A water-filled spherical shell sonar bell device and underwater target identification method

Abstract

A water-filled spherical shell sonar clock device in water comprises: an elastic spherical shell made of stainless steel, with at least one water injection hole and at least one air outlet hole on the surface; and a water injection device for injecting a preset amount of water into the elastic spherical shell through the water injection hole. The present invention utilizes the unique intermediate frequency matching resonance characteristics of the elastic spherical shell in water, regulates the intermediate frequency matching resonance characteristics by adjusting the thickness of the spherical shell, the water filling degree and the internal horizontal plank structure, constructs a classification and recognition model in combination with a BP neural network, establishes a mapping relationship between the sonar clock structure and its echo sound identification, and realizes passive sound identification based on the spherical shell sonar clock device, and has a small size, strong echo, a wide range of applicable frequency bands, no need to carry external energy, and has the advantages of good durability and strong concealment. It is suitable for marking surface and underwater navigation targets, position marking and tracking of underwater sunken ships, oil and gas pipelines and other structures, as well as underwater navigation and positioning of underwater vehicles and surface ships.

Description

Technical Field

[0001] The invention relates to a passive acoustic identification of an underwater target and an underwater navigation positioning device, in particular to an underwater water-filled spherical shell sonar bell device and an underwater target identification method. Background Art

[0002] With the continuous enrichment and development of underwater target types, from traditional large surface and underwater ships to various small unmanned vehicles, mines and other small targets, to collaborative cluster targets, and even underwater civil facilities such as submarine pipelines, underwater identification, positioning and navigation are becoming more and more important for their normal operation. Sound waves that can propagate over long distances in water are currently the most commonly used communication method underwater. Underwater remote positioning, identification and navigation rely heavily on underwater acoustic beacons. At present, underwater acoustic beacons mainly work in an active way by actively transmitting acoustic signals. Their communication has problems such as narrow frequency band, low communication rate and high bit error rate. It will also reduce the underwater acoustic stealth performance of the target and destroy its concealment. At the same time, its working time is limited by the energy it carries, and it occupies a large space and has a relatively high cost. Therefore, it is expected to explore new working mechanisms. Compared with active methods, there are fewer passive underwater identification methods. At present, there are only corner reflector structures that use the sound ray focusing enhancement effect and polymer (PMMA) solid ball structures that use the low-frequency Rayleigh wave resonance effect. These enhancement / resonance features have good application prospects underwater. The diverse target echo characteristics need to be further explored and applied in the field of target detection and identification, and the target detection, identification and navigation technical means in complex marine environments and cluster operations need to be further enriched and improved. The present invention proposes to design a sonar bell device using a spherical shell structure with a shell bending wave intermediate frequency matching resonance effect, and to achieve target-specific acoustic marking or underwater auxiliary navigation and positioning of a vehicle through sonar bells of different structural forms. It has a simple and practical structure, a wide frequency band, and is suitable for active sonar detection and identification in water. Summary of the invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides an underwater water-filled spherical shell sonar bell device and an underwater target identification method. By regulating the intermediate frequency matching resonance characteristics of the elastic spherical shell with different spherical shell thicknesses, water filling degrees and internal cross-boards, a classification and recognition model is constructed with the help of a BP neural network to establish a mapping relationship between the sonar bell structure and the echo sound identification, thereby realizing passive sound identification based on the spherical shell sonar bell device, which has good concealment. The detected target does not need to carry energy and its supporting instruments and equipment, thereby improving the durability and stability of the device and saving additional space and mass of the target.

[0004] Technical solution of the present invention

[0005] An underwater water-filled spherical shell sonar bell device is characterized in that it includes:

[0006] An elastic spherical shell, which is made of stainless steel and has at least one water injection hole and at least one air outlet hole on its surface. The water injection hole and the air outlet hole are sealed by watertight bolts to ensure the sealing of the spherical shell;

[0007] The water injection device is used to inject a preset amount of water into the elastic spherical shell through the water injection hole.

[0008] Preferably, at least one transverse plank is provided inside the elastic spherical shell, and the thickness of the transverse plank is equivalent to the shell thickness of the elastic spherical shell, which is used to increase the propagation path of the shell elastic wave, thereby generating more resonance characteristics and expanding the form of the sound identification structure.

[0009] Preferably, a plurality of hooks are provided on the surface of the elastic spherical shell for connecting external ropes for installation.

[0010] Preferably, the water injection device is a needle-tube water injection device or a funnel-type water injection device.

[0011] By changing the thickness of the elastic spherical shell, the amount of water filled, and the position and number of the cross planks, the intermediate frequency matching characteristics of the sonar clock device can be changed, thereby forming a variety of acoustic identifiers or codes in the frequency domain.

[0012] Specifically, by changing the thickness and radius ratio of the elastic spherical shell, the resonance peaks of the spherical shell at the same outer diameter are distributed in different frequency bands, thereby forming a variety of acoustic identifications or codes in the frequency domain. As the thickness-to-diameter ratio of the spherical shell increases, its mid-range resonance frequency decreases. As the amount of water increases, the amplitude of its morphological function increases, and the resonance frequency shifts. The closer the radius of the spherical shell cross-laying board is to the radius of the spherical shell, the larger the resonance frequency range corresponding to its morphological function.

[0013] By changing the amount of water, the propagation speed of the surround wave on the surface of the spherical shell changes, the resonance peak shifts, and multiple echo paths are generated. As the amount of water increases, the amplitude of its morphological function increases and the resonance peak shifts. When the amount of water changes from no water to full water, the medium on both sides of the spherical shell changes, the propagation speed of the surround wave on the surface of the spherical shell changes, and because the surround wave is reflected near the water interface, multiple echo paths are generated, and the time domain echo sequence of the spherical shell changes.

[0014] By adding a transverse board inside the spherical shell, multiple resonance peaks are generated when the echo meets the phase interference condition at a specific frequency. The closer the radius of the transverse board of the spherical shell is to the radius of the spherical shell, the larger the resonance frequency range corresponding to its morphology function.

[0015] The acoustic principle of the present invention is:

[0016] Under active sonar illumination, bending waves a 0-The wave propagates in the spherical shell. At a specific frequency, the echo and the incident wave produce phase interference, and the phase difference satisfies an integer multiple of 2π, producing a strong resonance peak in the medium and high frequency bands. This echo feature can be used for target acoustic identification and scattered sound field control design.

[0017] The normalized frequency ka value corresponding to the echo resonance characteristic is about 6.28 to 50.3, so that the resonance characteristic regulation of the lower frequency band can be achieved by using a smaller spherical shell. For example, for a spherical shell with a radius of 15 cm, the ratio of shell thickness to radius is about 4%, and the frequency matching resonance frequency is within the frequency band of 10kHz to 40kHz, which has a wider frequency band range and a large available space, and is also a more suitable frequency band for active sonar detection.

[0018] The sound wave at a specific frequency couples with the surface of the spherical shell and circulates along the surface of the spherical shell before decoupling and radiating outward. At the decoupling point, part of the surrounding wave continues to circulate along the spherical shell, and part of it decouples and radiates outward. The surrounding wave circulates along the surface of the spherical shell, and the arrival time difference between the surrounding wave and the mirror reflection wave can be expressed by the following formula.

[0019]

[0020] Wherein, n=1, 2, ... represents the n+1th echo in the spherical shell time domain echo sequence. for a 0- The wave group velocity, c is the speed of sound in water, and a is the radius of the spherical shell.

[0021] There are three main ways to design sonar bells of different structures to achieve echo feature control:

[0022] The first method is to change the thickness of the spherical shell. The change in the ratio of thickness to radius makes the resonance peaks of the spherical shell distributed in different frequency bands under the same outer diameter, thereby forming a variety of acoustic identifiers or codes in the frequency domain. The structural form is designed and the shell thickness is calculated according to the needs of underwater structure echo feature recognition.

[0023] The second method is to change the water filling amount. Under water filling conditions, due to the change of the medium on both sides of the spherical shell, the propagation speed of the surround wave on the surface of the spherical shell changes, causing the resonance peak to shift. In the process of propagation in the structure, the surround wave is continuously decoupled from the shell surface and leaked into the water, generating multiple echo paths, and the echo amplitude changes. According to the specific spectrum peak distribution of the spherical shell echo morphology function at different water filling heights, a variety of acoustic identification or coding is formed in the frequency domain. The structural form is designed and the water filling amount is calculated according to the needs of underwater structure echo feature recognition.

[0024] The third method is to add a transverse board inside the spherical shell. The propagation path of the bending wave on the surface of the spherical shell changes, so that multiple resonance peaks are generated when the echo meets the phase interference condition at a specific frequency. The structural form and the position of the transverse board are designed according to the needs of identifying the characteristics of the underwater structure echo.

[0025] The method also includes a step of processing the echo signal of the sonar clock device and constructing a sound recognition model, the step comprising:

[0026] Extract the original transmission signal and the original echo signal according to the time window, and perform convolution processing with the long pulse frequency modulation signal of the same frequency respectively;

[0027] The convolved transmission signal and echo signal are subjected to Hilbert transform to obtain the envelope, and the intensity of the transmission signal and the echo signal are obtained. The ratio of the two is multiplied by the detection distance r of the target (energy conversion is performed according to the attenuation of spherical waves) and compared with the reflected sound pressure amplitude a / 2 of the absolute reflection sphere, which is the backscattering morphology function of the target.

[0028]

[0029] Where |F| is the amplitude of the morphological function, |p i | and |p s | is the transmitted signal and echo amplitude, f is the frequency, a is the radius of the spherical shell, and r is the distance from the active sonar to the target.

[0030] The morphological functions of the sonar bells of the above three structural types are obtained in all directions. All morphological function data are labeled according to the target structure type, and all directions of each structural type target are labeled with the same label, thereby establishing a database based on the echo morphological functions of different structural types.

[0031] The number of them is randomly divided into training set and test set according to the appropriate ratio, and the training set is trained by BP neural network, the appropriate number of network layers and the number of neurons in each layer are set, and the appropriate activation function is selected. The trained model is tested for classification and recognition by the test set.

[0032] When designing the structure of the sonar bell, full consideration is given to the changes in the peak value of the morphological function spectrum, so that the spectral characteristics of its elastic wave echo have great differences, thereby ensuring a high accuracy rate in the classification and recognition test of the training model, and completing the acoustic identification of sonar bells with different shell thicknesses, water filling states, and added cross planks.

[0033] The device of the present invention can adjust the size of the spherical shell according to the application scenario, calculate the target characteristic frequency band according to the normalized frequency ka value, and thus adjust the active sonar action frequency band.

[0034] The device of the present invention can be used for underwater position marking and navigation, including surface and underwater navigation target marking, underwater shipwreck and oil and gas pipeline and other structure position marking and tracking, underwater navigation and positioning of underwater vehicles and surface ships. When used for underwater target marking, it is installed on the target, and when used for route calibration and navigation positioning, it can be placed in the water alone.

[0035] On the other hand, the present invention also provides a method for underwater target identification using the above-mentioned underwater water-filled spherical shell sonar bell device, which is characterized in that it includes:

[0036] Inject a preset amount of water into the elastic spherical shell, and seal the water injection hole and the air outlet hole with watertight bolts;

[0037] The sonar clock device is installed on an underwater target, or placed in the water alone for navigation and positioning of a waterway;

[0038] Using active sonar to illuminate the sonar clock device, and receiving and analyzing its echo signal;

[0039] According to the resonance characteristics of the echo signal, a pre-trained sound recognition model is used to identify the structural form of the sonar bell device, thereby determining the position of the underwater target or the navigation information of the waterway.

[0040] The present invention has the following advantages:

[0041] (1) The present invention utilizes the echo characteristics of the bending wave in the spherical shell to produce a strong coincident resonance effect in the medium and high frequency bands for target acoustic identification and echo control design. The elastic wave resonance characteristics are significant, and the resonance characteristics of the lower frequency band can be controlled by using a smaller spherical shell. In addition, the present invention has a wider frequency band range and a large available space, which is more suitable for the working frequency band of active sonar detection.

[0042] (2) The sonar clock of the present invention is a passive identification device that does not require energy and supporting instruments and equipment to maintain active signal transmission. It has a simple and practical structure, low cost, good durability and strong concealment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of active sonar detection based on spherical shell echo intermediate frequency coincidence resonance provided by the present invention;

[0044] Figure 2 The sonar bells and water injection devices of different structural forms provided by the present invention include: (a) a light spherical shell, (b) a water-filled spherical shell, (c) a spherical shell with a transverse slab, (d) a water injection device, (e) a watertight bolt installation device, and (f) a watertight bolt;

[0045] Figure 3 A flow chart for establishing an active sonar echo signal processing and sound recognition model provided by the present invention;

[0046] Figure 4 The echo morphology functions of the sonar bells of different structural forms provided by the present invention are: (a) light spherical shell, (b) water-filled spherical shell, and (c) spherical shell with cross panels;

[0047] Figure 5The model training and voice recognition results based on the BP neural network provided in the embodiment of the present invention.

[0048] Numbers in the figure: 1, steel ball shell; 2, water injection hole; 3, air outlet; 4, watertight bolt; 5, water injection device; 6, hook; 7, water; 8, cross board; 9, rubber sealing ring. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] See also Figure 1 and Figure 2 The underwater water-filled spherical shell sonar bell device of the present invention comprises an elastic spherical shell, a water-filling device and watertight bolts.

[0051] The elastic spherical shell is a stainless steel spherical shell with water injection holes and air outlet holes on its surface. The openings should not be too large to affect the structural sound scattering characteristics. The outer diameter of the spherical shell can be 0.15m, the shell thickness is 6mm, and the bolt specifications of the water injection holes and air outlet holes are M8.

[0052] According to the preset water filling amount, water is injected into the spherical shell through the water injection hole by means of a water injection device. The water injection device can be a common needle-type water injection device or a funnel-type water injection device, and its water injection diameter is smaller than the water injection hole.

[0053] The air outlet holes are used to discharge the air in the shell, and both holes are sealed with the watertight bolts to ensure that the bolts have sufficient tightening force.

[0054] A transverse plank structure may be added inside the elastic spherical shell, the thickness of the plank being equal to the shell thickness. The transverse plank increases the propagation path of the shell elastic wave, thereby generating more resonance characteristics and expanding more forms of acoustic identification structures.

[0055] The surface of the elastic spherical shell is provided with six small hooks distributed in six coordinate axis directions for connecting Kevlar ropes so that the device can be installed on an underwater target for target acoustic identification, or independently installed in the water for channel navigation and positioning. It is not advisable to use a hard connection method to avoid affecting the structural sound scattering characteristics.

[0056] The acoustic principle of the designed sonar bell device is:

[0057] Under active sonar illumination, bending waves a 0-The wave propagates in the spherical shell. At a specific frequency, the echo and the incident wave produce phase interference, and the phase difference satisfies an integer multiple of 2π, producing a strong resonance peak in the medium and high frequency bands. This echo feature can be used for target acoustic identification and scattered sound field control design.

[0058] The normalized frequency ka value corresponding to the echo resonance characteristic is about 6.28 to 50.3, so that the resonance characteristic regulation of the lower frequency band can be achieved by using a smaller spherical shell. For example, for a spherical shell with a radius of 15 cm, the ratio of shell thickness to radius is about 4%, and the frequency matching resonance frequency is within the frequency band of 10kHz to 40kHz, which has a wider frequency band range and a large available space, and is also a more suitable frequency band for active sonar detection.

[0059] The sound waves at a specific frequency couple with the surface of the spherical shell and circulate along the surface of the spherical shell before being decoupled and radiated outward. At the decoupling point, part of the surrounding waves continue to circulate along the surface of the spherical shell, and part of them are decoupled and radiated outward into the water. The surrounding waves circulate along the surface of the spherical shell, and the arrival time difference between the surrounding waves and the mirror reflection waves can be expressed by the following formula.

[0060]

[0061] Wherein, n=1, 2, ... represents the n+1th echo in the spherical shell time domain echo sequence. for a 0- The wave group velocity, c is the speed of sound in water, and a is the radius of the spherical shell.

[0062] There are three main ways to design sonar bells of different structures to achieve echo feature control:

[0063] The first method is to change the thickness of the spherical shell. The change in the ratio of thickness to radius makes the resonance peaks of the spherical shell distributed in different frequency bands under the same outer diameter, thereby forming a variety of acoustic identifiers or codes in the frequency domain. The structural form is designed and the shell thickness is calculated according to the needs of underwater structure echo feature recognition.

[0064] The second method is to change the water filling amount. Under water filling conditions, due to the change of the medium on both sides of the spherical shell, the propagation speed of the surround wave on the surface of the spherical shell changes, causing the resonance peak to shift. In the process of propagation in the structure, the surround wave is continuously decoupled from the shell surface and leaked into the water, generating multiple echo paths, and the echo amplitude changes. According to the specific spectrum peak distribution of the spherical shell echo morphology function at different water filling heights, a variety of acoustic identification or coding is formed in the frequency domain. The structural form is designed and the water filling amount is calculated according to the needs of underwater structure echo feature recognition.

[0065] The third method is to add a transverse board inside the spherical shell. The propagation path of the bending wave on the surface of the spherical shell changes, so that multiple resonance peaks are generated when the echo meets the phase interference condition at a specific frequency. The structural form and the position of the transverse board are designed according to the needs of identifying the characteristics of the underwater structure echo.

[0066] Figure 4 The morphological function results for different spherical shell thickness-diameter ratios, water filling amounts, and spherical shell cross-plate positions are given. As the spherical shell thickness-diameter ratio increases, the mid-range resonance frequency decreases. As the water filling amount increases, the amplitude of the morphological function increases and the resonance frequency shifts. The closer the radius of the spherical shell cross-plate is to the spherical shell radius, the larger the resonance frequency range corresponding to the morphological function is.

[0067] For the three types of sonar bells mentioned above, data processing is performed on the sonar bell echoes and a sound recognition model is established. Figure 3 The specific method is:

[0068] Take the time window to extract the transmission signal and the echo signal, convolve them with the long pulse frequency modulation signal of the same frequency, and use Hilbert transform to get the envelope to get the transmission signal and echo signal strength. The ratio of the two is the backscattering morphology function. For the morphology function results of the typical structure sonar bell, please refer to Figure 4 .

[0069]

[0070] where |F| is the amplitude of the morphology function, |p i | and |p s | is the transmitted signal and echo amplitude, f is the frequency, a is the radius of the spherical shell, and r is the distance from the active sonar to the target.

[0071] The morphological functions of the sonar bells of the above three structural types in all directions are obtained, and the morphological function curves are fitted. All morphological function fitting data are labeled according to the target structure type, and all directions of each structural type target are labeled with the same label, so as to establish a database based on the echo morphological functions of different structural types.

[0072] The number of them is randomly divided into training set and test set in a ratio of 7:3. The training set is trained using BP neural network, the appropriate number of network layers and number of neurons in each layer are set, and the appropriate activation function is selected. The trained model is tested by classification using the test set.

[0073] When designing the sonar bell structure, the peak value change of the morphological function spectrum is fully considered to make the elastic wave echo spectrum characteristics have a large difference, so as to ensure that the training model classification and recognition test has a high accuracy rate, and complete the acoustic identification of sonar bells with different shell thickness, water filling state, and cross-planking structures. Please refer to the model training and acoustic recognition results based on BP neural network Figure 5 In the figure, the horizontal axis represents the sample number of the test set, and the vertical axis represents the target classification, which is divided into 6 categories: 1-spherical shell filled with 1 / 3 water; 2-spherical shell filled with 2 / 3 water; 3-air thickness to diameter ratio of 0.04 inside the spherical shell; 4-air thickness to diameter ratio of 0.05 inside the spherical shell; 5-adding a plate inside the spherical shell at 1 / 3 of the diameter; 6-adding a plate inside the spherical shell at 2 / 3 of the diameter. The red dots represent the correct classification number in the test set, and the black dots represent the classification number predicted by the trained BP neural network for the test set, with a prediction accuracy of 90.2%.

[0074] The device of the present invention can adjust the size of the spherical shell according to the application scenario, calculate the target characteristic frequency band according to the normalized frequency ka value, and thus adjust the active sonar action frequency band.

[0075] The device of the present invention can be used for underwater position marking and navigation, including surface and underwater navigation target marking, underwater shipwreck and oil and gas pipeline and other structure position marking and tracking, underwater navigation and positioning of underwater vehicles and surface ships. When used for underwater target marking, it is installed on the target, and when used for route calibration and navigation positioning, it can be placed in the water alone.

[0076] The experiment shows that the present invention uses a spherical shell structure with a shell bending wave intermediate frequency matching resonance effect to design a sonar clock device, which has significant elastic wave resonance characteristics, can use a smaller spherical shell to achieve resonance characteristics regulation of a lower frequency band, and has a wider frequency band range, a large available space, and is more suitable for the active sonar detection frequency band. The device is a passive identification device, does not need to carry energy and its supporting instruments and equipment to maintain active transmission signals, has a simple and practical structure, low cost, and has the advantages of good durability and strong concealment.

[0077] The above product can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-filled spherical shell sonar bell device, characterized in that: include: An elastic spherical shell, which is made of stainless steel and has at least one water injection hole and at least one air outlet hole on its surface. The water injection hole and the air outlet hole are sealed by watertight bolts to ensure the tightness of the spherical shell. At least one transverse paving board is provided inside the elastic spherical shell. The thickness of the transverse paving board is equivalent to the shell thickness of the elastic spherical shell, and is used to increase the propagation path of the shell elastic wave, thereby generating more resonance characteristics and expanding the form of the sound identification structure; A water injection device, used for injecting a preset amount of water into the elastic spherical shell through the water injection hole; By changing the thickness of the elastic spherical shell, the amount of water filled, and the position and number of the cross planks, the intermediate frequency matching characteristics of the sonar clock device can be changed, thereby forming a variety of acoustic identifiers or codes in the frequency domain.

2. The underwater water-filled spherical shell sonar clock device according to claim 1, characterized in that: A plurality of hooks are also provided on the surface of the elastic spherical shell for connecting external ropes for installation.

3. The underwater water-filled spherical shell sonar clock device according to claim 1, characterized in that: The water injection device is a needle-tube type water injection device or a funnel type water injection device.

4. The underwater water-filled spherical shell sonar clock device according to claim 1, characterized in that: By changing the ratio of the thickness and radius of the elastic spherical shell, the resonance peaks of the spherical shell at the same outer diameter are distributed in different frequency bands, thereby forming a variety of acoustic identifications or codes in the frequency domain.

5. The underwater water-filled spherical shell sonar clock device according to claim 1, characterized in that: By changing the amount of water filling, the propagation speed of the surround wave on the surface of the spherical shell changes, the resonance peak shifts, and multiple echo paths are generated.

6. The underwater water-filled spherical shell sonar clock device according to claim 1, characterized in that: By adding transverse panels inside the spherical shell, multiple resonance peaks are generated when the echo meets the phase interference condition at a specific frequency.

7. The underwater water-filled spherical shell sonar clock device according to any one of claims 1 to 6, characterized in that: The method also includes a step of processing the echo signal of the sonar clock device and constructing a sound recognition model, the step comprising: Extract the original transmission signal and the original echo signal according to the time window, and perform convolution processing with the long pulse frequency modulation signal of the same frequency respectively; Perform Hilbert transform on the convolved transmission signal and echo signal to obtain the envelope, and obtain the intensity of the transmission signal and echo signal. The ratio of the two is the backscattering morphology function. Obtain the morphological functions of all directions of spherical shell sonar clocks with different structural forms, fit and mark the morphological function curves, and establish a database based on the backscattering morphological functions of different structural types to distinguish sonar clock devices with different structural forms; The BP neural network is used to train the training set in the database, and the trained model is classified and tested through the test set to complete the sonar bell acoustic identification of different shell thicknesses, water filling states, and cross-planking structures.

8. The underwater water-filled spherical shell sonar clock device according to claim 7, characterized in that: The backscattering morphology function is: Where |F| is the amplitude of the backscattering morphology function, |p i | is the amplitude of the transmitted signal, |p s | is the echo signal amplitude, f is the frequency, a is the radius of the elastic spherical shell, and r is the distance from the active sonar to the target.

9. A method for underwater target identification using the underwater water-filled spherical shell sonar bell device according to any one of claims 1 to 6, characterized in that: include: Inject a preset amount of water into the elastic spherical shell, and seal the water injection hole and the air outlet hole with watertight bolts; The sonar clock device is installed on an underwater target, or placed in the water alone for navigation and positioning of a waterway; Using active sonar to illuminate the sonar clock device, and receiving and analyzing its echo signal; According to the resonance characteristics of the echo signal, a pre-trained sound recognition model is used to identify the structural form of the sonar bell device, thereby determining the position of the underwater target or the navigation information of the waterway.

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