An underwater sound source positioning system and method based on phononic crystal sensing

Abstract

The present invention discloses an underwater sound source positioning system and method based on phononic crystal sensing, including a sensing module, an information acquisition module and a sound source positioning module; the incident sound wave first acts on the sensing module, and then the information acquisition module receives the sound signal of the transmitted wave and transmits it to the sound source positioning module. In the sensing module, a rotator is used to control the rotation of the phononic crystal, and a hydrophone converts the pressure signal of the phononic crystal transmitted wave into an electrical signal. When the program control terminal in the sound source positioning module displays that the amplitude of the sound signal collected by the information acquisition module is zero, it is judged that the incident sound wave and the surface of the phononic crystal form an angle of 49°, thereby determining the orientation of the sound source relative to the plane of the phononic crystal, and then combining the angle of rotation of the phononic crystal, the orientation of the sound source relative to the fixed reference system can be determined; two orientations are obtained according to two sensing modules arranged at different positions, and then combined with the distance between the two sensing modules, an inversion algorithm is used to determine the specific position of the sound source in the two-dimensional plane.

Description

Technical Field

[0001] The present invention relates to the field of underwater acoustic detection, and in particular to an underwater sound source positioning system and method based on phononic crystal sensing. Background Art

[0002] As the most effective means of transmitting energy and information underwater, sound waves are widely used in long-distance underwater acoustic communications or underwater target detection. Using the received acoustic information, in military applications, the location of enemy acoustic targets can be sensed and discovered; in marine applications, aquatic organisms such as whales and dolphins can be tracked and monitored in real time. At present, phased array technology is relatively mature and the most widely used method for locating underwater sound sources. Its basic principle is based on time delay estimation technology, which measures the relative time delay of sound waves reaching each array element to estimate the distance and direction of the target. This method requires a large number of array elements and combines complex algorithms to improve detection accuracy, and has disadvantages such as high power consumption and large size.

[0003] In recent years, the abnormal propagation characteristics of elastic waves in acoustic metamaterials have attracted widespread attention from scholars at home and abroad. More and more studies tend to design acoustic sensor devices based on acoustic metamaterials and apply them in different sensing fields. If the abnormal acoustic information transmission characteristics of acoustic metamaterials can be used to construct new acoustic sensor elements, it will be expected to improve the shortcomings of traditional phased array technology and provide a new design idea for sound source detection. One-dimensional fluid-solid phononic crystals are the simplest type of acoustic metamaterials, which have excellent characteristics such as simple structure, easy construction, and easy real-time regulation. In recent years, researchers have discovered its inherent ultra-low frequency acoustic bandgap, which is extremely sensitive to the incident angle of sound waves. Based on this characteristic, the present invention will propose an underwater sound source positioning system and method based on phononic crystal sensing. Summary of the invention

[0004] The present invention proposes a novel underwater sound source positioning system based on phononic crystal sensing to realize the positioning of underwater sound source targets, so as to make up for the shortcomings of the existing phased array technology.

[0005] The present invention is achieved through the following technical solutions:

[0006] An underwater sound source positioning system based on phononic crystal sensing. The system consists of two sensing modules, one information collection module, and one sound source positioning module. The incident sound wave first acts on the two sensing modules, and then the information collection module receives the sound signal of the transmitted wave and transmits it to the sound source positioning module. The rotator is used in the sensing module to control the rotation of the phononic crystal, and the hydrophone converts the pressure signal of the phononic crystal transmitted wave into an electrical signal for collection by the information collection module. When the program control terminal in the sound source positioning module shows that the amplitude of the sound signal collected by the information collection module is zero, it can be judged that the incident sound wave and the surface of the phononic crystal form an angle of 49°, thereby determining the orientation of the sound source relative to the plane of the phononic crystal, and then combining the angle of rotation of the phononic crystal, the orientation of the sound source relative to the fixed reference system (the reference system of the present invention is established with a fixed sensing module as a reference) can be determined; two directions can be obtained according to two sensing systems arranged at different positions, and then combined with the distance between the two sensing modules, the specific position of the sound source in the two-dimensional plane can be determined by using an inversion algorithm.

[0007] Preferably, the phononic crystal is composed of 4 layers of PMMA plates and 4 layers of water arranged alternately. When the propagation direction of the incident wave is 49° with the surface of the phononic crystal, a special low-frequency acoustic bandgap will be generated, that is, no transmission wave will be generated.

[0008] Preferably, the rotation accuracy of the rotator is better than 0.001°.

[0009] Preferably, the information acquisition module uses a NI data acquisition card as its core to collect acoustic signals of the transmission waves.

[0010] Preferably, the hydrophone is made of piezoelectric material and can convert pressure signals into electrical signals.

[0011] Preferably, the Labview program receives the acoustic signal collected by the NI data acquisition card and displays the signal waveform in real time.

[0012] Preferably, according to the two sensor modules arranged at different positions, two different directions of the sound source can be obtained, and the position of the sound source in the two-dimensional plane can be located in combination with known parameters between the two sensor modules.

[0013] According to the above positioning system, the present invention proposes an underwater sound source positioning method based on phononic crystal sensing, including the following:

[0014] The two sensor modules are placed at a distance L 1 Arranged in water, take the center line of the two sensor modules as the x-axis, then take the center of one of the sensor modules as the origin, then establish the y-axis with a line perpendicular to the center line of the two sensor modules, and finally establish the z-axis with a direction perpendicular to the xy plane. Assume that the counterclockwise rotation of the sensor module around the coordinate axis is positive. Figure 3Taking the sensor module 1 on the left as an example, the phononic crystal is rotated continuously. When the information received by the information acquisition module undergoes a sudden change, that is, it changes from strong to weak and then to strong again, the propagation direction of the incident sound wave forms an angle of 49° with the surface of the phononic crystal. Suppose the rotation angle of the phononic crystal is θ 3 , and record the rotation angle θ 3 , since the rotation angle of the phononic crystal is θ 3 It is known that the angle between the surface of the phononic crystal and the horizontal plane is θ 3 , and then the incident wave direction is 49° with the surface of the phononic crystal, we can get θ 1 =θ 3 +49°, similarly, we can get θ 2 =θ 4 +49°; due to the distance L between the two sensor modules 1 Known, determine the distance L between the sound source and the left sensor module 2 =|L 1 *sinθ 2 / sin(θ 2 -θ 1 )|, the distance L between the sound source and the right sensor module 3 =|L 1 *sinθ 1 / sin(θ 2 -θ 1 )|, the sound source position in the two-dimensional plane is obtained according to the angle and distance of the sound source distance sensor module.

[0015] In the above positioning method, when the information received by the information acquisition module changes suddenly, the Labview program issues an alarm.

[0016] The beneficial effects of the present invention are:

[0017] (1) The system structure is ingenious, simple, easy to implement and low cost. The conventional underwater sound source localization method uses more arrays to determine the sound source, relies on a complex system, and has a high overall cost. The present invention overcomes these problems of the prior art.

[0018] (2) Traditional sound source localization methods require the use of complex algorithms, while the algorithm of the method of the present invention is relatively simple and has high accuracy (the positioning error of 1 km is 4.4 m).

[0019] (3) Compared with the prior art, the present invention has the characteristic of low power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. 4 is a system block diagram in an embodiment.

[0021] Figure 2 Schematic diagram of the sensor module in the embodiment.

[0022] Figure 3 It is a schematic diagram of two-dimensional plane positioning in the embodiment.

[0023] Numbers in the figure are: 1-PMMA, 2-water, 3-hydrophone; DETAILED DESCRIPTION

[0024] The purpose, technical solution and advantages of the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0025] Example

[0026] This embodiment provides an underwater sound source positioning system based on phononic crystal sensing, such as Figure 1 As shown in the figure, the system includes two sensing modules, one information acquisition module, and one sound source localization module. When the incident sound wave from the left interacts with the sensing module, the hydrophone receives the acoustic pressure signal of the transmitted wave and converts it into an electrical signal, which is then transmitted to the sound source localization module through the information acquisition module.

[0027] Figure 2 The above is a schematic diagram of the sensor module structure. The sensor module is composed of a phononic crystal + a hydrophone + a rotator. In the figure, 1 is PMMA, 2 is water, 1 and 2 constitute a PMMA-water structure, and the phononic crystal has a total of 4 layers of PMMA-water structure. When the external incident sound wave is incident on the surface of the phononic crystal, a transmission wave will be formed, and the sound pressure signal of the transmission wave will be converted into an electrical signal through the hydrophone. 3 is a hydrophone, which uses piezoelectric materials and can convert the sound pressure signal into an electrical signal. The rotator controls the rotation of the phononic crystal with a rotation accuracy of 0.001°, and feeds back the rotation angle to the sound source positioning system. Figure 2 The left picture is a front view of the phononic crystal and the hydrophone (with the right picture as a reference), and the right picture is a rotator device used to place the phononic crystal and the hydrophone. The left side is used to receive sound waves, and the remaining five sides are wrapped and packaged with sound-absorbing materials, so that sound waves cannot penetrate. The right side is used to transmit signals. The phononic crystal can rotate around the y-axis and the z-axis.

[0028] The information acquisition module includes: data acquisition card, filter, signal amplifier, and Labview program control interface. The data acquisition card is controlled by Labview, and the sampling frequency is 100kHz. The signal waveform is displayed in real time using Labview programming. The sound source localization module records the phononic crystal position when the real-time waveform signal is zero. Figure 3 The inversion algorithm obtains the sound source position. Figure 3 In the example, the distance between the two sensors is L. 1, take the center line of the two sensor modules as the x-axis, then take the center of sensor module 1 as the origin, then establish the y-axis with the center line perpendicular to the two sensor modules, and finally establish the z-axis with the direction perpendicular to the xy plane. Assume that the rotation direction of the phononic crystal around the coordinate axis is counterclockwise as positive. Take the sensor module 1 on the left as an example, and continuously rotate the phononic crystal. When the signal received by the information acquisition module changes suddenly (from strong to weak, and then to strong again), it indicates that the direction of the incident sound wave forms an angle of 49° with the surface of the phononic crystal. Assume that its rotation angle is θ 3 . ; At this time, the Labview program issues an alarm and records the rotation angle θ of the phononic crystal 3 ,like Figure 3 As shown, since the rotation angle of the phononic crystal is θ 3 It can be seen that the angle between the surface of the phononic crystal and the horizontal plane is θ 3 , and because the incident wave direction is 49° to the surface of the phononic crystal, θ 1 =θ 3 +49°, similarly, we can get θ 2 =θ 4 +49°; θ 1 is the direction of the sound source from the left sensor module 1, θ 2 is the direction of the sound source from the right sensor module 2, θ 3 is the rotation angle of the phononic crystal in the left sensor module, θ 4 for Figure 3 The rotation angle of the phononic crystal in the sensor module on the right; due to the distance L between the two sensor modules 1 It is known that the distance L between the sound source and the left sensor module 1 can be determined 2 =|L 1 *sinθ 2 / sin(θ 2 -θ 1 )|, the distance L between the sound source and the right sensor module 2 3 =|L 1 *sinθ 1 / sin(θ 2 -θ 1 )|, the sound source can be located in a two-dimensional plane according to the angle and distance of the sound source distance sensor module.

[0029] The present invention is not limited to the above-mentioned embodiments. Any obvious improvement, replacement or deformation that can be made by those skilled in the art without departing from the design principle of the present invention belongs to the protection scope of the present invention.

Claims

1. An underwater sound source positioning system based on phononic crystal sensing, characterized in that: It includes: two sensing modules, an information collection module and a sound source positioning module; the sensing modules, the information collection module and the sound source positioning module are connected in sequence; the sensing module can track and detect underwater sound wave signals in real time, output different signals according to different receiving angles of the sound waves, and send the output signal of the sensing module to the sound source positioning module through the information collection module; the sound source positioning module calculates the position of the sound source according to the output signal and the position and direction information of the sensing module; When the control terminal of the sound source positioning module displays that the amplitude of the sound signal collected by the signal acquisition module is zero, it is concluded that the incident sound wave forms an angle of 49° with the surface of the phononic crystal. Combined with the angle of rotation of the phononic crystal, the orientation of the sound source relative to the fixed reference system can be determined; two directions can be obtained based on two phononic crystals placed at different positions, and combined with the placement distance between the two phononic crystals, the inversion algorithm is used to determine the specific position of the sound source in the two-dimensional plane; The sensing module comprises a rotator, a phononic crystal and a hydrophone (3); the rotator can control the rotation of the phononic crystal; the hydrophone can convert the transmission wave pressure signal of the phononic crystal into an electrical signal, and the electrical signal is collected by the information collection module; The phononic crystal is composed of several layers of PMMA plates and water arranged alternately; The phononic crystal is preferably composed of four layers of PMMA plates (1) and water (2) arranged alternately; The phononic crystal can output a signal with zero amplitude when the incident sound wave forms an angle of 49° with the surface of the phononic crystal; The information acquisition module uses NI data acquisition card; the sound source localization module is implemented by Labview program; The two sensor modules are placed at a distance Arranged in water, with the center line of the two sensor modules as the x-axis, and then the center of one of the sensor modules as the origin, and then the y-axis is established with the center line perpendicular to the two sensor modules, and finally the z-axis is established with the direction perpendicular to the xy plane. The counterclockwise rotation of the sensor module around the coordinate axis is assumed to be positive, and the phononic crystal is rotated continuously. When the information received by the information acquisition module undergoes a sudden change, that is, it changes from strong to weak and then becomes strong again, the propagation direction of the incident sound wave forms an angle of 49° with the surface of the phononic crystal. The rotation angle of the phononic crystal is assumed to be , and record the rotation angle , since the rotation angle of the phononic crystal is It is known that the angle between the surface of the phononic crystal and the horizontal plane is , and then the incident wave direction is 49° with the surface of the phononic crystal, we can get , similarly, we can get ;in, is the rotation angle of the phononic crystal in the other sensor; due to the distance between the two sensor modules Known, determine the distance between the sound source and the left sensor module , the distance between the sound source and the right sensor module , the sound source position in the two-dimensional plane is obtained according to the angle and distance of the sound source distance sensor module; When the information received by the information acquisition module changes suddenly, the Labview program will issue an alarm.

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