Bionic low-frequency pulse generation device and method based on gun and shrimp structure

Abstract

The invention discloses a bionic low-frequency pulse generation device and method based on a gun and shrimp structure, and relates to the technical field of underwater acoustics and bubble acoustics. Comprising a power module, a bionic sounding module, a control module, a power module and a fixed platform, the power module is used for converting the accumulated elastic potential energy into kinetic energy; the bionic sound production module is connected with the power module and the fixed platform and is used for forming sound pulses; the control module is connected with the power module and used for controlling the characteristics of the sound pulses; the power module is connected with the control module through a wire and used for providing direct-current power; and the fixing platform is connected with the control module and used for fixing device components. A bionic acoustic miniaturized structure device is designed with bionics as a starting point, controllable generation of low-frequency and broadband acoustic signals is achieved, and a new reference thought is provided for design of a novel underwater acoustic transducer.

Description

Technical Field

[0001] The present invention relates to the technical fields of underwater acoustics and bubble acoustics, and particularly to a bionic low-frequency pulse generation device and method based on the structure of a pistol shrimp. Background Art

[0002] Seawater has frequency differences in the attenuation of sound waves. The lower the frequency of the sound wave, the smaller the attenuation, so it has better long-distance propagation ability and can better meet the needs of medium- and long-distance underwater acoustic communication and detection. In addition, with the continuous improvement of vibration and noise reduction technologies, the noise level of modern submarines shows a rapid downward trend, which brings difficulties to passive detection. Modern submarines use anechoic tiles to reduce their own noise and target strength, but the anechoic tiles have poor energy absorption for low-frequency sound waves, which provides greater feasibility for using low-frequency sound waves for active detection of modern submarines. This means that underwater acoustic transducers need to develop in the directions of low frequency, wideband, and high power. However, due to the working characteristics of existing low-frequency sound sources in the low-frequency band, the wavelength is often large, resulting in technical bottlenecks such as large size and narrow working bandwidth of low-frequency sound sources. Developing new low-frequency and wideband sound sources has significant scientific value and potential application prospects.

[0003] The pistol shrimp is a natural low-frequency, wideband, and strong radiation sound source existing in the ocean. The pistol shrimp has strong aggressiveness and can emit ultrasonic pulses with an energy of up to 230 dB to protect its territory. When the large claw of the pistol shrimp closes quickly, it emits a high-speed water jet, and a vortex will be formed around it. A strong pressure relief occurs in the vortex core, resulting in the formation of a cavitation ring. The cavitation ring moves along the axis of the jet, and it will collapse and rebound shortly after its formation, generating a powerful sound pulse, which has the characteristics of low frequency and wideband. This provides a natural reference for the design of low-frequency, wideband, and strong radiation sound sources.

[0004] Therefore, providing a bionic low-frequency pulse generation device and generation method based on the structure of a pistol shrimp to solve the difficulties existing in the prior art is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a bionic low-frequency pulse generation device and method based on the structure of a pistol shrimp. Starting from bionics, a bionic acoustic miniaturized structural device is designed to achieve controllable generation of low-frequency and wideband acoustic signals, providing a new reference idea for the design of new underwater acoustic transducers.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A bionic low-frequency pulse generation device based on the structure of a pistol shrimp, comprising a power module, a bionic sound generation module, a control module, a power supply module, and a fixed platform; The power module is used to convert the stored elastic potential energy into kinetic energy; The bionic sound - generating module, connected to the power module and the fixed platform, is used to generate sound pulses; The control module, connected to the power module, is used to control the characteristics of the sound pulses; The power supply module, connected to the control module by wires, is used to provide DC power; The fixed platform, connected to the control module, is used to fix the device components.

[0007] Optionally, the power module uses a torsion spring. The included angle at both ends of the torsion spring is 0°, and the working rotation center is consistent with the rotation center of the moving part of the bionic sound - generating module.

[0008] Optionally, it further includes an auxiliary module. The auxiliary module includes a bearing unit and wires.

[0009] Optionally, the bionic sound - generating module includes a movable chela and a fixed chela. A plunger is provided on the movable chela, and a rotating shaft is provided on the plunger. The movable chela is rigidly connected to one end of the torsion spring, and the rotating shaft is fixed on the fixed platform through the bearing unit; a cavity is provided on the fixed chela and is fixed to the fixed platform.

[0010] Optionally, the control module includes a high - torque servo, a ratchet, a pawl, a pawl - control servo, and a control circuit board for controlling the operation of the high - torque servo and the pawl - control servo. The high - torque servo is rigidly connected to the other end of the torsion spring. The ratchet is rigidly connected to the rotating shaft of the movable chela. The pawl is rigidly connected to the fixed platform through the bearing unit. The rotating arm of the pawl - control servo is rigidly connected to the pawl. The pawl - control servo is fixed to the fixed platform, and the ratchet cooperates with the pawl and the pawl - control servo to work.

[0011] Optionally, the power supply module and the control circuit board are the above - water part of the system, and the rest of the components are the underwater part. The fixed platform is embedded with grooves and fixing devices for fixing the underwater part, and the underwater part and the above - water part are connected by wires.

[0012] A bionic low - frequency pulse generation method based on the structure of a snapping shrimp, applied to the bionic low - frequency pulse generation device described in any one of the above, includes the following steps: Reconstruct the snapping - shrimp chela model based on CT scanning technology; Generate a movable chela and a fixed chela based on the snapping - shrimp chela model, and establish a 3D model file in combination with SOLIDWORKS software; Use 3D printing technology to print the 3D model file to obtain the bionic low - frequency pulse - generating device; Make the pawl - control servo rotate counter - clockwise so that the pawl contacts the ratchet. The control circuit board issues an instruction, and the high - torque servo rotates forward from its original position to drive the chela to rotate to a set angle, and the pawl fixes the ratchet; Reverse the high-torque servo to its original position. One end of the torsion spring is fixed to one end of the movable chela, and the other end is fixed to the high-torque servo. The rotation of the high-torque servo stores energy in the torsion spring. At the set moment, the ratchet pawl controls the servo to rotate clockwise, and the ratchet pawl rotates away from the ratchet wheel, causing the movable chela to rotate to achieve the rapid closing of the movable chela and the fixed chela; When the two chelas are closed, the water in the fixed chela cavity is ejected from the nozzle, forming a high-speed jet, generating a vortex, causing a pressure drop, reducing the cavitation number to form cavitation bubbles. The bubbles vibrate and burst, forming a bionic pistol shrimp pulse signal.

[0013] Optionally, the expression for the radius change of the cavitation bubble is: , where R, , are respectively the radius of the bubble and its first and second derivatives with respect to time, c is the speed of sound in water, is the density of water, is the surface tension of the water-vapor interface, P(t) is the pressure outside the bubble, P(R,t) is the pressure inside the bubble, is the viscosity of water, P vap is the water vapor pressure.

[0014] Optionally, the vibration of the cavitation bubble radiates sound waves to form a sound pulse. The sound pressure radiated by the cavitation bubble and the expression for the radius change are:

[0015] where r is the distance between the receiving point and the cavitation bubble. When the cavitation bubble collapses, the generated sound pressure is the largest.

[0016] Through the above technical solutions, compared with the prior art, the present invention provides a bionic low-frequency pulse generation device and method based on the structure of the pistol shrimp, having the following beneficial effects: 1) The present invention uses CT scanning technology to obtain a high-resolution three-dimensional structure model of the pistol shrimp and uses it to design a bionic pistol shrimp acoustic device, more accurately restoring the sound-generating structure of the pistol shrimp; 2) The present invention focuses on the generation of low-frequency and broadband sound signals, and uses a waterproof and controllable high-torque servo for driving to achieve mechanized and controllable operation, eliminating the need for manual operation required by the previous bionic pistol shrimp structure and further realizing the adjustment of acoustic signals; 3) The present invention uses 3D printing technology, which can quickly assemble and disassemble the device and can also quickly replace a damaged part, greatly reducing the maintenance and repair costs and meeting the practical requirements; 4) The present invention designs a bionic acoustic miniaturized structure device based on bionics, realizing the controllable generation of low-frequency and broadband sound signals, providing a reference for the design of new underwater acoustic transducers, and having scientific research value and engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the provided drawings.

[0018] Figure 1 It is a block diagram of a bionic low-frequency pulse generation device based on the structure of a pistol shrimp disclosed by the present invention; Figure 2 It is a schematic diagram of the principle of a bionic low-frequency pulse generation device based on the structure of a pistol shrimp disclosed in the embodiment of the present invention; Figure 3 It is a front view of a bionic low-frequency pulse generation device based on the structure of a pistol shrimp disclosed in the embodiment of the present invention; Figure 4 It is a top view of a bionic low-frequency pulse generation device based on the structure of a pistol shrimp disclosed in the embodiment of the present invention; Figure 5 It is a side view of a bionic low-frequency pulse generation device based on the structure of a pistol shrimp disclosed in the embodiment of the present invention; Figure 6 It is a schematic diagram of a moving chela disclosed in the embodiment of the present invention; Figure 7 It is a flowchart of a method for generating bionic low-frequency pulses based on the structure of a pistol shrimp disclosed in the embodiment of the present invention; Figure 8 It is a schematic diagram of the bionic sound signal emitted by the bionic low-frequency sound source of the pistol shrimp disclosed by the present invention; Among them, 1 is the moving chela; 2 is the fixed chela; 3 is the torsion spring; 4 is the high-torque servo; 5 is the ratchet; 6 is the pawl; 7 is the pawl control servo; 8 is the bearing unit; 9 is the fixed platform. Specific embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] The present invention discloses a bionic low-frequency pulse generation device based on the structure of a pistol shrimp, including a power module, a bionic sound generation module, a control module, a power supply module, and a fixed platform 9; The power module is used to convert the accumulated elastic potential energy into kinetic energy; The bionic sound generation module is connected to the power module and the fixed platform 9 and is used to form a sound pulse; A control module, connected to the power module, for controlling the characteristics of the acoustic pulse; A power supply module, connected to the control module by wires, for providing a DC power supply; A fixed platform 9, connected to the control module, for fixing the device components.

[0021] Further, referring to Figures 2 - 5 As shown, the power module uses a torsion spring 3. The included angle between the two ends of the torsion spring 3 is 0°, and the working rotation center is the same as the rotation center of the moving part of the bionic sound - generating module.

[0022] In this embodiment, the wire diameter of the torsion spring 3 is 2.5 mm, the outer diameter is 25 mm, and there are 8 turns in total, which can generate sufficient rotational angular velocity.

[0023] Further, it further includes an auxiliary module. The auxiliary module includes a bearing unit 8 and wires.

[0024] Specifically, the auxiliary module further includes a waterproof box, etc. The wires are circuit connection wires, used for power supply or data signal transmission. The waterproof box is a selected device, used for placing the water - based part of the system, that is, the power supply module and the control circuit board, and has the function of waterproofing.

[0025] Further, the bionic sound - generating module includes a movable chela 1 and a fixed chela 2. The shape of the movable chela 1 is as Figure 6 shown. There is a plunger on it. There is a rotating shaft on the plunger. The movable chela 1 is rigidly connected to one end of the torsion spring 3. The rotating shaft is fixed on the fixed platform 9 through the bearing unit 8; there is a cavity on the fixed chela 2, which is fixed on the fixed platform 9.

[0026] In this embodiment, the maximum length of the movable chela 1 is 36 mm, which is larger than the movable chela 1 of the actual scanned snapping shrimp. During the sound - generating process, the plunger on the movable chela 1 rotates rapidly by the energy provided by the torsion spring 3, squeezing the water body in the cavity. When the two chelae close, the water body in the cavity sprays out from the nozzle, forming a high - speed jet to generate a vortex, causing a pressure drop, and then resulting in a decrease in the local cavitation number. When the cavitation number is less than 1, cavitation bubbles may be generated. When the cavitation bubbles are squeezed and vibrated by the surrounding high - pressure water body, low - frequency and broadband acoustic pulses similar to the real snapping shrimp sound signal can be generated. When the cavitation number is less than 1, cavitation inception occurs. When the cavitation number is less than 0.5, stable cavitation will occur. After cavitation occurs, the vibration of the cavitation bubbles can radiate sound waves outward. Especially when the cavitation bubbles collapse, high - energy, low - frequency and broadband acoustic pulses are generated.

[0027] Further, the control module includes a high - torque servo 4, a ratchet 5, a pawl 6, a pawl control servo 7, and a control circuit board for controlling the operation of the high - torque servo 4 and the pawl control servo 7, The large-torque servo 4 is rigidly connected to the other end of the torsion spring 3. The ratchet 5 is rigidly connected to the rotating shaft of the moving chela 1. The pawl 6 is rigidly connected to the fixed platform 9 through the bearing unit 8. The rotating arm of the pawl control servo 7 is rigidly connected to the pawl 6. The pawl control servo 7 is fixed to the fixed platform 9. The ratchet 5 cooperates with the pawl 6 and the pawl control servo 7 to work.

[0028] In this embodiment, the large-torque servo 4 is a waterproof servo device. The supply voltage of the large-torque servo 4 is 5 - 9VDC, the working current is 1900mA, and the maximum torque is 73kg·cm. It is used to open the moving chela 1 in the closed bionic sound-generating structure to a set angle. The torsion spring 3 stores energy when the large-torque servo 4 rotates. Triggered at a set moment, the moving chela 1 rotates quickly under the drive of the energy of the above power module, generating a sound pulse. Through the control of the above servo, the generation time of the sound signal can be controlled by controlling the closing moment of the moving chela 1, and the initial energy can be controlled by controlling the opening angle of the moving chela 1, changing the characteristics of the generated cavitation bubbles, and thus controlling the characteristics of the sound pulse.

[0029] The ratchet 5 is a toothed ratchet, which can be used to control the rotation angle of the moving chela 1. The angle resolution is related to the number of teeth of the ratchet. If the number of teeth of the ratchet is n , then the adjustable angle resolution through this ratchet is 360 / n degrees. In this embodiment, the number of teeth of the ratchet is 4, so the adjustable angle resolution through this ratchet is 90 degrees. The ratchet 5 cooperates with the above pawl 6 and the pawl control servo 7 to work, and the pawl control servo 7 is a waterproof device. The pawl 6 makes the ratchet 5 rotate in only one direction, and when it rotates to the set angle, the pawl 6 can be used to fix the ratchet 5, so that the moving chela 1 in the bionic sound-generating module can be rotated to the set angle, thereby controlling the characteristics of the sound pulse. The supply voltage of the pawl control servo 7 is 4.8 - 6.5VDC, which is controlled by a PWM signal. When it rotates counterclockwise, the pawl 6 rotates towards the fixed platform 9 and contacts the ratchet 5, thereby being able to fix the ratchet 5. When the moving chela 1 rotates to the set angle and the torsion spring 3 stores energy, the pawl control servo 7 rotates clockwise, and the pawl 6 moves away from the ratchet 5, so that the torsion spring 3 releases its elastic potential energy, driving the moving chela 1 to rotate quickly, squeezing the water body in the cyst cavity to generate a high-speed jet, and thus generating a sound pulse.

[0030] In this embodiment, the control circuit board belongs to a programmable module. The control circuit board is electrically connected to both the large-torque servo 4 and the pawl control servo 7. The rotation angle and speed of the large-torque servo 4 can be controlled through program code, and the rotation direction of the pawl control servo 7 can be controlled. In this embodiment, the used control circuit board is an Arduino MEGA development board, which can be programmed through the official Arduino software to control the rotation speed and angle of the servo, as well as the rotation direction of the pawl control servo 7.

[0031] Furthermore, the power module and the control circuit board are the above-water part of the system, and the rest of the components are the underwater part. The fixed platform 9 is embedded with grooves and fixing devices for fixing the underwater part, and the underwater part is connected to the above-water part by wires.

[0032] Furthermore, the power module is a rechargeable DC power supply for supplying power to the control circuit board, the high-torque servo 4, and the pawl control servo 7.

[0033] In this embodiment, the power module is a lithium battery with a supply voltage of 7.2 VDC, which can directly supply power to the high-torque servo 4, and supplies power to the pawl control servo 7 and the control circuit board through a buck module.

[0034] A bionic low-frequency pulse generation method based on the structure of the pistol shrimp is applied to the bionic low-frequency pulse generation device according to any one of the above. Referring to Figure 7 as shown, it includes the following steps: Reconstruct the pistol shrimp chela model based on CT scanning technology; Generate the movable chela 1 and the fixed chela 2 based on the pistol shrimp chela model, and establish a 3D model file in combination with SOLIDWORKS software; Print the 3D model file by 3D printing technology to obtain the bionic low-frequency pulse generating device; Make the pawl control servo 7 rotate counterclockwise so that the pawl 6 contacts the ratchet 5. The control circuit board issues an instruction, and the high-torque servo 4 rotates forward from its original position to drive the chela 1 to rotate to a set angle, and the pawl 6 fixes the ratchet 5; Make the high-torque servo 4 reverse back to its original position. One end of the torsion spring 3 is fixed to one end of the movable chela 1, and the other end is fixed to one end of the high-torque servo 4. The high-torque servo 4 rotates to store energy in the torsion spring 3. At a set moment, the pawl control servo 7 rotates clockwise, and the pawl 6 rotates away from the ratchet 5, so that the movable chela 1 rotates and closes with the fixed chela 2; When the two chelae are closed, the water in the cavity of the fixed chela 2 is ejected from the nozzle, forming a high-speed jet, generating a vortex, causing a pressure drop, reducing the cavitation number to form cavitation bubbles, and the bubbles vibrate and burst to form a bionic pistol shrimp pulse signal.

[0035] Furthermore, computer tomography (CT) technology is a widely used non-destructive three-dimensional imaging technology at present, which can reflect the spatial structure of the sample in-situ without introducing artificial defects. Using this technology to perform three-dimensional imaging modeling on the large chela structure of the live pistol shrimp can greatly restore the real shrimp chela sound-generating structure. Remove the root of the shrimp chela, leaving only the fixed chela 2 with a cavity and the movable chela 1 with a plunger, in order to generate low-frequency and broadband sound pulses close to those emitted by real pistol shrimps.

[0036] Furthermore, the cavitation number calculation formula is: , In the formula, and are the pressure and velocity of the jet respectively, P V is the saturated vapor pressure of the water body at the ambient temperature, is the density of water. When the cavitation number is less than 1, cavitation inception occurs. When the cavitation number is less than 0.5, stable cavitation will be generated.

[0037] Furthermore, the expression for the radius change of the cavitation bubble is: , wherein, R, , are the radius of the bubble, its first derivative with respect to time and the second derivative with respect to time respectively, c is the speed of sound in water, is the density of water, is the surface tension of the water-vapor interface, P(t) is the pressure outside the bubble, and P(R,t) is the pressure inside the bubble, is the viscosity of water, P vap is the water vapor pressure, and P(R,t) is the pressure inside the bubble, which follows the van der Waals equation of state, and the expression is: , wherein, R0 is the initial radius of the bubble micro-core, P0 is the initial pressure inside the bubble, is the polytropic coefficient of the gas, and b is the van der Waals coefficient.

[0038] Furthermore, the vibration of the cavitation bubble radiates sound waves outward to form a sound pulse. The expression for the sound pressure radiated by the cavitation bubble and the radius change is: , wherein, r is the distance between the receiving point and the cavitation bubble. When the cavitation bubble collapses, the generated sound pressure is the maximum.

[0039] In a specific embodiment, the wire diameter of the torsion spring 3 is set to 2.5 mm, the outer diameter is 25 mm, and there are 8 turns in total. An acoustic emission test is carried out at a depth of 1.5 m underwater. During the test, when the moving chela 1 rotates and generates a cavitation bubble when switching from the open state to the closed state, the generated bionic pistol shrimp pulse signal is as Figure 8 shown.

[0040] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bionic low-frequency pulse generation device based on the structure of a pistol shrimp, characterized in that, It includes a power module, a bionic sound - generating module, a control module, a power supply module, and a fixed platform (9); The power module is used to convert the stored elastic potential energy into kinetic energy; The bionic sound - generating module is connected to the power module and the fixed platform (9), and is used to form sound pulses; The control module is connected to the power module and is used to control the characteristics of the sound pulses; The power supply module is connected to the control module by wires and is used to provide a DC power supply; The fixed platform (9) is connected to the control module and is used to fix the device components; The power module adopts a torsion spring (3). The included angle between the two ends of the torsion spring (3) is 0°, and the working rotation center is the same as the rotation center of the moving part of the bionic sound - generating module; It further includes an auxiliary module. The auxiliary module includes a bearing unit (8) and wires; The bionic sound - generating module includes a movable chela (1) and a fixed chela (2). A plunger is provided on the movable chela (1), and a rotating shaft is provided on the plunger. The movable chela (1) is rigidly connected to one end of the torsion spring (3), and the rotating shaft is fixed to the fixed platform (9) through the bearing unit (8). A cavity is provided on the fixed chela (2) and is fixed to the fixed platform (9).

2. The bionic low - frequency pulse generating device based on the structure of a pistol shrimp according to claim 1, wherein, The control module includes a high - torque servo (4), a ratchet (5), a pawl (6), a pawl control servo (7), and a control circuit board for controlling the operation of the high - torque servo (4) and the pawl control servo (7); The high - torque servo (4) is rigidly connected to the other end of the torsion spring (3), the ratchet (5) is rigidly connected to the rotating shaft of the movable chela (1), the pawl (6) is rigidly connected to the fixed platform (9) through the bearing unit (8), the rotating arm of the pawl control servo (7) is rigidly connected to the pawl, the pawl control servo (7) is fixed to the fixed platform (9), and the ratchet (5) cooperates with the pawl (6) and the pawl control servo (7) to work.

3. The bionic low - frequency pulse generating device based on the structure of a pistol shrimp according to claim 2, wherein, The power supply module and the control circuit board are the above - water part of the system, and the rest of the components are the underwater part. The fixed platform (9) is embedded with grooves and fixing devices for fixing the underwater part, and the underwater part is connected to the above - water part by wires.

4. A bionic low-frequency pulse generation method based on the structure of the pistol shrimp, which is used to execute a bionic low-frequency pulse generation device based on the structure of the pistol shrimp according to any one of claims 1-3, characterized in that, It includes the following steps: Reconstruct the pistol shrimp chela model based on CT scanning technology; Generate the movable chela (1) and the fixed chela (2) based on the pistol shrimp chela model, and establish a 3D model file by combining with SOLIDWORKS software; Print the 3D model file by using 3D printing technology to obtain the bionic low - frequency pulse generating device; Make the pawl control servo (7) rotate counter - clockwise so that the pawl (6) contacts the ratchet (5). The control circuit board issues an instruction, and the high - torque servo (4) rotates forward from its original position to drive the chela (1) and the ratchet (5) to rotate to a set angle, and the pawl (6) fixes the ratchet (5); Make the high - torque servo (4) rotate back to its original position. One end of the torsion spring (3) is fixed to one end of the movable chela (1), and the other end is fixed to the high - torque servo (4). The high - torque servo (4) rotates to store energy in the torsion spring (3). At a set moment, the pawl control servo (7) rotates clockwise, and the pawl (6) rotates away from the ratchet (5) to make the movable chela (1) rotate and quickly close with the fixed chela (2); When the two chelae are closed, the water in the sac cavity of the fixed chela (2) is ejected from the nozzle, forming a high-speed jet, generating a vortex, causing a pressure drop, reducing the cavitation number to form cavitation bubbles, and the bubbles vibrate and burst to form a bionic snapping shrimp pulse signal.

5. A bionic low-frequency pulse generation method based on the structure of a snapping shrimp according to claim 4, wherein The expression for the radius change of the cavitation bubble is: ， wherein, R, , are respectively the radius of the bubble, its first derivative with respect to time, and its second derivative with respect to time, c is the sound speed in water, is the density of water, is the surface tension of the water-gas interface, P(t) is the pressure outside the bubble, P(R,t) is the pressure inside the bubble, is the viscosity of water, P vap is the vapor pressure.

6. A bionic low-frequency pulse generation method based on the structure of a snapping shrimp according to claim 4, wherein The vibration of the cavitation bubble radiates sound waves outward to form a sound pulse, and the sound pressure radiated by the cavitation bubble and the expression for the radius change are: ， where r is the distance between the receiving point and the cavitation bubble, and the sound pressure generated is the maximum when the cavitation bubble collapses.

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