Digital simulation model method for typical target

Abstract

The invention relates to a digital simulation model method for a typical target, and the method is based on the construction of a mine detection environment in underwater acoustic engineering, and comprises the following steps: collecting data, building a mathematical simulation model of the typical target, building a target image and posture, and carrying out the application. And applying the constructed typical target digital simulation model to a sonar simulation model. According to the digital simulation model method, a digital simulation model of a typical target is constructed, a sinking mine, an anchoring mine and other small targets are integrated, shapes and materials of the targets are collected, and the digital simulation model of the typical target is constructed according to different laying postures; a mathematical simulation model for a typical mine target is established according to a column method, and simulation analysis is performed on a waveform structure, target strength and the like.

Description

Technical Field

[0001] The invention relates to the technical field of digital simulation in the field of underwater acoustics, and in particular to a digital simulation model method for a typical target. Background Art

[0002] Underwater target detection and positioning is a hot issue in hydroacoustic engineering. In order to effectively deal with the threat of mines, we should comprehensively strengthen our mine detection capabilities. In the process of detecting small targets, domestic high-frequency sonars use long-term work experience to identify target types, which greatly affects the optimization of tactical decisions and the effectiveness of equipment. Therefore, a solution is urgently needed, that is, through the analysis of the adaptability of the current and under-development mine hunting equipment to the marine environment, target posture analysis, and target performance analysis for sonar detection and identification, a digital simulation model of a typical target is established, which will ultimately provide technical support for my country's mine detection capabilities. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a digital simulation model method for typical targets, which is built based on the mine detection environment in underwater hydroacoustic engineering and includes the following steps:

[0004] Step S1: data collection, collecting target type, material type and absorption coefficient calculation method;

[0005] Step S2: Establish a mathematical simulation model of a typical target. ① For a spherical target, the target strength TS can be calculated according to the formula:

[0006] TS=10log(R 2 / 4) (1)

[0007] R in the formula is the radius of the spherical target;

[0008] ② For cylindrical targets, the target intensity is calculated by the cylindrical cube method. For a finite-length cylindrical target, it is approximated as a part of an infinite-length cylinder and the end face. For an infinite-length cylinder, assuming that a unit plane wave is incident on its surface, the sound pressure of the incident wave is expressed as:

[0009]

[0010] Where φ is the azimuth angle. Here, it is assumed that the transmitter, target, and receiver are on the same horizontal plane, so φ = 0°; J n (.) represents the nth-order Bessel function, ε n is the Newman coefficient, when n=0, the value is 1; when n is a positive integer, the value is 2;

[0011] The other scattered waves are expressed as:

[0012]

[0013] In the formula, is the first kind n-order Hankel function, B n is a coefficient whose magnitude is determined by the boundary conditions;

[0014] Step S3: Establish a target image and posture, establish the spherical target or cylindrical target in step S2, determine the target placement posture, calculate and obtain the three-dimensional coordinates of the target, and at the same time calculate the tracking angle from the sound source to the target based on the obtained sound field image, record the angle between the target and the sound line tracking, and calculate the target sound source intensity of each contact surface according to the sound line contact points evenly distributed on the target contact surface;

[0015] Step S4: Application: applying the constructed typical target digital simulation model to the sonar simulation model.

[0016] In one embodiment of the present invention, in step S2, a spherical coordinate system is further used to replace the Cartesian coordinate system, and a point on the cylinder is represented by the spherical coordinate system; by substituting equations (2) and (3), the waveform function of the scattered wave can be obtained as follows:

[0017]

[0018] In the formula,

[0019]

[0020] Therefore, the scattering waveform f of the cylindrical part is cylin This is shown in formula (4).

[0021] In one embodiment of the present invention, the scattering waveform f generated by the end face end The calculation is done by Kirchhoff integration:

[0022]

[0023] In the formula, g0=ρ1-ρ, h0=k-k1; ρ1 and ρ represent the propagation speed of sound waves in the cylinder and the speed of sound in the liquid medium respectively; k1 and k represent the wave number in the cylinder and the wave number in the liquid medium respectively.

[0024] In one embodiment of the present invention, equation (7) is integrated to obtain:

[0025]

[0026] In the formula,

[0027]

[0028] φ0=arctan(sinθs sinφ s / (sinθ i -sinθ s cosφ s )) (9)

[0029] Parameter B n Determined by boundary conditions;

[0030] For a rigid target, the scattering of sound waves on its surface belongs to the scattering on an absolutely hard interface, and the magnitude of its boundary condition is:

[0031]

[0032] Where p = p i +p s .

[0033] In one embodiment of the present invention, the expression of sound pressure is substituted into equation (9) to obtain:

[0034]

[0035] So in summary, the scattering waveform function of a finite length cylinder is

[0036] f=f cylin +f end (12)

[0037] The expression of target strength is:

[0038] TS=20lgf (13)

[0039] For a transponder target, its TS is its sound source level strength, which is generally 165-170dB.

[0040] The above technical solution of the present invention has the following advantages over the prior art: the digital simulation model method described in the present invention constructs bottom mines, anchor mines and other small targets, target forms with various postures and materials, which are used to simulate sonar detection and identification of targets in the ocean. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0042] Figure 1 It is a computer software page diagram for parameter settings in the model design of the present invention;

[0043] Figure 2 The invention is to establish a two-dimensional sound field image in the vertical direction;

[0044] Figure 3 is the three-dimensional image of the spheroid target of the present invention;

[0045] Figure 4 It is the three-dimensional image of the cylindrical target of the present invention;

[0046] Figure 5 It is the sonar detection simulation image of the present invention;

[0047] Figure 6 It is a schematic diagram of a model of the finite length cylindrical target described in the present invention. DETAILED DESCRIPTION

[0048] This embodiment provides a digital simulation model method for a typical target, and the digital simulation model method is built based on a mine detection environment in underwater hydroacoustic engineering, and includes the following steps:

[0049] Step S1: data collection, collecting target type, material type and absorption coefficient calculation method;

[0050] Specifically, obtain Figure 1 The parameter types displayed are the setting parameters of the underwater target, which can be set separately: target type, target posture, target material, target position, target size and other information.

[0051] According to the investigation, bottom mines and anchor mines are divided into two types: columnar and spherical. The posture of the columnar can be divided into horizontal and vertical directions. According to the collected materials, the target materials of bottom mines and anchor mines can be divided into gel material, fiberglass, aluminum and iron.

[0052] Step S2: Establish a mathematical simulation model of a typical target. ① For a spherical target, the target strength TS can be calculated according to the formula:

[0053] TS=10log(R 2 / 4) (1)

[0054] R in the formula is the radius of the spherical target;

[0055] ② For cylindrical targets, the target strength is calculated using the cylindrical cube method, where Figure 6 As shown in the figure, the model of the finite length cylindrical target has a radius of b and a length of L. The axis direction of the cylinder is used to establish a coordinate system, with the axis direction being z and θ i is the incident wave direction, θ s is the direction of the scattered wave.

[0056] For a finite-length cylindrical target, it is approximated as a part of an infinite-length cylinder and the end face part. For an infinite-length cylinder, assuming that a unit plane wave is incident on its surface, the sound pressure of the incident wave is expressed as:

[0057]

[0058] Where φ is the azimuth angle. Here, it is assumed that the transmitter, target, and receiver are on the same horizontal plane, so φ = 0°; J n (.) represents the nth-order Bessel function, ε n is the Newman coefficient, when n=0, the value is 1; when n is a positive integer, the value is 2;

[0059] The other scattered waves are expressed as:

[0060]

[0061] In the formula, is the first kind n-order Hankel function, B n is a coefficient whose magnitude is determined by the boundary conditions;

[0062] It is also necessary to further replace the Cartesian coordinate system with a spherical coordinate system and express a point on the cylinder with a spherical coordinate system; substituting equations (2) and (3) into the spherical coordinate system, the waveform function of the scattered wave can be obtained as follows:

[0063]

[0064] In the formula,

[0065]

[0066]

[0067] Therefore, the scattering waveform f of the cylindrical part is cylin This is shown in formula (4).

[0068] The scattered waveform f generated by the end face end The calculation is done by Kirchhoff integration:

[0069]

[0070] In the formula, g0=ρ1-ρ, h0=k-k1; ρ1 and ρ represent the propagation speed of sound waves in the cylinder and the speed of sound in the liquid medium respectively; k1 and k represent the wave number in the cylinder and the wave number in the liquid medium respectively.

[0071] Integrating formula (7) yields:

[0072]

[0073] In the formula,

[0074]

[0075] φ0=arctan(sinθ s sinφ s / (sinθ i -sinθ s cosφ s )) (9)

[0076] Parameter B n Determined by boundary conditions;

[0077] For a rigid target, the scattering of sound waves on its surface belongs to the scattering on an absolutely hard interface, and the magnitude of its boundary condition is:

[0078]

[0079] Where p = p i +p s .

[0080] At the same time, substituting the expression of sound pressure into equation (9), we get:

[0081]

[0082] So in summary, the scattering waveform function of a finite length cylinder is

[0083] f=f cylin +f end (12)

[0084] The expression of target strength is:

[0085] TS=20lgf (13)

[0086] For a transponder target, its TS is its sound source level strength, which is generally 165-170dB.

[0087] Step S3: Create target image and pose, and establish Figure 3 and Figure 4 The target image is obtained, the target placement posture is determined, and the three-dimensional coordinates of the target are calculated. Figure 2 The tracking angle from the sound source to the target is calculated in this way, the angle between the target and the sound line tracking is recorded, and the target sound source intensity of each contact surface is calculated according to the sound line contact points evenly distributed on the target contact surface;

[0088] like Figure 2 As shown, the acoustic array generates an acoustic signal, which propagates in the ocean until the target is detected, and the coordinates and incident angle of the target contact point in the vertical direction are calculated, and the decibel value lost when the sound source level reaches each contact point is recorded.

[0089] and Figure 3 and Figure 4They are three-dimensional images of a column and a sphere, respectively. Their coordinates can be changed according to the placement position, and their shapes and coordinates can be changed according to the placement posture.

[0090] Step S4: Apply the constructed typical target digital simulation model to the sonar simulation model to achieve the following Figure 5 Displays a sonar detection simulation image.

[0091] like Figure 5 In the sonar detection simulation image shown, the small red dot in the middle of the distance is the result of the target in the sonar simulation calculation. This is a simulated sonar detection target. The coordinate position of the target is (150m, 0m, 40m). The target is an anchor mine, which is spherical and mainly made of iron. The color ratio of the sonar image changes from red to blue, and the sonar decibel value gradually decreases. The sonar image is fan-shaped. After normalization, the near point image appears red, which is the strongest sound source level and has the highest decibel value. As the detection distance increases, the decibel value decreases, and the color also changes from positive red to dark blue. The target position and deployment posture selection in the sonar image are both optimal, so the red bright spot can be clearly seen at the center of the image target, and the intensity of the target center gradually decreases along both sides.

[0092] The target calculation in this simulation image not only considers the target incident angle in the horizontal direction, but also considers the selection of multiple different materials in the vertical direction, which is more than the commonly used two-dimensional target calculation. Figure 5 The simulated target establishes a sonar image containing more similar targets and establishes the distinction between the target and other small targets. It can be used for the operation training of sonar operators and can also be used to construct a sonar detection image in a certain sea area.

[0093] In the digital simulation model method described in this embodiment, a digital simulation model of a typical target is constructed, which includes bottom mines, anchor mines and other small targets, collects the shapes and materials of the targets, and constructs a digital simulation model of a typical target according to different deployment postures. A mathematical simulation model for a typical mine target is established based on the column method, and the waveform structure, target strength, etc. are simulated and analyzed. On this basis, a mine hunting sonar model is further constructed, and the detection results of the mine hunting sonar are simulated, laying a theoretical foundation for the analysis of the detection characteristics of the mine hunting sonar on the mine target.

[0094] In summary, the main problems overcome in this embodiment are: 1. Posture construction: it is not a single target, and it can be adjusted according to the change of the target position to present a three-dimensional effect; 2. Material construction: due to the diversity of mine targets, the contact points between the mine surface and the sonar signal are different, and the target strength of different materials under different target conditions is established; 3. Large-scale simulation targets to establish a group of small submarine targets with ambiguous points.

[0095] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A digital simulation model method for typical targets, the digital simulation model method is built based on the mine detection environment in underwater hydroacoustic engineering, characterized in that: The steps include: Step S1: data collection, collecting target type, material type and absorption coefficient calculation method; Step S2: Establish a mathematical simulation model of a typical target. ① For a spherical target, the target strength TS can be calculated according to the formula: TS=10log(R 2 / 4) (1) R in the formula is the radius of the spherical target; ② For cylindrical targets, the target intensity is calculated by the cylindrical cube method. For a finite-length cylindrical target, it is approximated as a part of an infinite-length cylinder and the end face. For an infinite-length cylinder, assuming that a unit plane wave is incident on its surface, the sound pressure of the incident wave is expressed as: Where φ is the azimuth angle. Here, it is assumed that the transmitter, target, and receiver are on the same horizontal plane, so φ = 0°; J n (.) represents the nth-order Bessel function, ε n is the Newman coefficient, when n=0, the value is 1; when n is a positive integer, the value is 2; The other scattered waves are expressed as: In the formula, is the first kind n-order Hankel function, B n is a coefficient whose magnitude is determined by the boundary conditions; Step S3: Establish a target image and posture, establish the spherical target or cylindrical target in step S2, determine the target placement posture, calculate and obtain the three-dimensional coordinates of the target, and at the same time calculate the tracking angle from the sound source to the target based on the obtained sound field image, record the angle between the target and the sound line tracking, and calculate the target sound source intensity of each contact surface according to the sound line contact points evenly distributed on the target contact surface; Step S4: Application: applying the constructed typical target digital simulation model to the sonar simulation model.

2. The digital simulation model method according to claim 1, characterized in that: In step S2, it is necessary to further use a spherical coordinate system to replace the Cartesian coordinate system, and express a point on the cylinder with a spherical coordinate system; by substituting equations (2) and (3), the waveform function of the scattered wave can be obtained as follows: In the formula, Therefore, the scattering waveform f of the cylindrical part is cylin That is shown in formula (4).

3. The digital simulation model method according to claim 2, characterized in that: The scattered waveform f generated by the end face end The calculation is done by Kirchhoff integration: In the formula, g0=ρ1-ρ, h0=k-k1; ρ1 and ρ represent the propagation speed of sound waves in the cylinder and the speed of sound in the liquid medium respectively; k1 and k represent the wave number in the cylinder and the wave number in the liquid medium respectively.

4. The digital simulation model method according to claim 3, characterized in that: Integrating formula (7) yields: In the formula, φ0=arctan(sinθ s sinφ s / (sinθ i -sinθ s cosφ s )) (9) Parameter B n Determined by boundary conditions; For a rigid target, the scattering of sound waves on its surface belongs to the scattering on an absolutely hard interface, and the magnitude of its boundary condition is: In the formula, p = p i +p s .

5. The digital simulation model method according to claim 4, characterized in that: At the same time, substituting the expression of sound pressure into equation (9), we get: So in summary, the scattering waveform function of a finite length cylinder is f=f cylin +f end (12) The expression of target strength is: TS=20lgf (13) For a transponder target, its TS is its sound source level strength, which is generally 165-170dB.

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