A submarine enclosure structure acoustic tomographic image rapid generation method, electronic equipment and program product
By using the acoustic transmission iterative physical acoustic method and acoustic tomography principle, efficient and accurate acoustic tomographic images of underwater hull structures were generated, solving the problems of low efficiency and insufficient accuracy in existing generation methods and improving the detection and identification capabilities of submarines.
Patent Information
- Application Number
- CN202411508116.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2025-12-16
- Estimated Expiration
- 2044-10-28
AI Technical Summary
Existing technologies lack efficient methods for generating acoustic tomography images of shell structures, which cannot meet the future detection needs of underwater targets. Furthermore, traditional methods ignore phase information, resulting in insufficient image accuracy.
By employing the iterative physical acoustic method of sound transmission combined with the principle of acoustic tomography, a geometric model of the submarine's conning tower structure and a model of its reflection/transmission coefficients are established to calculate the scattered sound field and generate acoustic tomographic images.
It enables rapid and accurate generation of acoustic tomography images of underwater hull structures, improving the detection and identification capabilities of submarines and providing information on the geometric scale, structural features, and materials of targets.
Smart Images
Figure CN119720372B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of underwater acoustic engineering technology, and specifically relates to a method for rapidly generating acoustic tomography images of a shell structure, an electronic device, a storage medium, and a program product. Background Technology
[0002] The sail structure is one of the iconic structures of a submarine, serving as the core component of the modern submarine's command center for navigation and observation missions. Unlike other pressure hulls of a submarine filled with air, the sail is a water-filled, acoustically transparent structure. When active sonar is applied to the sail, sound waves can penetrate into the structure, undergoing multiple reflections and transmissions. Accurately understanding the acoustic scattering characteristics of the sail structure is crucial for improving the detection and identification capabilities of active sonar systems for submarines. From a target identification perspective, acoustic tomography can provide increasingly intuitive target information, including not only the target's distance and orientation but also its geometric dimensions, structural features, and material information. However, current research on the fine features of acoustic tomography images resulting from multiple reflections and transmissions in underwater transmission structures is limited, and efficient methods for generating acoustic tomography images of sail structures are lacking, failing to meet future underwater target detection needs. Summary of the Invention
[0003] One embodiment of this disclosure provides a method for rapidly generating acoustic tomographic images of a shell structure based on iterative physical acoustics, the method comprising the following steps:
[0004] Step 1: Preprocessing, establishing the geometric model and reflection / transmission coefficient model of the submarine's conning tower structure;
[0005] Step 2: Calculate the scattered sound field of the submarine conning tower;
[0006] Step 3: Generate an acoustic tomography image of the submarine's sail structure.
[0007] The preprocessing process in step one includes: constructing a three-dimensional model of the submarine's sail structure, including a mesh model of the sail structure, and establishing a geometric model and a reflection / transmission coefficient model of the sail structure.
[0008] In step two, a sound field scattering from the shell structure is calculated using a physical acoustic solution method based on multiple reflections / transmissions and iterative sound transmission.
[0009] The sound-transmitting iterative physical acoustic solution method includes: iteratively calculating the qth-order outer and inner surface potential function using the first-order outer and inner surface potential function of the shell structure, and calculating the scattering potential function at the field point.
[0010] The process of generating the acoustic tomography image in step three includes: obtaining the frequency-angle spectrum of the omnidirectional echo signal of the shell structure, obtaining the two-dimensional spatial spectrum of the shell structure, and generating the acoustic tomography image of the shell structure.
[0011] This disclosure provides a method for rapidly generating acoustic tomographic images of underwater hull structures. By establishing a geometric model and a reflection / transmission coefficient model, the scattered sound field is calculated using an iterative physical acoustic method, and the image is generated based on the principles of acoustic tomography. This method can effectively characterize the multiple reflection / transmission effects of sound waves within the hull structure, improving the detection and identification capabilities of submarines. Attached Figure Description
[0012] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of the invention are illustrated in the drawings by way of example, not limitation, in which:
[0013] Figure 1 Flowchart of a method for generating acoustic tomography images of a shell structure according to one embodiment of the present disclosure.
[0014] Figure 2 A schematic diagram of a standard submarine model sail structure according to one of the embodiments of this disclosure.
[0015] In this diagram, 2-a is a schematic diagram of the 3D model, and 2-b is a schematic diagram of the mesh model.
[0016] Figure 3 A schematic diagram of a partial reflection / transmission model of a shell structure according to one embodiment of the present disclosure.
[0017] Figure 4 An example diagram of the reflectance / transmission coefficient of a shell structure according to one embodiment of this disclosure.
[0018] Wherein, 4-a is the magnitude of the reflection coefficient, 4-b is the phase angle of the reflection coefficient, 4-c is the magnitude of the transmission coefficient, and 4-d is the phase angle of the transmission coefficient.
[0019] Figure 5 A schematic diagram of acoustic scattering of a closed water-filled thin-shell structure according to one embodiment of the present disclosure.
[0020] Figure 6 A schematic diagram of an acoustic tomography model of an underwater shell structure according to one embodiment of the present disclosure.
[0021] Figure 7 A schematic diagram of the time-angle spectrum of the scattered echo from a 1:20 scale model of the shell structure according to one embodiment of the present disclosure.
[0022] Among them, 7-a is the simulation result and 7-b is the experimental result.
[0023] Figure 8 Example diagram of acoustic tomography of a shell structure according to one embodiment of the present disclosure. Detailed Implementation
[0024] Underwater acoustic tomography (ACT) images typically refer to images acquired in underwater environments using sonar technology. It's a technique that utilizes the characteristics of sound waves propagating underwater to detect and image underwater objects. The acquisition process generally involves: emitting sound waves underwater using one or more sound sources (such as sonar transmitters); reflecting, refracting, or scattering the sound waves when they encounter objects of different densities or elasticity; and receiving the reflected or scattered sound waves from an array of hydrophones (underwater microphones). By analyzing information such as the time, intensity, and phase of the received sound waves, algorithms are used to reconstruct an image of the underwater object.
[0025] For acquiring acoustic tomographic images of underwater enclosure structures, existing methods generally rely on Circular Synthetic Aperture Sonar (CSAS) systems for field testing. This system is a side-scan sonar system that utilizes synthetic aperture technology to improve underwater imaging resolution. It is typically mounted on a mobile platform, such as a ship, submarine, or remotely operated vehicle (ROV), and scans the underwater environment as the platform moves in a circular motion. Here, field testing generally refers to testing and measurement work conducted in actual natural or operational environments, as opposed to indoor testing under laboratory conditions. The purpose of field testing is to verify the system's performance in real-world application environments, including its stability, reliability, and accuracy. While this approach can provide detailed acoustic tomographic images, its high requirements for test sites, specialized equipment, specific test models, and experienced personnel significantly increase economic costs and extend the testing cycle.
[0026] Furthermore, while traditional energy superposition models incorporate the equivalent transmission coefficient of the outer shell to account for the scattering effect of the inner surface of the acoustically transparent structure, enabling rapid generation of acoustic tomographic images of such structures, their limitation of ignoring phase information leads to an inability to accurately reconstruct the speckle information of the image. Here, an acoustically transparent structure refers to a structure that has minimal impact on sound wave propagation, allowing sound waves to pass through with almost no loss. The energy superposition model, in acoustic imaging, is a mathematical model used to simulate and calculate the influence of acoustically transparent structures (such as the outer shell of sonar equipment or other sound wave propagation media) on sound wave propagation. This model is primarily used to predict the energy distribution and phase changes of sound waves as they pass through the acoustically transparent structure, thereby generating acoustic tomographic images.
[0027] In view of the aforementioned problems with existing solutions, constructing an efficient and accurate method for generating acoustic tomographic images of underwater hull structures is of great significance for improving submarine acoustic stealth technology. Therefore, this disclosure proposes a method for generating acoustic tomographic images of underwater hull structures. This method combines the iterative physical acoustic method with the principle of acoustic tomography to accurately characterize the multiple reflection / transmission effects of incident sound waves inside the structure in the image domain.
[0028] According to one or more embodiments, a method for rapidly generating acoustic tomographic images of a shell structure based on iterative physical acoustics is provided. This method generally consists of three parts:
[0029] The first part is the preprocessing process, which involves establishing the geometric model of the shell structure and the reflection / transmission coefficient model;
[0030] The second part is to establish a sound transmission iterative physical acoustic method that takes into account multiple reflection / transmission effects, and to use this method to calculate the scattered sound field of the enclosure.
[0031] The third part involves generating acoustic tomographic images of the shell structure by combining the principles of acoustic tomography.
[0032] Combining the above approaches, a method for generating acoustic tomographic images of shell structures based on iterative physical acoustics can be constructed. The technical approach of this method is as follows: Figure 1 As shown.
[0033] The preprocessing process includes: constructing a 3D model of the shell structure, meshing the shell structure, and establishing a model of the shell structure's reflection / transmission coefficients;
[0034] The acoustic transmission iterative physical acoustics method is a numerical iterative method for solving acoustic problems. It separates time and space variables by expanding the sound field into a Fourier series. The solution obtained using this method has clear physical meaning, being a combination of all harmonic orders, and is suitable for studying the propagation characteristics of nonlinear sound waves in liquids. Here, the solution process of the acoustic transmission iterative physical acoustics method includes: calculating the first-order outer and inner surface potential functions of the shell structure, iteratively calculating the q-th order outer and inner surface potential functions, and calculating the scattering potential function at the field point;
[0035] The process of generating acoustic tomography images includes: the frequency-angle spectrum of the omnidirectional echo signal of the shell structure, the two-dimensional spatial spectrum of the shell structure, and the generation of acoustic tomography images of the shell structure.
[0036] In the first part, during the preprocessing, a three-dimensional model of the shell structure is constructed using modeling software, and then the surface of the structure is meshed, wherein the mesh size is no larger than one-sixth of the wavelength corresponding to the maximum calculation frequency, thereby realizing the geometric modeling of the shell structure.
[0037] Figure 2 It is a 3D model and mesh model of the standard submarine's conning tower structure. Figure 3 This is a partial reflection / transmission model of the shell structure. Both the external and internal media of the shell are fluids with sound velocity and density of [missing information]. , The intermediate structure is a shell structure with a thickness of [missing information]. The reflection coefficient of the shell structure is
[0038] (1)
[0039] and transmission coefficient is
[0040] (2)
[0041] in, and These are the mechanical impedance of the structure and the acoustic impedance of the fluid, respectively.
[0042] This embodiment calculates the reflectance of a 3mm thick steel plate. and transmission coefficient Angle of incidence of sound wave Harmony sound frequency Change cloud map as Figure 4 As shown.
[0043] Part Two, the iterative physical acoustic method for sound transmission includes, with Figure 5 Taking the horizontal cross-section of the shell shown as an example, consider the sound scattering problem of a closed, water-filled thin shell. It is the origin of the coordinate system, and is generally taken as the geometric center. Let the outer boundary of the shell be... The internal boundary is , The outer area is , The internal area is A spatial sound source Located in the outer area Emitting sound waves, field point Located in the outer area The received echoes have position vectors respectively. and . It is the surface The outer normal vector, It is the surface The outer normal vector, and The position vector of any point on the shell surface is .
[0044] In acoustics, the Helmholtz integral formula is used to calculate the sound field resulting from the distribution of sound sources. This formula shows that the sound pressure at a point is derived from the integral contribution of all sound source points through the normal derivative of the sound source density. According to the Helmholtz integral formula satisfied by a water-filled thin-shell structure, the field pressure at a point... The potential function of the scattered acoustic field at the location is
[0045] (3)
[0046] in, The total scattering order is . For free space Green's function, Position vector First The outer surface potential function of order 1. Position vector First The potential function of the inner surface of the order.
[0047] The difference between the first-order external and internal surface potential functions is
[0048] (4)
[0049] in, and These represent the reflection coefficient and the transmission coefficient, respectively. Let be the incident wave potential function.
[0050] For the ( The difference between the potential functions of the outer and inner surfaces of order ) is
[0051] (5)
[0052] in, Position vector First The outer surface potential function of order 1. Position vector First The potential function of the inner surface of the order.
[0053] Part Three: Acoustic Tomography Image Model of the Shell Structure. Consideration Figure 6 The underwater shell structure acoustic tomography problem shown is centered on the imaging region. Establish a Cartesian coordinate system with the origin. The distances from the source point and the field point to the target center are respectively and The incident and exit directions of the sound waves are the same as The included angles of the axes are respectively and The source point is the position coordinate of the transmitting transducer, and the field point is the position coordinate of the receiving transducer.
[0054] Calculation of the frequency-angle spectrum of the omnidirectional echo signal of the shell structure using the iterative physical acoustic method of sound transmission According to the relation and Mapping the echo frequency-angle spectrum to a two-dimensional spatial spectral plane, we have:
[0055] (6)
[0056] in, It is the wave number. and Wavenumber of To components and Towards the component.
[0057] The theoretical basis of acoustic tomography is the Fourier central slice theorem, which essentially involves analyzing the two-dimensional spatial spectrum of the target image. and target two-dimensional spatial image function Image simulation is achieved by using a pair of two-dimensional Fourier transforms of each other. Perform a two-dimensional Fourier transform to obtain the two-dimensional spatial image function of the shell structure.
[0058] (7)
[0059] To further verify the effectiveness of the embodiments of this disclosure, for example... Figure 2 The standard submarine model's conning tower structure, shown in the figure, was simulated using a 1:20 scale model with 0-360 degree horizontal omnidirectional time-domain echo. A 0.2ms short pulse and a 60kHz–80kHz linear frequency modulated signal were used as the transmission signal. The sound wave transmission point and the receiving point were 10.9m and 7.6m away from the sound center of the model, respectively. Figure 7 (a) and (b) present the simulation and experimental results of the time-angle distribution of the received echo pulse sequences from various azimuths, respectively. The horizontal axis represents the incident azimuth angle, the vertical axis represents the echo pulse time, and the color represents the echo amplitude. Corresponding to the bow incidence, Corresponding to normal transverse incidence, Incident at the stern. From Figure 7 It can be seen that the echo structures of the experiment and simulation are quite consistent. High-order scattering echo highlights of the water-filled acoustically transparent shell structure can be clearly observed in the echoes. This shows that the method of this patent can accurately predict the distribution of multiple reflection / transmission echo highlights of the underwater shell structure, providing identifiable and fine features for underwater submarine target identification.
[0060] Furthermore, utilizing, such as Figure 7(a) shows the echo time-angle spectrum of a 1:20 scale model of the quasi-submarine model's sail structure. Using the principles of acoustic tomography, an acoustic tomographic image of the sail structure is generated, as follows: Figure 8 As shown. By Figure 8 It can be seen that the first-order scattering bright spot accurately reproduces the shape contour features of the shell structure, while other higher-order scattering features reflect the water-filled sound transmission characteristics of the shell structure.
[0061] In summary, the beneficial effects of this disclosure include: the method can accurately and efficiently generate acoustic tomography images of underwater water-filled acoustically transparent conning structures, accurately characterize the multiple reflection and transmission effects of incident sound waves inside the conning structure, and provide data support for improving the detection and identification capabilities of active sonar systems for submarines.
[0062] It should be understood that in the embodiments of the present invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, the character " / " in this document generally indicates that the preceding and following associated objects have an "or" relationship.
[0063] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.
[0064] If the integrated unit is implemented as 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, in essence, 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. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for generating acoustic tomographic images of a submarine sail structure, characterized in that, The method includes the following steps: Step 1: Preprocessing, establishing the geometric model and reflection / transmission coefficient model of the submarine's conning tower structure; Step 2: Calculate the scattered sound field of the submarine conning tower; Step 3: Generate an acoustic tomographic image of the submarine's sail structure; In step two, a physical acoustic solution method based on multiple reflections / transmissions is used to calculate the scattered sound field of the shell structure. The sound-transmitting iterative physical acoustic solution method includes: iteratively calculating the qth-order outer and inner surface potential function using the first-order outer and inner surface potential function of the shell structure, and calculating the scattering potential function at the field point; The process of generating the acoustic tomography image in step three includes: obtaining the frequency-angle spectrum of the omnidirectional echo signal of the shell structure, obtaining the two-dimensional spatial spectrum of the shell structure, and generating the acoustic tomography image of the shell structure.
2. The method according to claim 1, characterized in that, The preprocessing process in step one includes: constructing a three-dimensional model of the submarine's sail structure, including a mesh model of the sail structure, and establishing a geometric model and a reflection / transmission coefficient model of the sail structure.
3. The method according to claim 1, characterized in that, The enclosure structure is a closed, water-filled thin-shell structure.
4. The method according to claim 3, characterized in that, The scattered acoustic potential function of the shell structure satisfies the Helmholtz integral formula.
5. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the method as described in any one of claims 1 to 4.
6. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 4.
7. 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 4.