Scanning sonar image simulation modeling method and system based on workflow

Abstract

The invention provides a scanning sonar image simulation modeling method and system based on a workflow, and the method comprises the steps: carrying out the modeling of a target and a marine environment, and obtaining the parameters of the target and the marine environment; modeling the sonar and processing the signal; and performing simulation imaging according to the target, the marine environment parameters and the processed signals. According to the method, the sonar workflow is disassembled, each component is simulated according to the sonar workflow, finally, the image data is obtained, the result of simulating the sonar image has consistent characteristics with the real sonar image, and certain support can be provided for design verification, test groping and image algorithm research; by modeling the target and the seabed and setting different parameter selections, sonar simulation images under different targets can be obtained, and expansion of other targets is supported.

Description

Technical Field

[0001] The present invention belongs to the field of hydroacoustics, and in particular, relates to a scanning sonar image simulation modeling method and system based on a workflow. Background Art

[0002] During the development and testing phases of sonar, it is necessary to demonstrate possible results based on prior knowledge. Each demonstration is often cumbersome and the results are not intuitive enough. Therefore, a sonar simulation model is needed to support design, performance prediction, experimental investigation and fault diagnosis.

[0003] In addition, with the rapid development and application of deep learning in the field of optical images, deep learning applications on sonar images have also ushered in a boom. However, unlike the readily available target image data of optical images, the target image data of sonar images often need to be obtained through experiments, and sonar experiments often require high costs and a lot of manpower. At the same time, the data obtained often cannot meet the needs of training networks. Therefore, simulating sonar images instead of real data is an important and convenient approach.

[0004] Common sonar image simulation is to use rendering to directly simulate the sonar image based on the characteristics of the sonar image, but this does not have a way to verify the performance of the sonar.

[0005] The main content of the patent document "A Method for Implementing an Adaptive Sonar Equipment Simulation System Platform" (CN113267766A) is the simulation of passive linear array sonar. The parameters of the sonar installation platform affect the sound field, sonar performance, and situation simulation. It directly uses image tools or deep learning tools to directly compare with real sonar images for simulation. There is no simulation of each workflow, and it is not a scanning image sonar.

[0006] Therefore, it is necessary to establish a simulation model of scanning sonar, analyze and simulate the various work processes of scanning sonar, and establish data flow to output simulated sonar images. Summary of the invention

[0007] In view of the defects in the prior art, the object of the present invention is to provide a scanning sonar image simulation modeling method and system based on workflow.

[0008] The scanning sonar image simulation modeling method based on workflow provided by the present invention comprises:

[0009] Step S1: Modeling the target and the ocean environment to obtain the target and ocean environment parameters;

[0010] Step S2: Modeling the sonar according to the target and ocean environment parameters and processing the signal;

[0011] Step S3: Simulate imaging based on the target and ocean environment parameters and the processed signal.

[0012] Preferably, the step S1 comprises:

[0013] Reverberation level step: seabed reverberation simulation, calculate the seabed scattering intensity S according to the seabed texture, grazing angle and sound wave frequency b =10lgμ+10lg(sin 2 θ), to obtain the equivalent plane wave reverberation level

[0014] Among them, μ represents the ocean bottom parameters;

[0015] θ represents the incident angle of the sound wave;

[0016] SL means sound source level;

[0017] r represents the propagation distance;

[0018] Indicates the directivity beam width;

[0019] c represents the speed of sound;

[0020] τ represents the pulse width.

[0021] Signal level step: Run ray acoustics. According to the sonar equation, the propagation loss TL = 20lg r+ar+60-k L , Echo signal level EL = SL-2TL + TS;

[0022] Where α represents the sound absorption coefficient;

[0023] SL means sound source level;

[0024] TS represents the effect of target strength;

[0025] k L Indicates abnormal near-field propagation;

[0026] f represents the frequency of the transmitted signal.

[0027] Target step: Set the target as a sphere or cylinder, and use the sonar relative coordinate system to model it according to the sonar equation. The sonar coordinates are always (0,0,0). The coordinates of the target are determined based on the target's relative sonar position.

[0028] When the target is a sphere, the target is suspended in the water, and the seabed reverberation is not considered. The target intensity

[0029] When the target is a cylinder, half of the target is buried in the seabed. Considering the seabed reverberation, the incident direction of the sound wave is perpendicular to the cylinder axis. The target intensity

[0030] Where a is the target radius;

[0031] L is the column length;

[0032] λ is the wavelength of the sound wave.

[0033] Acoustic shadow step: The acoustic shadow area is calculated by simulating the occlusion of light, and a negative gain is given to the acoustic shadow area in the echo calculation.

[0034] Preferably, in step S2, the anchor mine is simulated and modeled using the sonar equation SL-2TL+TS-(NL-DI)=DT based on noise, and the bottom mine is simulated and modeled using the sonar equation SL-2TL+TS-RL=DT based on reverberation.

[0035] Through workflow analysis, sonar is broken down into emission, sound propagation, target sound scattering, reception, signal processing and display.

[0036] The simulation was performed at a beam width of 1° at a time, starting from a 45° angle on one side and repeated 90 times.

[0037] Among them, SL represents the sound source level of the active sonar;

[0038] TL represents transmission loss;

[0039] TS represents target strength;

[0040] NL represents the marine ambient noise level;

[0041] DI represents the sonar directivity coefficient;

[0042] RL means reverberation level;

[0043] DT represents the detection threshold.

[0044] In step S3, sonar parameters and target parameters are set to obtain emission signal simulation results and seabed and target modeling results, sample and normalize the processed signals, and then use a color table algorithm to map them to a pseudo-color image display to obtain a sonar image simulation result.

[0045] Preferably, step S2 comprises:

[0046] Step S2.1: The signal time domain expression of CW single-frequency rectangular pulse is: The time domain expression of LFM linear frequency modulation pulse signal is: T0=2r / c, adjust the parameters to simulate the transmission signal;

[0047] Where f0 represents frequency;

[0048] A represents the amplitude of the signal;

[0049] T represents the signal pulse width, which represents the width of the pulse signal;

[0050] j represents the imaginary part;

[0051] k represents the chirp frequency;

[0052] t represents the time of the signal;

[0053] T represents the time of the signal;

[0054] T0 represents the pulse repetition period, which is the total length of the signal;

[0055] r represents the propagation distance;

[0056] c represents the speed of sound.

[0057] Step S2.2: echo signal level EL = SL-2TL + TS, calculate the echo signal delay through the sound propagation model The echo signal voltage is calculated through the target acoustic scattering model and the seabed reverberation model. Generates target echo.

[0058] Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b), frequency domain value of the total echo signal The time domain data of the echo signal is obtained by inverse Fourier transform, and the signal is compensated by TVG.

[0059] The beam opening angle of each scan is simulated separately to obtain 90 channels of echo data.

[0060] Among them, MX represents the response sensitivity of the receiving array;

[0061] n represents the total number of echo signals;

[0062] signal(b) represents the transmitted time domain signal;

[0063] signalfft(b) indicates the transmission of frequency domain signal;

[0064] b represents the sampling point on the phase;

[0065] α represents the sound absorption coefficient;

[0066] SL means sound source level;

[0067] TS represents the effect of target strength;

[0068] TL represents transmission loss;

[0069] EL represents the echo signal level.

[0070] Preferably, the normalization is to normalize the data value to a grayscale value g(x,y) of 0 to 254 according to upper and lower thresholds [min max], and map the grayscale value g(x,y) to a pseudo-color image:

[0071] g(x,y)=0 f(x,y)<min

[0072]

[0073] g(x,y)=254 f(x,y)>max;

[0074] Wherein, f(x,y) represents the simulated echo matrix;

[0075] x represents the channel number;

[0076] y represents the corresponding data point on the channel number.

[0077] The mapping is to obtain the corresponding RGB intensity value according to the grayscale value by setting a colorbar with a length of 255 pixels.

[0078] The sonar parameters include the type of transmitted signal, signal frequency, signal pulse width, range, pitch angle, sonar beam opening angle, sonar vertical opening angle and sonar scanning angle.

[0079] The target parameters include target type, target length, target diameter, target relative position and seabed bottom type.

[0080] The transmission signal simulation result is output in the form of time domain expression and frequency domain expression.

[0081] A scanning sonar image simulation modeling system based on workflow provided by the present invention comprises:

[0082] Module M1: Model the target and the ocean environment to obtain the target and ocean environment parameters;

[0083] Module M2: Model the sonar according to the target and ocean environment parameters and process the signal;

[0084] Module M3: Simulate imaging based on target and ocean environment parameters and processed signals.

[0085] Preferably, the module M1 comprises:

[0086] Reverberation level module: seabed reverberation simulation, calculate the seabed scattering intensity S according to the seabed quality, grazing angle and sound wave frequency b =10lgμ+10lg(sin 2 θ), to obtain the equivalent plane wave reverberation level

[0087] Among them, μ represents the ocean bottom parameters;

[0088] θ represents the incident angle of the sound wave;

[0089] SL means sound source level;

[0090] r represents the propagation distance;

[0091] Indicates the directivity beam width;

[0092] c represents the speed of sound;

[0093] τ represents the pulse width.

[0094] Signal level module: Run ray acoustics. According to the sonar equation, the propagation loss TL = 20lg r+ar+60-k L , Echo signal level EL = SL-2TL + TS;

[0095] Where α represents the sound absorption coefficient;

[0096] SL means sound source level;

[0097] TS represents the effect of target strength;

[0098] k L Indicates abnormal near-field propagation;

[0099] f represents the frequency of the transmitted signal.

[0100] Target module: Set the target as a sphere or cylinder, and use the sonar relative coordinate system to model the target according to the sonar equation. The sonar coordinates are always (0,0,0). The coordinates of the target are determined based on the target's relative sonar position.

[0101] When the target is a sphere, the target is suspended in the water, and the seabed reverberation is not considered. The target intensity

[0102] When the target is a cylinder, half of the target is buried in the seabed. Considering the seabed reverberation, the incident direction of the sound wave is perpendicular to the cylinder axis. The target intensity

[0103] Where a is the target radius;

[0104] L is the column length;

[0105] λ is the wavelength of the sound wave.

[0106] Acoustic shadow module: The acoustic shadow area is calculated by simulating the occlusion of light, and a negative gain is provided to the acoustic shadow area in the echo calculation.

[0107] Preferably, the anchor mine in the module M2 is simulated and modeled using the sonar equation SL-2TL+TS-(NL-DI)=DT based on noise, and the bottom mine is simulated and modeled using the sonar equation SL-2TL+TS-RL=DT based on reverberation.

[0108] Through workflow analysis, sonar is broken down into emission, sound propagation, target sound scattering, reception, signal processing and display.

[0109] The simulation was performed at a beam width of 1° at a time, starting from a 45° angle on one side and repeated 90 times.

[0110] Among them, SL represents the sound source level of the active sonar;

[0111] TL represents transmission loss;

[0112] TS represents target strength;

[0113] NL represents the marine ambient noise level;

[0114] DI represents the sonar directivity coefficient;

[0115] RL means reverberation level;

[0116] DT represents the detection threshold.

[0117] The module M3 sets sonar parameters and target parameters to obtain emission signal simulation results and seabed and target modeling results, samples and normalizes the processed signals, and then uses a color table algorithm to map them to a pseudo-color image display to obtain sonar image simulation results.

[0118] Preferably, the module M2 comprises:

[0119] Module M2.1: The signal time domain expression of CW single-frequency rectangular pulse is: The time domain expression of LFM linear frequency modulation pulse signal is: T0=2r / c, adjust the parameters to simulate the transmission signal;

[0120] Where f0 represents frequency;

[0121] A represents the amplitude of the signal;

[0122] T represents the signal pulse width, which represents the width of the pulse signal;

[0123] j represents the imaginary part;

[0124] k represents the chirp frequency;

[0125] t represents the time of the signal;

[0126] T represents the time of the signal;

[0127] T0 represents the pulse repetition period, which is the total length of the signal;

[0128] r represents the propagation distance;

[0129] c represents the speed of sound.

[0130] Module M2.2: echo signal level EL = SL-2TL + TS, the echo signal delay is calculated through the sound propagation model The echo signal voltage is calculated through the target acoustic scattering model and the seabed reverberation model. Generates target echo.

[0131] Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b), frequency domain value of the total echo signal The time domain data of the echo signal is obtained by inverse Fourier transform, and the signal is compensated by TVG.

[0132] The beam opening angle of each scan is simulated separately to obtain 90 channels of echo data.

[0133] Among them, MX represents the response sensitivity of the receiving array;

[0134] n represents the total number of echo signals;

[0135] signal(b) represents the transmitted time domain signal;

[0136] signalfft(b) indicates the transmission of frequency domain signal;

[0137] b represents the sampling point on the phase;

[0138] α represents the sound absorption coefficient;

[0139] SL means sound source level;

[0140] TS represents the effect of target strength;

[0141] TL represents transmission loss;

[0142] EL represents the echo signal level.

[0143] Preferably, the normalization is to normalize the data value to a grayscale value g(x,y) of 0 to 254 according to upper and lower thresholds [min max], and map the grayscale value g(x,y) to a pseudo-color image:

[0144] g(x,y)=0f(x,y)<min

[0145]

[0146] g(x,y)=254f(x,y)>max;

[0147] Wherein, f(x,y) represents the simulated echo matrix;

[0148] x represents the channel number;

[0149] y represents the corresponding data point on the channel number.

[0150] The mapping is to obtain the corresponding RGB intensity value according to the grayscale value by setting a colorbar with a length of 255 pixels.

[0151] The sonar parameters include the type of transmitted signal, signal frequency, signal pulse width, range, pitch angle, sonar beam opening angle, sonar vertical opening angle and sonar scanning angle.

[0152] The target parameters include target type, target length, target diameter, target relative position and seabed bottom type.

[0153] The transmission signal simulation result is output in the form of time domain expression and frequency domain expression.

[0154] Compared with the prior art, the present invention has the following beneficial effects:

[0155] 1. The present invention disassembles the sonar workflow and simulates each component separately, which can provide certain support for design verification, experimental investigation and image algorithm research.

[0156] 2. The present invention simulates each process according to the sonar workflow, and finally obtains simulated image data. The result of the simulated sonar image has consistent features with the real sonar image.

[0157] 3. The present invention can obtain sonar simulation images under different targets by modeling the target and the seabed and setting different parameter options considering the sonar image related parameters, and supports the expansion of other targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0158] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0159] Figure 1 It is a flow chart of the simulation modeling method for scanning sonar images;

[0160] Figure 2 It is a schematic diagram of scanning sonar based on workflow;

[0161] Figure 3 Schematic diagram for scanning sonar colobar selection;

[0162] Figure 4 This is a schematic diagram of a scanning sonar cylindrical target;

[0163] Figure 5 Schematic diagram for scanning sonar acoustic shadow calculation;

[0164] Figure 6 This is a schematic diagram of the time domain and frequency domain waveforms of the scanning sonar transmission signal;

[0165] Figure 7 Schematic diagram of scanning sonar seabed simulation modeling;

[0166] Figure 8 This is a schematic diagram of scanning sonar simulation;

[0167] Fig. 9 Schematic diagram for comparing the scanning sonar image simulation and actual results. DETAILED DESCRIPTION

[0168] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0169] According to the workflow-based scanning sonar image simulation modeling method provided by the present invention, the workflow of the sonar is disassembled and simulated, a data stream is established, echo data is obtained by simulation, and finally displayed through a display control algorithm. Figure 1 Take the following as an example, simulate the target and the seabed model, then perform sonar modeling, simulate the emission, sound propagation, and reception, and finally perform signal processing and display on the simulated reception data. The specific steps include:

[0170] Step S1: target and ocean environment modeling;

[0171] Step S1.1: Seabed reverberation simulation.

[0172] The influence of seabed sediments on the sonar model is mainly reflected in reverberation. The expression of the equivalent plane wave reverberation level RL of seabed reverberation is:

[0173]

[0174] Wherein, SL represents the sound source level;

[0175] r represents the propagation distance;

[0176] Indicates the directivity beam width;

[0177] c represents the speed of sound;

[0178] τ represents the pulse width.

[0179] Seafloor scattering intensity S b The value of is affected by many factors, including the seabed, grazing angle and sound wave frequency. When the grazing angle and frequency of the incident sound wave are constant, the seabed scattering intensity depends on the different seabed types. Using Lambert's law, the scattering of sound waves on rough surfaces is quantitatively calculated. According to the definition of scattering intensity, we can get:

[0180] S b =10lgμ+10lg(sin 2 θ);

[0181] Among them, μ represents the ocean bottom parameters;

[0182] θ represents the incident angle of the sound wave.

[0183] The marine environment model provides five common marine substrates as options (silt, rock, clay, sand), and the corresponding calculation parameters are as follows:

[0184] Substrate type 10lgμ Sediment -19.7 sand -20.2 clay -11.7 rock -5.6

[0185] Step S1.2: High frequency sound propagation.

[0186] The ray acoustic field model is widely used in the study of high-frequency sound propagation. Ray acoustics regards the propagation of sound waves as the propagation of countless rays perpendicular to the equal phase plane. Each ray is perpendicular to the equal phase plane and is called a sound ray. The distance traveled by the sound ray represents the path of sound wave propagation, the time experienced by the sound ray is the time of sound wave propagation, and the energy carried by the sound ray beam is the energy of sound wave propagation. The ray acoustic method is a commonly used approximate method to study the characteristics of sound propagation in the ocean under high-frequency conditions. It has a concise description method, clear physical images, and fast calculation speed.

[0187] The following assumptions need to be met when running ray acoustics:

[0188] The direction of the sound ray is the direction of sound propagation, and the sound ray is always perpendicular to the wavefront;

[0189] Sound rays carry energy, and the sound energy at a point in the sound field is the sum of the energy carried by all the sound rays reaching that point;

[0190] The energy in the sound tube bundle is conserved, and there is no energy exchange with the outside of the tube.

[0191] According to the sonar equation, the echo signal level EL is:

[0192] EL = SL-2TL + TS;

[0193] The echo signal is affected by the SL sound source level, TL propagation loss and TS target strength.

[0194] The sound propagation process requires the calculation of TL propagation loss:

[0195] TL=20lg r+ar+60-k L ;

[0196] Where α is the sound absorption coefficient.

[0197]

[0198] k L It is a near-field propagation anomaly, which is related to the sea state and seabed type;

[0199] f represents the frequency of the transmitted signal.

[0200] In addition, the sonar's horizontal opening angle, vertical opening angle and range must also be taken into account, and only the data within the sonar's "viewing angle" must be calculated.

[0201] Step S1.3: Target simulation.

[0202] The targets are set as spheres and cylinders according to common mine types. The target simulation is achieved by calculating the target strength in the sonar equation:

[0203] When the target is a sphere, the target is considered to be suspended in the water and the seabed reverberation is not considered. The target strength TS is calculated as follows:

[0204]

[0205] Where a is the target radius;

[0206] When the target is a cylinder, Figure 4 For example, consider that the target is half buried under the seabed, and the seabed reverberation needs to be considered.

[0207] The incident direction of the sound wave is perpendicular to the column axis. The calculation formula is as follows:

[0208]

[0209] Where a is the target radius;

[0210] L is the column length;

[0211] λ is the wavelength of the sound wave.

[0212] The coordinate system used in modeling is the sonar relative coordinate system. The sonar coordinates are always (0,0,0). The coordinates of the target are determined based on the target's relative sonar position.

[0213] Step S1.4: Establish an acoustic shadow model.

[0214] Since ray acoustics is adopted, the acoustic shadow area can be calculated by simulating the occlusion of light, and a small negative gain is provided to the acoustic shadow area in the echo calculation, making the acoustic shadow in the simulation result more realistic. Figure 5 For example.

[0215] Step S2: sonar modeling;

[0216] Sonar equations are the key to sonar simulation. The active sonar equation is an equation obtained by organically combining sonar parameters according to the workflow of the active sonar system. The sonar equation integrates the influence of sonar parameters on sonar performance from an energy perspective and is an important basis for sonar design and use. Sonar equations are divided into noise-based and reverberation-based.

[0217] The anchor mine uses the sonar equation based on noise: SL-2TL+TS-(NL-DI)=DT;

[0218] Bottom mines use the sonar equation based on reverberation: SL-2TL+TS-RL=DT;

[0219] Among them, SL is the sound source level of the active sonar, TL is the propagation loss, TS is the target strength, NL is the ocean ambient noise level, DI is the sonar directivity coefficient, RL is the reverberation level, and DT is the detection threshold.

[0220] In the formula, SL-2TL+TS is called the echo signal level, denoted by EL, which represents the sound level of the echo signal on the active sonar receiving transducer. The echo simulation of the sonar signal is simulated based on the echo signal level EL.

[0221] By sorting out the workflow, sonar can be broken down into emission, sound propagation, target sound scattering, reception, signal processing and display.

[0222] Scanning sonar uses a mechanically rotating sonar beam to form a 90° fan-shaped scanning angle to complete detection. Scanning sonar scans by continuously rotating the sonar beam through a series of small angles. Each sonar beam width is 1°. After scanning 90 times, it will return data on distance and echo intensity, and form a sonar image of the underwater environment based on this data.

[0223] To simulate the workflow of scanning sonar, Figure 2 For example, each time only the simulation is performed with a beam width of 1°, and the simulation is repeated 90 times starting from a 45° angle on one side.

[0224] Step S2.1: Launch simulation.

[0225] The function of the transmitter is to transmit signals, so the focus of the simulation is to simulate the transmission signal. In order to facilitate the recording of target echo signals, most of the signals transmitted by sonar are pulse signals. Common transmission signals include CW single-frequency rectangular pulses and LFM linear frequency modulation pulses.

[0226] CW signal time domain expression:

[0227]

[0228] LFM signal time domain expression:

[0229]

[0230] The main parameters of the pulse signal are frequency, pulse repetition period and pulse width.

[0231] Among them, f0 is the frequency, which is related to the propagation attenuation of sound waves in water, the directivity index of the transducer, etc.

[0232] A is the amplitude of the signal, which is usually 1 after normalization.

[0233] T is the signal pulse width, which represents the width of the pulse signal and affects the detection distance and distance resolution of the sonar.

[0234] j represents the imaginary part;

[0235] k represents the chirp frequency;

[0236] t represents the time of the signal;

[0237] T represents the time of the signal;

[0238] The pulse repetition period T0 is the total length of the signal and depends on the sonar range.

[0239] T0=2r / c

[0240] Among them, r is the propagation distance and c is the speed of sound.

[0241] The signal form, frequency, pulse repetition period, pulse width and other parameters can be changed to complete the simulation of the transmitted signal.

[0242] Step S2.2: Receive simulation.

[0243] The focus of receiver simulation is to simulate the echo signal. According to the sonar equation, the echo signal level EL = SL-2TL + TS.

[0244] After the acoustic signal is converted by the transducer, it propagates in the seawater and reaches the target, generating an echo that is then received by the transducer. The echo simulation needs to consider the target acoustic scattering model, acoustic propagation model, seabed reverberation, etc. Finally, the signal delay is calculated through the acoustic propagation model, and the voltage value of the echo signal is calculated through the target acoustic scattering model and seabed reverberation model, and finally the target echo is generated.

[0245] The echo signal level can be calculated according to the following formula to obtain the echo time domain signal:

[0246] Echo signal voltage

[0247] Echo signal delay

[0248] Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b);

[0249] Frequency domain value of the total echo signal

[0250] Among them, MX represents the response sensitivity of the receiving array;

[0251] n represents the total number of echo signals;

[0252] signal(b) represents the transmitted time domain signal;

[0253] signalfft(b) indicates the transmission of frequency domain signal;

[0254] b represents the sampling point on the phase.

[0255] Finally, the time domain data of the echo signal can be obtained through inverse Fourier transform, and then the signal is compensated for TVG according to the formula. The commonly used TV compensation formula is as follows:

[0256]

[0257] According to the characteristics of scanning sonar, the beam opening angle of each scan is simulated separately to obtain 90 channels of echo data.

[0258] Step S3: imaging simulation;

[0259] The signal preprocessed by the receiver is sampled and normalized, and then displayed in pseudo-color using a color table algorithm.

[0260] Normalization and color table mapping: Data values ​​are normalized to grayscale values ​​g(x,y) of 0 to 254 according to upper and lower thresholds [min max]:

[0261] g(x,y)=0f(x,y)<min

[0262]

[0263] g(x,y)=254f(x,y)>max;

[0264] Where, f(x,y) represents the simulated echo matrix;

[0265] x represents the channel number, and y represents the corresponding data point on the channel number;

[0266] Then the grayscale value g(x,y) is mapped to the pseudo-color image by using the prepared 255-pixel-long colorbar to obtain the corresponding RGB intensity value according to the grayscale value. Figure 3 For example, a variety of colorbars are provided for selection.

[0267] In more preferred embodiments, step S3.1 is included: parameter input.

[0268] Input sonar parameters are as follows:

[0269] Transmit signal type: CW;

[0270] Signal frequency: 600kHz;

[0271] Signal pulse width: 25us;

[0272] Measuring range: 8m;

[0273] Pitch angle: 15°;

[0274] Sonar beam opening angle: 1°;

[0275] Sonar vertical opening angle: 20°;

[0276] Sonar scanning angle: 90°;

[0277] Enter the target parameters as follows:

[0278] Target type: cylinder;

[0279] Target length: 2m;

[0280] Target diameter: 0.533m;

[0281] Target relative position: (6,0,2);

[0282] Seabed type: sand;

[0283] Applicable to scanning image sonar. Mainly consider the relevant parameters that affect the sonar image, target location information, target shape, ocean environment information, by simulating the real workflow of sonar, emission, ocean propagation, target echo, reception, signal processing, display, and finally generate simulation data close to the real image.

[0284] Step S3.2: Transmit signal simulation results:

[0285] by Figure 6 Taking as an example, the simulation results of the transmitted signal are output in the time domain and the frequency domain.

[0286] Step S3.3: Figure 7 Take as an example to obtain the seabed and target modeling results.

[0287] Step S3.4: Sonar image simulation results:

[0288] The simulation results of the sonar image are obtained by calculation. Figure 8 For example.

[0289] In more preferred examples, according to the selection of parameters, sonar simulation images under different targets can be obtained, and the model supports the expansion of other targets. Fig. 9 For example, the left side is the real sonar image, and the right side is the simulated sonar image.

[0290] The present invention also provides a workflow-based scanning sonar image simulation modeling system. The workflow-based scanning sonar image simulation modeling system can be implemented by executing the process steps of the workflow-based scanning sonar image simulation modeling method, that is, those skilled in the art can understand the workflow-based scanning sonar image simulation modeling method as a preferred implementation of the workflow-based scanning sonar image simulation modeling system.

[0291] A scanning sonar image simulation modeling system based on workflow provided by the present invention comprises:

[0292] Module M1: Model the target and the ocean environment to obtain the target and ocean environment parameters;

[0293] Module M2: Model the sonar according to the target and ocean environment parameters and process the signal;

[0294] Module M3: Simulate imaging based on target and ocean environment parameters and processed signals.

[0295] In more preferred embodiments, the module M1 includes:

[0296] Reverberation level module: seabed reverberation simulation, calculate the seabed scattering intensity S according to the seabed quality, grazing angle and sound wave frequencyb =10lgμ+10lg(sin 2 θ), to obtain the equivalent plane wave reverberation level

[0297] Among them, μ represents the ocean bottom parameters;

[0298] θ represents the incident angle of the sound wave;

[0299] SL means sound source level;

[0300] r represents the propagation distance;

[0301] Indicates the directivity beam width;

[0302] c represents the speed of sound;

[0303] τ represents the pulse width.

[0304] Signal level module: Run ray acoustics. According to the sonar equation, the propagation loss TL = 20lg r + αr + 60-k L , Echo signal level EL = SL-2TL + TS;

[0305] Where α represents the sound absorption coefficient;

[0306] SL means sound source level;

[0307] TS represents the effect of target strength;

[0308] k L Indicates abnormal near-field propagation;

[0309] f represents the frequency of the transmitted signal.

[0310] Target module: Set the target as a sphere or cylinder, and use the sonar relative coordinate system to model the target according to the sonar equation. The sonar coordinates are always (0,0,0). The coordinates of the target are determined based on the target's relative sonar position.

[0311] When the target is a sphere, the target is suspended in the water, and the seabed reverberation is not considered. The target intensity

[0312] When the target is a cylinder, half of the target is buried in the seabed. Considering the seabed reverberation, the incident direction of the sound wave is perpendicular to the cylinder axis. The target intensity

[0313] Where a is the target radius;

[0314] L is the column length;

[0315] λ is the wavelength of the sound wave.

[0316] Acoustic shadow module: The acoustic shadow area is calculated by simulating the occlusion of light, and a negative gain is provided to the acoustic shadow area in the echo calculation.

[0317] In more preferred examples, the anchor mine in the module M2 is simulated and modeled using the sonar equation SL-2TL+TS-(NL-DI)=DT based on noise, and the bottom mine is simulated and modeled using the sonar equation SL-2TL+TS-RL=DT based on reverberation.

[0318] Through workflow analysis, sonar is broken down into emission, sound propagation, target sound scattering, reception, signal processing and display.

[0319] The simulation was performed at a beam width of 1° at a time, starting from a 45° angle on one side and repeated 90 times.

[0320] Among them, SL represents the sound source level of the active sonar;

[0321] TL represents transmission loss;

[0322] TS represents target strength;

[0323] NL represents the marine ambient noise level;

[0324] DI represents the sonar directivity coefficient;

[0325] RL means reverberation level;

[0326] DT represents the detection threshold.

[0327] The module M3 sets sonar parameters and target parameters to obtain emission signal simulation results and seabed and target modeling results, samples and normalizes the processed signals, and then uses a color table algorithm to map them to a pseudo-color image display to obtain sonar image simulation results.

[0328] In more preferred embodiments, the module M2 includes:

[0329] Module M2.1: The signal time domain expression of CW single-frequency rectangular pulse is: The time domain expression of LFM linear frequency modulation pulse signal is: T0=2r / c, adjust the parameters to simulate the transmission signal;

[0330] Where f0 represents frequency;

[0331] A represents the amplitude of the signal;

[0332] T represents the signal pulse width, which represents the width of the pulse signal;

[0333] j represents the imaginary part;

[0334] k represents the chirp frequency;

[0335] t represents the time of the signal;

[0336] T represents the time of the signal;

[0337] T0 represents the pulse repetition period, which is the total length of the signal;

[0338] r represents the propagation distance;

[0339] c represents the speed of sound.

[0340] Module M2.2: echo signal level EL = SL-2TL + TS, the echo signal delay is calculated through the sound propagation model The echo signal voltage is calculated through the target acoustic scattering model and the seabed reverberation model. Generates target echo.

[0341] Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b), frequency domain value of the total echo signal The time domain data of the echo signal is obtained by inverse Fourier transform, and the signal is compensated by TVG.

[0342] The beam opening angle of each scan is simulated separately to obtain 90 channels of echo data.

[0343] Among them, MX represents the response sensitivity of the receiving array;

[0344] n represents the total number of echo signals;

[0345] signal(b) represents the transmitted time domain signal;

[0346] signalfft(b) indicates the transmission of frequency domain signal;

[0347] b represents the sampling point on the phase;

[0348] α represents the sound absorption coefficient;

[0349] SL means sound source level;

[0350] TS represents the effect of target strength;

[0351] TL represents transmission loss;

[0352] EL represents the echo signal level.

[0353] In more preferred embodiments, the normalization is to normalize the data value to a grayscale value g(x,y) of 0 to 254 according to the upper and lower thresholds [min max], and map the grayscale value g(x,y) to a pseudo-color image:

[0354] g(x,y)=0 f(x,y)<min

[0355]

[0356] g(x,y)=254 f(x,y)>max;

[0357] Wherein, f(x,y) represents the simulated echo matrix;

[0358] x represents the channel number;

[0359] y represents the corresponding data point on the channel number.

[0360] The mapping is to obtain the corresponding RGB intensity value according to the grayscale value by setting a colorbar with a length of 255 pixels.

[0361] The sonar parameters include the type of transmitted signal, signal frequency, signal pulse width, range, pitch angle, sonar beam opening angle, sonar vertical opening angle and sonar scanning angle.

[0362] The target parameters include target type, target length, target diameter, target relative position and seabed bottom type.

[0363] The transmission signal simulation result is divided into a time domain signal and a frequency domain signal.

[0364] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0365] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A scanning sonar image simulation modeling method based on workflow, characterized in that: include: Step S1: Modeling the target and the ocean environment to obtain the target and ocean environment parameters; Step S2: Modeling the sonar according to the target and ocean environment parameters and processing the signal; Step S3: Simulate imaging based on the target and ocean environment parameters and the processed signal.

2. The scanning sonar image simulation modeling method based on workflow according to claim 1 is characterized in that: The step S1 comprises: Reverberation level step: seabed reverberation simulation, calculate the seabed scattering intensity S according to the seabed texture, grazing angle and sound wave frequency b =10lgμ+10lg(sin 2 θ), to obtain the equivalent plane wave reverberation level Among them, μ represents the ocean bottom parameters; θ represents the incident angle of the sound wave; SL means sound source level; r represents the propagation distance; Indicates the directivity beam width; c represents the speed of sound; τ represents the pulse width; Signal level step: Run ray acoustics. According to the sonar equation, the propagation loss TL = 20lgr+ar+60-k L , Echo signal level EL = SL-2TL + TS; Where α represents the sound absorption coefficient; SL means sound source level; TS represents the effect of target strength; k L Indicates abnormal near-field propagation; f represents the frequency of the transmitted signal; Target step: Set the target as a sphere or cylinder, and use the sonar relative coordinate system to model it according to the sonar equation. The sonar coordinates are always (0,0,0). The coordinates of the target are determined according to the target's relative sonar position. When the target is a sphere, the target is suspended in the water, and the seabed reverberation is not considered. The target intensity When the target is a cylinder, half of the target is buried in the seabed. Considering the seabed reverberation, the incident direction of the sound wave is perpendicular to the cylinder axis. The target intensity Where a is the target radius; L is the column length; λ is the wavelength of the sound wave; Acoustic shadow step: The acoustic shadow area is calculated by simulating the occlusion of light, and a negative gain is given to the acoustic shadow area in the echo calculation.

3. The scanning sonar image simulation modeling method based on workflow according to claim 1 is characterized in that: In step S2, the anchor mine adopts the sonar equation SL-2TL+TS-(NL-DI)=DT based on noise to perform simulation modeling, and the bottom mine adopts the sonar equation SL-2TL+TS-RL=DT based on reverberation to perform simulation modeling; Through workflow analysis, sonar is broken down into emission, sound propagation, target sound scattering, reception, signal processing and display; The simulation was performed at a beam width of 1° only, starting from a 45° angle on one side and repeated 90 times; Among them, SL represents the sound source level of the active sonar; TL represents transmission loss; TS represents target strength; NL represents the marine ambient noise level; DI represents the sonar directivity coefficient; RL means reverberation level; DT represents the detection threshold; In step S3, sonar parameters and target parameters are set to obtain emission signal simulation results and seabed and target modeling results, sample and normalize the processed signals, and then use a color table algorithm to map them to a pseudo-color image display to obtain a sonar image simulation result.

4. The scanning sonar image simulation modeling method based on workflow according to claim 3 is characterized in that: The step S2 comprises: Step S2.1: The signal time domain expression of CW single-frequency rectangular pulse is: The time domain expression of LFM linear frequency modulation pulse signal is: T0=2r / c, adjust the parameters to simulate the transmission signal; Where f0 represents frequency; A represents the amplitude of the signal; T represents the signal pulse width, which represents the width of the pulse signal; j represents the imaginary part; k represents the chirp frequency; t represents the time of the signal; T represents the time of the signal; T0 represents the pulse repetition period, which is the total length of the signal; r represents the propagation distance; c represents the speed of sound; Step S2.2: echo signal level EL = SL-2TL + TS, calculate the echo signal delay through the sound propagation model The echo signal voltage is calculated through the target acoustic scattering model and the seabed reverberation model. Generate target echo; Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b), frequency domain value of the total echo signal The time domain data of the echo signal is obtained by inverse Fourier transform, and the signal is compensated by TVG. The beam opening angle of each scan is simulated separately to obtain 90 channels of echo data; Among them, MX represents the response sensitivity of the receiving array; n represents the total number of echo signals; signal(b) represents the transmitted time domain signal; signalfft(b) indicates the transmission of frequency domain signal; b represents the sampling point on the phase; α represents the sound absorption coefficient; SL means sound source level; TS represents the effect of target strength; TL represents transmission loss; EL represents the echo signal level.

5. The scanning sonar image simulation modeling method based on workflow according to claim 3 is characterized in that: The normalization is to normalize the data value to a grayscale value g(x,y) of 0 to 254 according to the upper and lower thresholds [min max], and map the grayscale value g(x,y) to a pseudo-color image: g(x,y)=0f(x,y)<min g(x,y)=254f(x,y)>max; Wherein, f(x,y) represents the simulated echo matrix; x represents the channel number; y represents the corresponding data point on the channel number; The mapping is to obtain the corresponding RGB intensity value according to the gray value by setting a colorbar with a length of 255 pixels; The sonar parameters include the type of transmitted signal, signal frequency, signal pulse width, range, pitch angle, sonar beam opening angle, sonar vertical opening angle and sonar scanning angle; The target parameters include target type, target length, target diameter, target relative position and seabed sediment type; The transmission signal simulation result is output in the form of time domain expression and frequency domain expression.

6. A scanning sonar image simulation modeling system based on workflow, characterized in that: include: Module M1: Model the target and the ocean environment to obtain the target and ocean environment parameters; Module M2: Model the sonar according to the target and ocean environment parameters and process the signal; Module M3: Simulate imaging based on target and ocean environment parameters and processed signals.

7. The scanning sonar image simulation modeling system based on workflow according to claim 6 is characterized in that: The module M1 comprises: Reverberation level module: seabed reverberation simulation, calculate the seabed scattering intensity S according to the seabed quality, grazing angle and sound wave frequency b =10lgμ+10lg(sin 2 θ), to obtain the equivalent plane wave reverberation level Among them, μ represents the ocean bottom parameters; θ represents the incident angle of the sound wave; SL means sound source level; r represents the propagation distance; Indicates the directivity beam width; c represents the speed of sound; τ represents the pulse width; Signal level module: Run ray acoustics. According to the sonar equation, the propagation loss TL = 20lgr + αr + 60-k L , Echo signal level EL = SL-2TL + TS; Where α represents the sound absorption coefficient; SL means sound source level; TS represents the effect of target strength; k L Indicates abnormal near-field propagation; f represents the frequency of the transmitted signal; Target module: Set the target as a sphere or cylinder, and use the sonar relative coordinate system to model the target according to the sonar equation. The sonar coordinates are always (0,0,0). The coordinates of the target are determined according to the target's relative sonar position. When the target is a sphere, the target is suspended in the water, and the seabed reverberation is not considered. The target intensity When the target is a cylinder, half of the target is buried in the seabed. Considering the seabed reverberation, the incident direction of the sound wave is perpendicular to the cylinder axis. The target intensity Where a is the target radius; L is the column length; λ is the wavelength of the sound wave; Acoustic shadow module: The acoustic shadow area is calculated by simulating the occlusion of light, and a negative gain is provided to the acoustic shadow area in the echo calculation.

8. The scanning sonar image simulation modeling system based on workflow according to claim 6 is characterized in that: In the module M2, the anchor mine adopts the sonar equation SL-2TL+TS-(NL-DI)=DT based on noise for simulation modeling, and the bottom mine adopts the sonar equation SL-2TL+TS-RL=DT based on reverberation for simulation modeling; Through workflow analysis, sonar is broken down into emission, sound propagation, target sound scattering, reception, signal processing and display; The simulation was performed at a beam width of 1° only, starting from a 45° angle on one side and repeated 90 times; Among them, SL represents the sound source level of the active sonar; TL represents transmission loss; TS represents target strength; NL represents the marine ambient noise level; DI represents the sonar directivity coefficient; RL means reverberation level; DT represents the detection threshold; The module M3 sets sonar parameters and target parameters to obtain emission signal simulation results and seabed and target modeling results, samples and normalizes the processed signals, and then uses a color table algorithm to map them to a pseudo-color image display to obtain sonar image simulation results.

9. The scanning sonar image simulation modeling system based on workflow according to claim 8 is characterized in that: The module M2 comprises: Module M2.1: The signal time domain expression of CW single-frequency rectangular pulse is: The time domain expression of LFM linear frequency modulation pulse signal is: T0=2r / c, adjust the parameters to simulate the transmission signal; Where f0 represents frequency; A represents the amplitude of the signal; T represents the signal pulse width, which represents the width of the pulse signal; j represents the imaginary part; k represents the chirp frequency; t represents the time of the signal; T represents the time of the signal; T0 represents the pulse repetition period, which is the total length of the signal; r represents the propagation distance; c represents the speed of sound; Module M2.2: echo signal level EL = SL-2TL + TS, the echo signal delay is calculated through the sound propagation model The echo signal voltage is calculated through the target acoustic scattering model and the seabed reverberation model. Generate target echo; Echo signal phase Phase(b) = e -j*2π*signal(b)*delay *voltage*signalfft(b), frequency domain value of the total echo signal The time domain data of the echo signal is obtained by inverse Fourier transform, and the signal is compensated by TVG. The beam opening angle of each scan is simulated separately to obtain 90 channels of echo data; Among them, MX represents the response sensitivity of the receiving array; n represents the total number of echo signals; signal(b) represents the transmitted time domain signal; signalfft(b) indicates the transmission of frequency domain signal; b represents the sampling point on the phase; α represents the sound absorption coefficient; SL means sound source level; TS represents the effect of target strength; TL represents transmission loss; EL represents the echo signal level.

10. The scanning sonar image simulation modeling system based on workflow according to claim 8, characterized in that: The normalization is to normalize the data value to a grayscale value g(x,y) of 0 to 254 according to the upper and lower thresholds [min max], and map the grayscale value g(x,y) to a pseudo-color image: g(x,y)=0f(x,y)<min g(x,y)=254f(x,y)>max; Wherein, f(x,y) represents the simulated echo matrix; x represents the channel number; y represents the corresponding data point on the channel number; The mapping is to obtain the corresponding RGB intensity value according to the gray value by setting a colorbar with a length of 255 pixels; The sonar parameters include the type of transmitted signal, signal frequency, signal pulse width, range, pitch angle, sonar beam opening angle, sonar vertical opening angle and sonar scanning angle; The target parameters include target type, target length, target diameter, target relative position and seabed sediment type; The transmission signal simulation result is output in the form of time domain expression and frequency domain expression.

Images