Concave surface structure forward-looking sonar image rapid generation method based on time domain model, electronic equipment and program product
Through the rapid generation method of concave structure forward-view sonar image based on time domain model, the problem of difficult to quickly and accurately generate concave structure images in the prior art is solved, high-quality and real-time image generation is achieved, and the physics of sound images is improved Reality and consistency.
Patent Information
- Application Number
- CN202411525251.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-02-07
AI Technical Summary
The prior art is difficult to quickly and accurately generate forward-view sonar images of concave structures, especially when multiple scattering and high-frequency broadband time domain echoes are considered. The traditional method has low computational efficiency and is difficult to reflect the physics of underwater targets. feature.
The rapid generation method of foreview sonar images of concave structures based on time domain model is adopted. By establishing a grid model of concave structures and a multiple scattering time domain iterative physical acoustic model, combined with the working principle of foreview sonar, it is generated using equivalent imaging method. image.
It quickly and accurately simulates the physical characteristics of multiple scattering caused by concave structures, improves the physical reality of the acoustic images, ensures the high consistency between the generated images and the measured data in physical features, and simplifies the sonar image generation process.
Smart Images
Figure CN119395670A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of underwater acoustic detection, and particularly relates to a method for quickly generating a forward-looking sonar image of a concave structure based on a time domain model, an electronic device and a program product. Background Art
[0002] As a core equipment in the fields of ocean exploration, deep sea development and marine defense, forward-looking sonar has a particularly remarkable long-range detection capability and can provide high-resolution acoustic images even in turbid water. However, for acoustic research, if experiments and data collection must be carried out on lakes or large anechoic pools, the operation cost is too high and the time is too long. In addition, forward-looking sonar may have difficulty in obtaining test data of non-cooperative targets. This situation has greatly restricted the further development and application of sonar technology. Summary of the invention
[0003] One of the embodiments of the present disclosure is a method for quickly generating a forward-looking sonar image of a concave structure based on a time domain model, comprising the steps of:
[0004] Step 1, establishing a grid model of the concave structure of the detection target;
[0005] Step 2, establishing a multiple scattering time-domain iterative physical acoustic model;
[0006] Step 3: Generate a forward-looking sonar image of the concave structure of the detection target using an equivalent imaging method.
[0007] Furthermore, the step 1 includes constructing a geometric model of the concave structure, and meshing the surface of the structure so that the surface of the structure is discretized into N face elements.
[0008] Furthermore, the step 2 includes calculating the time domain echo of each facet of the concave structure through the multiple scattering time domain iterative physical acoustic model.
[0009] Furthermore, step 3 includes generating a forward-looking sonar image of a concave structure by using an equivalent imaging method, and the process includes: setting forward-looking sonar working parameters, receiving time domain echoes of each surface element in a narrow beam, transforming to a range direction, compensating for time-varying gain, adding noise, and rendering an acoustic image. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:
[0011] Figure 1A flow chart of a method for rapidly generating forward-looking sonar images of concave structures based on a time domain model according to one embodiment of the present invention.
[0012] Figure 2 A schematic diagram of a concave structure model according to one embodiment of the present invention,
[0013] in, Figure 2 -a is the geometric model, Figure 2 -b is the mesh model.
[0014] Figure 3 Schematic diagram of multiple acoustic scattering of the m-th surface element and the n-th surface element according to one embodiment of the present invention.
[0015] Figure 4 A schematic diagram of multiple acoustic scattering of the mth plane element and the nth plane element according to one embodiment of the present invention,
[0016] in, Figure 4 -a is a wide beam transmitting sound source, Figure 4 -b is narrow beam reception.
[0017] Figure 5 Flow chart of forward-looking sonar image simulation of concave structure based on time-domain iterative physical acoustics according to one embodiment of the present invention
[0018] Figure 6 Schematic diagram of simulation results of five typical target forward-looking sonar images according to one embodiment of the present invention. Figure 7 A schematic diagram showing a comparison between a forward-looking sonar image simulation and a test result of a typical concave structure according to one embodiment of the present invention,
[0019] in, Figure 7 -a is a photo of a concave structure, Figure 7 -b is the simulation result, Figure 7 -c is the test result. DETAILED DESCRIPTION
[0020] In view of the technical difficulties mentioned above, in order to accelerate the research progress in the field of acoustic technology, it is urgent and important to build an accurate and efficient forward-looking sonar image generation model. This model can not only play a vital role in the research and development of sonar systems, but also provide a large amount of labeled training data for image classification, target recognition and reconstruction assisted by deep learning.
[0021] Considering the sonar imaging model based on rasterization rendering technology, although it can generate visually realistic sonar images, it is difficult to reflect the physical characteristics of real underwater targets, such as coherent speckle noise caused by scattered echo interference, and multiple scattered bright spots caused by concave structures. In addition, when considering the working mode of the forward-looking sonar system emitting high-frequency broadband transient signals, the traditional sonar image generation method based on the frequency domain model requires point-by-point frequency scanning, which has low computational efficiency. Therefore, the present disclosure proposes a method for quickly generating forward-looking sonar images based on time domain model construction and applicable to concave structures, so as to accurately and quickly simulate the multiple scattering physical characteristics caused by concave structures and enhance the physical realism of acoustic images.
[0022] The present disclosure proposes a time-domain iterative physical acoustic model based on Kirchhoff approximation, which can accurately and quickly calculate the high-frequency broadband time-domain echo of the concave structure taking into account the multiple scattering effect by iteratively solving the Helmholtz surface integral equation. The present disclosure combines the model with the working principle of the forward-looking sonar, and adopts an equivalent imaging method to achieve real-time, high-quality generation of forward-looking sonar images. The method proposed in the present disclosure not only ensures a high degree of consistency in physical characteristics between the generated image and the measured data, but also greatly simplifies the sonar image generation process, providing strong data support for research and application in the fields of ocean exploration and underwater target recognition.
[0023] According to one or more embodiments, a method for quickly generating a forward-looking sonar image of a concave structure based on a time domain model includes three parts:
[0024] The first is the preprocessing process, which is to establish a concave structure mesh model;
[0025] The second is to establish a time-domain iterative physical acoustic model that takes into account multiple scattering effects, and use this method to calculate the time-domain echo of each facet of the concave structure;
[0026] Third, combining the working principle of forward-looking sonar, an equivalent imaging method is used to generate forward-looking sonar images of concave structures.
[0027] Combining the above schemes, a method for quickly generating forward-looking sonar images based on a time domain model and applicable to concave structures can be established, such as Figure 1 shown.
[0028] The preprocessing process includes: constructing a concave structure geometric model; dividing the grid and discretizing the structure surface into N face elements.
[0029] The solution process of the time-domain iterative physical acoustic method includes: calculating the time-domain echo of multiple scattering of each facet;
[0030] The forward-looking sonar image simulation process includes: setting forward-looking sonar working parameters, receiving time-domain echoes of each narrow beam element, transforming to range direction, compensating time-varying gain, adding noise, and rendering acoustic images.
[0031] The specific steps are as follows.
[0032] 1. Preprocessing process.
[0033] The concave structure geometric model is constructed using modeling software, and then the structure surface is meshed, where the mesh size is no larger than one-sixth of the wavelength corresponding to the maximum calculation frequency, and the structure surface S is meshed into N triangular face elements ΔS n (n=1,2,…,N). Figure 2 It is the geometric model and mesh model of the concave structure.
[0034] 2. Time domain iterative physical acoustic model.
[0035] like Figure 3 As shown, taking the mth and nth bins as examples, the time domain echo of multiple scattering between bins is calculated, C m and C n are the geometric centers of the mth and nth face elements, respectively, and their radius vectors are r cm and r cn ; F m and F n They are arbitrary points on the mth and nth surface elements, and their radius vectors are r m and r n . Thus we have:
[0036] R An =r A -r cn ,R An =|R An |,
[0037] R Bn =r B -r cn ,R Bn =|R Bn |,
[0038] σ n =r n -r cn (1c)
[0039] R nm =r cn -r cm ,R nm =|R nm |,
[0040] Among them, R An Represents the geometric center r of the nth face element cn and the sound source position r A The vector between |R An | is R An The modulus value, YesR An The unit vector of R Bn Represents the geometric center r of the nth face element cn With the field point position r B The vector between |R Bn | is R Bn The modulus value, YesR Bn The unit vector of n is the radius vector r of any point on the nth surface element n and the geometric center r of the nth face element cn The vector between nm Represents the geometric center r of the nth face element cn and the geometric center r of the mth face element c m, |R nm | is R nm The modulus value, YesR nm The formula (1) is also valid for the mth panel, just replace the subscript "n" with "m".
[0041] For the direct acoustic scattering of the nth surface element, the first-order time domain echo of the nth surface element at field point B is
[0042]
[0043] in, represents the convolution operation, S i (t) is the time domain signal of the incident sound wave, c is the speed of sound in water, is the unit external normal vector of the nth face element, J Bn is the time domain radiation function.
[0044] For the coupled acoustic scattering between the nth and mth face elements, the qth (q≥2)th order time domain echo of the nth face element at field point B is:
[0045]
[0046] in, is the (q-1)th order time domain echo of the mth bin, is the unit external normal vector of the mth face element, J nm is the time domain coupling function.
[0047] The Q-order scattered time domain echo of the nth plane element is coherently superimposed to obtain the total scattered time domain echo of the nth plane element at field point B.
[0048]
[0049] 3. Forward-looking sonar image simulation model.
[0050] The forward-looking sonar is located at the bow of the carrier platform and is the main equipment used for mine hunting detection. Its transducer generally includes a wide-beam transmitting sound source and a narrow-beam receiving array. Figure 4 The geometric diagram of the forward-looking sonar transmitting and receiving beams is given, where θ max is the horizontal opening angle of the receiving beam, [Rmax min ] is the detection range, M θ is the number of receive beams.
[0051] The time-domain iterative physical acoustic model is combined with the working principle of forward-looking sonar, and the forward-looking sonar image of the concave structure is generated by using an equivalent imaging method. The process is as follows: Figure 5 shown.
[0052] First, according to the forward-looking sonar parameters (receiving shaped beam horizontal opening angle, detection range, number of receiving beams, etc.), the time domain iterative physical acoustic model is used to calculate the time domain echo of each facet in the receiving narrow beam, that is,
[0053]
[0054] Among them, N θ is the number of elements in the receiving narrow beam.
[0055] Then, by distance-time conversion Transform it to the distance direction, that is
[0056] P scat,n (θ n ,t)=P scat,n (θ n ,R), (7)
[0057] Compensation for time-varying gain
[0058]
[0059] Adding Noise
[0060]
[0061] Among them, Y scat,n (θ n ,R) is the additive noise signal.
[0062] Finally, the time domain echoes of the bins in each narrow beam are stitched and rendered in sequence according to the order of the receiving sub-beams to generate the forward-looking sonar image.
[0063] Figure 5 The narrow beam facet time domain echo simulation technology solution based on time domain iterative physical acoustics is shown. A part of the figure shows the basic concept of narrow beam facet time domain echo. Through the forward-looking sonar and grid model, the propagation and reflection of sound waves in the medium can be simulated to generate time domain echo signals. The time domain echo is obtained by coherently superimposing the echoes of the facets in the beam at different time points. The figure shows the echo signals at three different time points (First, Second, Third) and their sum (Total).
[0064] Figure 5 The first part describes the conversion process from time domain echo signal to sonar image. First, by rendering the acoustic image, the propagation of sound waves at different angles and distances is simulated. Then, by adding noise, the noise interference in actual sonar detection is simulated. Then, by compensating the time-varying gain, the signal strength is adjusted to simulate the change in target echo intensity at different distances. Finally, by transforming to the range direction, the time domain signal is converted into a range-time (Rt) domain signal to generate a sonar image.
[0065] Figure 5 The part of the figure shows the corresponding acoustic images at different stages. These images show the distribution of the sound wave at different propagation stages, from left to right: initial sound wave propagation, reflection after the sound wave encounters the target, the sound wave continues to propagate and is finally received by the receiver, and the final output acoustic image is obtained after the above processing.
[0066] In order to verify the model proposed in the present disclosure, the following example is given.
[0067] Example 1: The forward-looking sonar images of five typical targets are generated using the method proposed in the present disclosure. The targets are a truncated cone, a cylinder, a sphere, a dihedral corner reflector, and a semi-cylindrical concave reflector. Figure 6 It can be seen that the disclosed method is not only applicable to the acoustic image simulation of convex structures (such as truncated cones, cylinders, and spheres), but also to concave structures (such as dihedral corner reflectors and semi-cylindrical concave reflectors), which verifies the wide applicability and high flexibility of the disclosed method.
[0068] Example 2, for a typical concave structure - a semi-cylindrical concave reflector, the forward-looking sonar image is generated using the method proposed in the present disclosure and compared with the experimental measured results, as shown in FIG. Figure 7 It can be seen that the test results are consistent with the simulation results. Not only can the first-order scattering bright spots consistent with the outer contour be observed, but also the high-order scattering features beyond the outer contour can be accurately restored, which verifies the accuracy of the disclosed method.
[0069] In summary, the present disclosure realizes the conversion from time domain echo signals to sonar images by simulating the propagation and reflection of sound waves in a medium and subsequent signal processing steps.
[0070] Therefore, the beneficial effects of the present disclosure include: the method of the present disclosure can generate forward-looking sonar images suitable for concave structures in real time and with high quality, which can not only accurately characterize the multiple scattering effects of incident sound waves on the surface of the concave structure, ensuring the high consistency of the generated image with the measured data in physical characteristics, but also greatly simplifies the forward-looking sonar image simulation process, providing data support for research and application in the fields of ocean exploration, underwater target recognition, etc.
[0071] It should be understood that in the embodiments of the present invention, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.
[0072] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.
[0073] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.
[0074] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.
Claims
1. A method for generating a forward-looking sonar image, wherein the detection target of the forward-looking sonar has a concave structure, characterized in that: The following steps are involved: Step 1, establishing a grid model of the concave structure of the detection target; Step 2, establishing a multiple scattering time-domain iterative physical acoustic model; Step 3: Generate a forward-looking sonar image of the concave structure of the detection target using an equivalent imaging method.
2. The method according to claim 1, characterized in that The step 1 includes constructing a geometric model of the concave structure and meshing the surface of the structure so that the surface of the structure is discretized into N face elements.
3. The method according to claim 1, characterized in that The step 2 includes calculating the time domain echo of each facet of the concave structure by using the multiple scattering time domain iterative physical acoustic model.
4. The method according to claim 1, characterized in that: The step 3 includes generating a forward-looking sonar image of a concave structure by using an equivalent imaging method, and the process includes: setting forward-looking sonar working parameters, receiving time domain echoes of each facet in a narrow beam, transforming to a range direction, compensating for time-varying gain, adding noise, and rendering an acoustic image.
5. The method according to claim 2, characterized in that: In step 1, after constructing the geometric model of the concave structure, the surface of the concave structure is meshed, wherein: The grid size is no larger than one sixth of the wavelength corresponding to the maximum calculation frequency, and the concave surface S is divided into N triangular facets ΔS n , where n = 1, 2,…, N.
6. The method according to claim 5, characterized in that The total scattered time domain echo of the nth bin at any field point is the coherent superposition of the Q-order scattered time domain echoes, that is, 7. The method according to claim 1, characterized in that The detection target of the forward-looking sonar has a convex structure.
8. The method according to claim 1, characterized in that The detection target includes a dihedral corner reflector or a semi-cylindrical concave reflector.
9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: The processor runs the computer program to implement the method according to any one of claims 1 to 8.
10. A computer program product, comprising a computer program, characterized in that The computer program is executed by a processor to implement the method according to any one of claims 1 to 8.