A method for three-dimensional positioning of a target in a direct sound zone based on a deep-sea seabed double-horizontal array

Abstract

This invention belongs to the fields of underwater acoustic detection, underwater acoustic positioning, and sonar technology, and relates to a three-dimensional positioning method for targets in a direct sound zone based on a dual-horizontal array on the deep seabed. To solve the problem of three-dimensional positioning of near-surface moving line spectrum sound sources within a direct sound zone using a dual-horizontal array on the deep seabed, this invention obtains target azimuth estimation through beamforming of the dual-horizontal array; targets are estimated by tracking the maximum output power of the dual-horizontal array beams and the tracking azimuth angle; the estimated target distance, the preset sound source depth, and marine environmental parameters measured in actual marine experiments are input into a ray model to obtain the time delay difference between the direct path and the first reflection path from the sea surface, and a copy sound pressure field is constructed; finally, a depth estimation fusion ambiguity function for the dual-horizontal array is established, and its maximum value is the target depth. This invention is applicable to scenarios where the two horizontal arrays have arbitrary array configurations.

Description

Technical Field

[0001] This invention belongs to the fields of underwater acoustic detection, underwater acoustic positioning, and sonar technology, and relates to a three-dimensional positioning method for direct acoustic targets based on a dual-horizontal array on the deep seabed. Background Technology

[0002] With the proposal of my country's maritime power strategy, the importance of deep-sea maritime security has become increasingly prominent. Deploying multiple passive sonar nodes on the deep seabed to achieve large-area underwater early warning and detection is currently one of the important directions in underwater acoustic detection. Seabed horizontal arrays are located on the seabed, offering good concealment. Information is transmitted via cable, allowing for long-term, continuous monitoring of specific sea areas. Once deployed, they can operate continuously without the need for retrieval. Furthermore, the seabed working environment is quiet, with low marine environmental noise, and unaffected by adverse sea conditions. Three-dimensional positioning of underwater targets, namely target bearing, distance, and depth estimation, is a crucial function of sonar. Acquiring target depth information is one of the key criteria for identifying surface and underwater targets, and has always been a key and challenging problem in the field of underwater acoustic detection.

[0003] In the deep-sea direct-access acoustic zone (usually referring to sea areas where the horizontal distance between the sound source and the receiving array is within 5 times the sea depth), the sound field excited by underwater sound sources near the sea surface typically exhibits a regular interference pattern of alternating bright and dark areas. This pattern is closely related to parameters such as the distance to the sound source, depth, and frequency. Therefore, in recent years, sound field interference structures in the deep-sea direct-access acoustic zone have been used to solve the difficult problem of underwater sound source depth estimation. Currently, target depth is mainly studied using acoustic signals acquired by synchronous or asynchronous vertical arrays or single-vector hydrophones. The main methods include matched-field localization, multipath delay, and interference fringe matching. The matched-field localization method requires the array aperture to be comparable to the sea depth, resulting in very high costs and computational demands. It is also sensitive to mismatches in marine environmental parameters, making practical application difficult.

[0004] The multipath delay method requires a sufficiently large number of identifiable multipaths. The multipath delays are then matched with model calculations under different assumed target depths to estimate the target depth. When only one multipath can be extracted, target depth estimation is impossible. For example, Chinese patent application CN 106707240 A, "A Deep-Sea Sound Source Depth Estimation Method Based on Multipath Delay" (publication date: 2017-05-24), uses a vertical hydrophone array to cross-correlate received signals and extracts the delays between four sound paths: seabed reflection, sea surface-seabed reflection, seabed-sea surface reflection, and sea surface-seabed-sea surface reflection, to passively locate the sound source. However, when the sound source's radiation level is low, the energy of multiple reflection paths from the sea surface and seabed is very weak, making it difficult for the array to extract such multipath signals. Furthermore, the delay resolution of this method is proportional to the bandwidth of the sound source; for targets with narrow signal bandwidth or line spectrum targets, this method cannot estimate small multipath delays and may even fail.

[0005] Because the interference between the direct wave from a near-surface target and the reflected wave from the sea surface forms a Lloyd's mirror interference phenomenon, a receiving hydrophone near the seabed can observe alternating strong and weak interference fringes on a time-frequency chart. The period and structure of these interference fringes are closely related to parameters such as the distance and depth of the sound source. Therefore, the interference fringe matching method typically requires using a vertical array with a vertical aperture or a vector hydrophone and array to estimate the target elevation angle, thereby obtaining the target distance, and then combining this with the Lloyd's mirror interference phenomenon to estimate the target depth. For example, Chinese invention patents "A Deep-Sea Broadband Target Depth Estimation Method Based on Fringe Interference Structure" (ZL201711452031.0) and "A Long-Term Cumulative Estimation Method for the Depth of Weak Multi-Targets in Deep Sea" (ZL201811578134.6) use vertical linear arrays placed near the seabed to estimate the target distance and extract the broadband interference fringe structure. They then use a sound field model to simulate the interference fringe structure at different sound source depths and construct a cost function to estimate the sound source depth. Currently, this type of method has not been applied to target estimation using dual seabed horizontal arrays in deep sea. Summary of the Invention

[0006] To address the problem of three-dimensional localization of near-surface motion spectrum sound sources within a direct sound range using dual-horizontal arrays on the deep seabed, this invention obtains target azimuth estimation through beamforming of the dual-horizontal arrays. Target distance is estimated by tracking the maximum output power of the dual-horizontal array beams and the tracking azimuth angle. The estimated target distance, the preset sound source depth, and marine environmental parameters measured in actual marine experiments are input into a ray model to obtain the time delay difference between the direct path and the first reflection path from the sea surface, thus constructing a copied sound pressure field. Finally, a depth estimation fuzzy function for the dual-horizontal arrays is established, and its maximum value represents the target depth. This invention is applicable to scenarios where the two horizontal arrays have arbitrary configurations.

[0007] The specific steps of this method are as follows:

[0008] Step 1: Establish a coordinate system for the dual horizontal arrays and moving sound sources deployed on the deep seabed.

[0009] Let the first element of array 1 in the double horizontal array be the origin, and establish a rectangular coordinate system with the northeast direction as the coordinate axis. The number of elements in the two horizontal arrays are M1 and M2, respectively. The center coordinates of the m-th element in the n-th array are χ... nm =[x nm ,y nm [H] T (n = 1, 2; m = 1, 2, ..., M) n), where the superscript T indicates transpose of the vector; H is the known sea depth, which can usually be obtained through actual measurement during array deployment or from nautical charts. This invention does not require the array shape of each horizontal array and is applicable to scenarios where each horizontal array is a linear array or an arbitrary area array.

[0010] Assume the sound source is near the sea surface at a depth of z. s The frequency of the line spectrum signal emitted by the sound source is constant throughout the observation process. The real-time coordinate at time t is γ. s (t)=[x s (t),y s (t),z s ] T , where x s (t) represents the x-coordinate of the sound source at time t, y s (t) represents the ordinate of the sound source at time t. Since the depth of the sound source is constant, z s It does not change over time. At this moment, the horizontal propagation distance R from the moving sound source to the m-th element of the n-th array is... nm (t) is calculated as Since the deep-sea direct sound zone refers to the area where the horizontal distance between the sound source and the array is 5 times the sea depth, in order to ensure the effective implementation of the method of this invention, the distance between the sound source and the two arrays should not exceed 5 times the sea depth when using this method.

[0011] Step 2: Use the spectral signal of the nth array to perform conventional beamforming processing to obtain the beam energy B of the nth array at frequency ω as a function of time and guide angle. n (θ,t):

[0012]

[0013] in P represents the spectral signal of the nth array, where ω = 2πf is the source frequency in radians per second; nm (ω,t) represents the spectral signal of the m-th element of the n-th array, obtained by performing a Fourier transform on the time-domain signal directly measured from the array; steering vector θ is the steering angle; k = ω / c, where c is the speed of sound at the array depth in the seawater.

[0014] Step 3: The beam energy B of the nth array in the dual horizontal array. n The angle corresponding to the peak beam energy at each time t in (θ,t) is extracted as the target azimuth angle θ. sn (t), and further record all beam energy peaks as the target beam energy sequence B. n (θ sn (t),t).

[0015] Step 4: Using θ sn (t) estimates the distance of the moving sound source relative to each array first element.

[0016] Using the first element of array 1 in the double horizontal array as the reference position, the horizontal coordinates of the target can be calculated using the geometric relationship between the double horizontal array and the target's orientation.

[0017]

[0018] in It is a 2×2 dimensional matrix; It is a 2×1 dimensional column vector; pinv represents the pseudo-inverse of the matrix.

[0019] Therefore, the estimated horizontal propagation distance of the moving sound source relative to the nth array first element can be obtained as follows:

[0020]

[0021] However, this estimated horizontal propagation distance only considers the distance between the moving sound source and the first element of the nth array after the projection onto the plane. In reality, since the moving sound source and the first element of the nth array are not at the same depth, the distance between the moving sound source and the first element of the nth array should also take into account the influence of the sea depth H. Therefore, the distance between the moving sound source and each array first element can be calculated by the following formula (Reference: Yanqun Wu, et al. Directional response of a horizontal linear array to an acoustic source at close range in deepwater. Acoustics Australia, 2021, DOI:10.1007 / s40857-021-00250-5):

[0022]

[0023] Step 5: Let the preset depth of the sound source be z, and use the estimated distance R' obtained in Step 4. 11 (t), R' 21 (t) The copy field sound pressure signal at the preset depth is obtained by calculation.

[0024] Let the preset depth of the sound source be z, and let the estimated horizontal distance R' of the moving sound source relative to the nth array first element be... n1(t) and marine environmental parameters (including sound velocity profile and seabed sediment parameters) obtained from actual marine experiments are input into the Bellhop ray model (reference: MBPorter. The BELLHOP Manual and User's Guide: Preliminary Draft. 2011. Available online: http: / / oalib.hlsresearch.com / Rays / HLS-2010-1.pdf.), to calculate the time it takes for the sound signal emitted by the moving sound source at the preset depth to reach the array's first element through the direct path and the first reflection path from the sea surface. and Where n = 1, 2. Typically, underwater vehicles travel at depths not exceeding 200m. Therefore, to reduce computational load, the traversal range of the target depth z is preset to 0m to 200m.

[0025] This invention utilizes the multipath time delay difference between the direct path and the sea surface path to construct a copy field sound pressure signal Λ at a preset depth z of the sound source. replic,n (z,t) is used to reduce computational complexity, and the algorithm's robustness is improved by utilizing the insensitivity of this time delay difference to seabed sediment parameters.

[0026]

[0027] Step 6: Traverse all possible preset depths z of the sound sources, calculate the fusion ambiguity function C(z) of the two arrays, and take the preset depth z of the sound source where the function value is maximum as the estimated depth of the target.

[0028] Define a two-array fusion ambiguity function C(z), and find the optimal target depth that simultaneously matches the time series of energy peaks from both arrays.

[0029] C(z)=C1(z)C2(z)

[0030] in The depth corresponding to the maximum value of the ambiguity fusion function C(z) is the estimated depth of the target.

[0031] Thus, steps 3, 4, and 6 have yielded the target azimuth angle θ. sn (t), distance R' n1 (t) and depth This constitutes the three-dimensional positioning result of the target.

[0032] Beneficial effects

[0033] This invention proposes a method for three-dimensional localization (i.e., estimation of target azimuth, distance, and depth) of a near-surface moving line spectrum sound source within a direct-access acoustic zone using a dual-horizontal array on the deep-sea seabed. This technique is implemented in two steps: First, the target azimuth is estimated using the dual-horizontal array, followed by target cross-range measurement to obtain the target distance; second, a copy sound pressure signal is constructed using the multipath delay difference between the direct path and the sea surface path, and the target depth is estimated based on the dual-array fusion ambiguity function of interferometric fringe matching. This method utilizes two small-aperture seabed horizontal arrays for monitoring the sea area, eliminating the need for a large-aperture seabed horizontal array to estimate the depth of the line spectrum sound source, resulting in low cost and ease of engineering implementation. Typically, obtaining seabed sediment parameters is very costly, especially in deep-sea marine engineering where implementation is difficult and expensive. This invention utilizes the multipath delay difference between the direct path and the sea surface path to construct a copy field, which not only requires less computation but also exhibits good robustness to seabed acoustic parameter mismatches because the multipath delay difference is insensitive to seabed acoustic parameter information, thus demonstrating high feasibility for marine experimental verification. This invention is applicable to dual horizontal arrays deployed on the seabed in any formation. With appropriate modifications at the ranging and positioning fusion point, it can be extended to scenarios where multiple horizontal arrays are used for target depth estimation. Because seabed horizontal arrays are well-concealed and easy to deploy, they can provide long-term, continuous monitoring of specific sea areas. Combined with this invention, it can support the positioning of surface and underwater targets using such equipment. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the working environment of the deep-sea seabed dual-horizontal array. (a) Schematic diagram of the geometric relationship between the deep-sea seabed dual-horizontal array and the moving sound source; (b) Sound velocity profile used in the simulation.

[0035] Figure 2 This is a top view of the simulation coordinate system used in the embodiment, including the coordinates of the dual horizontal arrays on the seabed and the trajectory coordinates of the moving sound source. Arrays 1 and 2 are located on the x-axis, and the first primitives of arrays 1 and 2 are [0,0] respectively. T and [1000,0] T The trajectory of the moving sound source relative to the array moves from far to near and then back to a distance.

[0036] Figure 3 This is an azimuth history diagram obtained after beamforming of array 1 in the embodiment. The horizontal axis in the diagram is the azimuth angle, and the vertical axis is time. Figures (a) and (b) show the results obtained at target depths of 10m and 80m, respectively.

[0037] Figure 4 The present invention integrates ambiguity functions in two cases: when the actual target depth is 10m (dashed line) and 80m (solid line). The maximum value of the ambiguity function in the figure is the estimated target depth, and the pentagram and square markers represent the actual target depth. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments and accompanying drawings. Through these descriptions, the features and advantages of the present invention will become clearer. However, it should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0039] This invention proposes a method for estimating the depth of deep-sea targets in a direct acoustic zone based on dual horizontal arrays. The method is characterized by utilizing two synchronous horizontal arrays deployed on the seabed to receive single-frequency signals radiated by moving targets near the sea surface, and then estimating their azimuth, range, and depth. The specific steps are as follows:

[0040] Step 1: Establish a coordinate system for the dual horizontal arrays and moving sound sources deployed on the deep seabed.

[0041] To illustrate the method of the present invention, the embodiments are provided. Figure 1 A schematic diagram of the working environment for locating moving sound sources using two horizontal arrays on the deep seabed is given, in which... Figure 1 (a) Schematic diagram of the geometric relationship between two horizontal arrays on the seabed in the deep sea and the moving sound source. Figure 1 (b) The sound velocity profile used in the simulation is given. Although this invention is applicable to scenarios where each horizontal array is a linear array or an arbitrary surface array, the embodiment provides a uniform linear array that is easy to deploy at sea. That is, it is assumed that the two horizontal arrays deployed on the deep seabed are uniform linear arrays with the number of elements M1 = M2 = 16 and the element spacing d = 6.25m; the horizontal distance between the heads of the two horizontal arrays is r0 = 1000m; the sea depth for array deployment is H = 3000m, and the seabed is flat. Let the first element of array 1 in the double horizontal array be the origin of the coordinate system, and establish a rectangular coordinate system with the northeast direction, as follows. Figure 2 As shown. Arrays 1 and 2 are located on the x-axis, and the coordinates of their first primitives are [0,0] respectively. T and [1000,0] T Then the coordinates of the m-th primitive in arrays 1 and 2 are respectively

[0042] χ 1m =[(m-1)d,0,H] T (m = 1, 2, ..., 16)

[0043] χ 2m =[r0+(m-1)d,0,H] T (m = 1, 2, ..., 16)

[0044] Assume the sound source is near the sea surface at a depth of z. sThe depth remained constant throughout the observation process. To illustrate this method, the sound source depth was set to 10m and 80m, representing surface ships and underwater vehicles, respectively. The line spectrum signal radiated by the sound source was a single-frequency signal with a frequency of f = 120Hz, and its trajectory projected onto the horizontal plane is shown below. Figure 2 As shown. The moving sound source moves from farthest to nearer and then further away from arrays 1 and 2, maintaining a speed of 5 m / s, with an observation time of T = 50 minutes. At this time, according to the horizontal propagation distance calculation formula, the closest distance of the sound source to the first element of array 1 is 1.1 km, and the farthest distance is 14.8 km. Since the deep-sea direct sound zone refers to the area where the horizontal distance between the sound source and the array is 5 times the sea depth, to ensure the effective implementation of the method of this invention, when the sea depth H = 3000 m, the distance between the sound source and the two arrays should not exceed 15 km.

[0045] Step 2: Use the spectral signal of the nth array to perform conventional beamforming processing to obtain the beam energy B of the nth array at frequency ω as a function of time and guide angle. n (θ,t):

[0046]

[0047] Where P n (ω,t)=[P n1 (ω,t),P n2 (ω,t),...,P n16 (ω,t)] T (n=1,2) represents the spectral signal of the nth array, ω=2πf is the sound source frequency, and the unit is radians / second; P nm (ω,t) represents the spectral signal of the m-th element in the n-th array, obtained by performing a Fourier transform on the time-domain signal directly measured from the array; θ is the steering angle, and the corresponding steering vector is... k = ω / c, where c is the speed of sound at the depth of the array in the seawater.

[0048] In the embodiment, to obtain the sound pressure signal P of the nth array... n (ω,t) is obtained here using the sound field calculation program KrakenC, which provides spectral signals from sound sources with a frequency of 120Hz and depths of 10m and 80m to each element of the two arrays. The ocean acoustic environment parameters used in the simulation are as follows: the sound velocity profile is shown in the figure. Figure 1 As shown in (b); the seabed parameters are a sound speed of 1650 m / s and a density of 1.6 g / cm³. 3 The absorption loss is 0.1 dB / λ, where λ is the wavelength. After obtaining the spectral signal of the dual horizontal arrays, conventional beamforming was performed on arrays 1 and 2 respectively, and the beam energy variation with time and guide angle was obtained as shown in graphs B1(θ,t) and B2(θ,t). Figure 3 (a) and Figure 3 (b) Beam energy diagrams B1(θ,t) of the array at target depths of 10m and 80m, respectively. The horizontal axis represents the azimuth angle, and the vertical axis represents time. The results for array 2 are similar.

[0049] Step 3: The beam energy B of the nth array in the dual horizontal array. n The angle corresponding to the peak beam energy at each time t in (θ,t) is extracted as the target azimuth angle θ. sn (t), and further record all beam energy peaks as the target beam energy sequence B. n (θ sn (t),t).

[0050] In the embodiment, for array 1, at a sound source depth of 10m ( Figure 3 (a)) and 80m ( Figure 3 (b) In both cases, the angle corresponding to the peak beam energy B1(θ,t) of array 1 at each time t is the target azimuth angle θ. s1 (t), where the white solid line represents the angle sequence θ corresponding to the beam energy peak. s1 (t), the peak beam energy at the white solid line is recorded as the target beam energy sequence B1(θ). s1 (t),t). The beam energy results for array 2 are similar, yielding the angle sequence corresponding to the beam energy peak as θ. s2 (t), and record the peak beam energy as the target beam energy sequence B2(θ). s2 (t),t). Comparison Figure 3 (a) and Figure 3 (b) It can be seen that when the sound source depth is 10m, the target beam energy sequence B1(θ) s1 The number of alternating bright and dark stripes corresponding to (t),t) is relatively small. As the sound source depth increases, i.e. at a depth of 80m, the target beam energy sequence B1(θ) s1 The number of interference fringes corresponding to (t),t) increases. Therefore, the structure of the interference fringes is closely related to the target depth. However, the structure of the interference fringes also depends on the horizontal distance between the sound source and the array. The horizontal distance needs to be decoupled before the target depth can be further estimated.

[0051] Step 4: Using θ sn (t) estimates the horizontal distance of the moving sound source relative to each array first element.

[0052] Using the first element of array 1 in the double horizontal array as the reference position, the horizontal coordinates of the target can be calculated using the geometric relationship between the double horizontal array and the target's orientation.

[0053]

[0054] in It is a 2×2 dimensional matrix; It is a 2×1 dimensional column vector; pinv represents the pseudo-inverse of the matrix.

[0055] Therefore, the estimated horizontal propagation distance of the moving sound source relative to the nth array first element can be obtained as follows:

[0056]

[0057] However, this estimated horizontal propagation distance only considers the distance between the moving sound source and the first element of the nth array after the projection onto the plane. In reality, since the moving sound source and the first element of the nth array are not at the same depth, the distance between the moving sound source and the first element of the nth array should also take into account the influence of the sea depth H. Therefore, the distance between the moving sound source and each array first element can be calculated by the following formula (Reference: Yanqun Wu, et al. Directional response of a horizontal linear array to an acoustic source at close range in deepwater. Acoustics Australia, 2021, DOI:10.1007 / s40857-021-00250-5):

[0058]

[0059] In the embodiment, the θ obtained in step 3 is... s1 (t), θ s2 (t) Substituting the values ​​into the target coordinate equation and solving, the estimated distance R' of the sound source relative to the first primitives of the first and second arrays can be calculated. 11 (t), R' 21 (t).

[0060] Step 5: Let the preset depth of the sound source be z, and use the estimated distance R' obtained in Step 4. 11 (t), R' 21 (t) The copy field sound pressure signal at the preset depth is obtained by calculation.

[0061] In this embodiment, it is assumed that the maximum depth of the target does not exceed 200m, and the preset traversal range of the target depth z is set to 1m to 200m, where the depth search interval is 1m. The estimated distance R' calculated in step 4 is then used. 11 (t), R' 21 (t) Substitute into the Bellhop ray model to calculate the arrival time of the target at a preset depth z, including the direct path to the two horizontal arrays and the path of the first reflection from the sea surface. and Where n = 1, 2. Finally, a copy of the sound pressure signal is constructed based on the two arrival delays:

[0062]

[0063] Step 6: Traverse all possible preset depths z of the sound sources, calculate the fusion ambiguity function C(z) of the two arrays, and take the preset depth z of the sound source where the function value is maximum as the estimated depth of the target.

[0064] Define a two-array fusion ambiguity function C(z), and find the optimal target depth that simultaneously matches the time series of energy peaks from both arrays.

[0065] C(z)=C1(z)C2(z)

[0066] in The depth corresponding to the maximum value of the ambiguity fusion function C(z) is the estimated depth of the target.

[0067] In the embodiments, appendix Figure 4 The fusion function C(z) for estimating the ambiguity of depth estimation between two arrays is given for shallow and deep source scenarios. The dashed line corresponds to a target depth of 10m (shallow source), and the solid line corresponds to a target depth of 80m (deep source). The pentagram and square in the figure represent the actual target depths of 10m and 80m, respectively. Figure 4 As can be seen, the maximum values ​​of the fuzzy ambiguity function C(z) point to the true depth of the target, proving the effectiveness of the method of this invention. Thus, steps 3, 4, and 6 have yielded the target azimuth angle θ. sn (t), distance R' n1 (t) and depth This constitutes the three-dimensional positioning result of the target.

[0068] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-dimensional positioning method for targets in a direct acoustic zone based on a dual-horizontal array on the deep seabed, characterized in that, This method consists of the following steps: Step 1: Establish a coordinate system for the dual horizontal arrays and moving sound sources deployed on the deep seabed; Let the first element of array 1 in the double horizontal array be the origin, and establish a rectangular coordinate system with the northeast direction as the origin; the number of elements of the two horizontal arrays are respectively and The center coordinates of the m-th element in the n-th array are respectively , The superscript T indicates that the vector is transposed; H is the known sea depth. Assuming the sound source is near the sea surface, its depth is... The frequency of the line spectrum signal emitted by the sound source remains constant throughout the observation process. The unit is Hz, and the real-time coordinates at time t are: ,in The x-coordinate of the sound source at time t is represented. This represents the ordinate of the sound source at time t; since the depth of the sound source is constant, therefore The horizontal propagation distance of the moving sound source to the m-th element of the n-th array does not change over time. Calculated as ; Step 2: Use the spectral signal of the nth array to perform conventional beamforming processing to obtain the frequency of the nth array. Beam energy varying with time and guide angle : ， in For the spectral signal of the nth array, The frequency of the sound source is expressed in radians per second. The spectral signal of the m-th element in the n-th array is obtained by performing a Fourier transform on the time-domain signal directly measured from the array; steering vector ; For the guide angle; c is the speed of sound at the depth of the array in the seawater; Step 3: Beam energy from the nth array in the dual horizontal array Extract the angle corresponding to the peak beam energy at each time t as the target azimuth angle. Furthermore, all beam energy peaks are recorded as target beam energy sequences. ; Step 4: Utilize The distance of the moving sound source relative to each array first element is estimated; Using the first element of array 1 in the dual horizontal array as the reference position, the horizontal coordinates of the target are calculated using the geometric relationship between the dual horizontal array and the target's orientation. ， in for A 3D matrix; for A column vector of dimension; pinv denotes the pseudo-inverse of a matrix; Therefore, the estimated horizontal propagation distance of the moving sound source relative to the nth array first element is obtained as follows: ， The distance of the moving sound source relative to each array first element is calculated using the following formula: ； Step 5: Let the preset depth of the sound source be z, and use the estimated distance obtained in Step 4. , The copy field sound pressure signal at the preset depth was calculated; Let the preset depth of the sound source be z, and the estimated horizontal distance of the moving sound source relative to the first primitive element of the nth array is... Using the Bellhop ray model and the marine environmental parameters obtained from actual on-site marine experiments, the time it takes for the acoustic signal emitted by the moving sound source at a preset depth to reach the array's first element via the direct path and the first reflection path from the sea surface is calculated. and ; The sound pressure signal of the copy field at a preset depth z is constructed by utilizing the multipath time delay difference between the direct path and the sea surface path. : ； Step 6: Traverse all possible sound sources at the preset depth z and calculate the fusion ambiguity function of the two arrays. The pre-depth z of the sound source at the point where the function value is maximum is taken as the estimated depth of the target. ; Define the ambiguity function for fusing two arrays. To find the optimal target depth that simultaneously matches the time series of energy peaks from two beam arrays, i.e. ， in Fusion ambiguity function The depth corresponding to the maximum value is the estimated depth of the target. T represents the length of the observation period; Thus, steps 3, 4, and 6 have yielded the target azimuth. ,distance and depth This constitutes the three-dimensional positioning result of the target.

2. A three-dimensional positioning method for a direct acoustic zone target based on a deep-sea seabed dual-horizontal array according to claim 1, characterized in that: In step 1, the known sea depth H is obtained either through actual measurement during array deployment or from nautical charts.

3. A three-dimensional positioning method for a direct acoustic zone target based on a deep-sea seabed dual-horizontal array according to claim 1, characterized in that: In step 1, the distance between the sound source and the two arrays should not exceed 5 times the ocean depth.

4. A three-dimensional positioning method for a direct acoustic zone target based on a deep-sea seabed dual-horizontal array according to claim 1, characterized in that: In step 5, in order to reduce the amount of computation, the traversal range of the target depth z is preset to 0m to 200m.

5. A three-dimensional positioning method for a direct acoustic zone target based on a deep-sea seabed dual-horizontal array according to any one of claims 1 to 4, characterized in that: There are no requirements for the formation of each horizontal array, making it suitable for scenarios where each horizontal array is a linear array or an arbitrary area array.

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