Static positioning method of magnetic target and positioning device

Abstract

The application provides a static positioning method and positioning device of a magnetic target, comprising: obtaining full tensor magnetic gradient data of a moving magnetic target at n measuring positions within a preset time period based on a static magnetic target positioning device; selecting one of the measuring positions as an initial position of the magnetic target, obtaining each measuring position of the magnetic target based on the initial position and full tensor invariant, and fitting according to the motion trajectory characteristics of the magnetic target to obtain a minimum mean square error after fitting; changing the initial position of the magnetic target and performing the above step cyclically; taking the initial position with the optimal minimum mean square error after fitting as a final solution, obtaining the position information of the magnetic target based on the full tensor invariant and the final solution of the initial position, and realizing the positioning of the magnetic target. The application realizes the positioning of the magnetic target based on the full tensor invariant and the motion trajectory constraint, can simply and quickly realize the positioning of the fixed magnetic moment magnetic source through a set of measuring processes and experimental data post-processing, and has high positioning precision and low cost.

Description

Technical Field

[0001] This invention relates to the field of magnetic detection, and in particular to a static positioning method and device for magnetic targets. Background Technology

[0002] The full tensor magnetic gradient describes the rate of change of the magnetic field vector in three-dimensional space, that is, the gradients of the three components of the magnetic field vector in three directions in space. The measurement results of the full tensor magnetic gradient have advantages such as being less affected by the magnetization direction, reflecting the vector magnetic moment information of the target body, and better retrieving field source parameters (azimuth, magnetic moment, etc.). Therefore, it can be used to locate and track field sources, improving the resolution of magnetic source bodies. The measurement and interpretation of the full tensor magnetic gradient is considered a major breakthrough in magnetic exploration, and it has important application value in resource exploration, military, archaeology, and environmental fields.

[0003] According to the theory of linear algebra, the full tensor magnetic gradient matrix and its attitude-projected matrix are similar matrices, therefore they have the same eigenvalues. That is, at a certain measurement point, regardless of its attitude, the full tensor magnetic gradient matrix formed by the measurement results of the full tensor magnetic gradient measurement component has the same real eigenvalues. Three types of geometric invariants can be derived from its eigenvalues ​​and their corresponding eigenvectors: the angle between the magnetic source magnetic moment and the position vector can be uniquely represented by the three eigenvalues ​​of the full tensor magnetic gradient matrix; the eigenvector corresponding to the eigenvalue with the smallest absolute value of the full tensor magnetic gradient matrix is ​​perpendicular to the magnetic moment and the position vector; and the unit vectors of the magnetic moment and the position vector can be represented by the eigenvalues ​​of the full tensor magnetic gradient matrix and the eigenvectors corresponding to the two remaining eigenvalues ​​other than the smallest absolute value.

[0004] Currently known technologies cannot achieve the goal of locating a moving magnetic source in a static state using a single full-tensor magnetic gradient measurement device. This requires either the total field information of the magnetic source or information from multiple measurement points. However, the total field of the magnetic source is difficult to obtain accurately during actual measurements due to fluctuations in the Earth's magnetic field. Furthermore, even using multi-point measurements in motion to locate a magnetic source over a long distance will fail if the distance between the measurement points is insufficient, resulting in an inadequate signal-to-noise ratio, which is equivalent to static measurement. For superconducting full-tensor magnetic gradient measurement devices, not only are the devices themselves expensive, but SQUIDs are also sensitive to motion. Therefore, the ability to locate a moving magnetic source in a static state using a single superconducting full-tensor magnetic gradient measurement device would have significant practical implications.

[0005] Therefore, the currently available magnetic source localization methods based on full tensor invariants cannot effectively achieve magnetic source localization in a static state using a single full tensor magnetic gradient measurement device. There is an urgent need for a method that can achieve magnetic source localization in a static state, which is crucial for strategically important superconducting magnetic measurement systems.

[0006] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a static positioning method and positioning device for magnetic targets, which solves the problem that the prior art cannot effectively achieve magnetic source positioning based on a single set of full tensor magnetic gradient measurement devices in a static state.

[0008] To achieve the above and other related objectives, the present invention provides a static positioning method for a magnetic target, the magnetic target positioning method comprising at least:

[0009] 11) Based on a static magnetic target positioning device, acquire the full tensor magnetic gradient data of a moving magnetic target at n measurement positions within a preset time period, where n is a natural number greater than or equal to 3.

[0010] 12) Select one of the measurement positions as the initial position of the magnetic target, calculate each measurement position of the magnetic target based on the initial position and the full tensor invariants in the full tensor magnetic gradient data, and fit the motion trajectory characteristics of the magnetic target to obtain the minimum mean square error after fitting.

[0011] 13) Change the initial position of the magnetic target and repeat step 12) until the minimum mean square error corresponding to all initial positions is calculated;

[0012] 14) The initial position with the minimum mean square error after fitting is taken as the final solution. Based on the full tensor invariants and the final solution of the initial position, the position information of the magnetic target is obtained, and the magnetic target is located.

[0013] Optionally, in step 11), the full tensor gradient data of m measurement locations are obtained, and a threshold for the feature quantity of the full tensor magnetic gradient matrix is ​​set. Full tensor magnetic gradient data with the feature quantity greater than the threshold are retained to obtain data with a signal-to-noise ratio that meets the processing requirements; where m is a natural number greater than or equal to n.

[0014] Optionally, the initial position of the magnetic target can be changed using the gray wolf algorithm or region traversal.

[0015] Optionally, the method for determining the measurement positions of the magnetic target based on the initial position of the magnetic target and the total tensor invariant includes:

[0016] 21) Calculate the ratio of the distance from the initial position to the magnetic target positioning device to the distances from each of the other measurement positions to be calculated to the magnetic target positioning device, and then obtain the distances from each measurement position of the magnetic target to the magnetic target positioning device.

[0017] 22) The unit vector of the magnetic moment vector, which determines the position vector of the magnetic target;

[0018] 23) The position of the magnetic target is determined based on the distance between the magnetic target positioning device and the corresponding measurement position, and the unit vector of the position vector of the magnetic target.

[0019] Alternatively, in step 21), the ratio satisfies:

[0020]

[0021] in, R0 is the ratio of the distance from the initial position to the magnetic target positioning device to the distance from the i-th measurement position to the magnetic target positioning device, where i is a natural number less than or equal to n-1; R0 is the distance from the initial position to the magnetic target positioning device, Ri is the distance from the initial position to the magnetic target positioning device. i Let NTi be the distance from the i-th measurement position to the magnetic target positioning device, NT0 be the total tensor invariant of the initial position, and NTi be the total tensor invariant of the initial position. i Let be the total tensor invariant at the i-th measurement position.

[0022] Alternatively, step 22) includes:

[0023] 221) Based on the full tensor magnetic gradient data, obtain the four unit vectors of the position vector of the magnetic target;

[0024] 222) Remove the two imaginary solutions of the position vector of the magnetic target based on the magnetic moment direction vector whose sign is not determined;

[0025] 223) The unique solution of the unit vector of the position vector of the magnetic target is determined by supplementing the actual prior conditions.

[0026] Alternatively, in step 221), the four unit vectors of the position vector of the magnetic target are calculated based on the following formula:

[0027]

[0028] in, Let λ1, λ2, and λ3 be the unit vector of the position vector of the magnetic target, and let λ1, λ2, and λ3 be the eigenvalues ​​of the full tensor magnetic gradient matrix, respectively, and let λ2 ≥ λ3 ≥ λ1, |λ1| ≥ |λ3|, and |λ2| ≥ |λ3|.

[0029] Alternatively, in step 222), dummy solutions are removed based on the following formula:

[0030]

[0031] V3·m=0;

[0032]

[0033]

[0034] in, Let λ1 and λ2 be the unit vectors of the magnetic moment vector of the magnetic target, respectively, and let λ2 ≥ λ3 ≥ λ1, |λ1| ≥ |λ3|, |λ2| ≥ |λ3|. Let V1 be the eigenvector of the eigenvalue λ1 of the full tensor magnetic gradient matrix, V2 be the eigenvector of the eigenvalue λ2 of the full tensor magnetic gradient matrix, and V3 be the eigenvector corresponding to the eigenvalue λ3 of the full tensor magnetic gradient matrix.

[0035] Alternatively, the prior conditions in step 223) include: the approximate orientation of the magnetic target.

[0036] Optionally, the method for fitting and obtaining the minimum mean square error in step 12) includes:

[0037] 31) Analyze the trajectory of the magnetic target according to the prior conditions, and express it abstractly using mathematical formulas;

[0038] 32) Based on least squares or intelligent algorithms, the calculated trajectory of the magnetic target is fitted using the mathematical formula to minimize the mean square error;

[0039] 33) Based on the fitting results, obtain the minimum mean square error after fitting.

[0040] Alternatively, the prior conditions in step 31) may include the type of the magnetic target.

[0041] Alternatively, when the trajectory of the magnetic target is a straight line in space, the mathematical formula satisfies:

[0042]

[0043] Where x, y, and z are the positions of the magnetic target, x0, y0, and z0 are the initial positions of the magnetic target, and P, Q, and H are the direction vectors of the spatial straight lines obtained by abstracting the motion trajectory.

[0044] Alternatively, when the trajectory of the magnetic target is a straight line in a plane, the mathematical formula satisfies:

[0045]

[0046] Where x, y, and z are the positions of the magnetic target, and a, b, and c are the parameters of the plane straight line obtained by abstracting the motion trajectory.

[0047] Alternatively, the mean square error satisfies:

[0048]

[0049] Where H0 is the mean square error, f xi f yi f zi To determine the position of the magnetic target based on the initial position (x0, y0, z0) of the magnetic target, k xi k yi k zi The spatial position is the result of fitting the mathematical formula.

[0050] To achieve the above and other related objectives, the present invention also provides a magnetic target positioning device, which includes at least: a support, a full tensor magnetic gradient measurement component, and a measurement and control component;

[0051] The bracket is used to support the full tensor magnetic gradient measurement component and the measurement and control component;

[0052] The full tensor magnetic gradient measurement component is used to detect magnetic targets;

[0053] The measurement and control component is electrically connected to the full tensor magnetic gradient measurement component, and is used to provide test signals to the full tensor magnetic gradient measurement component and read and process the data collected by the full tensor magnetic gradient measurement component.

[0054] Optionally, the magnetic target positioning device further includes a locator, which is disposed on the support and is used to acquire the latitude, longitude and / or altitude information of the full tensor magnetic gradient measurement component.

[0055] As described above, the static positioning method and positioning device for magnetic targets of the present invention have the following beneficial effects:

[0056] The method of this invention achieves magnetic target localization based on full tensor invariants and motion trajectory constraints. The device constructed by this method can quickly and easily achieve the localization of a fixed magnetic moment source through a set of measurement procedures and experimental data post-processing. This invention can achieve magnetic source localization in a static state, with high positioning accuracy and low cost. Attached Figure Description

[0057] Figure 1 The diagram shown is a flowchart illustrating the static positioning method for magnetic targets according to the present invention.

[0058] Figure 2 The diagram shows four possible combinations of magnetic moment vector and position vector.

[0059] Figure 3 The diagram shown illustrates the principle of the static positioning method for magnetic targets according to the present invention.

[0060] Figure 4 The diagram shown is a structural schematic of the system in which the magnetic target positioning device of the present invention is located.

[0061] Component designation explanation

[0062] 1. Full Tensor Magnetic Gradient Measurement Component

[0063] 2 brackets

[0064] 3 Measurement and Control Components

[0065] 4. Positioner

[0066] 5 Magnetic Targets

[0067] 6. Ground Detailed Implementation

[0068] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0069] Please see Figures 1-4 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0070] For the magnetic source localization problem, one method based on full tensor geometric invariants is as follows: First, the distance and magnetic moment magnitude of the magnetic dipole relative to the measurement point are solved using the eigenvalues ​​of the full tensor magnetic gradient matrix and the total field. Then, the position of the magnetic dipole and the unit vector of the magnetic moment vector are solved using geometric invariants. Finally, after removing the dummy solutions for the magnetic dipole position and magnetic moment vector, the position of the magnetic source can be obtained by synthesizing their unit vectors and magnitudes. However, this method cannot provide real-time localization when the total field information of the magnetic source is unknown, and it requires multi-point measurements, meaning it cannot locate the magnetic source in a static state.

[0071] Another static localization method for magnetic sources, based on the known initial position of the magnetic source or obtained by moving a full tensor magnetic gradient measurement device, achieves real-time localization of the magnetic source in motion. While this method provides a way to achieve real-time localization of a magnetic target in a stationary state, it requires the initial position of the magnetic target.

[0072] To address the aforementioned problems, this invention provides a static positioning method for magnetic targets. This method utilizes the magnetic target's motion trajectory as a constraint to solve the positioning problem, and can even improve the positioning accuracy of the magnetic target. Figure 1 As shown, the method for locating the magnetic target includes:

[0073] 11) Based on the static magnetic target positioning device, acquire the full tensor magnetic gradient data of the moving magnetic target at n measurement positions within a preset time period, where n is a natural number greater than or equal to 3.

[0074] Specifically, the magnetic target positioning device of the present invention is stationary during measurement, while the magnetic target is in motion. The device acquires the full tensor magnetic gradient data of the magnetic target within a preset time period. The full tensor magnetic gradient data at different time points correspond to different measurement positions on the motion trajectory, and the acquired data corresponds to at least three different measurement positions. Theoretically, the more measurement positions, the more accurate the positioning, but the larger the amount of data that needs to be processed. Therefore, the number of measurement positions can be set according to actual needs.

[0075] More specifically, when the number of corresponding measurement locations m (greater than or equal to n) is relatively large, a subset of data can be selected as needed to obtain data with a high signal-to-noise ratio (SNR) (facilitating subsequent signal recognition and processing; for example, an SNR of not less than 2; including but not limited to 3, 5, 6, and 10), thereby improving positioning accuracy and precision. For example, data corresponding to m measurement locations can be obtained, where m is greater than 5, including but not limited to 7, 10, 15, 18, and 20, which will not be elaborated here. The eigenvalues ​​(also known as invariants) of the full tensor magnetic gradient matrix are used as the basis for data selection. A threshold is set for the eigenvalues ​​of the full tensor magnetic gradient matrix, and full tensor magnetic gradient data with eigenvalues ​​greater than the threshold are retained, thus obtaining data with an SNR that meets the processing requirements. In this example, the eigenvalues ​​of the full tensor magnetic gradient matrix are represented in the form of the Frobenius norm.

[0076] 12) Select one of the measurement positions as the initial position of the magnetic target. Based on the initial position and the full tensor invariants in the full tensor magnetic gradient data, calculate each measurement position of the magnetic target. Fit the magnetic target according to its motion trajectory characteristics and obtain the minimum mean square error after fitting.

[0077] Specifically, in this embodiment, the initial position selected for the first time is random and an initial value is assigned (therefore, the distance from the initial position selected for the first time to the magnetic target positioning device is known); in actual use, the middle position, the two ends position, etc. can also be selected as the initial position as needed, which will not be elaborated here.

[0078] Specifically, methods for determining the measurement positions of a magnetic target based on its initial position and total tensor invariants include:

[0079] 21) Calculate the ratio of the distance from the initial position to the magnetic target positioning device to the distances from each of the other measurement positions to be calculated. This will give you the distances from each measurement position of the magnetic target to the magnetic target positioning device. Note that these distances only have magnitude, not direction. As an example, the following relationship applies:

[0080]

[0081] in, R0 is the ratio of the distance from the initial position to the magnetic target positioning device to the distance from the i-th measurement position to the magnetic target positioning device, where i is a natural number less than or equal to n-1; R0 is the distance from the initial position to the magnetic target positioning device; Ri .... i Let NTi be the distance from the i-th measurement position to the magnetic target positioning device; NT0 be the total tensor invariant of the initial position, and NTi be the total tensor invariant of the initial position. i For the total tensor invariant at the i-th measurement position, satisfying: λ1, λ2, and λ3 are the eigenvalues ​​of the full tensor magnetic gradient matrix, and λ2≥λ3≥λ1, |λ1|≥|λ3|, |λ2|≥|λ3|, μ0 is the free permeability, M is the magnitude of the magnetic moment, and R is the distance between the magnetic source (measurement position) and the magnetic target positioning device.

[0082] 22) Calculate and determine the position vector of the magnetic target; specifically including:

[0083] First, 221) the unit vector of the magnetic target's position vector is obtained based on the full tensor magnetic gradient data. satisfy:

[0084]

[0085] Where a1 and a2 are coefficients represented by eigenvalues. This step calculates four unit vectors, which contain virtual solutions.

[0086] Further, 222) remove the two virtual solutions of the magnetic target's position vector based on the undetermined positive and negative magnetic moment direction vector. According to the full tensor magnetic gradient characteristics: the eigenvector corresponding to the smallest absolute value of the full tensor magnetic gradient matrix is ​​perpendicular to the magnetic moment vector and the position vector, i.e., V3·m=0(6), V3·r=0(7), it can be seen that the eigenvectors V3 of the two measurement positions are the normal vectors of the plane formed by their respective magnetic moment vectors and position vectors. If the magnetic moment is fixed, i.e., the direction vector of the magnetic moment vector remains unchanged, then according to spatial geometry, the vector product of the eigenvectors V3 of the two measurement positions is the direction vector of the magnetic moment. The unit vector of the magnetic moment vector of the magnetic target. satisfy:

[0087]

[0088] Where V3 is the eigenvector of the eigenvalue λ3 (the eigenvalue with the smallest absolute value), m is the magnetic moment vector, and r is the position vector; β1 and β2 are coefficients represented by the eigenvalues.

[0089] like Figure 2 As shown, based on the obtained magnetic moment direction vector with uncertain sign, combined with the following relations (11)~(14) (given that the angle between the magnetic moment vector and the position vector is determined, there are only four combinations of unit vectors of the magnetic moment vector and the position vector that can be satisfied), two virtual solutions of the magnetic moment vector and the position vector can be directly removed:

[0090]

[0091] Where V1 is the eigenvector of the eigenvalue λ1 of the full tensor magnetic gradient matrix, and V2 is the eigenvector of the eigenvalue λ2 of the full tensor magnetic gradient matrix.

[0092] Finally, 223) supplemented with actual prior conditions, and by removing a dummy solution, the unique solution of the unit vector of the magnetic target's position vector can be determined. Prior conditions include, but are not limited to, the approximate direction of the magnetic target; any prior condition that can determine the unique solution of the unit vector of the magnetic target's position vector is applicable to this invention and is not limited to this embodiment.

[0093] It should be noted that any method that can determine the position vector of a magnetic target using a unit vector is applicable to this invention, and will not be elaborated upon here.

[0094] 23) Based on the distance between the magnetic target positioning device and the corresponding measurement position, and the unit vector of the magnetic target's position vector, the position of the magnetic target is determined; once the distance and direction are determined, accurate position information can be obtained, such as... Figure 3 As shown.

[0095] Specifically, methods for fitting and obtaining the minimum mean square error include:

[0096] 31) Analyze the trajectory of a magnetic target based on prior conditions and express it abstractly using mathematical formulas. The prior conditions include, but are not limited to, the type of magnetic target. In the real world, the trajectory of a magnetic target is usually regular, and its trajectory can be easily determined based on the type of the magnetic target. For example, the short-term trajectory of a ship sailing on the water can be described as a straight line in space, or even simplified to a straight line in a plane.

[0097] More specifically, when the trajectory of a magnetic target is a straight line in space, the mathematical formula satisfies:

[0098]

[0099] Where x, y, z are the coordinates of the measured position of the magnetic target, x0, y0, z0 are the coordinates of the initial position of the magnetic target, and P, Q, H are the direction vectors of the spatial straight lines obtained by abstracting the motion trajectory.

[0100] When the trajectory of the magnetic target is a straight line in the plane, the mathematical formula satisfies:

[0101]

[0102] Where x, y, and z are the coordinates of the measured position of the magnetic target, and a, b, and c are the parameters of the plane straight line obtained by abstracting the motion trajectory.

[0103] When the trajectory of a magnetic target is otherwise, corresponding mathematical formulas can be established based on the actual situation, which will not be elaborated here.

[0104] 32) Based on least squares or intelligent algorithms, the calculated trajectory of the magnetic target is fitted using abstractly expressed mathematical formulas to minimize the mean square error. In this example, the mean square error satisfies:

[0105]

[0106] Where H0 is the mean square error, f xi f yi f zi To determine the position of the magnetic target based on the initial position (x0, y0, z0) of the magnetic target, k xi k yi k zi The spatial position is the result of fitting the mathematical formula.

[0107] 33) Based on the fitting results, obtain the minimum mean square error after fitting.

[0108] It should be noted that any algorithm or method that can calculate the minimum mean square error is applicable to this invention and is not limited to this embodiment.

[0109] 13) Change the initial position of the magnetic target and repeat step 12) until the minimum mean square error corresponding to all initial positions is calculated.

[0110] Specifically, as an example, an intelligent algorithm is used to change the initial position (one of the measurement positions) of the magnetic target. This intelligent algorithm includes, but is not limited to, the Grey Wolf algorithm. The initial position setting ends when the algorithm terminates; that is, the initial position may be a subset or all of the measurement positions, determined based on the actual algorithm. As another example, a region traversal method is used to change the initial position (one of the measurement positions) of the magnetic target. In this case, each measurement position is used as the initial position for a minimum mean square error calculation.

[0111] 14) The initial position with the minimum mean square error after fitting is taken as the final solution. Based on the final solution of the full tensor invariants and the initial position, the position information of the magnetic target is obtained, and the magnetic target is located.

[0112] Specifically, the initial position with the smallest mean square error is selected as the final initial position, and the position information of the magnetic target is obtained based on the final solution. As an example, the position information of the magnetic target corresponding to the final solution is obtained directly from step 12) or step 13) (see steps 21) to 23). As another example, the position information of the magnetic target is recalculated based on the final solution and the full tensor invariant. In this case, each measurement position may be partially or completely different from the measurement positions in steps 12) and 13).

[0113] Current methods for localization based on full tensor invariants can be implemented using a single full tensor magnetic gradient measurement component or a combination of multiple triaxial magnetometers. This invention, however, uses a single full tensor magnetic gradient measurement component. After acquiring a segment of full tensor magnetic gradient information in a static state, and using the full tensor magnetic gradient data of a single magnetic target localization device, and based on full tensor invariants and motion trajectory constraints, magnetic target localization can be achieved. Currently disclosed methods for achieving magnetic target localization in a static state require total field information or the initial position of the magnetic target, while this invention can achieve true magnetic target localization in a static state.

[0114] like Figure 4 As shown, the present invention also provides a magnetic target positioning device, comprising: a full tensor magnetic gradient measurement component 1, a support 2, and a measurement and control component 3.

[0115] like Figure 4 As shown, the bracket 2 is used to support the full tensor magnetic gradient measurement component 1 and the measurement and control component 3.

[0116] Specifically, in this example, the bracket 2 is set on the ground 6. In actual use, the bracket 2 can be set on any device that is fixed in a relative position to the ground, and is not limited to the illustrations of this invention.

[0117] like Figure 4 As shown, the full tensor magnetic gradient measurement component 1 is used to detect the magnetic target 5 (magnetic source).

[0118] Specifically, the structure of the full tensor magnetic gradient measurement component 1 is not limited; any structure capable of measuring the gradients of the three components of the magnetic field vector in three directions in space is applicable.

[0119] like Figure 4 As shown, the measurement and control component 3 is electrically connected to the full tensor magnetic gradient measurement component 1, and is used to provide test signals to the full tensor magnetic gradient measurement component 1 and read and process the data collected by the full tensor magnetic gradient measurement component 1.

[0120] As another example of the present invention, when the location of the magnetic target positioning device is unknown, the magnetic target positioning device further includes a locator 4, which is mounted on the support 2 and is used to acquire the latitude, longitude, and / or altitude information of the full tensor magnetic gradient measurement component 1. If the location of the magnetic target positioning device can be obtained from the relative positional relationship between the magnetic target positioning device and other objects at known locations, then the locator 4 is not required.

[0121] Specifically, the locator 4 includes, but is not limited to, a GPS receiver, used to acquire the latitude, longitude, and altitude information of the magnetic target positioning device, and to correct the latitude, longitude, and altitude information of the full tensor magnetic gradient measurement component 1 (i.e., the position information of the magnetic target positioning device in the above method) based on the spatial position deviation between the locator 4 and the probe of the full tensor magnetic gradient measurement component 1, thereby correcting the latitude, longitude, and altitude information of the magnetic target in geographic coordinates. The spatial position deviation between the locator 4 and the full tensor magnetic gradient measurement component 1 can be accomplished by common measuring tools such as a ruler, which will not be elaborated here.

[0122] In summary, this invention provides a static positioning method and device for magnetic targets, comprising: acquiring full tensor magnetic gradient data of a moving magnetic target at n measurement positions within a preset time period using a static magnetic target positioning device, where n is a natural number greater than or equal to 3; selecting one of the measurement positions as the initial position of the magnetic target, calculating each measurement position of the magnetic target based on the initial position and the full tensor invariants in the full tensor magnetic gradient data, and fitting the data according to the motion trajectory characteristics of the magnetic target to obtain the minimum mean square error after fitting; changing the initial position of the magnetic target and repeating the previous step until the minimum mean square error corresponding to all initial positions is calculated; taking the initial position with the optimal minimum mean square error after fitting as the final solution, and obtaining the position information of the magnetic target based on the full tensor invariants and the final solution of the initial position, thereby realizing the positioning of the magnetic target. The method of this invention achieves magnetic target positioning based on full tensor invariants and motion trajectory constraints. The device constructed by this method can easily and quickly realize the positioning of a fixed magnetic moment source through a set of measurement procedures and experimental data post-processing. This invention can achieve magnetic source positioning in a static state, with high positioning accuracy and low cost. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0123] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for static positioning of a magnetic target, characterized in that, The method for locating the magnetic target includes at least the following: 11) Based on a static magnetic target positioning device, acquire the full tensor magnetic gradient data of a moving magnetic target at n measurement positions within a preset time period, where n is a natural number greater than or equal to 3. 12) Select one of the measurement positions as the initial position of the magnetic target, calculate each measurement position of the magnetic target based on the initial position and the full tensor invariants in the full tensor magnetic gradient data, and fit the motion trajectory characteristics of the magnetic target to obtain the minimum mean square error after fitting. 13) Change the initial position of the magnetic target and repeat step 12) until the minimum mean square error corresponding to all initial positions is calculated; 14) The initial position with the minimum mean square error after fitting is taken as the final solution. Based on the full tensor invariants and the final solution of the initial position, the position information of the magnetic target is obtained, and the magnetic target is located. The method for determining the measurement positions of the magnetic target based on its initial position and the total tensor invariant includes: 21) Calculate the ratio of the distance from the initial position to the magnetic target positioning device to the distances from each of the other measurement positions to be calculated to the magnetic target positioning device, and then obtain the distances from each measurement position of the magnetic target to the magnetic target positioning device. 22) Determine the position vector of the magnetic target based on the unit vector of the magnetic moment vector; Step 22) includes: 221) obtaining the four unit vectors of the position vector of the magnetic target based on the following formula: in, Let λ1, λ2, and λ3 be the unit vector of the position vector of the magnetic target, and let λ2 ≥ λ3 ≥ λ1, |λ1| ≥ |λ3|, and |λ2| ≥ |λ3|. 222) By removing the two imaginary solutions of the position vector of the magnetic target from the magnetic moment direction vector whose sign is not determined, the following condition is met: V3·m=0; in, V1 is the unit vector of the magnetic moment vector of the magnetic target, V2 is the eigenvector of the eigenvalue λ1 of the full tensor magnetic gradient matrix, V3 is the eigenvector of the eigenvalue λ2 of the full tensor magnetic gradient matrix, and V4 is the eigenvector corresponding to the eigenvalue λ3 of the full tensor magnetic gradient matrix. 223) The unique solution of the unit vector of the position vector of the magnetic target is determined by supplementing actual prior conditions; 23) The position of the magnetic target is determined based on the distance between the magnetic target positioning device and the corresponding measurement position, and the unit vector of the position vector of the magnetic target.

2. The static positioning method for a magnetic target according to claim 1, characterized in that: In step 11), the full tensor gradient data of m measurement positions are obtained, and a threshold for the feature quantity of the full tensor magnetic gradient matrix is ​​set. Full tensor magnetic gradient data with the feature quantity greater than the threshold are retained to obtain data with a signal-to-noise ratio that meets the processing requirements; where m is a natural number greater than or equal to n.

3. The static positioning method for magnetic targets according to claim 1, characterized in that: The initial position of the magnetic target can be changed using either the Grey Wolf algorithm or a region traversal method.

4. The static positioning method for a magnetic target according to claim 1, characterized in that: In step 21), the ratio satisfies: in, R0 is the ratio of the distance from the initial position to the magnetic target positioning device to the distance from the i-th measurement position to the magnetic target positioning device, where i is a natural number less than or equal to n-1; R0 is the distance from the initial position to the magnetic target positioning device, Ri is the distance from the initial position to the magnetic target positioning device. i Let NTi be the distance from the i-th measurement position to the magnetic target positioning device, NT0 be the total tensor invariant of the initial position, and NTi be the total tensor invariant of the initial position. i Let be the total tensor invariant at the i-th measurement position.

5. The static positioning method for a magnetic target according to claim 1, characterized in that: The prior conditions in step 223) include the approximate orientation of the magnetic target.

6. The static positioning method for a magnetic target according to claim 1, characterized in that: The methods for fitting and obtaining the minimum mean square error in step 12) include: 31) Analyze the trajectory of the magnetic target according to the prior conditions, and express it abstractly using mathematical formulas; 32) Based on least squares or intelligent algorithms, the calculated trajectory of the magnetic target is fitted using the mathematical formula to minimize the mean square error; 33) Based on the fitting results, obtain the minimum mean square error after fitting.

7. The static positioning method for a magnetic target according to claim 6, characterized in that: The prior conditions in step 31) include the type of the magnetic target.

8. The static positioning method for a magnetic target according to claim 6, characterized in that: When the trajectory of the magnetic target is a straight line in space, the mathematical formula satisfies: Where x, y, and z are the positions of the magnetic target, x0, y0, and z0 are the initial positions of the magnetic target, and P, Q, and H are the direction vectors of the spatial straight lines obtained by abstracting the motion trajectory.

9. The static positioning method for a magnetic target according to claim 6, characterized in that: When the trajectory of the magnetic target is a straight line in the plane, the mathematical formula satisfies: Where x, y, and z are the positions of the magnetic target, and a, b, and c are the parameters of the plane straight line obtained by abstracting the motion trajectory.

10. The static positioning method for a magnetic target according to claim 6, characterized in that: Mean square error satisfies: Where H0 is the mean square error, f xi f yi f zi To determine the position of the magnetic target based on the initial position (x0, y0, z0) of the magnetic target, k xi k yi k zi The spatial position is the result of fitting the mathematical formula.

11. A magnetic target positioning device for implementing the static positioning method for a magnetic target as described in any one of claims 1-10, characterized in that, The magnetic target positioning device includes at least: a support, a full tensor magnetic gradient measurement component, and a measurement and control component; The bracket is used to support the full tensor magnetic gradient measurement component and the measurement and control component; The full tensor magnetic gradient measurement component is used to detect magnetic targets; The measurement and control component is electrically connected to the full tensor magnetic gradient measurement component, and is used to provide test signals to the full tensor magnetic gradient measurement component and read and process the data collected by the full tensor magnetic gradient measurement component.

12. The magnetic target positioning device according to claim 11, characterized in that: The magnetic target positioning device further includes a locator, which is mounted on the support and is used to acquire the latitude, longitude and / or altitude information of the full tensor magnetic gradient measurement component.

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