A modeling method for low-frequency electromagnetic noise induced by underwater platform motion

Abstract

The application discloses a modeling method of low-frequency electromagnetic noise induced by underwater platform motion, and establishes an underwater platform motion posture equation under the influence of sea waves based on a Maxwell equation set, and analyzes the change of a velocity field of the underwater platform to realize modeling of low-frequency electromagnetic field noise induced by underwater platform motion, and then obtains amplitude distribution and spectrum characteristics of the low-frequency electromagnetic noise through simulation. The application provides a model and a method for analyzing and suppressing noise when low-frequency electromagnetic signals of an underwater target are used for detection and positioning.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetics technology, specifically relating to a method for modeling low-frequency electromagnetic noise induced by motion of an underwater platform. Background Technology

[0002] While sonar remains the primary technology for ocean exploration, its application is subject to several limitations. The propagation of sound waves in seawater is affected by factors such as water temperature, salinity, depth, and sea state, leading to unstable detection performance. Active sonar requires signal transmission, resulting in poor stealth and easily revealing the platform's location; while passive sonar, although stealthy, struggles to acquire sufficient radiated noise characteristics against modern low-noise targets, significantly reducing detection range and reliability.

[0003] With sonar performance limitations, electromagnetic detection has gained increasing attention as a supplementary method. Low-frequency electromagnetic fields propagate more stably in seawater, and underwater metal structures, motors, and motion processes all generate perceptible electromagnetic characteristics, enabling the system to passively and covertly acquire target information. For acoustically stealthy targets, electromagnetic detection can often provide detailed detection data that is difficult to obtain with sonar, especially in complex areas such as shallow seas. However, the underwater electromagnetic environment is highly complex, affected by both geomagnetic noise disturbances and electromagnetic noise generated by the moving platform on which the detection equipment is located. In particular, the low-frequency electromagnetic noise induced by the moving platform often overlaps with the frequency band of the electromagnetic signals radiated by the target, making the detection of weak target electromagnetic signals extremely difficult. Therefore, establishing a corresponding model of the low-frequency noise induced by the underwater platform's motion to understand its noise statistics and spectral characteristics is crucial for improving the processing and feature extraction of underwater target electromagnetic signals. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a method for modeling low-frequency electromagnetic noise induced by the motion of underwater platforms. Based on Maxwell's equations, it establishes the motion attitude equations of the underwater platform under the influence of ocean waves. By analyzing the changes in the velocity field of the underwater platform, it models the low-frequency electromagnetic noise induced by the motion of the underwater platform. Then, through simulation, it obtains the amplitude distribution and spectral characteristics of the low-frequency electromagnetic noise. This invention provides a model and method for noise analysis and suppression when using low-frequency electromagnetic signals of underwater targets for detection and positioning.

[0005] The technical solution adopted by this invention to solve its technical problem is as follows:

[0006] Step 1: Calculate the platform's roll, pitch, and bow angles based on the underwater platform type and wave frequency;

[0007] Step 2: Calculate the real-time velocity field of the underwater platform;

[0008] Step 3: Calculate the motion-induced electric field noise of the underwater platform using Maxwell's equations;

[0009] Step 4: Calculate the noise of the motion-induced magnetic field;

[0010] Step 5: Based on the motion-induced electric field noise obtained in Step 3 and the motion-induced magnetic field noise obtained in Step 4, calculate the amplitude distribution and spectral density of the electric field noise and the magnetic field noise.

[0011] Preferably, step 1 specifically comprises:

[0012] Step 1-1: Determine the inherent parameters of the underwater platform and the ocean waves, including gravitational acceleration. The underwater platform has high initial stability. Length of underwater platform underwater platform speed , wave height Ocean wave angular frequency ;

[0013] Step 1-2: Calculate the natural frequency of the underwater platform The calculation formula is shown in equation (1):

[0014]

[0015] Steps 1-3: Calculate wave forces Speed ​​Influence Factor Force of waves on the platform The calculation formulas are shown in equations (2), (3), and (4) respectively:

[0016]

[0017]

[0018]

[0019] In the formula Represents random frequency coefficients. Indicates the random wave direction angle. Represents a random number between 0 and 1. Here, t represents the observation time, and e represents the natural constant.

[0020] Steps 1-4: Based on the second-order damped motion equations, solve for the roll, pitch, and yaw angles of the underwater platform's motion attitude; the formulas for calculating the roll angle are shown in equation (5), the formulas for calculating the pitch angle are shown in equation (6), and the formulas for calculating the yaw angle are shown in equation (7).

[0021]

[0022]

[0023]

[0024] In the formula, This represents the roll acceleration. Indicates the roll angular velocity. Indicates the roll angle. Indicates the roll damping ratio. This represents the scaling factor for the natural frequency of the roll. Represents the pitch acceleration. Indicates the pitch angular velocity, Indicates the pitch angle. Indicates pitch damping ratio, This represents the scaling factor for the natural pitch frequency; This represents the bow roll acceleration. Indicates the bow roll angular velocity. Indicates the bow roll angle. Indicates the bow roll damping ratio. This represents the proportionality coefficient of the natural frequency of bow roll;

[0025] The roll angle is obtained by solving equations (5), (6), and (7). Pitch angle Bow roll .

[0026] Preferably, step 2 specifically comprises:

[0027] Step 2-1: Based on the roll, pitch, and yaw angles obtained in Step 1, obtain the rotation matrices in three different directions in the underwater platform coordinate system and the absolute coordinate system; the calculation formulas for the roll, pitch, and yaw rotation matrices are shown in equations (8) to (10):

[0028]

[0029]

[0030]

[0031] In the formula, , , These represent the roll rotation matrix, pitch rotation matrix, and yaw rotation matrix, respectively.

[0032] Step 2-2: Combine the rotation matrices in the order of "bow → pitch → roll" to obtain the total rotation matrix and velocity conversion formula; compensate for the velocity in the z-axis direction after conversion; the total rotation matrix formula is shown in Equation (11), the velocity conversion formula is shown in Equation (12), and the z-axis velocity compensation formula is shown in Equation (13):

[0033]

[0034]

[0035]

[0036] In the formula, Represents the total rotation matrix; This represents the three-axis velocity components of the underwater platform in the ship's coordinate system. This represents the three-axis velocity components of the transformed velocity in the absolute coordinate system after the rotation matrix transformation. Indicates the compensation coefficient. Indicates a time interval;

[0037] Obtain the transformation speed after the total rotation matrix transformation. .

[0038] Preferably, step 3 specifically comprises:

[0039] Step 3-1: The formula for calculating the motion-induced electric field is as follows:

[0040]

[0041] In the formula This indicates the geomagnetic field component at the location of the underwater platform. This represents the three-directional motion-induced electric field noise component generated by the underwater platform cutting through the Earth's magnetic field.

[0042] set up The magnitude of the Earth's magnetic field is represented by the magnetic inclination angle. Magnetic declination is Expanding equation (14), the formula for calculating the induced electric field is transformed into equation (15):

[0043]

[0044] Step 3-2: Change the speed of the underwater platform By taking the velocity magnitude in the figure and repeating step 3-1, we can obtain the simulation results of motion-induced electric field noise at different velocities.

[0045] Preferably, step 4 specifically comprises:

[0046] Using the induced electric field noise calculated in step 3 as the input parameter, and combining the differential form of Ampere's circuital law with the constitutive relation of the medium, the motion-induced electric field noise is calculated. Calculate motion-induced magnetic field noise The calculation formula is as follows:

[0047]

[0048] In the formula, Represents the permeability of free space. Indicates electrical conductivity. Represents the vacuum permittivity. This represents the relative permittivity.

[0049] Preferably, step 5 specifically comprises:

[0050] Step 5-1: Further process the motion-induced electric field noise calculated in Step 3; plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the electric field noise and plot a histogram to obtain the amplitude distribution of the electric field noise; through analysis, clarify the characteristics of the motion-induced electric field noise obtained from the simulation.

[0051] Step 5-2: Further process the motion-induced magnetic field noise calculated in Step 4; plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the magnetic field noise and plot a histogram to obtain the amplitude distribution of the magnetic field noise; through analysis, clarify the characteristics of the motion-induced magnetic field noise obtained from the simulation.

[0052] An electronic device includes: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to enable the electronic device to perform the above-described low-frequency electromagnetic noise modeling method.

[0053] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described low-frequency electromagnetic noise modeling method.

[0054] A chip includes a processor for calling and running a computer program from a memory, causing a device on which the chip is installed to perform the aforementioned low-frequency electromagnetic noise modeling method.

[0055] A computer program product includes a computer storage medium storing a computer program, the computer program including instructions executable by at least one processor, which, when executed by the at least one processor, implement the aforementioned low-frequency electromagnetic noise modeling method.

[0056] The beneficial effects of this invention are as follows:

[0057] This invention converts the actual velocity of the platform in the waves into velocity components in the absolute coordinate system by calculating the rotation matrix between the platform coordinate system and the absolute coordinate system. Then, based on Faraday's law of electromagnetic induction and Ampere's circuital law, the low-frequency electromagnetic noise induced by the motion of the underwater platform is calculated, and the noise characteristics are analyzed. This invention provides a model and method for the analysis and suppression of noise when detecting and locating underwater targets based on low-frequency electromagnetic signals. Attached Figure Description

[0058] Figure 1 This is a schematic flowchart of the method of the present invention;

[0059] Figure 2 This is a schematic diagram of the underwater platform's motion space in the method of the present invention;

[0060] Figure 3 This is a schematic diagram of the total velocity after the rotation matrix transformation in the method of the present invention;

[0061] Figure 4 This is a schematic diagram of the velocity in the x-direction after transformation by the rotation matrix in the method of the present invention;

[0062] Figure 5 This is a schematic diagram of the velocity in the y-direction after transformation by the rotation matrix in the method of the present invention;

[0063] Figure 6 This is a schematic diagram of the velocity in the z-direction after transformation by the rotation matrix in the method of the present invention;

[0064] Figure 7 This is a schematic diagram of the time-domain waveform of the electric field noise calculated by the method of the present invention;

[0065] Figure 8 This is a schematic diagram of the electric field noise power spectral density at 1-30Hz calculated by the method of the present invention.

[0066] Figure 9 This is a schematic diagram of the electric field noise amplitude distribution calculated by the method of the present invention;

[0067] Figure 10 This is a schematic diagram of the time-domain waveform of the magnetic field noise calculated by the method of the present invention;

[0068] Figure 11 This is a schematic diagram of the 1-30Hz power spectral density of magnetic field noise calculated by the method of the present invention;

[0069] Figure 12 This is a schematic diagram of the magnetic field noise amplitude distribution calculated by the method of the present invention. Detailed Implementation

[0070] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0071] This invention provides a method for modeling low-frequency electromagnetic noise induced by the motion of an underwater platform. Based on Maxwell's equations, the method establishes the motion attitude equations of the underwater platform under the influence of ocean waves. By analyzing the changes in the velocity field of the underwater platform, the method can model the low-frequency electromagnetic noise induced by the motion of the underwater platform. Then, the amplitude distribution and spectral characteristics of the low-frequency electromagnetic noise are obtained through simulation.

[0072] This invention includes the following steps:

[0073] S1: Calculate the platform's roll, pitch, and bow angles based on the type of underwater platform and the frequency of ocean waves;

[0074] Step S1.1: Determine the inherent parameters of the underwater platform and ocean waves, such as gravitational acceleration. The underwater platform has high initial stability. Length of underwater platform underwater platform speed , wave height Ocean wave angular frequency .

[0075] Step S1.2: Based on the gravitational acceleration, initial stability of the underwater platform, and length parameters obtained in Step S1.1, calculate the natural frequency of the underwater platform. :

[0076]

[0077] Step S1.3: Calculate the wave force based on the underwater platform speed, wave height, and wave angular frequency obtained in Step S1.1. Speed ​​Influence Factor Force of waves on the platform :

[0078]

[0079]

[0080]

[0081] Step S1.4: Based on the natural frequency obtained in step S1.2 The wave force on the platform obtained in step S1.3 Based on the second-order damped motion equations, the roll, pitch, and bow angles of the underwater platform's motion attitude are solved:

[0082]

[0083]

[0084]

[0085] The roll angle is obtained through the above solution process. Pitch angle Bow roll .

[0086] S2: Calculate the real-time velocity field of the underwater platform based on the angle information obtained in step S1;

[0087] Step S2.1: Based on the roll, pitch, and bow angles obtained in Step S1, obtain the rotation matrices in three different directions in the underwater platform coordinate system and the absolute coordinate system:

[0088]

[0089]

[0090]

[0091] Step S2.2: Combine the rotation matrices in the order of "bow → pitch → roll" to obtain the total rotation matrix and velocity conversion formula. Simultaneously, to avoid long-term displacement accumulation, compensate for the velocity in the z-axis direction after conversion.

[0092]

[0093]

[0094]

[0095] In the formula It requires compensation and iteration.

[0096] After the above solution, the transformation speed after the total rotation matrix transformation is finally obtained. .

[0097] S3: Based on the real-time velocity field in step S2, calculate the motion-induced electric field noise of the underwater platform using Maxwell's equations;

[0098] Step S3.1: The movement of the underwater platform will cause it to cut through the Earth's magnetic field, generating an induced electric field. The corresponding induced electric field is calculated using Faraday's law of electromagnetic induction. The formula for calculating the induced electric field is as follows:

[0099]

[0100] Expanding equation (14), the formula for calculating the induced electric field is transformed into equation (15):

[0101]

[0102] Step S3.2: Change the speed of the underwater platform By taking the velocity magnitude value in the figure and repeating step S3.1, the simulation results of motion-induced electric field noise at different speeds are obtained.

[0103] S4: Calculate the motion-induced magnetic field noise based on the motion-induced electric field noise in step S3;

[0104] Using the induced electric field noise calculated in step S3 as the input parameter, and combining the differential form of Ampere's circuital law with the constitutive relation of the medium, the motion-induced electric field noise is calculated. Calculate motion-induced magnetic field noise The calculation formula is as follows:

[0105]

[0106] In Equation 16 Represents the permeability of free space. Indicates electrical conductivity. Represents the vacuum permittivity. This represents the relative permittivity.

[0107] S5: Based on the motion-induced electric field noise obtained in step S3 and the motion-induced magnetic field noise obtained in step S4, calculate the amplitude distribution and spectral density of the electric field and magnetic field noise.

[0108] Step S5.1: Further process the motion-induced electric field noise calculated in Step 3. Plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the electric field noise and plot a histogram to obtain the amplitude distribution of the electric field noise. Through the above analysis, clarify the characteristics of the motion-induced electric field noise obtained from the simulation.

[0109] Step S5.2: Further process the motion-induced magnetic field noise calculated in Step 4. Plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the magnetic field noise and plot a histogram to obtain the amplitude distribution of the magnetic field noise. Through the above analysis, clarify the characteristics of the motion-induced magnetic field noise obtained from the simulation.

[0110] Example:

[0111] To verify the effectiveness of the proposed method for modeling low-frequency electromagnetic noise induced by underwater platform motion, simulation modeling was carried out according to the steps outlined in the invention. The low-frequency electromagnetic noise generated by the motion of a certain type of underwater platform was taken as an example.

[0112] The specific steps for step S1 are as follows:

[0113] Step S1.1: Determine the inherent parameters of the underwater platform and ocean waves, such as gravitational acceleration. Taking 9.81, the initial stability of the underwater platform is high. Take 1.5m, underwater platform length Take 100m and the speed of the underwater platform Take sections 1, 3, 10, 50, and 100, where the angle between the velocity direction and the positive x-axis and y-axis is 45 degrees. Figure 2 The wave height is indicated by the bold dashed arrow. Take 2m, wave angular frequency It varies over time and is represented as a one-dimensional array with an average frequency of 0.16 Hz, such as... The solid wavy line represents the shape.

[0114] Step S1.2: Based on the gravitational acceleration, initial stability of the underwater platform, and length parameters obtained in step S1.1, calculate the natural frequency of the underwater platform. :

[0115]

[0116] Calculated Approximately 0.077

[0117] Step S1.3: Calculate the wave force based on the underwater platform speed, wave height, and wave angular frequency obtained in step S1.1. Speed ​​Influence Factor Force of waves on the platform :

[0118]

[0119]

[0120]

[0121] because , , , All of these are parameters that change over time, i.e. and The calculated result is also a one-dimensional array, and its length is the same as the length of the wave angular frequency array.

[0122] Take speed influence factor middle It is 0.8. If it is -0.25, then These are also parameters that vary with the speed of the underwater platform. Take... middle Given a value of 1, at the same underwater platform speed, the final result is obtained as the wave angular frequency changes. The changing force of the waves on the platform

[0123] Step S1.4, based on the natural frequency obtained in step S1.2 The wave force on the platform is obtained from step S1.3. Based on the second-order damped motion equations, the roll, pitch, and bow angles of the underwater platform's motion attitude are solved:

[0124]

[0125]

[0126]

[0127] Pick The is 0.1, and j is 0.15. The value is 0.2. After the above solution process, the roll angle is obtained. Pitch angle Bow roll These three angle data are also related to the wave angular frequency. Arrays of the same length.

[0128] The specific steps for step S2 are as follows:

[0129] Step S2.1: Based on the roll, pitch, and bow angles obtained in Step S1, obtain the rotation matrices in three different directions in the underwater platform coordinate system and the absolute coordinate system:

[0130]

[0131]

[0132]

[0133] Step S2.2: Combine the rotation matrices in the order of "bow → pitch → roll" to obtain the total rotation matrix and velocity conversion formula. Simultaneously, to avoid long-term displacement accumulation, compensate for the velocity in the z-axis direction after conversion.

[0134]

[0135]

[0136]

[0137] After the above solution, the wave angular frequency is... Each element at each time step receives the transformation velocity after the transformation by the total rotation matrix at that time step. , It is related to the angular frequency of ocean waves Arrays of the same length, and along with The changes are constant. Changing the speed at 1, 3, 10, 50, and 100 knots... The changes of its components along each axis over time are plotted as follows: , , , As shown.

[0138] Step S3 is performed as follows:

[0139] Step S3.1: The movement of the underwater platform will cause it to cut through the Earth's magnetic field, generating an induced electric field. The corresponding induced electric field is calculated using Faraday's law of electromagnetic induction. The formula for calculating the induced electric field is as follows:

[0140]

[0141] In the calculation formula Take 50000nT, Take 8 degrees. Take -10 degrees, its direction is shown as follows As indicated by the thick solid line arrow.

[0142] Step S3.2: Take the speed of the underwater platform The simulation results of motion-induced electric field noise are obtained in three sections.

[0143] The specific operation of step S4 is as follows:

[0144] Using the induced electric field noise calculated in step S3 as the input parameter, and combining the differential form of Ampere's circuital law with the constitutive relation of the medium, the motion-induced electric field noise is calculated. Calculate motion-induced magnetic field noise The calculation formula is as follows:

[0145]

[0146] Pick = 4π×10 −7 H / m, =4.8S / m, = 8.85×10 −12 F / m, =80, and the motion-induced magnetic field noise is calculated.

[0147] Step S5 is performed as follows:

[0148] Step S5.1: Further process the motion-induced electric field noise calculated in Step 3. Plot the time-domain waveform; calculate and plot the power spectral density curve within the 1-30Hz frequency band, and simultaneously average the power spectral density within this band to obtain the spectral density; statistically analyze the amplitude of the electric field noise and plot a histogram to obtain the amplitude distribution of the electric field noise. Through the above analysis, clarify the characteristics of the motion-induced electric field noise obtained from the simulation, such as... , , As shown.

[0149] Step S5.2: Further process the motion-induced magnetic field noise calculated in Step 4. Plot the time-domain waveform; calculate and plot the power spectral density curve within the 1-30Hz frequency band, and simultaneously average the power spectral density within this band to obtain the spectral density; statistically analyze the amplitude of the magnetic field noise and plot a histogram to obtain the amplitude distribution of the magnetic field noise. Through the above analysis, clarify the characteristics of the motion-induced magnetic field noise obtained from the simulation, such as... , , As shown.

[0150] Step S5.3: Take the underwater platform's movement speed as 1, 3, 10, 50, and 100 knots, repeat the above calculation process, and calculate the spectral density of the motion-induced electric field noise and magnetic field noise in the 1-30Hz range for each initial underwater platform movement speed, and analyze the impact of speed on noise level.

[0151] Simulation results:

[0152] (1) , , , This demonstrates how the underwater platform's velocity changes due to the force of ocean waves at different moving speeds. It can be seen that when the underwater platform speed is high, the output transformation speed after calculation is basically stable, and the initial speed is basically the same numerically. and The changes in the x-axis and y-axis components of the transformation velocity show that the trends of the x-axis and y-axis components are basically the same. The information indicates that the velocity component generated along the z-axis is stronger at low speeds than at high speeds. The overall speed changes in the medium and low speeds show similar trends: the speed is basically stable at high speeds, while the speed changes significantly at low speeds, which is consistent with the general understanding of high-speed wave resistance.

[0153] (2) to This reflects the time-domain waveform, power spectrum, and amplitude distribution of motion-induced electric field noise in the 1-30Hz frequency band during section 3. It can be seen that the motion-induced electric field noise intensity is highest in the y-axis direction, with a peak-to-peak value of approximately 4 uV / m, while the motion-induced electric field noise intensity is lower in the x-axis direction, with a peak-to-peak value of approximately 0.5 uV / m. From It can be seen that its power spectrum shows a generally low noise level in the 1-30Hz range, while the power spectrum of the motion-induced electric field noise is strongest in the y-axis direction, with the noise approaching 0 dB at the highest frequency. It can be seen that the amplitude distribution of motion-induced electric field noise exhibits a certain regularity, which is close to the normal fitting curve, and can be approximately considered to conform to the normal distribution.

[0154] (3) to This reflects the time-domain waveform, power spectrum, and amplitude distribution of motion-induced magnetic field noise in the 1-30Hz frequency band at section 3. It can be seen that the motion-induced magnetic field noise intensity is highest in the x-axis direction, with a peak-to-peak value of approximately 20 pT, while the motion-induced electric field noise intensity is lower in the z-axis direction, with a peak-to-peak value of approximately 2 pT. It can be seen that its power spectrum shows a generally low noise level in the 1-30Hz range, while the power spectrum of the motion-induced magnetic field noise is strongest in the x-axis direction, with noise exceeding 0 dB at the highest frequency. From It can be seen that the amplitude distribution of motion-induced magnetic field noise follows a certain pattern, which is close to the normal fitting curve, and can be approximately considered to conform to the normal distribution.

[0155] (4) As shown in Table 1, for motion-induced electric field noise, the electric field noise spectral density at section 1 is approximately 0.16. Furthermore, as the underwater platform's speed increases, the spectral density of its motion-induced electric field noise decreases, becoming negligible above 50 knots. The overall magnitude of motion-induced magnetic field noise is also very small, and it can be considered negligible under geomagnetic field interference. At speeds below 10 knots, the spectral density of the motion-induced magnetic field noise fluctuates somewhat, but the fluctuations are small. When the speed exceeds 50 knots, the spectral density of the magnetic field noise decreases significantly with increasing speed, mirroring the trend of the induced electric field noise. In summary, this indicates that increasing the underwater platform's speed can, to some extent, suppress motion-induced electromagnetic field noise in the 1-30Hz frequency band.

[0156] surface Electromagnetic field noise spectral density within 1-30Hz at different speeds on underwater platforms

[0157]

[0158] Based on the implementation examples, it can be concluded that the underwater platform motion-induced low-frequency electromagnetic noise modeling method proposed in this invention can mathematically model the induced low-frequency electromagnetic noise generated by the underwater platform's motion cutting the geomagnetic field, and analyze and summarize the noise characteristics of the underwater platform motion-induced electromagnetic field noise.

Claims

1. A method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms, characterized in that, Includes the following steps: Step 1: Calculate the platform's roll, pitch, and bow angles based on the underwater platform type and wave frequency; Step 2: Calculate the real-time velocity field of the underwater platform; Step 3: Calculate the motion-induced electric field noise of the underwater platform using Maxwell's equations; Step 4: Calculate the noise of the motion-induced magnetic field; Step 5: Based on the motion-induced electric field noise obtained in Step 3 and the motion-induced magnetic field noise obtained in Step 4, calculate the amplitude distribution and spectral density of the electric field noise and the magnetic field noise.

2. The method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms according to claim 1, characterized in that, Step 1 specifically involves: Step 1-1: Determine the inherent parameters of the underwater platform and the ocean waves, including gravitational acceleration. The underwater platform has high initial stability. Length of underwater platform underwater platform speed , wave height Ocean wave angular frequency ; Step 1-2: Calculate the natural frequency of the underwater platform The calculation formula is shown in equation (1): ； Steps 1-3: Calculate wave forces Speed ​​Influence Factor Force of waves on the platform The calculation formulas are shown in equations (2), (3), and (4) respectively: ； ； ； In the formula Represents random frequency coefficients. Indicates the random wave direction angle. Represents a random number between 0 and 1. Here, t represents the observation time, and e represents the natural constant. Steps 1-4: Based on the second-order damped motion equations, solve for the roll, pitch, and yaw angles of the underwater platform's motion attitude; the formulas for calculating the roll angle are shown in equation (5), the formulas for calculating the pitch angle are shown in equation (6), and the formulas for calculating the yaw angle are shown in equation (7). ； ； ； In the formula, This represents the roll acceleration. Indicates the roll angular velocity. Indicates the roll angle. Indicates the roll damping ratio. This represents the scaling factor for the natural frequency of the roll. Represents the pitch acceleration. Indicates the pitch angular velocity, Indicates the pitch angle. Indicates pitch damping ratio, This represents the scaling factor for the natural pitch frequency; This represents the bow roll acceleration. Indicates the bow roll angular velocity. Indicates the bow roll angle. Indicates the bow roll damping ratio. This represents the proportionality coefficient of the natural frequency of bow roll; The roll angle is obtained by solving equations (5), (6), and (7). Pitch angle Bow roll .

3. The method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms according to claim 2, characterized in that, Step 2 specifically involves: Step 2-1: Based on the roll, pitch, and yaw angles obtained in Step 1, obtain the rotation matrices in three different directions in the underwater platform coordinate system and the absolute coordinate system; the calculation formulas for the roll, pitch, and yaw rotation matrices are shown in equations (8) to (10): ； ； ； In the formula, , , These represent the roll rotation matrix, pitch rotation matrix, and yaw rotation matrix, respectively. Step 2-2: Combine the rotation matrices in the order of "bow → pitch → roll" to obtain the total rotation matrix and velocity conversion formula; compensate for the velocity in the z-axis direction after conversion; the total rotation matrix formula is shown in Equation (11), the velocity conversion formula is shown in Equation (12), and the z-axis velocity compensation formula is shown in Equation (13): ； ； ； In the formula, Represents the total rotation matrix; This represents the three-axis velocity components of the underwater platform in the ship's coordinate system. This represents the three-axis velocity components of the transformed velocity in the absolute coordinate system after the rotation matrix transformation. Indicates the compensation coefficient. Indicates a time interval; Obtain the transformation speed after the total rotation matrix transformation. .

4. The method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms according to claim 3, characterized in that, Step 3 specifically involves: Step 3-1: The formula for calculating the motion-induced electric field is as follows: (14)； In the formula This indicates the geomagnetic field component at the location of the underwater platform. This represents the three-directional motion-induced electric field noise component generated by the underwater platform cutting through the Earth's magnetic field. set up The magnitude of the Earth's magnetic field is represented by the magnetic inclination angle. Magnetic declination is Expanding equation (14), the formula for calculating the induced electric field is transformed into equation (15): ； Step 3-2: Change the speed of the underwater platform By taking the velocity magnitude in the figure and repeating step 3-1, we can obtain the simulation results of motion-induced electric field noise at different velocities.

5. The method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms according to claim 4, characterized in that, Step 4 specifically involves: Using the induced electric field noise calculated in step 3 as the input parameter, and combining the differential form of Ampere's circuital law with the constitutive relation of the medium, the motion-induced electric field noise is calculated. Calculate motion-induced magnetic field noise The calculation formula is as follows: ； In the formula, Represents the permeability of free space. Indicates electrical conductivity. Represents the vacuum permittivity. This represents the relative permittivity.

6. The method for modeling low-frequency electromagnetic noise induced by motion in underwater platforms according to claim 5, characterized in that, Step 5 specifically involves: Step 5-1: Further process the motion-induced electric field noise calculated in Step 3; plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the electric field noise and plot a histogram to obtain the amplitude distribution of the electric field noise; through analysis, clarify the characteristics of the motion-induced electric field noise obtained from the simulation. Step 5-2: Further process the motion-induced magnetic field noise calculated in Step 4; plot the time-domain waveform; calculate and plot the power spectral density curve in the 1-30Hz frequency band, and average the power spectral density in this frequency band to obtain the spectral density; statistically analyze the amplitude of the magnetic field noise and plot a histogram to obtain the amplitude distribution of the magnetic field noise; through analysis, clarify the characteristics of the motion-induced magnetic field noise obtained from the simulation.

7. An electronic device, characterized in that, include: Processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to cause the electronic device to perform the method as described in any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 6.

9. A chip, characterized in that, include: A processor for retrieving and running a computer program from memory, causing a device on which the chip is mounted to perform the method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, The computer program product includes a computer storage medium storing a computer program, the computer program including instructions executable by at least one processor, which, when executed by the at least one processor, implement the method as described in any one of claims 1 to 6.

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