A sound fence type multibeam sonar imaging device and method

Abstract

This invention discloses an acoustic fence-type multibeam sonar imaging device, comprising an acoustic uniform linear array assembly capable of electroacoustic conversion for signal transmission / reception, a multi-channel impedance matching module to improve the electroacoustic conversion efficiency of the underwater acoustic transducers in the acoustic uniform linear array assembly, a multi-channel transmitter module for signal phase shifting and driving the underwater acoustic transducers to transmit signals, a multi-channel receiver module for signal phase shifting, conditioning, and acquiring received signals, and a signal control processing module for separately controlling the multi-channel transmitter module and the multi-channel receiver module to transmit or receive signals. Utilizing the acoustic fence principle, a broadband excitation signal is applied to the acoustic uniform linear array to achieve multibeam scanning imaging sonar. In this invention, only four channels are required for a single acoustic uniform linear array, significantly reducing circuit size and design complexity, thereby reducing the cost, size, weight, and power of the sonar system, and making it easier to achieve product miniaturization.

Description

Technical Field

[0001] This invention belongs to the field of acoustic detection, and particularly relates to an acoustic fence type multibeam sonar imaging device and method. Background Technology

[0002] Underwater visual images help humans intuitively understand the ocean, increasing their sensory perception of it. It is well known that optical imaging and electromagnetic wave imaging technologies are well-developed on land, but their applications are limited in underwater environments. Due to the complexity of the water medium, radio waves and light waves have limited propagation distances and suffer severe attenuation. General optical imaging equipment can only achieve short-range imaging in clear seawater. Therefore, in underwater environments, sound waves are used to image objects or structures—this is imaging sonar technology.

[0003] Based on the number of sound beams transmitted and received in a single imaging session, imaging sonar technology is divided into single-beam imaging and multi-beam imaging. Single-beam imaging sonar can only transmit a sound beam in one direction at a time, and then processes the echo signal to generate an image containing a single angle. Multi-beam sonar, on the other hand, can transmit multiple sound beams in different directions at once, and then processes the echo signals to generate images containing multiple angles. Compared to single-beam imaging sonar, multi-beam imaging sonar can provide more accurate, efficient, and comprehensive underwater imaging results.

[0004] Multibeam imaging sonar has wide applications in various fields, especially in underwater surveying and mapping, underwater maintenance and inspection, underwater navigation, and marine biological research.

[0005] 1. Underwater surveying and mapping: Multibeam imaging sonar can be used to create high-resolution maps of seabed and underwater structures, which helps in the planning and construction of marine infrastructure such as pipelines, bridges and offshore wind farms.

[0006] 2. Underwater maintenance and inspection: Multibeam imaging sonar can be used to inspect and maintain underwater structures such as oil drilling platforms, pipelines and bridges, helping engineers and technicians to identify any damage or corrosion and carry out repairs.

[0007] 3. Underwater navigation: Multibeam imaging sonar can provide accurate underwater environmental images, improve the positioning and navigation accuracy of underwater vehicles, and also help underwater vehicles avoid obstacles.

[0008] 4. Marine Biology Research: Multibeam imaging sonar can be used to study underwater organisms, such as fish population studies, fishing resource management, and marine ecology research, providing researchers with a high-resolution, high-efficiency, and non-invasive research tool.

[0009] In traditional multibeam imaging sonar, the signals received by each element of the acoustic array will have certain differences in time and amplitude. Therefore, it is necessary to perform signal processing on the signals of each element separately to make their signals phase consistent in a specific direction. Then, the beam signal in that direction is obtained by weighted summation. This technique is called "phased multibeam".

[0010] In existing technologies, phased-array multibeam imaging sonar typically has hundreds or thousands of array elements. In this technology, each element of the acoustic array needs to be brought out independently. Although this approach improves the flexibility of signal processing algorithms, it also requires the design of independent transmission, reception, and signal processing channels for each element. This not only increases the circuit scale and design difficulty, but more importantly, it increases the cost, size, weight, and power of the sonar system, making it difficult to achieve product miniaturization. Summary of the Invention

[0011] The technical objective of this invention is to provide a sound fence-type multibeam sonar imaging device and method to facilitate underwater imaging.

[0012] To solve the above problems, the technical solution of the present invention is as follows:

[0013] A sound fence type multibeam sonar imaging device includes:

[0014] Acoustic uniform linear array combination, multi-channel impedance matching module, multi-channel transmitter module, multi-channel receiver module and signal control and processing module;

[0015] Acoustic uniform linear arrays are used to perform electroacoustic conversion to achieve signal transmission and reception, and to decompose / synthesize narrowband acoustic signals into broadband electrical signals.

[0016] The multi-channel impedance matching module is connected to the acoustic uniform linear array combination signal to improve the electroacoustic conversion efficiency of the underwater acoustic transducer in the acoustic uniform linear array combination.

[0017] The multi-channel transmitter module is signal-connected to the multi-channel impedance matching module and is used for phase shifting of the signal and driving the acoustic uniform linear array to transmit signals.

[0018] The multi-channel receiver module is signal-connected to the multi-channel impedance matching module and is used to perform phase shifting, conditioning, and acquisition on the received signal.

[0019] The signal control and processing module is connected to the multi-channel transmitter module and the multi-channel receiver module respectively, and is used to control the multi-channel transmitter module and the multi-channel receiver module to transmit or receive signals, and to realize sonar imaging processing.

[0020] The acoustic uniform linear array combination includes at least three acoustic uniform linear arrays, and each acoustic uniform linear array includes N sets of array elements. Each set of array elements includes four array elements arranged in polarity +, -, -, +.

[0021] The first positive element of each array element group is connected to channel CH1;

[0022] The first negative pole element of each array element group is connected to channel CH2;

[0023] The second negative pole element of each array element group is connected to channel CH3;

[0024] The second positive element of each array element group is connected to channel CH4.

[0025] If the phase difference between the four channels is +90°, a directional beam can be formed on the right side of the normal. The formula for the directional beam is as follows:

[0026]

[0027] If the phase difference between the four channels is -90°, a directional beam can be formed to the left of the normal. The formula for the directional beam is as follows:

[0028]

[0029] If the phase difference between the four channels is 0°, a symmetrical directional beam can be formed on the left and right sides of the normal. The formula for the directional beam is as follows:

[0030]

[0031] Where c is the speed of sound, M is the number of array elements equal to 4N, d is the element spacing, f is the signal frequency, and θ is the direction;

[0032] The absolute values ​​of the main lobe positions of the three directional beams mentioned above are:

[0033]

[0034] Specifically, the multi-channel transmitter module includes a phase shifter, a digital-to-analog converter, and a power amplifier connected in sequence;

[0035] Specifically, the multi-channel receiver module includes a phase shifter, a signal conditioner, and an analog-to-digital converter connected in sequence.

[0036] Specifically, the signal control and processing module includes a signal connection FPGA unit, a DSP unit, and an ARM unit.

[0037] More preferably, an image display and control module is also provided, which is connected to the signal control and processing module. The image display and control module is used to input control commands to control the acoustic fence type multibeam sonar imaging device, and to receive and display image data output from the signal control and processing module.

[0038] More preferably, a sonar power module is also provided to provide power support for the various modules within the acoustic fence type multibeam sonar imaging device.

[0039] A method for acoustic fence-type multibeam sonar imaging, configured in the acoustic fence-type multibeam sonar imaging device as described above, includes the following steps:

[0040] S1: The signal control and processing module controls the multi-channel transmitter module to transmit signals, while the multi-channel receiver module starts receiving echo signals at fixed intervals.

[0041] S2: Input the echo signal to the signal control and processing module for preprocessing;

[0042] S3: Using the signal control and processing module, time-frequency analysis is used to perform multi-beam imaging processing on the preprocessed echo signal;

[0043] S4: Transmit the processed multibeam image data to the image display and control module for display;

[0044] S5: Repeat steps S1 to S4.

[0045] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art:

[0046] This invention utilizes the acoustic fence principle to propose an acoustic fence-type multibeam sonar imaging device and method. Specifically, by applying a broadband excitation signal to an acoustic uniform linear array, multibeam scanning imaging sonar is achieved, which can be called acoustic fence-type multibeam sonar imaging technology. In this technology, a single acoustic uniform linear array only needs to bring out 4 channels, which greatly reduces the circuit scale and design difficulty, thereby reducing the cost, size, weight, and power of the sonar system, making it easier to achieve the goal of product miniaturization. Using multiple acoustic uniform linear arrays can achieve a continuous and wide field of view. Attached Figure Description

[0047] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention.

[0048] Figure 1 This is a schematic diagram of the frame of a sound fence type multibeam sonar imaging device according to the present invention;

[0049] Figure 2 The polarity and wiring of each element of the acoustic uniform linear array of the present invention are shown.

[0050] Figure 3 This is the beam pattern of the normal-side dual-beam scanning of the present invention;

[0051] Figure 4 This is an example of a sound barrier type multibeam;

[0052] Figure 5 This invention relates to a design for a combination of multiple acoustic uniform linear arrays.

[0053] Figure 6 This is another design for combining multiple acoustic uniform linear arrays according to the present invention;

[0054] Figure 7 This is a schematic flowchart of a sound fence-type multibeam sonar imaging method according to the present invention. Detailed Implementation

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0056] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0057] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed account of the acoustic fence-type multibeam sonar imaging device and method proposed in this invention. The advantages and features of this invention will become more apparent from the following description and claims.

[0058] Example 1

[0059] See Figures 1 to 6 This embodiment provides an acoustic fence-type multibeam sonar imaging device, including: an acoustic uniform linear array assembly, a multi-channel impedance matching module, a multi-channel transmitter module, a multi-channel receiver module, a signal control and processing module, an image display and control module, and a sonar power supply module.

[0060] See Figure 1In this embodiment, the acoustic uniform linear array is responsible for completing the electroacoustic conversion to achieve signal transmission and reception, and decomposing / synthesizing narrowband acoustic signals into broadband electrical signals. The multi-channel impedance matching module is connected to the acoustic uniform linear array, enabling bidirectional signal transmission. It is responsible for impedance transformation and can improve the electroacoustic conversion efficiency of the underwater acoustic transducer of the acoustic uniform linear array.

[0061] The multi-channel transmitter module is signal-connected to the multi-channel impedance matching module and can output signals to the multi-channel impedance matching module. Specifically, the multi-channel transmitter module includes, but is not limited to, a phase shifter, a digital-to-analog converter, and a power amplifier connected in sequence, which are responsible for phase shifting the signal and driving the underwater acoustic transducer to transmit signals.

[0062] The multi-channel receiver module is signal-connected to the multi-channel impedance matching module, and can receive echo signals from the multi-channel impedance matching module. Specifically, the multi-channel receiver module includes, but is not limited to, a phase shifter, a signal conditioner, and an analog-to-digital converter connected in sequence, which are responsible for phase shifting, conditioning, and acquisition (analog-to-digital conversion) of the echo signals.

[0063] The signal control and processing module is connected to both the multi-channel transmitter module and the multi-channel receiver module. It can send control signals to the multi-channel transmitter module to transmit signals, or receive the acquired echo signals from the multi-channel receiver module. Specifically, the signal control and processing module includes, but is not limited to, signal processors such as FPGA units, DSP units, and ARM units. Therefore, the signal control and processing module is primarily responsible for controlling the multi-channel transmitter module and the multi-channel receiver module, and for implementing sonar imaging processing.

[0064] The image display and control module is connected to the signal control and processing module, enabling bidirectional signal transmission. It may consist of, but is not limited to, a computer and a dedicated display device. Users can input control commands through the image display and control module to control this embodiment. Furthermore, it can receive and display output image data from the signal control and processing module.

[0065] The sonar power module is responsible for providing power to the modules mentioned above in this embodiment.

[0066] See Figure 2In this embodiment, the acoustic uniform linear array combination is described below. The acoustic uniform linear array combination includes at least three acoustic uniform linear arrays, and each acoustic uniform linear array includes N array element groups. Each array element group includes four array elements arranged in a polarity of +, -, -, +. The first positive array element of each array element group is connected to channel CH1, that is, array elements numbered 1, 5 (from left to right), etc., are led out as channel CH1. The first negative array element of each array element group is connected to channel CH2, that is, array elements numbered 2, 6, etc., are led out as channel CH2. The second negative array element of each array element group is connected to channel CH3, that is, array elements numbered 3, 7, etc., are led out as channel CH3. The second positive array element of each array element group is connected to channel CH4, that is, array elements numbered 4, 8, etc., are led out as channel CH4.

[0067] like Figure 2 If the four channels are sequentially phased by +90°, a directional beam can be formed on the right side of the normal. The formula for the directional beam is as follows:

[0068]

[0069] like Figure 2 If the four channels are sequentially phased by -90°, a directional beam can be formed to the left of the normal. The formula for the directional beam is as follows:

[0070]

[0071] like Figure 2 If the four channels are sequentially phase-differenced by 0°, then symmetrical directional beams can be formed on the left and right sides of the normal. The formula for a directional beam is as follows:

[0072]

[0073] Where c is the speed of sound, M is the number of array elements (equal to 4N), d is the element spacing, f is the signal frequency, and θ is the direction; according to the formula for directional beams with a phase difference of +90°, the absolute values ​​of the main lobe positions of the three directional beams mentioned above are:

[0074]

[0075] For a given acoustic uniform linear array, changing the signal frequency f alters the position of the main lobe of the beam, thereby achieving multi-beam scanning. Figure 3 For example, a beammap of normal-side beam scanning is given.

[0076] It should be noted that although theoretically the absolute value formula for changing the position of the main lobe of the beam can be any value for the signal frequency f, in practice, an excessively large signal frequency f will produce grating lobes, while a small signal frequency f will cause the main lobe of the beam to widen, resulting in a decrease in angular resolution.

[0077] See Figure 4 An example of an acoustic fence-type multibeam sonar is presented. The figure illustrates a simplified sonar workflow from left to right, showing the broadband excitation electrical signal generated by the signal source, with a frequency range of f1, f2, ... f1. N The broadband electrical signal is phase-shifted after passing through the transmitter channel and applied to... Figure 2 On the four channels of the uniform acoustic linear array, the broadband signal is naturally split into numerous sound beams in different directions under the effect of the acoustic grating effect. These beams then radiate outwards into the water in a fan-shaped pattern, forming a set of directional sound beams with different angular directions based on frequency. These directional sound beams are reflected in the marine environment. Utilizing the reverse process of the acoustic grating principle, the uniform acoustic linear array can simultaneously receive sound signals with different frequencies based on angle, forming broadband electrical signals. Time-frequency analysis separates the target echo signals at different time angles, allowing the target's angle and distance to be displayed graphically.

[0078] See Figure 5 and Figure 6 In this embodiment, by exciting a uniform acoustic linear array with a broadband signal and analyzing a time-frequency signal, multiple beams can be generated to achieve acoustic imaging of a certain viewing angle (left and right viewing fan angles slightly greater than 20 degrees). If a large viewing angle is required, multiple uniform acoustic linear arrays can be used (and combined) to achieve imaging field coverage at any angle. For example, the combination of three linear arrays can achieve a 130-degree viewing angle. Figure 5 and Figure 6 Several possible combinations of multiple acoustic uniform linear arrays are presented.

[0079] Example 2

[0080] See Figure 7 This embodiment provides a sound fence type multibeam sonar imaging method, configured in the sound fence type multibeam sonar imaging device as in Embodiment 1, including the following steps:

[0081] First, in step S1, the user can input commands through the image display and control module. After processing by the signal control and processing module, a control signal is sent to control the multi-channel transmitter module to transmit signals. At the same time, the multi-channel receiver module starts receiving echo signals at fixed intervals.

[0082] Next, proceed to step S2, where the echo signal is input to the signal control and processing module for echo signal preprocessing.

[0083] Subsequently, in step S3, the signal control processing module is used to perform multi-beam imaging processing on the preprocessed echo signal using time-frequency analysis.

[0084] Finally, S4 transmits the processed multibeam image data to the image display and control module for display.

[0085] Repeat steps S1 to S4 to perform multiple underwater imaging operations.

[0086] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A sound fence type multibeam sonar imaging device, characterized in that, include: Acoustic uniform linear array combination, multi-channel impedance matching module, multi-channel transmitter module, multi-channel receiver module and signal control and processing module; The acoustic uniform linear array is used to complete electroacoustic conversion to realize signal transmission and reception, and to decompose / synthesize narrowband acoustic signals into broadband electrical signals. The multi-channel impedance matching module is connected to the acoustic uniform linear array combination to improve the electroacoustic conversion efficiency of the underwater acoustic transducer in the acoustic uniform linear array combination. The multi-channel transmitter module is signal-connected to the multi-channel impedance matching module and is used to phase-shift the signal and drive the acoustic uniform linear array to transmit the signal. The multi-channel receiver module is signal-connected to the multi-channel impedance matching module and is used to perform phase shifting, conditioning, and acquisition on the received signal. The signal control and processing module is connected to the multi-channel transmitter module and the multi-channel receiver module respectively, and is used to control the multi-channel transmitter module and the multi-channel receiver module to transmit or receive signals, and to realize sonar imaging processing. The acoustic uniform linear array combination includes at least three acoustic uniform linear arrays, and each acoustic uniform linear array includes N array element groups, each array element group including four array elements arranged in polarity +, -, -, +. The first positive element of each array element group is connected to channel CH1; The first negative pole element of each array element group is connected to channel CH2; The second negative pole element of each array element group is connected to channel CH3; The second positive element of each array element group is connected to channel CH4.

2. The acoustic fence type multibeam sonar imaging device according to claim 1, characterized in that, If the phase difference between the four channels is +90°, a directional beam can be formed on the right side of the normal. The formula for the directional beam is as follows: If the phase difference between the four channels is -90°, a directional beam can be formed to the left of the normal. The formula for the directional beam is as follows: If the phase difference between the four channels is 0°, a symmetrical directional beam can be formed on the left and right sides of the normal. The formula for the directional beam is as follows: in, For the speed of sound, The number of array elements is equal to 4N. For the spacing between array elements, For signal frequency, For direction; The absolute values ​​of the main lobe positions of the three directional beams mentioned above are: 。 3. The acoustic fence type multibeam sonar imaging device according to claim 1, characterized in that, The multi-channel transmitter module includes a phase shifter, a digital-to-analog converter, and a power amplifier connected in sequence. The multi-channel receiver module includes a phase shifter, a signal conditioner, and an analog-to-digital converter connected in sequence.

4. The acoustic fence type multibeam sonar imaging device according to claim 1, characterized in that, The signal control and processing module includes a signal connection FPGA unit, a DSP unit, and an ARM unit.

5. The acoustic fence type multibeam sonar imaging device according to claim 1, characterized in that, It also includes an image display and control module, which is connected to the signal control and processing module. The image display and control module is used to input control commands to control the acoustic fence type multibeam sonar imaging device and to receive and display image data output from the signal control and processing module.

6. The acoustic fence type multibeam sonar imaging device according to claim 1, characterized in that, It also includes a sonar power module to provide power to the various modules within the acoustic fence-type multibeam sonar imaging device.

7. A method for acoustic fence-type multibeam sonar imaging, configured in the acoustic fence-type multibeam sonar imaging device as described in any one of claims 1 to 6, characterized in that, The steps include: S1: The signal control and processing module controls the multi-channel transmitter module to transmit signals, while the multi-channel receiver module starts receiving echo signals at fixed intervals. S2: Input the echo signal to the signal control and processing module for preprocessing; S3: Using the signal control and processing module, time-frequency analysis is used to perform multi-beam imaging processing on the preprocessed echo signal; S4: Transmit the processed multibeam image data to the image display and control module for display; S5: Repeat steps S1 to S4.

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