Method for positioning an alternating magnetic dipole source in seawater, positioning method and system

Abstract

The application is a kind of seawater alternating magnetic dipole source positioning modeling method, positioning method and system, belonging to the target positioning field; the application is to eliminate the positioning error in the positioning experiment on the sea, on the basis of the magnetic dipole magnetic field model in the air, the attenuation coefficient k related to the frequency of alternating magnetic dipole and seawater conductivity is introduced, and the model F' = K F of the positioning of alternating magnetic dipole source in seawater is established. The system comprises n single component inductive sensors, data acquisition module and host computer; the n single component inductive sensor array is arranged, and is connected with the host computer through the data acquisition module; the data acquisition module transmits the magnetic field value measured by the sensor array to the host computer; the host computer calculates the position information of the target by using the magnetic field data and the attenuation coefficient of the sensor through the built-in positioning algorithm. The application improves the accuracy of the positioning of alternating radiation source in seawater, and expands the application environment of the alternating radiation source positioning system.

Description

Technical Field

[0001] This invention belongs to the field of target positioning, specifically relating to a modeling method, positioning method and system for positioning alternating magnetic dipole sources in seawater. Background Technology

[0002] In near-field localization of underwater targets, the transmitting coil of the target's electromagnetic fuse is typically modeled as a magnetic dipole. According to the propagation model of a magnetic dipole, if the magnetic moment information of the magnetic dipole is known, the magnetic field information it generates at any point in space can be calculated. Conversely, if the magnetic field distribution generated by the magnetic dipole at a certain point in space is obtained, the position of the magnetic dipole can be deduced; this is magnetic target localization. When the magnetic dipole radiation source is in motion, the sensors in the magnetic field information measurement system can collect a series of magnetic field data. Using this measurement data and the sensor's position, information such as the relative position and motion state of the magnetic target and the measurement system can be deduced.

[0003] In existing technologies, the positioning model for locating alternating magnetic dipole radiation sources uses the magnetic dipole propagation model in air. This model is only suitable for locating radiation sources in air or media with low conductivity (such as fresh water). When locating alternating radiation sources in seawater, the alternating electromagnetic waves propagate in the seawater, which has a high conductivity. This significantly alters the propagation model of the alternating electromagnetic waves. If the magnetic dipole model in air is still used for locating the alternating radiation source in this case, the positioning accuracy will be affected, resulting in certain errors. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To overcome the shortcomings of existing technologies, this invention provides a modeling method, positioning method, and system for locating alternating magnetic dipole sources in seawater. When an alternating magnetic dipole source moves in a conductive medium (seawater), such as in the terminal trajectory measurement of an electromagnetic torpedo, its radiated magnetic field will attenuate differently due to the electromagnetic properties of seawater compared to air. Background art models for locating alternating magnetic dipole sources do not consider the influence of seawater conductivity, leading to significant errors between the positioning results and the actual location, thus affecting the accuracy of the positioning system. To eliminate positioning errors during sea-based positioning experiments, this invention introduces an attenuation coefficient related to the alternating magnetic dipole frequency and seawater conductivity, based on the magnetic dipole magnetic field model in air, to establish a model for locating alternating magnetic dipole sources in seawater. This improves the accuracy of locating alternating radiation sources in seawater and expands the application environment of alternating radiation source positioning systems.

[0006] The technical solution of this invention is: a method for locating and modeling alternating magnetic dipole sources in seawater, characterized by the following specific steps:

[0007] Step 1: Establish the magnetic field strength matrix for n single-component magnetic sensors:

[0008]

[0009] Where (x0, y0, z0) are the position coordinates of the magnetic dipole radiation source, (x i y i , z i Let R be the position coordinates of the i-th sensor. i Let be the distance from the target to the i-th sensor, where i = 1, 2, ..., n;

[0010] Step 2: Establish a localization model for alternating magnetic dipole sources in seawater:

[0011] F′=K·F

[0012] in, p is the attenuation coefficient of the i-th sensor; i Let be the combined parameters of the i-th sensor.

[0013] A further technical solution of the present invention is: in step 2, the combination parameter p of the i-th sensor among the n single-component magnetic sensors is expressed as:

[0014]

[0015] in, Let μ be the distance from the target to the i-th sensor, μ be the magnetic permeability of the seawater medium, σ be the electrical conductivity of the seawater medium, and ω be the angular frequency of the alternating magnetic dipole source.

[0016] A method for locating alternating magnetic dipole sources in seawater, characterized by the following specific steps:

[0017] Step 1: Obtain the magnetic field measurement values ​​of the sensor array as input parameters.

[0018] Step 2: Solve for the attenuation coefficient Ki of the i-th sensor. ；

[0019] Step 3: Calculate the coefficient matrix of the alternating magnetic dipole source localization model in seawater;

[0020] Step 4: Use the Levenberg-Marquardt algorithm to solve the nonlinear least squares optimization problem and obtain the position coordinates (x0, y0, z0) of the alternating magnetic dipole source in seawater.

[0021] A further technical solution of the present invention is: in step 1, the input parameters include the magnetic permeability μ of the seawater medium, the electrical conductivity σ of the seawater medium, the angular frequency ω of the alternating magnetic dipole source, and the position coordinates (x, y, y) of the n single-component magnetic sensors in the measurement system. i ,y i ,z i ).

[0022] A further technical solution of the present invention is as follows: In step 2, let the position coordinates of the alternating magnetic dipole source be (x0, y0, z0). First, calculate the distance from the alternating magnetic dipole source to the i-th sensor, using the following formula:

[0023]

[0024] Then, calculate the attenuation coefficient K of the i-th sensor. i The formula is as follows:

[0025]

[0026] Among them, the combination parameters

[0027] A further technical solution of the present invention is: in step 3, the coefficient matrix F′=K·F of the alternating magnetic dipole source localization model in seawater is specifically formulated as follows:

[0028]

[0029] A further technical solution of the present invention is as follows: In step 4, the formula for solving the nonlinear least squares optimization problem is as follows:

[0030]

[0031] Where H represents the magnetic field measurements of n single-component magnetic sensors.

[0032] A positioning system for an alternating magnetic dipole source in seawater, characterized in that: it includes n single-component inductive sensors, a data acquisition module, and a host computer; the n single-component inductive sensors are arranged in an array and connected to the host computer through the data acquisition module respectively;

[0033] The data acquisition module transmits the magnetic field values ​​measured by the sensor array to the host computer;

[0034] The host computer uses magnetic field data and sensor attenuation coefficients to calculate the target's location information through a built-in positioning algorithm.

[0035] A further technical solution of the present invention is as follows: the number of single-component inductive sensors is 12, numbered from 1 to 12. A coordinate system is established with sensor 2 as the origin. The array is located in the xOy plane with z=0. The 6 sensors with odd numbers are placed in one column with a spacing of 6m; the 6 sensors with even numbers are placed in another column with a spacing of 6m, and the distance from the sensors in the odd-numbered column is 13.4m.

[0036] Beneficial effects

[0037] The beneficial effects of this invention are as follows: Based on the prior art, this invention considers the influence of the medium in which the magnetic dipole source is located on the propagation of electromagnetic waves. By introducing an attenuation coefficient, the coefficient matrix of the positioning model of alternating magnetic dipole source in seawater is calculated, thus eliminating the influence of the conductivity of the medium and improving the accuracy of positioning.

[0038] Experimental verification Figure 5 and Figure 6 For the purpose of comparing the positioning results of the background technology model and the model of this invention, Figure 7 To compare the positioning errors of the two methods, the RMSE (root mean square error) of the two methods was calculated, and the RMSE of the x-coordinate was found to be 2.75m and 3.54×10, respectively. -10 The RMSE values ​​for the m and y coordinates are 0.88m and 4.10 × 10, respectively. -10 The RMSE values ​​for the m and z coordinates are 8.63m and 4.09 × 10, respectively. -10 m. As can be seen from the figure and the error calculation, after applying the model in this invention, the positioning error is reduced and the accuracy is improved, providing technical support for the optimization of the magnetic sensor array-based measurement system. Attached Figure Description

[0039] Figure 1 Schematic diagram of magnetic dipole coordinates;

[0040] Figure 2 Roadmap for alternating magnetic dipole source localization technology;

[0041] Figure 3 Block diagram of alternating magnetic dipole source positioning system;

[0042] Figure 4 Schematic diagram of alternating magnetic dipole source localization scenario;

[0043] Figure 5 Sensor array positioning results (top view);

[0044] Figure 6 A comparison chart of the three coordinate estimates;

[0045] Figure 7 A comparison chart of the estimation errors of the three coordinates. Detailed Implementation

[0046] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0047] Example 1: Modeling method for locating alternating magnetic dipole sources in seawater:

[0048] The magnetic permeability μ of seawater is the same as that of air, both being 4π × 10⁻⁶. -7 H / m, conductivity σ=3~5Ωm, for an alternating magnetic dipole with magnetic moment M, pointing in the positive z-axis direction, and frequency not equal to 0, such as Figure 1 As shown, the center of the magnetic dipole is located at the origin of the coordinate system. Let the combined parameters be related to the magnetic permeability and conductivity of the seawater medium, the frequency of the alternating radiation source, and the distance between the measurement point and the source. Where R is the distance from the target magnetic dipole radiation source to the observation point. r is the radial component in the cylindrical coordinate system. x, y, z are the rectangular coordinates of the measurement point, and ω is the angular frequency of the magnetic field change.

[0049] Solving Maxwell's equations yields the magnitude of the magnetic field of a magnetic dipole:

[0050]

[0051]

[0052] Where H r H is the radial component of the magnetic field. z M is the axial component of the magnetic field. z M represents the axial component of the magnetic moment produced by the magnetic dipole. r Let be the radial component of the magnetic moment. In equation (1), the square root term can be simplified to...

[0053]

[0054] Therefore, the magnitude of the magnetic field component in the rectangular coordinate system can be expressed as follows:

[0055]

[0056]

[0057]

[0058] Where M x M is the component of the magnetic moment produced along the x-axis. y M represents the component of the magnetic moment along the y-axis. z This represents the component of the magnetic moment along the z-axis.

[0059] When ω = 0, i.e., the frequency of the alternating radiation source is 0, it is a static magnetic dipole. At this time, the combination parameter p = 0, and the propagation model attenuation coefficient in equations (4), (5), and (6) is also 0. When the frequency of the alternating radiation source is not zero (electromagnetic fuze) and it is located in a seawater environment, this attenuation factor cannot be ignored. Therefore, compared with the static magnetic dipole, the magnetic field of the alternating magnetic dipole in seawater is equal to the magnetic field of the static magnetic dipole multiplied by an attenuation coefficient, let it be K:

[0060]

[0061] Then, equations (4), (5), and (6) can be written in matrix form as follows:

[0062]

[0063] Assuming a measurement system consisting of n single-component magnetic sensors, the combined parameter p for each sensor is expressed as:

[0064]

[0065] in Let x be the distance from the target to the i-th sensor. i ,y i ,z i Let (x0, y0, z0) be the position coordinates of the i-th sensor, which are known; and let (x0, y0, z0) be the position coordinates of the magnetic dipole radiation source. Then, the attenuation coefficient of the i-th sensor is:

[0066]

[0067] Express the magnetic field values ​​at the n sensor locations in matrix form:

[0068]

[0069] Wherein, the coefficient matrix is:

[0070] K = [K1, K2, ..., K n (12)

[0071]

[0072] The localization model of alternating magnetic dipole sources in seawater is obtained:

[0073] F′=K·F (14)

[0074] When the sensor array measures a set of magnetic field values, the accurate location of the magnetic dipole source in seawater can be obtained by solving the equation H = F′M. Thus, a localization model for the alternating magnetic dipole source in seawater is obtained.

[0075] Example 2: Method for locating alternating magnetic dipole sources in seawater:

[0076] Reference Figure 2 The roadmap for alternating magnetic dipole source localization technology involves substituting the magnetic field measurements from the sensor array into the localization model, and then obtaining the target's position coordinates through model inversion.

[0077] The steps for locating an alternating magnetic dipole source in seawater are as follows:

[0078] S2.1 Input Parameters:

[0079] (1) The magnetic permeability of seawater medium μ=4π×10 -7 H / m;

[0080] (2) The conductivity σ of the seawater medium is obtained by measuring the conductivity meter;

[0081] (3) The angular frequency ω of the alternating magnetic dipole source;

[0082] (4) The position coordinates (x, y) of the n single-component magnetic sensors in the measurement system i ,y i ,z i ), i = 1, 2, ..., n.

[0083] S2.2 Let the position coordinates of the alternating magnetic dipole source be (x0, y0, z0), and further calculate the parameters:

[0084] (1) Distance from the alternating magnetic dipole source to the i-th sensor

[0085]

[0086] (2) For each magnetic sensor, there are: combined parameters Then the attenuation coefficient

[0087]

[0088] S2.3 Calculate the coefficient matrix of the alternating magnetic dipole source localization model in seawater.

[0089]

[0090] S2.4 uses the Levenberg-Marquardt algorithm to solve the nonlinear least squares optimization problem:

[0091]

[0092] The position coordinates (x0, y0, z0) of the alternating magnetic dipole source in seawater are obtained, where H is the magnetic field measurement value of n single-component magnetic sensors.

[0093] Example 3: Alternating Magnetic Dipole Source Localization System in Seawater

[0094] Reference Figure 3 This is a block diagram of a seawater alternating magnetic dipole source positioning system. The system consists of 12 single-component inductive sensors, a data acquisition module, and host computer software. The sensor array is connected to the data acquisition module, which in turn is connected to the host computer software. The data acquisition module transmits the magnetic field values ​​measured by the sensor array to the host computer software. Using the magnetic field data, the host computer estimates the target's location information through a built-in positioning algorithm. A model for positioning using an alternating magnetic dipole source in seawater is employed, introducing an attenuation coefficient related to the conductivity of the medium.

[0095] The simulation example is as follows:

[0096] 1. Inductive sensor array

[0097] A sensor array consisting of 12 inductive magnetic sensors, numbered 1 to 12, is used to establish a coordinate system with sensor number 2 as the origin, as follows: Figure 3 As shown, the array is located in the xOy plane at z=0. The six odd-numbered sensors are placed in one column, spaced 6m apart, with coordinates (0,13.4,0), (-6,13.4,0), (-12,13.4,0), (-18,13.4,0), (-24,13.4,0), and (-30,13.4,0). The six even-numbered sensors are placed in another column, also spaced 6m apart, at a distance of 13.4m from the odd-numbered sensors, with coordinates (0,0,0), (-6,0,0), (-12,0,0), (-18,0,0), (-24,0,0), and (-30,0,0).

[0098] 2. Other parameters

[0099] (1) The magnetic permeability of seawater medium μ=4π×10 -7 H / m;

[0100] (2) The conductivity σ of the seawater medium is taken as 4 S / m;

[0101] (3) The angular frequency of the alternating magnetic dipole source is ω = 2π × 688 (rad / s);

[0102] 3. Given the alternating magnetic dipole source position coordinates as (x0, y0, z0), further calculate the parameters:

[0103] (1) Distance from the alternating magnetic dipole source to the i-th sensor

[0104]

[0105] (2) For each magnetic sensor, there are: combined parameters Then the attenuation coefficient

[0106]

[0107] 4. Calculate the coefficient matrix of the localization model for alternating magnetic dipole sources in seawater.

[0108]

[0109] 5. Solving nonlinear least squares optimization problems using the Levenberg-Marquardt algorithm:

[0110]

[0111] The position coordinates (x0, y0, z0) of the alternating magnetic dipole source in seawater were calculated, where H represents the simulated magnetic field values ​​of the 12 single-component magnetic sensors. The positioning results of this simulation example are shown in Table 1. Figure 4 and Figure 5 As shown, the RMSE (root mean square error) of the estimated values ​​from the background technology model and the present invention model were calculated respectively, and the RMSEs for the x-coordinate were 2.75m and 3.54 × 10⁻⁶, respectively. -10 The RMSE values ​​for the m and y coordinates are 0.88m and 4.10 × 10, respectively. -10 The RMSE values ​​for the m and z coordinates are 8.63m and 4.09 × 10, respectively. - 10 m. It can be seen that after using the model in this invention, the error of the positioning result is reduced and the accuracy is improved.

[0112] Table 1 Location Results

[0113]

[0114]

[0115]

[0116] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for locating and modeling alternating magnetic dipole sources in seawater, characterized in that... The specific steps are as follows: Step 1: Establish the magnetic field strength matrix for n single-component magnetic sensors: in, The coordinates of the magnetic dipole radiation source are ( , , Let be the position coordinates of the i-th sensor. To achieve the goal of The distance between the sensors, i = 1, 2, ..., n; Step 2: Establish a localization model for alternating magnetic dipole sources in seawater: in, , For the first Attenuation coefficient of each sensor; Let be the combined parameters of the i-th sensor.

2. The method for locating and modeling alternating magnetic dipole sources in seawater according to claim 1, characterized in that: In step 2, the combined parameters of the i-th sensor among the n single-component magnetic sensors... Represented as: in, To achieve the goal of The distance between the sensors The magnetic permeability of seawater is given by [insert value here]. The conductivity of seawater is given by [reference to a specific medium]. ω is the angular frequency of the alternating magnetic dipole source.

3. A method for locating an alternating magnetic dipole source in seawater, characterized in that... The specific steps are as follows: Step 1: Obtain the magnetic field measurement values ​​of the sensor array as input parameters; the input parameters include the magnetic permeability of the seawater medium. Electrical conductivity of seawater Angular frequency of alternating magnetic dipole source Measurement system Position coordinates of a single-component magnetic sensor ; Step 2: Solve for the attenuation coefficient of the i-th sensor. Let the position coordinates of the alternating magnetic dipole source be... First, calculate the alternating magnetic dipole source up to the th The distance between the sensors is calculated using the following formula: Then, calculate the attenuation coefficient of the i-th sensor. The formula is as follows: Among them, the combination parameters ; Step 3: Calculate the coefficient matrix of the alternating magnetic dipole source localization model in seawater; The specific formula is as follows: ； Step 4: Solve the nonlinear least squares optimization problem using the Levenberg-Marquardt algorithm to obtain the position coordinates of the alternating magnetic dipole source in seawater. .

4. The method for locating an alternating magnetic dipole source in seawater according to claim 3, characterized in that: In step 4, the formula for solving the nonlinear least squares optimization problem is as follows: in, Let be the magnetic field measurements from n single-component magnetic sensors.

5. An implementation system for the method of locating an alternating magnetic dipole source in seawater as described in claim 3 or 4, characterized in that: It includes n single-component inductive sensors, a data acquisition module, and a host computer; the n single-component inductive sensor arrays are arranged and connected to the host computer through the data acquisition module respectively; The data acquisition module transmits the magnetic field values ​​measured by the sensor array to the host computer; The host computer uses magnetic field data and sensor attenuation coefficients to calculate the target's location information through a built-in positioning algorithm.

6. The implementation system according to claim 5, characterized in that: The number of single-component inductive sensors is 12, numbered from 1 to 12. A coordinate system is established with sensor 2 as the origin. The array is located in the xOy plane with z=0. The 6 odd-numbered sensors are placed in one column with a spacing of 6m; the 6 even-numbered sensors are placed in another column with a spacing of 6m, and the distance from the odd-numbered column of sensors is 13.4m.

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