is used to acquire the initial vibration signal of the underwater target, preprocess the initial vibration signal to obtain the target vibration signal;

[0107] The phase distortion correction module 52 is used to perform preliminary positioning of the target vibration signal, obtain the approximate position of the underwater target relative to the optical fiber, obtain a first time difference based on the approximate position, correct the phase distortion of the approximate position based on the first time difference, and obtain the first precise position of the underwater target.

[0108] The optical cable deformation correction module 53 is used to collect strain data of the optical fiber, reconstruct the three-dimensional shape of the optical fiber using the strain data, optimize the three-dimensional shape by B-spline curve fitting, obtain the actual radius of curvature of the sound wave propagation path, obtain the second time difference based on the actual radius of curvature, correct the optical cable deformation at the first precise position based on the second time difference, and obtain the second precise position of the underwater target.

[0109] The dynamic compensation module 54 for sound path difference is used to dynamically compensate for the sound path difference according to the second time difference, to obtain the corrected sound path difference, and to obtain the final accurate position of the underwater target according to the corrected sound path difference.

[0110] The coordinate transformation and display module 55 is used to map the final precise location to a geographic coordinate system to perform coordinate transformation, obtain the real coordinates of the underwater target, and visualize the real coordinates.

[0111] Furthermore, such as Figure 3 As shown, based on the above-mentioned underwater target positioning method and system based on dynamic error suppression, the present invention also provides a terminal, which includes a processor 10, a memory 20 and a display 30. Figure 3 Only some of the terminal components are shown; however, it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0112] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as a hard disk or memory. In other embodiments, the memory 20 may be an external storage device of the terminal, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc. Further, the memory 20 may include both internal and external storage devices. The memory 20 is used to store application software and various types of data installed on the terminal, such as program code installed on the terminal. The memory 20 can also be used to temporarily store data that has been output or will be output. In one embodiment, the memory 20 stores an underwater target localization program 40 based on dynamic error suppression, which can be executed by the processor 10 to implement the underwater target localization method based on dynamic error suppression in this application.

[0113] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor, or other data processing chip, used to run program code stored in the memory 20 or process data, such as executing the underwater target positioning method based on dynamic error suppression.

[0114] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. The display 30 is used to display information on the terminal and to display a visual user interface. The components of the terminal communicate with each other via a system bus.

[0115] In one embodiment, when the processor 10 executes the underwater target localization program 40 based on dynamic error suppression in the memory 20, the following steps are performed:

[0116] Acquire the initial vibration signal of the underwater target, and preprocess the initial vibration signal to obtain the target vibration signal;

[0117] The target vibration signal is initially located to obtain a rough position of the underwater target relative to the optical fiber. A first time difference is obtained based on the rough position. The phase distortion of the rough position is corrected based on the first time difference to obtain the first precise position of the underwater target.

[0118] The strain data of the optical fiber is collected, the three-dimensional shape of the optical fiber is reconstructed using the strain data, and the three-dimensional shape is optimized by B-spline curve fitting to obtain the actual radius of curvature of the sound wave propagation path. The second time difference is obtained based on the actual radius of curvature, and the optical cable deformation at the first precise position is corrected based on the second time difference to obtain the second precise position of the underwater target.

[0119] The sound path difference is dynamically compensated based on the second time difference to obtain the corrected sound path difference, and the final precise position of the underwater target is obtained based on the corrected sound path difference.

[0120] The final precise location is mapped to a geographic coordinate system for coordinate transformation to obtain the true coordinates of the underwater target, and the true coordinates are then visualized.

[0121] Specifically, acquiring the initial vibration signal of the underwater target includes:

[0122] A short pulse of coherent laser light is injected into an optical fiber, and scattered light generated when the coherent laser light propagates in the optical fiber is received, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber.

[0123] The phase change and intensity change of the scattered light are obtained, and the initial vibration signal of the underwater target is obtained based on the phase change and intensity change.

[0124] Specifically, the preprocessing of the initial vibration signal to obtain the target vibration signal includes:

[0125] The initial vibration signal is subjected to bandpass filtering or wavelet transform to remove high-frequency noise and baseline drift, resulting in a filtered signal.

[0126] The filtered signal is divided into short-time windows to obtain a framed signal. Adaptive threshold detection is performed on the framed signal to obtain the target vibration signal, wherein the target vibration signal is an effective signal caused by vibration or sound waves along the optical fiber.

[0127] Specifically, the process of initially locating the target vibration signal to obtain a coarse position of the underwater target relative to the optical fiber, obtaining a first time difference based on the coarse position, and correcting the phase distortion of the coarse position based on the first time difference to obtain a first precise position of the underwater target includes:

[0128] The initial time difference between the arrival of the target vibration signal on the adjacent fiber segment is calculated. Based on the initial time difference and the sound velocity profile (SVP) model, the approximate location of the underwater target is generated.

[0129] Based on the approximate position, the phase difference of the spherical wave is calculated using the sound field propagation phase compensation model. The phase distortion of the approximate position is then corrected based on the spherical wave phase difference to obtain the corrected first time difference.

[0130] Based on the first time difference and combined with the sound velocity profile (SVP) model, the position of the underwater target is iteratively optimized to obtain the first precise position of the underwater target.

[0131] The step of acquiring strain data from the optical fiber and using the strain data to reconstruct the three-dimensional morphology of the optical fiber specifically includes:

[0132] Strain data at various points on the optical fiber are acquired by phase-sensitive optical time-domain reflectometry. The strain data is then processed by moving average or wavelet filtering to obtain denoised strain data. The thermal expansion effect of the denoised strain data is then eliminated by temperature-strain decoupling algorithm to obtain the target strain data.

[0133] The curvature of each point of the optical fiber is calculated based on the target strain data. The curvature is converted into a tangent direction angle change value. The tangent direction angle change value is integrated in three-dimensional space to obtain the three-dimensional morphological coordinates of the optical fiber. The three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

[0134] Specifically, the step of performing B-spline curve fitting optimization on the three-dimensional shape to obtain the actual radius of curvature of the sound wave propagation path, obtaining the second time difference based on the actual radius of curvature, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain the second precise position of the underwater target includes:

[0135] An initial B-spline curve is generated based on the three-dimensional morphological coordinates, wherein the initial B-spline curve is composed of control points and node vectors;

[0136] With the goal of minimizing the curvature error, the control points and node vectors of the initial B-spline are adjusted, and iterative optimization is performed using the Levenberg-Marquardt algorithm until the curvature error is less than a preset threshold, thus obtaining the actual curvature of the sound wave propagation path.

[0137] The changed length of the optical fiber is calculated based on the radius of the actual curvature, the original length of the optical fiber, and the cross-sectional radius of the optical fiber. The second time difference is obtained based on the changed length.

[0138] Based on the second time difference and combined with the sound velocity profile (SVP) model, the optical cable deformation at the first precise location is iteratively optimized to obtain the second precise location of the underwater target.

[0139] Specifically, the step of mapping the final precise location to a geographic coordinate system and performing coordinate transformation to obtain the true coordinates of the underwater target includes:

[0140] During the laying of the optical fiber, key points are marked using GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-marked. The key points of the optical fiber include the starting point, the turning point, and the ending point of the optical fiber.

[0141] Based on the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed using linear interpolation and B-spline curve fitting.

[0142] The final precise location is mapped to the mapping model for coordinate transformation, and the true coordinates of the underwater target are output.

[0143] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores an underwater target localization program based on dynamic error suppression, and the underwater target localization program based on dynamic error suppression implements the steps of the underwater target localization method based on dynamic error suppression as described above when executed by a processor.

[0144] In summary, this invention obtains the vibration signal of an underwater target using distributed fiber optic acoustic sensing technology. Based on the vibration signal, a coarse position of the underwater target is obtained. Based on this coarse position, a first time difference is obtained using a sound field propagation phase compensation model. The phase distortion of the coarse position is corrected using this first time difference to obtain a first precise position. Strain data of the optical fiber is collected, and the actual radius of curvature of the sound wave propagation path is obtained using this strain data. A second time difference is obtained based on this actual radius of curvature. The fiber optic cable deformation at the first precise position is corrected using this second time difference to obtain a second precise position. The sound path difference is dynamically compensated based on the second time difference to obtain a corrected sound path difference. The final precise position is obtained based on this corrected sound path difference. The final precise position is then transformed to obtain the true coordinates. This invention, combined with a multi-source signal fusion processing architecture, significantly improves near-field detection accuracy and robustness in complex marine environments.

[0145] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal that includes that element.

[0146] Of course, those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0147] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An underwater target localization method based on dynamic error suppression, characterized in that, The underwater target localization method based on dynamic error suppression includes: Acquire the initial vibration signal of the underwater target, and preprocess the initial vibration signal to obtain the target vibration signal; The target vibration signal is initially located to obtain a rough position of the underwater target relative to the optical fiber. A first time difference is obtained based on the rough position. The phase distortion of the rough position is corrected based on the first time difference to obtain the first precise position of the underwater target. The strain data of the optical fiber is collected, the three-dimensional shape of the optical fiber is reconstructed using the strain data, and the three-dimensional shape is optimized by B-spline curve fitting to obtain the actual radius of curvature of the sound wave propagation path. The second time difference is obtained based on the actual radius of curvature, and the optical cable deformation at the first precise position is corrected based on the second time difference to obtain the second precise position of the underwater target. The sound path difference is dynamically compensated based on the second time difference to obtain the corrected sound path difference, and the final precise position of the underwater target is obtained based on the corrected sound path difference. The final precise location is mapped to a geographic coordinate system for coordinate transformation to obtain the true coordinates of the underwater target, and the true coordinates are then visualized. The process of acquiring strain data from the optical fiber and reconstructing its three-dimensional morphology using that data specifically includes: Strain data at various points on the optical fiber are acquired by phase-sensitive optical time-domain reflectometry. The strain data is then processed by moving average or wavelet filtering to obtain denoised strain data. The thermal expansion effect of the denoised strain data is then eliminated by temperature-strain decoupling algorithm to obtain the target strain data. The curvature of each point of the optical fiber is calculated based on the target strain data. The curvature is converted into a tangent direction angle change value. The tangent direction angle change value is integrated in three-dimensional space to obtain the three-dimensional shape coordinates of the optical fiber. The three-dimensional shape coordinates are used to describe the actual shape of the optical fiber. The process of optimizing the three-dimensional shape by B-spline curve fitting to obtain the actual radius of curvature of the sound wave propagation path, obtaining the second time difference based on the actual radius of curvature, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain the second precise position of the underwater target specifically includes: An initial B-spline curve is generated based on the three-dimensional morphological coordinates, wherein the initial B-spline curve is composed of control points and node vectors; With the goal of minimizing the curvature error, the control points and node vectors of the initial B-spline are adjusted, and iterative optimization is performed using the Levenberg-Marquardt algorithm until the curvature error is less than a preset threshold, thus obtaining the actual curvature of the sound wave propagation path. The changed length of the optical fiber is calculated based on the radius of the actual curvature, the original length of the optical fiber, and the cross-sectional radius of the optical fiber, and the second time difference is obtained based on the changed length. Based on the second time difference and combined with the sound velocity profile (SVP) model, the optical cable deformation at the first precise location is iteratively optimized to obtain the second precise location of the underwater target.

2. The underwater target localization method based on dynamic error suppression according to claim 1, characterized in that, The acquisition of the initial vibration signal of the underwater target specifically includes: A short pulse of coherent laser light is injected into an optical fiber, and scattered light generated when the coherent laser light propagates in the optical fiber is received, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber. The phase change and intensity change of the scattered light are obtained, and the initial vibration signal of the underwater target is obtained based on the phase change and intensity change.

3. The underwater target localization method based on dynamic error suppression according to claim 1, characterized in that, The preprocessing of the initial vibration signal to obtain the target vibration signal specifically includes: The initial vibration signal is subjected to bandpass filtering or wavelet transform to remove high-frequency noise and baseline drift, resulting in a filtered signal. The filtered signal is divided into short-time windows to obtain a framed signal. Adaptive threshold detection is performed on the framed signal to obtain the target vibration signal, wherein the target vibration signal is an effective signal caused by vibration or sound waves along the optical fiber.

4. The underwater target localization method based on dynamic error suppression according to claim 1, characterized in that, The preliminary positioning of the target vibration signal to obtain a coarse position of the underwater target relative to the optical fiber, obtaining a first time difference based on the coarse position, and correcting the phase distortion of the coarse position based on the first time difference to obtain the first precise position of the underwater target specifically includes: The initial time difference between the arrival of the target vibration signal on the adjacent fiber segment is calculated. Based on the initial time difference and the sound velocity profile (SVP) model, the approximate location of the underwater target is generated. Based on the approximate position, the phase difference of the spherical wave is calculated using the sound field propagation phase compensation model. The phase distortion of the approximate position is then corrected based on the spherical wave phase difference to obtain the corrected first time difference. Based on the first time difference and combined with the sound velocity profile (SVP) model, the position of the underwater target is iteratively optimized to obtain the first precise position of the underwater target.

5. The underwater target localization method based on dynamic error suppression according to claim 1, characterized in that, The step of mapping the final precise location to a geographic coordinate system and performing coordinate transformation to obtain the true coordinates of the underwater target specifically includes: During the laying of the optical fiber, key points are marked using GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-marked. The key points of the optical fiber include the starting point, the turning point, and the ending point of the optical fiber. Based on the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed using linear interpolation and B-spline curve fitting. The final precise location is mapped to the mapping model for coordinate transformation, and the true coordinates of the underwater target are output.

6. An underwater target positioning system based on dynamic error suppression, characterized in that, The underwater target localization system based on dynamic error suppression is applied to the underwater target localization method based on dynamic error suppression according to any one of claims 1-5, wherein the underwater target localization system based on dynamic error suppression comprises: The data acquisition and processing module is used to acquire the initial vibration signal of the underwater target, and to preprocess the initial vibration signal to obtain the target vibration signal; A phase distortion correction module is used to perform preliminary positioning of the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtain a first time difference based on the rough position, and correct the phase distortion of the rough position based on the first time difference to obtain the first precise position of the underwater target. The optical cable deformation correction module is used to collect strain data of the optical fiber, reconstruct the three-dimensional shape of the optical fiber using the strain data, optimize the three-dimensional shape by B-spline curve fitting, obtain the actual radius of curvature of the sound wave propagation path, obtain the second time difference based on the actual radius of curvature, and correct the optical cable deformation at the first precise position based on the second time difference to obtain the second precise position of the underwater target. The dynamic sound path difference compensation module is used to dynamically compensate the sound path difference according to the second time difference to obtain the corrected sound path difference, and to obtain the final accurate position of the underwater target based on the corrected sound path difference. The coordinate transformation and display module is used to map the final precise location to a geographic coordinate system to perform coordinate transformation, obtain the real coordinates of the underwater target, and visualize the real coordinates.

7. A terminal, characterized in that, The terminal includes: a memory, a processor, and an underwater target localization program based on dynamic error suppression stored in the memory and executable on the processor. When the underwater target localization program based on dynamic error suppression is executed by the processor, it implements the steps of the underwater target localization method based on dynamic error suppression as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores an underwater target localization program based on dynamic error suppression, which, when executed by a processor, implements the steps of the underwater target localization method based on dynamic error suppression as described in any one of claims 1-5.

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