Three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation
By employing acoustic orbital angular momentum and Bessel compensation methods, the resolution and sidelobe problems in traditional acoustic 3D imaging have been solved, achieving high-resolution, high-contrast 3D sonar imaging suitable for underwater detection, medical ultrasound, and non-destructive testing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2026-04-23
- Publication Date
- 2026-06-02
AI Technical Summary
Traditional acoustic 3D imaging methods struggle to achieve high-resolution imaging in both pitch and azimuth directions, and are susceptible to sidelobe interference. In particular, wavefront distortion is common in inhomogeneous media, affecting image contrast and target identification.
Using acoustic orbital angular momentum and Bessel compensation, preliminary imaging results are obtained through primary beamforming. Phase and amplitude distortions are corrected using Bessel functions, and a modal-dimensional azimuth matching vector is constructed for secondary beamforming to suppress modal coupling and sidelobes.
It achieves high-resolution, high-contrast 3D sonar imaging, reduces sidelobe levels, improves imaging fidelity and target contour clarity, and enhances pitch and azimuth resolution, making it suitable for underwater exploration, medical ultrasound, and non-destructive testing.
Smart Images
Figure CN122131312A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of technology, and in particular to a three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation. Background Technology
[0002] Acoustic 3D imaging is a key technology in underwater exploration, medical ultrasound, non-destructive testing, and geological exploration. Its goal is to achieve high-precision spatial reconstruction of targets in three dimensions: elevation, azimuth, and radial distance. Traditional acoustic 3D imaging methods are mainly based on phased array beamforming technology. This involves receiving echo signals reflected or scattered by the target through an array of sensors and then delaying and superimposing them in the time or frequency domains to form a spatial image. Although these methods are widely used in engineering, their 3D resolution is limited by the physical aperture size, signal wavelength, and array design. High-resolution imaging is particularly difficult to achieve simultaneously in the elevation and azimuth directions, and they are often accompanied by high sidelobe levels, affecting image contrast and target identification capabilities.
[0003] Acoustic orbital angular momentum (OAM) possesses helical phase wavefront and orthogonal mode characteristics, which can break through the bottleneck of traditional array angular resolution. However, in practical applications, during the propagation of sound waves, especially when they are scattered by a target or propagating in an inhomogeneous medium, their wavefronts are prone to bending and distortion, which leads to coupling and crosstalk between different OAM modes and destroys the orthogonality between modes.
[0004] Therefore, how to effectively compensate for the phase and amplitude distortion of acoustic OAM modes during propagation and scattering, suppress sidelobe interference caused by mode coupling, and on this basis achieve high-resolution, high-contrast imaging in pitch and azimuth three-dimensional space has become a key technical problem that urgently needs to be solved in the field of acoustic imaging. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation.
[0006] The technical solution of this invention is: a three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation, comprising the following steps: S1) Perform beamforming on the received echo signals of multiple different modes in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results containing target spatial location information; S2) Extract the target elevation angle from the preliminary three-dimensional sonar imaging results, and obtain the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam mode by combining the acoustic wave propagation model and Bessel function. S3) The Bessel compensation factor is used to correct the phase and amplitude of the original multimodal OAM echo signal mode by mode in the time domain to suppress mode coupling and sidelobes. S4) Construct the modal dimension azimuth matching vector and perform a second azimuth beamforming on the corrected multimodal OAM echo signal; S5) outputs high-resolution, high-contrast three-dimensional sonar imaging results.
[0007] Preferably, in step S1), generating preliminary three-dimensional sonar imaging results containing target spatial location information includes: S11) The array transmits multimode OAM signals to form an acoustic OAM beam in space; after being scattered by the target, the array receives the multimode OAM echo signals. S12) After performing the first beamforming in the elevation and azimuth directions on the received multimodal OAM echo signal, preliminary three-dimensional sonar imaging results are obtained.
[0008] Preferably, in step S2), obtaining the Bessel compensation factor for compensating for acoustic OAM beammode phase and amplitude distortion includes: S21) From the preliminary three-dimensional sonar imaging results, determine the resolution cell where the target is located in the range and azimuth dimensions, and obtain the elevation angle corresponding to the resolution cell. As an initial estimate of the target pitch angle; S22), with target pitch angle Based on this, for each mode Amplitude compensation term and phase compensation term are constructed and combined to obtain the Bessel compensation factor.
[0009] Preferably, in step S4), the modal azimuth matching vector forms a matched filter covering all received modes and targeting a specific azimuth angle by utilizing the inherent coding relationship between each OAM mode and the target azimuth angle; the modal azimuth matching vector is used to perform a second azimuth beamforming on the corrected multimodal OAM echo signal to achieve azimuth super-resolution imaging.
[0010] Secondly, the technical solution provided by this invention is: a three-dimensional sonar imaging system based on acoustic orbital angular momentum and Bessel compensation, comprising: An array module is used to excite multimode OAM transmission signals to form an acoustic OAM beam and to receive multimode OAM echo signals scattered by the target. The preliminary imaging module is used to perform the first beamforming on the multimodal OAM echo signal in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results. The compensation factor generation module extracts the target elevation angle from the preliminary three-dimensional sonar imaging results and obtains the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam mode by combining the acoustic wave propagation model and the Bessel function. The time-domain compensation module is used to perform mode-by-mode correction on the original multimodal OAM echo signal in the time domain using the Bessel compensation factor to suppress mode coupling and sidelobes. The azimuth high-resolution beamforming module is used to construct the modal azimuth matching vector and perform a second azimuth beamforming on the corrected multimode OAM echo signal; The 3D imaging module is used to output high-resolution, high-contrast 3D sonar imaging results.
[0011] Thirdly, the present invention provides an electronic device, comprising: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the electronic device to perform the three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation.
[0012] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation.
[0013] The beneficial technical effects of this invention are as follows: 1. This invention uses a compensation factor obtained based on the target pitch angle and the characteristics of the Bessel function to accurately compensate for the amplitude and phase distortion of multimodal OAM echo signals, significantly reducing signal errors caused by wavefront bending, modal coupling and non-ideal scattering, restoring the orthogonality between different OAM modes and improving imaging fidelity. 2. This invention utilizes Bessel compensation to correct the echo signal in the time domain, which can significantly compress the imaging sidelobe level and tighten the main lobe width, solving the problems of high sidelobe and widened main lobe caused by traditional technology, making the target outline clearer, the boundary sharper, and the imaging contrast significantly improved. 3. This invention acquires target spatial information through primary beamforming, optimizes pitch resolution through Bessel compensation, and enhances azimuth resolution through modal-dimensional azimuth matching beamforming, thereby achieving high resolution in both pitch and azimuth directions. 4. Without increasing the array aperture or the signal frequency, this invention utilizes multimodal OAM information and two-stage signal processing to achieve more accurate target angle estimation and spatial positioning. Its detection and resolution capabilities for weakly scattering, small-sized, and close-range targets are significantly superior to existing algorithms such as conventional beamforming and MMBF. Attached Figure Description
[0014] Figure 1This is a flowchart illustrating the method of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the uniform circular array structure imaging in Embodiment 1 of the present invention; Figure 3 This is the beam pattern of a conventional beamforming system in Embodiment 1 of the present invention; Figure 4 This is the beammap based on the MMBF algorithm in Embodiment 1 of the present invention; Figure 5 This is an imaging beammap based on acoustic orbital angular momentum and Bessel compensation in Embodiment 1 of the present invention; Figure 6 This is a comparison diagram of the azimuth sectional planes of the three imaging methods in Embodiment 1 of the present invention. Detailed Implementation
[0015] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 As shown, this embodiment provides a three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation, including the following steps: S1) Perform beamforming on the received OAM echo signals of different modes in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results containing target spatial location information; specifically as follows: S11) The array transmits multimode OAM signals to form an acoustic OAM beam in space; after being scattered by the target, the array receives the multimode OAM echo signals. In this embodiment, as Figure 2 As shown, a uniform circular array is used to transmit and receive OAM momentum beams with different topological charges; the radius of the uniform circular array is... , No. The transmitted signal of each array element is: In the formula, for The transmission signal at any given moment; For the first The initial phase of each array element; The topological load number; For array element serial numbers; Unit phase increment; The frequency at which the sound waves are emitted; It is a complex number; any point in space sound pressure Represented as: In the formula, , , These represent the radial distance, elevation angle, and azimuth angle from any point in space to the center of the array, respectively. This is the attenuation term for the basic spherical wave; This represents the maximum amplitude of the sound source. It is the propagation phase term, carrying the time-domain signal and carrier wave; Indicates wave number; Indicates the frequency of the sound wave. Represents the speed of light; It is a constant phase factor; It is a Bessel function; It is the azimuth phase term that gives the beam a spiral wavefront structure, and its vortex acoustic wave topological charge number It directly corresponds to the OAM mode carried by the beam.
[0016] For any point , No. The multimode OAM echo signal received by each array element Represented as: ; In the formula, For the first The scattering coefficient of each scattering target point; They represent the first The elevation and azimuth angles of the target scattering points; Indicates the first The radial distance from each target scattering point to the center of the array; Indicates the noise term; S12) After performing the first beamforming in the elevation and azimuth directions on the received multimodal OAM echo signals, preliminary three-dimensional sonar imaging results are obtained; that is: In the formula, This represents the initial three-dimensional sonar imaging results obtained after the first beamforming. Represents the zeroth-order Bessel function of the first kind; The equivalent range factor, which is determined by both the elevation and azimuth differences between the beam pointing angle and the actual target angle, represents the effective range factor. This represents the total number of target scattering points; The equivalent range factor is jointly determined by the elevation angle difference and azimuth angle difference between the beam pointing angle and the actual target angle. Represented as: In the formula, , These represent the elevation angle and azimuth angle of the beam, respectively.
[0017] S2) Extract the target elevation angle from the preliminary 3D sonar imaging results, and obtain the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam modes by combining the acoustic wave propagation model and Bessel function; specifically as follows: S21) From the preliminary three-dimensional sonar imaging results, determine the resolution cell where the target is located in the range and azimuth dimensions, and obtain the elevation angle corresponding to the resolution cell. As an initial estimate of the target pitch angle; S22), with target pitch angle Based on this, for each mode The amplitude compensation term and the phase compensation term are constructed and combined to obtain the Bessel compensation factor, namely: ; In the formula, Indicates the Bessel compensation factor; Indicates a Bessel term; Indicates wave number; Let be the radius of the uniform circular array; The pitch angle for the target.
[0018] S3) The phase and amplitude of the original multimodal OAM echo signal are corrected mode by mode in the time domain using the Bessel compensation factor to suppress modal coupling and sidelobes; that is: ; In the formula, This represents the result after preliminary three-dimensional sonar imaging compensation; For the first The scattering coefficient of a scattering target point.
[0019] S4) Construct the modal dimension azimuth matching vector and perform a second azimuth beamforming on the corrected multimodal OAM echo signal; In this embodiment, the modal-dimensional azimuth matching vector utilizes the inherent coding relationship between each OAM mode and the target azimuth angle to form a matched filter that covers all received modes and is specific to a particular azimuth angle. A second azimuth beamforming is performed on the corrected multimodal OAM echo signal by using the modal dimension azimuth matching vector. This beamforming is synthesized in the modal dimension, which can sharply distinguish targets at different azimuth angles, thereby achieving azimuth super-resolution imaging. ; In the formula, This represents the imaging result after secondary azimuth beamforming; Indicates the total number of OAM modes used; Indicates the first The scattering intensity coefficient of each target scattering point.
[0020] S5) Outputs high-resolution, high-contrast three-dimensional sonar imaging results. .
[0021] This embodiment performs simulation verification, and the relevant simulation parameters are shown in Table 1.
[0022] Table 1 Simulation parameters for acoustic vortex imaging from Figure 3-5 The simulation results show that this embodiment outperforms conventional beamforming and MMBF-based imaging algorithms in azimuth resolution. The beammap also demonstrates that this embodiment exhibits more significant energy compression in the azimuth direction compared to the other two algorithms. Figure 6 The cross-sectional view further demonstrates that this embodiment has a narrower azimuth beam main lobe, lower sidelobe level, and higher azimuth resolution.
[0023] Example 2 This embodiment provides a three-dimensional sonar imaging system based on acoustic orbital angular momentum and Bessel compensation, including: An array module is used to excite multimode OAM transmission signals to form an acoustic OAM beam and to receive multimode OAM echo signals scattered by the target. OAM momentum beams with different topological charges are transmitted and received using a uniform circular array; the radius of the uniform circular array is... , No. The transmitted signal of each array element is: In the formula, for The transmission signal at a specific moment; For the first The initial phase of each array element; The topological load number; For array element serial numbers; Unit phase increment; The frequency at which the sound waves are emitted; It is a complex number; any point in space sound pressure Represented as: In the formula, , , These represent the radial distance, elevation angle, and azimuth angle from any point in space to the center of the array, respectively. This is the attenuation term for the basic spherical wave; This represents the maximum amplitude of the sound source. It is the propagation phase term, carrying the time-domain signal and carrier wave; Indicates wave number; It is a constant phase factor; It is a Bessel function; It is the azimuth phase term that gives the beam a spiral wavefront structure, and its vortex acoustic wave topological charge number It directly corresponds to the OAM mode carried by the beam.
[0024] For any point , No. The multimode OAM echo signal received by each array element Represented as: ; In the formula, For the first The scattering coefficient of each target scattering point; They represent the first The elevation and azimuth angles of the target scattering points; Indicates the first The radial distance from each target scattering point to the center of the array; This indicates the noise term.
[0025] The preliminary imaging module is used to perform initial beamforming on the multimodal OAM echo signal in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results; that is: In the formula, This represents the initial three-dimensional sonar imaging results obtained after the first beamforming. Represents the zeroth-order Bessel function; It represents the equivalent range factor determined by the difference between the elevation angle and the azimuth angle between the beam pointing angle and the actual angle of the target. Indicates the total number of target scattering points; The equivalent range factor is determined by the difference between the elevation angle and the azimuth angle between the beam pointing angle and the actual target angle. Represented as: In the formula, , These represent the elevation angle and azimuth angle of the beam, respectively.
[0026] The compensation factor generation module extracts the target elevation angle from the preliminary 3D sonar imaging results and, combined with the acoustic wave propagation model and Bessel function, obtains the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam modes; specifically as follows: S21) From the preliminary three-dimensional sonar imaging results, determine the resolution cell where the target is located in the range and azimuth dimensions, and obtain the elevation angle corresponding to the resolution cell. As an initial estimate of the target pitch angle; S22), with target pitch angle Based on this, for each mode The amplitude compensation term and the phase compensation term are constructed and combined to obtain the Bessel compensation factor, namely: ; In the formula, This represents the Bessel compensation factor.
[0027] The time-domain compensation module is used to perform mode-by-mode correction on the original multimodal OAM echo signal in the time domain using the Bessel compensation factor, thereby suppressing mode coupling and sidelobes; that is: In the formula, This represents the result after preliminary three-dimensional sonar imaging compensation; Indicates the first The scattering intensity of each target scattering point; The number of elements in a uniform circular array; Indicates the total number of target scattering points; The azimuth high-resolution beamforming module is used to construct the modal azimuth matching vector and perform a second azimuth beamforming on the corrected multimode OAM echo signal; In this embodiment, the modal-dimensional azimuth matching vector utilizes the inherent coding relationship between each OAM mode and the target azimuth angle to form a matched filter that covers all received modes and is specific to a particular azimuth angle. A second azimuth beamforming is performed on the corrected multimodal OAM echo signal using modal-dimensional azimuth matching vectors. This beamforming is synthesized in the modal dimension, which can sharply distinguish targets at different azimuth angles, thereby achieving azimuth super-resolution imaging. ; In the formula, This represents the imaging result after secondary azimuth beamforming; Indicates the total number of OAM modes used; The 3D imaging module outputs high-resolution, high-contrast 3D sonar imaging results. .
[0028] Example 3 This embodiment provides an electronic device, including: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the electronic device to perform the three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation.
[0029] In this embodiment, the memory can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.
[0030] Example 4 This embodiment provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation described in Embodiment 1.
[0031] The computer program includes computer program code, which may be in the form of source code, object code, executable file, or some intermediate form.
[0032] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.
Claims
1. A three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation, characterized in that, Includes the following steps: S1) Perform beamforming on the received echo signals of multiple different modes in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results containing target spatial location information; S2) Extract the target elevation angle from the preliminary three-dimensional sonar imaging results, and obtain the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam mode by combining the acoustic wave propagation model and Bessel function. S3) The Bessel compensation factor is used to correct the phase and amplitude of the original multimodal OAM echo signal mode by mode in the time domain to suppress mode coupling and sidelobes. S4) Construct the modal dimension azimuth matching vector and perform a second azimuth beamforming on the corrected multimodal OAM echo signal; S5) outputs high-resolution, high-contrast three-dimensional sonar imaging results.
2. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 1, characterized in that, S1) includes: S11) The array transmits multimode OAM signals to form an acoustic OAM beam in space; after being scattered by the target, the array receives the multimode OAM echo signals. S12) After performing the first beamforming in the elevation and azimuth directions on the received multimodal OAM echo signal, preliminary three-dimensional sonar imaging results are obtained.
3. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 2, characterized in that, S2) includes: S21) From the preliminary three-dimensional sonar imaging results, determine the resolution cell where the target is located in the range and azimuth dimensions, and obtain the elevation angle corresponding to the resolution cell as the initial estimate of the target elevation angle. S22), using the target pitch angle as a reference, for each mode Amplitude compensation term and phase compensation term are constructed and combined to obtain the Bessel compensation factor.
4. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 2, characterized in that, In S2), the Bessel compensation factor is expressed as: ； In the formula, Indicates the Bessel compensation factor; Indicates a Bessel term; Indicates wave number; Let be the radius of the uniform circular array; The pitch angle for the target.
5. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 4, characterized in that, In S3), the corrected multimodal OAM echo signal is represented as follows: In the formula, This represents the result after preliminary three-dimensional sonar imaging compensation; Indicates the first The scattering intensity of each target scattering point; This represents the number of elements in a uniform circular array. Indicates the total number of target scattering points; To represent a complex number; To transmit signals; Indicates the first The distance from each target scattering point to the reference point; The topological charge number represents the OAM mode; Indicates the first The azimuth angle of the target scattering point; Represents the zeroth-order Bessel function; It represents the equivalent range factor determined by the difference between the elevation angle and the azimuth angle between the beam pointing angle and the actual angle of the target. This indicates the noise term.
6. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 4, characterized in that, In S4), the modal azimuth matching vector forms a matched filter that covers all received modes and is specific to a particular azimuth angle by utilizing the inherent coding relationship between each OAM mode and the target azimuth angle; the modal azimuth matching vector is used to perform a second azimuth beamforming on the corrected multimodal OAM echo signal to achieve azimuth super-resolution imaging.
7. The three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation according to claim 5, characterized in that, In S4), a second azimuth beamforming is performed on the corrected multimodal OAM echo signal using the modal dimension azimuth matching vector to achieve azimuth super-resolution imaging. Specifically: In the formula, This represents the imaging result after secondary azimuth beamforming; Indicates the total number of OAM modes used; Indicates the first The scattering intensity coefficient of each target scattering point.
8. A three-dimensional sonar imaging system based on acoustic orbital angular momentum and Bessel compensation, characterized in that, include: An array module is used to excite multimode OAM transmission signals to form an acoustic OAM beam and to receive multimode OAM echo signals scattered by the target. The preliminary imaging module is used to perform the first beamforming on the multimodal OAM echo signal in the elevation and azimuth directions to generate preliminary three-dimensional sonar imaging results. The compensation factor generation module extracts the target elevation angle from the preliminary three-dimensional sonar imaging results and obtains the Bessel compensation factor to compensate for the phase and amplitude distortion of the acoustic OAM beam mode by combining the acoustic wave propagation model and the Bessel function. The time-domain compensation module is used to perform mode-by-mode correction on the original multimodal OAM echo signal in the time domain using the Bessel compensation factor to suppress mode coupling and sidelobes. The azimuth high-resolution beamforming module is used to construct the modal azimuth matching vector and perform a second azimuth beamforming on the corrected multimode OAM echo signal; The 3D imaging module outputs high-resolution, high-contrast 3D sonar imaging results.
9. An electronic device, comprising: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, characterized in that the computer program is executed by the at least one processor to cause the electronic device to perform the three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation as described in any one of claims 1-7.
10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the three-dimensional sonar imaging method based on acoustic orbital angular momentum and Bessel compensation as described in any one of claims 1-7.