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

Abstract

The invention discloses an underwater target positioning method and system based on dynamic error suppression, and a terminal, and the method comprises the steps: obtaining a vibration signal of an underwater target through a distributed optical fiber sound wave sensing technology, obtaining a rough position of the underwater target according to the vibration signal, and carrying out the positioning of the underwater target according to the rough position; obtaining a first time difference through a sound field propagation phase compensation model, and correcting the phase distortion of the rough position according to the first time difference to obtain a first accurate position; acquiring strain data of the optical fiber, obtaining an actual curvature radius of the sound wave propagation path by using the strain data, obtaining a second time difference according to the actual curvature radius, and correcting the deformation of the optical cable at the first accurate position according to the second time difference to obtain a second accurate position; dynamically compensating the sound path difference according to the second time difference to obtain a corrected sound path difference, and obtaining a final accurate position according to the corrected sound path difference; and performing coordinate conversion on the final accurate position to obtain a real coordinate. According to the invention, the precision of underwater target positioning is obviously improved.

Description

Technical Field

[0001] The present 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 Art

[0002] Distributed acoustic sensing (DAS) uses optical fiber as a sensing element to achieve continuous, distributed measurement of environmental parameters along a fiber path. DAS relies on the Rayleigh backscattering effect of optical fibers. Laser pulses are sent down the fiber, where lattice defects within the fiber scatter some of the light back to a demodulator. By analyzing this backscattered light, changes in longitudinal strain over time every few meters along the fiber can be inferred, enabling real-time monitoring of external sound waves and vibrations.

[0003] DAS technology was initially applied in fields such as oil pipeline monitoring and perimeter security. However, it faces technical bottlenecks in underwater target positioning, such as mismatched signal propagation models 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 long-term and high-precision requirements; and defects in the DAS near-field model: the coupling error problem between phase distortion and fiber deformation is not resolved.

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

[0005] The main purpose of the present invention is to provide an underwater target positioning method, system, terminal and computer-readable storage medium based on dynamic error suppression, aiming to solve the problem of insufficient underwater target positioning accuracy caused by acoustic or inertial navigation being limited by medium characteristics and cumulative errors, as well as phase distortion and optical fiber deformation when underwater target positioning is performed through DAS in the prior art.

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

[0007] Acquiring an initial vibration signal of an underwater target, and preprocessing the initial vibration signal to obtain a target vibration signal;

[0008] performing preliminary positioning on the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting a phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target;

[0009] collecting strain data of the optical fiber, reconstructing a three-dimensional shape of the optical fiber using the strain data, performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target;

[0010] Dynamically compensating the sound path difference according to the second time difference to obtain a corrected sound path difference, and obtaining a final accurate position of the underwater target according to the corrected sound path difference;

[0011] The final precise position is mapped to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target, and the real coordinates are visualized.

[0012] Optionally, in the underwater target positioning method based on dynamic error suppression, the step of obtaining an initial vibration signal of the underwater target specifically includes:

[0013] injecting a short pulse of coherent laser light into an optical fiber, and receiving scattered light generated when the coherent laser light propagates in the optical fiber, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber;

[0014] The phase change and the intensity change of the scattered light are acquired, and an initial vibration signal of the underwater target is obtained according to the phase change and the intensity change.

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

[0016] performing bandpass filtering or wavelet transform on the initial vibration signal to remove high-frequency noise and baseline drift of the initial vibration signal to obtain a filtered signal;

[0017] The filtered signal is divided into short-time windows to obtain a framed signal, and the framed signal is subjected to adaptive threshold detection to obtain a 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 positioning method based on dynamic error suppression, wherein the preliminary positioning of the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting the phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target, specifically includes:

[0019] Calculating the initial time difference between the target vibration signal and the adjacent optical fiber segments, and generating a rough position of the underwater target based on the initial time difference and a sound velocity profile (SVP) model;

[0020] Calculating a spherical wave phase difference based on the rough position using an acoustic field propagation phase compensation model, and correcting the phase distortion of the rough position based on the spherical wave phase difference to obtain a corrected first time difference;

[0021] According to the first time difference, combined with the sound speed 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 positioning method based on dynamic error suppression, wherein the collecting strain data of the optical fiber and reconstructing the three-dimensional shape of the optical fiber using the strain data, specifically includes:

[0023] Strain data at each point of the optical fiber is collected using phase-sensitive optical time-domain reflectometry, the strain data is subjected to sliding average processing or wavelet filtering to obtain denoised strain data, and the thermal expansion effect of the denoised strain data is eliminated using a temperature-strain decoupling algorithm to obtain 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, and the tangent direction angle change value is integrated in three dimensions to obtain the three-dimensional morphological coordinates of the optical fiber, wherein the three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

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

[0026] generating an initial B-spline curve according to 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 error of the curvature, adjusting the control points and the node vectors of the initial B-spline, and performing iterative optimization using the Levenberg-Marquardt algorithm until the error of the curvature is less than a preset threshold, thereby obtaining the actual curvature of the sound wave propagation path;

[0028] Calculating a changed length of the optical fiber according to the actual radius of curvature, the original length of the optical fiber, and the fiber cross-sectional radius of the optical fiber, and obtaining a second time difference according to the changed length;

[0029] According to the second time difference, combined with the sound speed profile SVP model, the optical cable deformation at the first precise position is iteratively optimized to obtain the second precise position of the underwater target.

[0030] Optionally, the underwater target positioning method based on dynamic error suppression, wherein mapping the final precise position to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target, specifically includes:

[0031] When laying the optical fiber, key points are calibrated by GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-calibrated, wherein the key points of the optical fiber include the optical fiber starting point, the optical fiber turning point and the optical fiber end point;

[0032] According to the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed by linear interpolation and B-spline curve fitting;

[0033] The final precise position is mapped to the mapping model to perform coordinate conversion, and the real coordinates of the underwater target are output.

[0034] In addition, to achieve the above-mentioned object, the present invention further provides an underwater target positioning system based on dynamic error suppression, wherein the underwater target positioning system based on dynamic error suppression includes:

[0035] A data acquisition and processing module is used to obtain an initial vibration signal of an underwater target, and pre-process the initial vibration signal to obtain a target vibration signal;

[0036] a phase distortion correction module, configured to perform preliminary positioning on 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 a first precise position of the underwater target;

[0037] an optical cable deformation correction module, configured to collect strain data of the optical fiber, reconstruct a three-dimensional shape of the optical fiber using the strain data, perform B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtain a second time difference based on the actual curvature radius, and correct the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target;

[0038] an acoustic path difference dynamic compensation module, configured to dynamically compensate the acoustic path difference according to the second time difference to obtain a corrected acoustic path difference, and obtain a final accurate position of the underwater target according to the corrected acoustic path difference;

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

[0040] In addition, to achieve the above-mentioned purpose, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and an underwater target positioning program based on dynamic error suppression stored on the memory and runnable on the processor, and when the underwater target positioning program based on dynamic error suppression is executed by the processor, the steps of the underwater target positioning method based on dynamic error suppression as described above are implemented.

[0041] In addition, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores an underwater target positioning program based on dynamic error suppression, and when the underwater target positioning program based on dynamic error suppression is executed by a processor, the steps of the underwater target positioning method based on dynamic error suppression as described above are implemented.

[0042] In this invention, the vibration signal of an underwater target is obtained through distributed fiber optic acoustic wave sensing technology. The rough position of the underwater target is obtained based on the vibration signal. Based on the rough position, a first time difference is obtained using an acoustic field propagation phase compensation model. The phase distortion of the rough position is corrected based on the first time difference to obtain the first precise position. Strain data of the optical fiber is collected and used to obtain the actual curvature radius of the acoustic wave propagation path. Based on the actual curvature radius, a second time difference is obtained. The optical cable deformation at the first precise position is corrected based on the second time difference to obtain the second precise position. The acoustic path difference is dynamically compensated based on the second time difference to obtain a corrected acoustic path difference. The final precise position is then converted to the true coordinates. This invention significantly improves the accuracy of underwater target positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Flowchart of a preferred embodiment of the underwater target positioning method based on dynamic error suppression of the present invention;

[0044] Figure 2 1 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 FIG. 4 is a structural diagram of a preferred embodiment of the terminal of the present invention. DETAILED DESCRIPTION

[0046] This application provides a method, system, and terminal for underwater target positioning based on dynamic error suppression. To make the objectives, technical solutions, and effects of this application more clear and explicit, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate 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 (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0048] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

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

[0050] Step S10: Acquire an initial vibration signal of an underwater target, and pre-process the initial vibration signal to obtain a target vibration signal.

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

[0052] injecting a short pulse of coherent laser light into an optical fiber, and receiving scattered light generated when the coherent laser light propagates in the optical fiber, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber;

[0053] The phase change and the intensity change of the scattered light are acquired, and an initial vibration signal of the underwater target is obtained according to the phase change and the intensity change.

[0054] It is understandable that DAS (Distributed Acoustic Sensing) is based on optical time-domain reflection technology and combined with the measurement of Rayleigh scattering or coherence effects. It mainly includes: Light pulse emission: injecting short pulses (usually nanoseconds) of coherent laser into the optical fiber. Scattered signal reception: When the light pulse propagates in the optical fiber, Rayleigh scattering will occur due to the unevenness of the optical fiber microstructure. Part of the scattered light will return to the transmitting end along the original path. External disturbance detection: When there are sound waves or vibrations in the environment around the optical fiber, the physical deformation (strain) of the optical fiber will be slightly changed, causing the phase or intensity of the scattered light to change. By monitoring these changes, the characteristics and location of the external disturbance can be inferred.

[0055] The DAS utilizes a narrow-linewidth (linewidth <1kHz) high-coherence laser (1550nm wavelength) to emit laser pulses with peak power >10W. Pulse widths are ≤100ns, and the system supports tunable pulse intervals (1-100μs) to meet varying spatial resolution requirements (0.1-10m). Based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) technology, it captures phase variations in Rayleigh scattered light through a balanced detector and a high-speed acquisition card (sampling rate ≥250MS / s). The system boasts a dynamic range >50dB and supports multi-channel parallel processing (e.g., 4-channel simultaneous acquisition). A single-channel monitoring range of up to 100km is possible, with a total coverage of 400km. The acoustically sensitive optical cable utilizes a double-layer armored tensile-strength cable with an acoustic pressure sensitivity ≥-150dB re 1rad / μPa and a tensile strength >100kN, making it suitable for submarine currents and mechanical stress environments. The laying method of the acoustic sensitive optical cable is: serpentine laying along the target area (such as submarine pipelines, target operation paths) to ensure the maximum efficiency of acoustic wave coupling.

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

[0057] performing bandpass filtering or wavelet transform on the initial vibration signal to remove high-frequency noise and baseline drift of the initial vibration signal to obtain a filtered signal;

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

[0059] It is understood that 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 optical fiber, while suppressing environmental noise (such as wind noise, electromagnetic interference). The specific process is as follows:

[0060] (1) Signal preprocessing:

[0061] Denoising filtering: Remove high-frequency noise and baseline drift through 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 the noise during quiet periods when no events occur (e.g., determined by statistical variance).

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

[0066] (3) Event detection and verification:

[0067] 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 adjacent fiber points) to further confirm the authenticity of the event.

[0069] Step S20: Preliminarily locate 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, correct the phase distortion of the rough position based on the first time difference, and obtain a first precise position of the underwater target.

[0070] Specifically, the initial time difference between the target vibration signal and the adjacent optical fiber segments is calculated, and the rough position of the underwater target is generated based on the initial time difference and the sound velocity profile SVP model.

[0071] It can be understood that if the signal emitted by the vibration source propagates at a speed v to the two detection points (A and B) on the optical fiber, their propagation times are t A and t B , then the time difference Δt=t B -t A The corresponding distance difference Δd = v·Δt. By using multiple sets of time difference and sound speed models, a hyperbola equation can be constructed to solve the vibration source location. Assuming the vibration source is located at coordinates (x, y), 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 speed is v, then: The obtained (x, y) is the rough position of the underwater target.

[0072] The sound velocity profile (SVP) model is used to correct for the influence of temperature, pressure, and other factors on the propagation velocity v of the vibration signal in the medium (water). Calibration using a high-precision temperature / pressure sensor or reference source ensures a sound velocity error of less than 0.5 m / s. For example, if Δt = 1 ms, a sound velocity error of 0.5 m / s results in a distance error of 0.5 mm, which meets the requirements of most applications.

[0073] Furthermore, according to the rough position, a spherical wave phase difference is calculated by using an acoustic field propagation phase compensation model, and the phase distortion of the rough position is corrected according to the spherical wave phase difference to obtain a corrected first time difference.

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

[0075] Furthermore, due to the near-field spherical wave (r b -r a ) is nonlinear, and the real phase difference needs to be restored through a compensation model. The compensation method of this application is to introduce a phase correction term in signal processing to convert the spherical wave phase into an equivalent plane wave phase. For example, for any detection point x i The phase compensation amount is: Among them, x c is the reference point, r c is the reference distance (usually the vertical distance from the vibration source to the optical fiber).

[0076] Therefore, according to the rough position (x, y), the process of calculating the spherical wave phase difference of each detection point through the sound field propagation phase compensation model is expressed as:

[0077]

[0078] A compensation function is generated based on the spherical wave phase difference, and the phase distortion of the rough position is corrected according to the compensation function to make it close to the phase difference under the plane wave assumption, thereby obtaining a corrected first time difference.

[0079] Furthermore, based on the first time difference and in combination with the sound speed 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, use the strain data to reconstruct the three-dimensional shape of the optical fiber, perform B-spline curve fitting optimization on the three-dimensional shape to obtain the actual curvature radius of the sound wave propagation path, obtain a second time difference based on the actual curvature radius, 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. The strain value at each measurement point reflects the local deformation at that location. By integrating the strain data, the three-dimensional shape of the optical fiber (including bends, twists, etc.) can be reconstructed section by section, thereby correcting the geometric model of the acoustic wave propagation path.

[0082] The collecting of strain data of the optical fiber and reconstructing the three-dimensional shape of the optical fiber using the strain data specifically includes:

[0083] Strain data at each point of the optical fiber is collected using phase-sensitive optical time-domain reflectometry, the strain data is subjected to sliding average processing or wavelet filtering to obtain denoised strain data, and the thermal expansion effect of the denoised strain data is eliminated using a temperature-strain decoupling algorithm to obtain 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, and the tangent direction angle change value is integrated in three dimensions to obtain the three-dimensional morphological coordinates of the optical fiber, wherein the three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

[0085] It's understandable that physical deformation of an optical fiber (such as bending or stretching) can alter the actual length and curvature of the acoustic wave propagation path, leading to positioning errors. Reconstructing the three-dimensional shape of the optical fiber using distributed strain data and calculating the curvature radius of the acoustic 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 obtain strain ε(') at each point on the optical fiber at a preset resolution (e.g., 0.1 meter), where ' represents the coordinate along the fiber. This strain data is then subjected to sliding averaging or wavelet filtering to obtain denoised strain data. Temperature compensation is then performed using a temperature-strain decoupling algorithm to eliminate thermal expansion effects in the denoised strain data, resulting in the target strain data.

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

[0088] Assuming that the optical fiber is a continuous elastic beam, the curvature k(x') is converted into the tangent direction angle change θ(x'), Furthermore, the tangent direction angle is converted into the three-dimensional morphological coordinates (X, Y, Z) of the optical fiber through three-dimensional spatial integration.

[0089] Further, performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the sound wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target, specifically including:

[0090] generating an initial B-spline curve according to 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 error of the curvature, adjusting the control points and the node vectors of the initial B-spline, and performing iterative optimization using the Levenberg-Marquardt algorithm until the error of the curvature is less than a preset threshold, thereby obtaining the actual curvature of the sound wave propagation path;

[0092] Calculating a changed length of the optical fiber according to the actual radius of curvature, the original length of the optical fiber, and the fiber cross-sectional radius of the optical fiber, and obtaining a second time difference according to the changed length;

[0093] According to the second time difference, combined with the sound speed profile SVP model, the optical cable deformation at the first precise position is iteratively optimized to obtain the second precise position of the underwater target.

[0094] In this embodiment, the changed length ΔL of the optical fiber is calculated according to the actual curvature radius R, the original length L of the optical fiber and the optical fiber cross-sectional radius r of the optical fiber, and the second time difference is calculated according to the changed length and the speed of sound, wherein the second time difference is calculated according to the actual curvature radius R, the original length L of the optical fiber and the optical fiber cross-sectional radius r of the optical fiber. The changed 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 a 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 from the vibration source propagates at a speed v to two detection points (A and B) on the optical fiber, their propagation times are t A and t B , then the time difference Δt=t B -t A , corresponding to the distance difference Δd = v·Δt, through multiple sets of time difference and sound speed models, a hyperbola equation can be constructed to solve the vibration source position.

[0097] The second time difference is dynamically compensated to obtain a corrected sound path difference, and the corrected sound path difference is substituted into the above mathematical model as Δd=v·Δt: , (x, y) is solved again and is the final accurate position of the underwater target.

[0098] Step S50: Map the final precise position to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target, and visualize the real coordinates.

[0099] Specifically, when laying the optical fiber, key points are calibrated by GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-calibrated, wherein the key points of the optical fiber include the optical fiber starting point, the optical fiber turning point and the optical fiber end point;

[0100] According to the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed by linear interpolation and B-spline curve fitting;

[0101] The final precise position is mapped to the mapping model to perform coordinate conversion, and the real coordinates of the underwater target are output.

[0102] It should be understood that the final precise location described in this disclosure is the location directly output by the DAS system and is a relative coordinate along the fiber (e.g., "1200 meters east of the starting point"). This is subject to the limitations of a local coordinate system and lacks geographic reference. Therefore, in this embodiment, these relative coordinates must be mapped to WGS-84 (a universally used latitude, longitude, and elevation coordinate system) to facilitate integration with geographic information platforms such as GIS maps and satellite imagery.

[0103] Specifically, the optical fiber is first geographically calibrated: when laying the optical fiber, the WGS-84 coordinates of key points (such as the starting point, turning point, and end point) are calibrated using GPS or RTK technology, and the density of the calibration points is ensured to be reasonable, with at least 3 GPS calibration points per kilometer, ensuring that the mapping error is less than 0.1 meters. Next, a mapping model is constructed: the mapping model is constructed using linear interpolation (applicable to straight optical fiber segments, converting the distance along the optical fiber into longitude and latitude increments) and B-spline curve fitting (for curved optical fibers, combining calibration points to generate a continuous geographic coordinate function of the optical fiber). Finally, the final precise position is mapped to the mapping model for coordinate conversion. Based on the local coordinate x of the vibration source (the distance from the optical fiber starting point), its WGS-84 coordinate is calculated, and the true coordinates of the underwater target (i.e., the WGS-84 coordinates) are output.

[0104] This paper addresses the core issues of existing underwater target positioning technologies, such as low positioning accuracy, poor environmental adaptability, and insufficient multi-target recognition capabilities. By proposing a real-time positioning method based on distributed fiber acoustic sensing (DAS), this method significantly improves near-field detection accuracy and robustness in complex marine environments through the coordinated optimization of a phase compensation algorithm and fiber deformation self-calibration technology, combined with a multi-source signal fusion processing architecture.

[0105] Further, if Figure 2 As shown, based on the above underwater target positioning method based on dynamic error suppression, 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:

[0106] The data acquisition and processing module 51 is used to obtain the initial vibration signal of the underwater target and pre-process the initial vibration signal to obtain the target vibration signal;

[0107] a phase distortion correction module 52 for performing preliminary positioning on the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting the phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target;

[0108] an optical cable deformation correction module 53 for collecting strain data of the optical fiber, reconstructing a three-dimensional shape of the optical fiber using the strain data, performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target;

[0109] an acoustic path difference dynamic compensation module 54, configured to dynamically compensate the acoustic path difference according to the second time difference to obtain a corrected acoustic path difference, and obtain a final accurate position of the underwater target according to the corrected acoustic path difference;

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

[0111] Further, if 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 components of the terminal are shown, but it should be understood that implementation of all of the shown components is not required, 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 of the terminal. In other embodiments, the memory 20 may also be an external storage device of the terminal, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the terminal. Furthermore, the memory 20 may also include both an internal storage unit of the terminal and an external storage device. The memory 20 is used to store application software and various types of data installed on the terminal, such as the program code of the installation terminal. The memory 20 may also be used to temporarily store data that has been output or is to be output. In one embodiment, the memory 20 stores an underwater target positioning program 40 based on dynamic error suppression, and the underwater target positioning program 40 based on dynamic error suppression can be executed by the processor 10, thereby realizing the underwater target positioning method based on dynamic error suppression in the present 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 the program code or process data stored in the memory 20, 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 positioning program 40 based on dynamic error suppression in the memory 20, the following steps are implemented:

[0116] Acquiring an initial vibration signal of an underwater target, and preprocessing the initial vibration signal to obtain a target vibration signal;

[0117] performing preliminary positioning on the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting a phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target;

[0118] collecting strain data of the optical fiber, reconstructing a three-dimensional shape of the optical fiber using the strain data, performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target;

[0119] Dynamically compensating the sound path difference according to the second time difference to obtain a corrected sound path difference, and obtaining a final accurate position of the underwater target according to the corrected sound path difference;

[0120] The final precise position is mapped to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target, and the real coordinates are visualized.

[0121] The step of obtaining the initial vibration signal of the underwater target specifically includes:

[0122] injecting a short pulse of coherent laser light into an optical fiber, and receiving scattered light generated when the coherent laser light propagates in the optical fiber, wherein the scattered light is generated by the inhomogeneity of the microstructure of the optical fiber;

[0123] The phase change and the intensity change of the scattered light are acquired, and an initial vibration signal of the underwater target is obtained according to the phase change and the intensity change.

[0124] The preprocessing of the initial vibration signal to obtain the target vibration signal specifically includes:

[0125] performing bandpass filtering or wavelet transform on the initial vibration signal to remove high-frequency noise and baseline drift of the initial vibration signal to obtain a filtered signal;

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

[0127] The performing preliminary positioning of the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting the phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target specifically includes:

[0128] Calculating the initial time difference between the target vibration signal and the adjacent optical fiber segments, and generating a rough position of the underwater target based on the initial time difference and a sound velocity profile (SVP) model;

[0129] Calculating a spherical wave phase difference based on the rough position using an acoustic field propagation phase compensation model, and correcting the phase distortion of the rough position based on the spherical wave phase difference to obtain a corrected first time difference;

[0130] According to the first time difference, combined with the sound speed profile SVP model, the position of the underwater target is iteratively optimized to obtain the first precise position of the underwater target.

[0131] The collecting of strain data of the optical fiber and reconstructing the three-dimensional shape of the optical fiber using the strain data specifically includes:

[0132] Strain data at each point of the optical fiber is collected using phase-sensitive optical time-domain reflectometry, the strain data is subjected to sliding average processing or wavelet filtering to obtain denoised strain data, and the thermal expansion effect of the denoised strain data is eliminated using a temperature-strain decoupling algorithm to obtain 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, and the tangent direction angle change value is integrated in three dimensions to obtain the three-dimensional morphological coordinates of the optical fiber, wherein the three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

[0134] The performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the sound wave propagation path, obtaining a second time difference based on the actual curvature radius, 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:

[0135] generating an initial B-spline curve according to 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 error of the curvature, adjusting the control points and the node vectors of the initial B-spline, and performing iterative optimization using the Levenberg-Marquardt algorithm until the error of the curvature is less than a preset threshold, thereby obtaining the actual curvature of the sound wave propagation path;

[0137] Calculating a changed length of the optical fiber according to the actual radius of curvature, the original length of the optical fiber, and the fiber cross-sectional radius of the optical fiber, and obtaining a second time difference according to the changed length;

[0138] According to the second time difference, combined with the sound speed profile SVP model, the optical cable deformation at the first precise position is iteratively optimized to obtain the second precise position of the underwater target.

[0139] The mapping of the final precise position to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target specifically includes:

[0140] When laying the optical fiber, key points are calibrated by GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-calibrated, wherein the key points of the optical fiber include the optical fiber starting point, the optical fiber turning point and the optical fiber end point;

[0141] According to the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed by linear interpolation and B-spline curve fitting;

[0142] The final precise position is mapped to the mapping model to perform coordinate conversion, and the real 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 positioning program based on dynamic error suppression, and when the underwater target positioning program based on dynamic error suppression is executed by a processor, the steps of the underwater target positioning method based on dynamic error suppression as described above are implemented.

[0144] In summary, the present invention obtains the vibration signal of the underwater target through distributed fiber optic acoustic wave sensing technology, obtains the rough position of the underwater target based on the vibration signal, obtains the first time difference based on the rough position through the acoustic field propagation phase compensation model, corrects the phase distortion of the rough position based on the first time difference to obtain the first precise position; collects the strain data of the optical fiber, uses the strain data to obtain the actual curvature radius of the acoustic wave propagation path, obtains the second time difference based on the actual curvature radius, corrects the optical cable deformation at the first precise position based on the second time difference, and obtains the second precise position; dynamically compensates the sound path difference based on the second time difference to obtain the corrected sound path difference, and obtains the final precise position based on the corrected sound path difference; performs coordinate conversion on the final precise position to obtain the real coordinate. The present invention combines a multi-source signal fusion processing architecture to significantly improve the near-field detection accuracy and robustness in complex ocean environments.

[0145] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or terminal comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or terminal comprising the element.

[0146] Of course, those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present 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), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0147] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for underwater target positioning based on dynamic error suppression, characterized in that: The underwater target positioning method based on dynamic error suppression includes: Acquiring an initial vibration signal of an underwater target, and preprocessing the initial vibration signal to obtain a target vibration signal; performing preliminary positioning on the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting a phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target; collecting strain data of the optical fiber, reconstructing a three-dimensional shape of the optical fiber using the strain data, performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target; Dynamically compensating the sound path difference according to the second time difference to obtain a corrected sound path difference, and obtaining a final accurate position of the underwater target according to the corrected sound path difference; The final precise position is mapped to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target, and the real coordinates are visualized.

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

3. The underwater target positioning 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: performing bandpass filtering or wavelet transform on the initial vibration signal to remove high-frequency noise and baseline drift of the initial vibration signal to obtain a filtered signal; The filtered signal is divided into short-time windows to obtain a framed signal, and the framed signal is subjected to adaptive threshold detection to obtain a 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 positioning method based on dynamic error suppression according to claim 1, characterized in that: The performing preliminary positioning on the target vibration signal to obtain a rough position of the underwater target relative to the optical fiber, obtaining a first time difference based on the rough position, and correcting the phase distortion of the rough position based on the first time difference to obtain a first precise position of the underwater target specifically includes: Calculating the initial time difference between the target vibration signal and the adjacent optical fiber segments, and generating a rough position of the underwater target based on the initial time difference and a sound velocity profile (SVP) model; Calculating a spherical wave phase difference based on the rough position using an acoustic field propagation phase compensation model, and correcting the phase distortion of the rough position based on the spherical wave phase difference to obtain a corrected first time difference; According to the first time difference, combined with the sound speed 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 positioning method based on dynamic error suppression according to claim 1, characterized in that: The collecting of strain data of the optical fiber and reconstructing the three-dimensional shape of the optical fiber using the strain data specifically includes: Strain data at each point of the optical fiber is collected using phase-sensitive optical time-domain reflectometry, the strain data is subjected to sliding average processing or wavelet filtering to obtain denoised strain data, and the thermal expansion effect of the denoised strain data is eliminated using a temperature-strain decoupling algorithm to obtain 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, and the tangent direction angle change value is integrated in three dimensions to obtain the three-dimensional morphological coordinates of the optical fiber, wherein the three-dimensional morphological coordinates are used to describe the actual shape of the optical fiber.

6. The underwater target positioning method based on dynamic error suppression according to claim 5, characterized in that: The performing B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the sound wave propagation path, obtaining a second time difference based on the actual curvature radius, and correcting the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target specifically includes: generating an initial B-spline curve according to 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 error of the curvature, adjusting the control points and the node vectors of the initial B-spline, and performing iterative optimization using the Levenberg-Marquardt algorithm until the error of the curvature is less than a preset threshold, thereby obtaining the actual curvature of the sound wave propagation path; Calculating a changed length of the optical fiber according to the actual radius of curvature, the original length of the optical fiber, and the fiber cross-sectional radius of the optical fiber, and obtaining a second time difference according to the changed length; According to the second time difference, combined with the sound speed profile SVP model, the optical cable deformation at the first precise position is iteratively optimized to obtain the second precise position of the underwater target.

7. The underwater target positioning method based on dynamic error suppression according to claim 1, characterized in that: Mapping the final precise position to a geographic coordinate system for coordinate conversion to obtain the real coordinates of the underwater target specifically includes: When laying the optical fiber, key points are calibrated by GPS or RTK technology, and the WGS-84 coordinates of the key points of the optical fiber are pre-calibrated, wherein the key points of the optical fiber include the optical fiber starting point, the optical fiber turning point and the optical fiber end point; According to the WGS-84 coordinates of the key points of the optical fiber, a mapping model is constructed by linear interpolation and B-spline curve fitting; The final precise position is mapped to the mapping model to perform coordinate conversion, and the real coordinates of the underwater target are output.

8. An underwater target positioning system based on dynamic error suppression, characterized in that: The underwater target positioning system based on dynamic error suppression includes: A data acquisition and processing module is used to obtain an initial vibration signal of an underwater target, and pre-process the initial vibration signal to obtain a target vibration signal; a phase distortion correction module, configured to perform preliminary positioning on 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 a first precise position of the underwater target; an optical cable deformation correction module, configured to collect strain data of the optical fiber, reconstruct a three-dimensional shape of the optical fiber using the strain data, perform B-spline curve fitting optimization on the three-dimensional shape to obtain an actual curvature radius of the acoustic wave propagation path, obtain a second time difference based on the actual curvature radius, and correct the optical cable deformation at the first precise position based on the second time difference to obtain a second precise position of the underwater target; an acoustic path difference dynamic compensation module, configured to dynamically compensate the acoustic path difference according to the second time difference to obtain a corrected acoustic path difference, and obtain a final accurate position of the underwater target according to the corrected acoustic path difference; The coordinate conversion and display module is used to map the final precise position to a geographic coordinate system for coordinate conversion, obtain the real coordinates of the underwater target, and visualize the real coordinates.

9. A terminal, characterized in that: The terminal includes: a memory, a processor, and an underwater target positioning program based on dynamic error suppression stored in the memory and runnable on the processor. When the underwater target positioning program based on dynamic error suppression is executed by the processor, the steps of the underwater target positioning method based on dynamic error suppression as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores an underwater target positioning program based on dynamic error suppression, and when the underwater target positioning program based on dynamic error suppression is executed by the processor, the steps of the underwater target positioning method based on dynamic error suppression according to any one of claims 1 to 7 are implemented.

Images