A method and device for compensating eddy current interference

Abstract

The present invention provides a method and device for compensating eddy current interference, comprising: placing an induction module at the center of a calibration module; the calibration module applies a unidirectional uniform magnetic field to the induction module respectively; the induction module obtains a corresponding magnetic field signal and a magnetic gradient signal based on each sampling frequency; the phase of the magnetic field signal corresponding to each sampling frequency is used as the initial phase, and an eddy current signal is obtained from the corresponding magnetic gradient signal after separation and extraction operations; the magnetic field intensity of the eddy current signal is fitted with the corresponding sampling frequency to obtain the eddy current coefficient of the X-axis, Y-axis and Z-axis; the eddy current coefficient is used to remove the eddy current interference in the magnetic gradient signal to complete the eddy current interference compensation. When the relative positions of the induction module and the calibration module are determined, the eddy current coefficient is uniquely determined without repeated calibration. After calibrating the eddy current coefficient on the ground, the eddy current interference expression under various complex environments is determined to perform compensation, which is simple to implement, easy to operate and has a wide range of applications.

Description

Technical Field

[0001] The invention relates to the field of magnetic exploration, and in particular to an eddy current interference compensation method and device. Background Art

[0002] The purpose of aviation magnetic interference compensation is to eliminate the interference magnetic field introduced by the flight platform and the system itself. For high-precision aviation magnetic detection, the quality of magnetic compensation directly affects the magnetic detection effect. Most magnetic compensation models are based on the method proposed by Reyak in 1961 based on the Landau-Lifshitz-Gilbert equation to estimate the magnetic interference during aircraft maneuvers, which is still the standard method for magnetic compensation. Although Reyak gave a method for estimating the magnetic interference during aircraft maneuvers, he did not propose a method for solving the magnetic interference coefficient. This problem was not solved until Beecher proposed a small signal solution method in 1979.

[0003] The Landau-Lifshitz-Gilbert equation model divides magnetic interference on the flight platform into three categories: permanent magnetic interference, inductive interference and eddy current interference. The sources and characteristics of the three types of interference are introduced below:

[0004] Permanent magnetic interference is generated by the residual magnetization of ferromagnetic materials in the flight platform. The direction and size of the magnetic field are consistent with the reference system of the flight platform. The essence is that the coercive force of the material is large, which is manifested as the material's strong ability to resist demagnetization. After being magnetized by the magnetic field, its residual magnetism can be maintained for a long time. Permanent magnetic interference mainly comes from hard magnetic materials such as instruments, magnets, engines, landing gears and energized wires on the flight platform, or magnetization by external magnetic fields during the manufacturing process of the aircraft.

[0005] The induced magnetic field is generated by the magnetization of ferromagnetic objects in the aircraft by the geomagnetic field. The size and direction of the magnetic field change with the aircraft's attitude and the geomagnetic field. The induced magnetic field is mainly generated by devices composed of soft magnetic materials on the aircraft. Soft magnetic materials mainly refer to those magnetic materials that are easily magnetized repeatedly and easily demagnetized after the external magnetic field is removed. They have high magnetic permeability and can obtain high magnetic induction intensity under a weak external magnetic field. They are quickly saturated with the increase of the external magnetic field. They have low coercive force. When the external magnetic field is removed, their magnetism basically disappears immediately.

[0006] The eddy current magnetic field is generated by the soft magnetic materials such as the aircraft fuselage skin, large metal sheets or metal shells on the wings cutting the earth's magnetic field. During the aircraft maneuvering process, the cutting of the three components of the earth's magnetic field causes the change of magnetic flux inside the metal material, thus generating eddy currents, which are essentially changes in magnetic flux.

[0007] The Landau-Lifshitz-Gilbert equation model approximates the aeromagnetic disturbance as a linear superposition of three disturbances, based on the following assumptions:

[0008] 1) Assume that the Earth's magnetic field is uniform and unchanging;

[0009] 2) Assume that the direction of the detector is always parallel to the direction of the Earth's magnetic field;

[0010] 3) Assume that the material that is magnetized to generate the induced field is a linear medium, that is, there is a simple linear relationship between the magnetization intensity and the magnetic induction intensity.

[0011] There are two types of aviation magnetic interference compensation schemes. One is to measure interference and compensate for it. First, the characteristics of the magnetic interference are measured, and then the magnetic interference is compensated by generating a compensation field that is equal to the magnetic interference in magnitude and opposite in direction. The other is to measure geomagnetic interference and compensate for it. The aircraft interference is divided into three components according to the longitudinal, lateral and vertical directions. There is a certain relationship between it and the three components of the geomagnetic field. The various compensation coefficients are solved through the magnetic compensation algorithm to compensate for the magnetic interference.

[0012] In addition to the least squares and principal element regression estimation algorithms, there are also some improved methods for solving compensation coefficients, such as ridge regression estimation algorithm and coefficient solution algorithm based on neural network. The commonly used method in engineering is the small signal solution method proposed by Beecher in 1979, such as Figure 1 This method is to solve the 16-term airborne platform magnetic interference equations through different actions (level flight, pitch and swing) in four navigation directions by making the aircraft perform small maneuvers in four directions at high altitude, so as to apply it to magnetic interference compensation in low-altitude flight.

[0013] The above-mentioned commonly used method of removing magnetic interference is not only cumbersome, but also the high-altitude environment is complex. Changes in air pressure and flight attitude will affect the quality of flight data, which will seriously affect the accuracy of solving the compensation coefficient. The compensation coefficient is not stable. A new eddy current magnetic interference compensation method has important practical significance. Summary of the invention

[0014] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method and device for compensating for eddy current interference, so as to solve the problems in the prior art that the process of removing eddy current interference is complicated and the accuracy of solving the compensation coefficient is greatly affected by the external environment.

[0015] To achieve the above objectives and other related objectives, the present invention provides an eddy current interference compensation method, which at least includes:

[0016] 1) In the test environment, the induction module is placed at the center of the calibration module, wherein the calibration module is used to generate a uniform magnetic field, and the induction module obtains a magnetic field signal B and a magnetic gradient signal G based on the uniform magnetic field, wherein the magnetic induction signal in the X-axis direction is B X , the magnetic field signal in the Y-axis direction is B Y , the magnetic field signal in the Z-axis direction is BZ ;

[0017] 2) The calibration module applies a unidirectional uniform magnetic field to each of the sensing modules;

[0018] 3) Setting the frequency sampling range of the calibration module and the sampling time of each sampling frequency, the sensing module acquires the corresponding magnetic field signal B and magnetic gradient signal G based on each sampling frequency;

[0019] 4) Taking the phase of the magnetic field signal B corresponding to each sampling frequency as the initial phase, the eddy current signal is obtained from the corresponding magnetic gradient signal G through separation and extraction operations;

[0020] The magnetic field strength of the eddy current signal of each sampling frequency is fitted with the sampling frequency to obtain the corresponding eddy current coefficient e. Based on each eddy current coefficient e, the eddy current coefficient e of the X axis is obtained. x , eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z ;

[0021] 5) Through the e obtained from the test environment x 、e y and e z , realize the eddy current interference compensation of the magnetic gradient signal G in the application environment, and obtain the compensation signal G of the magnetic gradient signal G 补偿 ,in,

[0022]

[0023] Optionally, the test environment is a ground environment; and the application environment is an aviation environment.

[0024] Optionally, the sensing module and the calibration module are strictly aligned in the X-axis, Y-axis and Z-axis directions respectively.

[0025] Optionally, the steps of applying unidirectional uniform magnetic fields are as follows: when a uniform magnetic field is applied in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions; when a uniform magnetic field is applied in the Y-axis direction, no magnetic field is applied in the X-axis and Z-axis directions; when a uniform magnetic field is applied in the Z-axis direction, no magnetic field is applied in the X-axis and Y-axis directions.

[0026] Optionally, through a dual-phase lock-in amplification operation, the eddy current coefficient e of the eddy current signal is obtained from the magnetic gradient signal B through separation and extraction operations, including:

[0027] 41) Based on the uniform magnetic field, the induction module obtains a magnetic field signal B and a magnetic gradient signal G, wherein:

[0028] B = A*sin(ω*t+Φ0), A is the amplitude of the magnetic field signal B, Φ0 is the initial phase, t is the time, ω is the angular frequency, where ω = 2π × sampling frequency;

[0029] G=u*A*sin(ω*t+Φ0)+e*A*ω*cos(ω*t+Φ0), where u is the unbalance coefficient of the magnetic gradient signal G, and the magnetic field strength of the eddy current signal is B e , B e =e*A*ω*cos(ω*t+Φ0);

[0030] 42) Construct a pair of zero-phase unit signals sin(ω*t) and cos(ω*t), multiply them with the magnetic field signal B to find the average value, and solve to get the initial phase, where: Among them, mean represents the average value operation;

[0031] 43) Construct a pair of unit signals sin(ω*t+Φ0) and cos(ω*t+Φ0), multiply them with the magnetic gradient signal G to get the average value, and obtain: u*A=2*mean(G*sin(ω*t+Φ0)), e*A*ω=2*mean(G*cos(ω*t+Φ0));

[0032] 44) Solve to obtain the eddy current coefficient e.

[0033] Optionally, the eddy current coefficient e of the X axis is obtained x , eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z The process is as follows: when a uniform magnetic field is applied in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions, the magnetic field strength and sampling frequency of the eddy current signal are fitted, and based on the operations of step 41) to step 44), the corresponding eddy current coefficient e is obtained, the eddy current coefficient e of each sampling frequency is averaged, and the average value is used as the eddy current coefficient e of the X-axis. x ; And so on, we get the eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z .

[0034] The present invention provides an eddy current interference compensation device for implementing the eddy current interference compensation method. The eddy current interference compensation device at least comprises: the eddy current interference compensation device at least comprises: the sensing module, the dewar, the calibration module, the signal generator and the power amplifier, wherein:

[0035] The sensing module is disposed in the low-temperature environment medium inside the dewar, and obtains a magnetic field signal B and a magnetic gradient signal G based on a uniform magnetic field;

[0036] The Dewar is placed inside the calibration module, wherein the Dewar is placed inside the calibration module by being placed on a non-magnetic turntable below;

[0037] The calibration module is used to generate a uniform magnetic field;

[0038] The power amplifier is connected to the calibration module, and the signal generator is connected to the power amplifier, wherein the test signal output by the signal generator is amplified by the power amplifier and then output to the calibration module, so that the calibration module generates a uniform magnetic field.

[0039] Optionally, the sensing module is a full tensor magnetic gradient component, and the calibration module is a three-dimensional Helmholtz coil.

[0040] Optionally, the full tensor magnetic gradient component includes: 1 three-axis magnetometer and 6 SQUID plane gradiometers, wherein the three-axis magnetometer is arranged on the side of the cube module to obtain the magnetic field signal B; the SQUID plane gradiometer is arranged on the side of the hexagonal pyramid module to obtain the magnetic gradient signal G; the upper and lower surfaces of the hexagonal pyramid module are both regular hexagons, and the side surfaces are isosceles trapezoids; the lower surface of the cube module is in contact with the upper surface of the hexagonal pyramid module.

[0041] As described above, the eddy current interference compensation method and device of the present invention have the following beneficial effects:

[0042] 1) In the eddy current interference compensation method and device of the present invention, when the relative position of the sensing module and the calibration module is determined (including the fixed position of the internal components of the sensing module to the outer shell of the sensing module), the eddy current coefficient is uniquely determined without the need for repeated calibration.

[0043] 2) The eddy current interference compensation method and device of the present invention can determine the eddy current interference expression in various complex environments, especially aviation environments, after calibrating the eddy current coefficient on the ground, so as to compensate for it. The method and device are simple to implement, easy to operate, and have a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure shows an exemplary functional flow chart of the compensation coefficient for solving aeromagnetic interference according to the present invention.

[0045] Figure 2 It is a functional flow chart of the eddy current interference compensation method of the present invention.

[0046] Figure 3 Shown is a schematic diagram of the dual-phase lock-in amplification operation function flow of the present invention.

[0047] Figure 4 Shown is a schematic structural diagram of the eddy current interference compensation device of the present invention.

[0048] Figure 5 Shown is a schematic diagram of the structure of the full tensor magnetic gradient assembly of the present invention.

[0049] Component number description

[0050] 1. Sensor module

[0051] 11 Three-axis magnetometer

[0052] 12 SQUID planar gradiometer

[0053] 13 Cube Module

[0054] 14 Hexagonal Module

[0055] 2 Dewar

[0056] 3 Calibration module

[0057] 4 Signal Generator

[0058] 5 Power Amplifier

[0059] 6 Non-magnetic turntable

[0060] Steps S1 to S5

[0061] Steps S41 to S44 DETAILED DESCRIPTION

[0062] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0063] See also Figures 2 to 5 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0064] Embodiment 1

[0065] like Figure 2 and Figure 3 As shown, this embodiment provides an eddy current interference compensation method, and the eddy current interference compensation method at least includes:

[0066] S1: Figure 2As shown, in the test environment, the sensing module is placed at the center of the calibration module, wherein the calibration module is used to generate a uniform magnetic field, and the sensing module obtains a magnetic field signal B and a magnetic gradient signal G based on the uniform magnetic field, wherein the magnetic field signal in the X-axis direction is B X , the magnetic field signal in the Y-axis direction is B Y , the magnetic field signal in the Z-axis direction is B Z .

[0067] Specifically, as an example, Figure 2 As shown, the test environment is a ground environment. It should be noted that when the aircraft is in flight, the eddy current signal in the frequency band of the flight environment is weak, the aircraft is constantly moving, and the flight environment is complex. Therefore, the eddy current coefficient e obtained from the flight environment is both inaccurate and unstable. When calibrating the eddy current coefficient from the ground environment, firstly, the eddy current signal is strong in the ground environment, and the electric field strength of the eddy current signal can be further increased by increasing the amplitude of the applied magnetic field signal B, thereby improving the signal-to-noise ratio, and the obtained eddy current coefficient is accurate and stable. At the same time, the ground environment is static relative to the flight environment, and can avoid the influence of various complex factors (such as attitude rotation, vibration, etc.). S2: As Figure 2 As shown, the calibration module applies a unidirectional uniform magnetic field to the sensing modules respectively.

[0068] Specifically, as an example, Figure 2 As shown, the sensing module and the calibration module are strictly aligned in the X-axis, Y-axis and Z-axis directions, respectively. It should be noted that, under normal circumstances, when the sensing module and the calibration module are strictly aligned in the X-axis, Y-axis and Z-axis directions, respectively, the accuracy of the eddy current coefficient e obtained is the highest. With the development of measurement technology and data computing capabilities, especially the widespread application of quantum computers, the corresponding methods of the sensing module and the calibration module include but are not limited to being strictly aligned in the X-axis, Y-axis and Z-axis directions, respectively. Any measurement and data computing method that can ensure the highest accuracy of the eddy current coefficient e is applicable, not limited to this embodiment.

[0069] More specifically, the steps of applying a unidirectional uniform magnetic field are as follows: when applying a uniform magnetic field in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions; when applying a uniform magnetic field in the Y-axis direction, no magnetic field is applied in the X-axis and Z-axis directions; when applying a uniform magnetic field in the Z-axis direction, no magnetic field is applied in the X-axis and Y-axis directions. It should be noted that when applying a unidirectional uniform magnetic field, the energy of the signals in the other two directions should be kept small enough, such as Figure 4 and Figure 5As shown, when the three-axis magnetometer 11 is used to collect the uniform magnetic field, the energy received by the three-axis magnetometer 11 is the largest and the signal-to-noise ratio is the largest only in the direction where the uniform magnetic field is applied, and the energy received in the other two directions is small enough and the signal-to-noise ratio is small enough, thereby ensuring the accuracy of the eddy current coefficient e.

[0070] S3: Figure 2 As shown, the frequency sampling range of the calibration module and the sampling time of each sampling frequency are set, and the sensing module obtains the corresponding magnetic field signal B and magnetic gradient signal G based on each sampling frequency.

[0071] Specifically, as an example, Figure 2 As shown, the frequency sampling range of the calibration module is [10Hz, 30Hz], and the sampling time of each sampling frequency is [5 seconds, 30 seconds]. It should be noted that, under normal circumstances, the target frequency band to be detected is 0.01-5Hz, and in the ground environment, the interference of this frequency band is very large and the signal-to-noise ratio is low. When the sampling frequency is below 100Hz, the relationship between the calibration module and the frequency is approximately linear. Under the current measurement technology and data computing capability, when the frequency sampling range of the calibration module is [10Hz, 30Hz], the highest accuracy can be guaranteed when the eddy current coefficient e is obtained. With the development of measurement technology and data computing capability, especially the widespread application of quantum computers, the frequency sampling range of the calibration module includes but is not limited to [10Hz, 30Hz]. Any frequency setting that can ensure the highest accuracy of the eddy current coefficient e is applicable, and the sampling time of each sampling frequency should be set according to the specific usage scenario, and is not limited to [5 seconds, 30 seconds], and is not limited to this embodiment.

[0072] S4: Figure 2 As shown, the phase of the magnetic field signal B corresponding to each sampling frequency is used as the initial phase, and the eddy current signal is obtained from the corresponding magnetic gradient signal G through separation and extraction operations;

[0073] The magnetic field strength of the eddy current signal of each sampling frequency is fitted with the sampling frequency to obtain the corresponding eddy current coefficient e. Based on each eddy current coefficient e, the eddy current coefficient e of the X axis is obtained. x , eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z .

[0074] Specifically, as an example, Figure 3 As shown, through the dual-phase lock-in amplification operation, the eddy current coefficient e of the eddy current signal is obtained from the magnetic gradient signal B through separation and extraction operations, including:

[0075] S41: Based on the uniform magnetic field, the induction module obtains a magnetic field signal B and a magnetic gradient signal G, where B=A*sin(ω*t+Φ0), A is the amplitude of the magnetic field signal B, Φ0 is the initial phase, t is the time, ω is the angular frequency, and ω=2π×sampling frequency;

[0076] G=u*A*sin(ω*t+Φ0)+e*A*ω*cos(ω*t+Φ0), where u is the unbalance coefficient of the magnetic gradient signal G, and the magnetic field strength of the eddy current signal is B e , B e =e*A*ω*cos(ω*t+Φ0).

[0077] S42: construct a pair of zero-phase unit signals sin(ω*t) and cos(ω*t), multiply them with the magnetic field signal B to find the average value, and solve to obtain the initial phase, where: Among them, mean represents the average value operation.

[0078] S43: Construct a pair of unit signals sin(ω*t+Φ0) and cos(ω*t+Φ0), multiply them with the magnetic gradient signal G respectively to obtain the average value, and obtain: u*A=2*mean(G*sin(ω*t+Φ0)), e*A*ω=2*mean(G*cos(ω*t+Φ0)).

[0079] S44: Solve to obtain the eddy current coefficient e.

[0080] It should be noted that the dual-phase lock-in amplification technology is one of the effective means of weak signal measurement. It has the characteristics of stable center frequency, narrow passband, high quality factor, etc., and is suitable for the extraction and separation of eddy current signals. If the imbalance of the magnetic gradient signal G (the imbalance coefficient u of the magnetic gradient signal G in step S41) is not considered, based on the magnetic field signal B=A*sin(ω*t+Φ0), the voltage U in the working area of ​​the eddy current signal is obtained, where,

[0081]

[0082] The working area of ​​the eddy current signal is in the shape of a ring, and the area of ​​the ring is S. According to the Biot-Savart law, the impedance of the working area of ​​the eddy current signal is (R+jωL), and the electric field strength of the eddy current signal is B. e ,in:

[0083]

[0084] Where k is the proportionality coefficient between voltage U and current; the eddy current coefficient e is obtained, where: Then we can get the magnetic field strength B of the eddy current signal. e=e*A*ω*cos(ω*t+Φ0). It should be further explained that, Figure 4 and Figure 5 As shown, the three-axis magnetometer 11 is located at the center of the dewar 2, far from the shielding layer, and is insensitive to near-source interference, while the SQUID planar gradiometer 12 (SQUID: Superconducting Quantum Interference Device) is close to the side wall and the ground, and is sensitive to near-edge interference, so the response of the SQUID planar gradiometer 12 to eddy current interference is greater than that of the three-axis magnetometer 11. Therefore, in the process of obtaining the eddy current coefficient e of the eddy current signal, the imbalance of the magnetic gradient signal G must be taken into account, and the eddy current coefficient e of the eddy current signal is obtained from the magnetic gradient signal G through separation and extraction operations by adopting steps S41 to S44 of this embodiment.

[0085] S5: Figure 2 As shown, the e obtained from the test environment x 、e y and e z , realize the eddy current interference compensation of the magnetic gradient signal G in the application environment, and obtain the compensation signal G of the magnetic gradient signal G 补偿 ,in,

[0086]

[0087] Specifically, as an example, Figure 2 As shown, the application environment is an aviation environment. It should be noted that, through steps S41 to S44, it can be known that by calibrating the eddy current coefficient e of the ground environment, the eddy current interference compensation expression of the magnetic gradient signal G in the application environment, especially the aviation environment, can be clarified, and eddy current interference compensation can be performed. The eddy current coefficient e of the X axis is obtained x , eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z The process is as follows: when a uniform magnetic field is applied in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions, the magnetic field strength and sampling frequency of the eddy current signal are fitted, and the corresponding eddy current coefficient e is obtained based on the operations of step S41 to step S44, and the eddy current coefficient e of each sampling frequency is averaged, and the average value is used as the eddy current coefficient e of the X-axis. x ; And so on, we get the eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z , and obtain the compensation signal G of the magnetic gradient signal G 补偿 , completing eddy current interference compensation.

[0088] In order to verify the effect of eddy current interference compensation, the following formula can be used for verification:

[0089]

[0090]

[0091] Among them, Eddy 提取 In order to extract the eddy current signal using the phase-locked amplification principle, Eddy 补偿后残差 V is the signal residual after eddy current signal compensation. pp is the peak-to-peak voltage. It has been verified that the eddy current interference compensation method provided in this embodiment is effective.

[0092] Embodiment 2

[0093] like Figure 4 and Figure 5 As shown, this embodiment provides an eddy current interference compensation device, which is used to implement an eddy current interference compensation method provided in Example 1. The eddy current interference compensation device includes: the sensing module 1, the dewar 2, the calibration module 3, the signal generator 4 and the power amplifier 5, wherein:

[0094] like Figure 4 As shown, the sensing module 1 is disposed in the low-temperature environment medium inside the Dewar 2, and obtains a magnetic field signal B and a magnetic gradient signal G based on a uniform magnetic field.

[0095] Specifically, as an example, Figure 4 and Figure 5 As shown, the induction module 1 is a full tensor magnetic gradient component, and the calibration module 3 is a three-dimensional Helmholtz coil. It should be noted that the calibration module 3 (here refers to the three-dimensional Helmholtz coil) only shows the positional relationship. In actual applications, the three-dimensional Helmholtz coil can be circular or square, or can be a combination of multiple three-dimensional Helmholtz coils. Figure 4It is not specifically shown in the specification, and the specific shape and combination should be set according to the actual use environment, which will not be described here one by one. More specifically, the full tensor magnetic gradient component includes: 1 three-axis magnetometer 11 and 6 SQUID plane gradiometers 12. The three-axis magnetometer 11 is arranged on the side of the cube module 13 to obtain the magnetic field signal B. The X-axis, Y-axis and Z-axis directions of the three-axis magnetometer 11 are arranged in accordance with the right-hand system; the SQUID plane gradiometer 12 is arranged on the side of the hexagonal pyramid module 14 to obtain the magnetic gradient signal G; the upper and lower surfaces of the hexagonal pyramid module 14 are both regular hexagons, and the side surfaces are isosceles trapezoids; the lower surface of the cube module 13 is in contact with the upper surface of the hexagonal pyramid module 14. It should be noted that the number of SQUID plane gradiometers 12 set in the full tensor magnetic gradient assembly includes but is not limited to 6. As long as it does not cause crosstalk between the SQUID plane gradiometers, any number of SQUID plane gradiometers 12 is applicable. In actual operation, the number of SQUID plane gradiometers 12 should be set according to the actual usage scenario and is not limited to this embodiment.

[0096] like Figure 4 and Figure 5 As shown, the dewar 2 is placed inside the calibration module 3, wherein the dewar 2 is placed inside the calibration module 3 by being placed on the non-magnetic turntable 6 below. It should be noted that the three-axis magnetometer 11 and the calibration module 3 (three-dimensional Helmholtz coil) are strictly aligned in the X-axis, Y-axis and Z-axis directions respectively.

[0097] like Figure 4 As shown, the calibration module 3 is used to generate a uniform magnetic field, the power amplifier 5 is connected to the calibration module 3, and the signal generator 4 is connected to the power amplifier 5, wherein the test signal output by the signal generator 4 is amplified by the power amplifier 5 and then output to the calibration module 3, so that the calibration module 3 generates a uniform magnetic field.

[0098] Specifically, as an example, Figure 4 and Figure 5 As shown, based on the eddy current interference compensation device, a compensation signal G of the magnetic gradient signal G is obtained. 补偿 , completing eddy current interference compensation.

[0099] In summary, the present invention provides an eddy current interference compensation method and device, comprising: in a test environment, placing a sensing module at the center of a calibration module, wherein the calibration module is used to generate a uniform magnetic field, and the sensing module obtains a magnetic field signal B and a magnetic gradient signal G based on the uniform magnetic field, wherein the magnetic induction signal in the X-axis direction is B X , the magnetic field signal in the Y-axis direction is B Y , the magnetic field signal in the Z-axis direction is BZ ; The calibration module applies a unidirectional uniform magnetic field to the sensing module respectively; the frequency sampling range of the calibration module and the sampling time of each sampling frequency are set, and the sensing module obtains the corresponding magnetic field signal B and magnetic gradient signal G based on each sampling frequency; the phase of the magnetic field signal B corresponding to each sampling frequency is used as the initial phase, and the eddy current signal is obtained from the corresponding magnetic gradient signal G after separation and extraction operations; the magnetic field intensity of the eddy current signal of each sampling frequency is fitted with the sampling frequency to obtain the corresponding eddy current coefficient e, and the eddy current coefficient e of the X axis is obtained based on each eddy current coefficient e x , eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z ; Through the e obtained from the test environment x 、e y and e z , realize the eddy current interference compensation of the magnetic gradient signal G in the application environment, and obtain the compensation signal G of the magnetic gradient signal G 补偿 . In the present invention, when the relative position of the sensing module and the calibration module is determined (including the fixed position of the internal components of the sensing module to the outer shell of the sensing module), the eddy current coefficient is uniquely determined without repeated calibration. In the present invention, after calibrating the eddy current coefficient on the ground, the eddy current interference expression under various complex environments can be determined, thereby compensating for it. The method and device for compensating for eddy current interference are simple to implement, easy to operate, and have a wide range of applications. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for compensating eddy current interference, characterized in that: The eddy current interference compensation method at least comprises: In the test environment, the sensing module is placed at the center of the calibration module, wherein the calibration module is used to generate a uniform magnetic field. The sensing module obtains a magnetic field signal B and a magnetic gradient signal G based on the uniform magnetic field, wherein the magnetic field signal in the X-axis direction is B. X , the magnetic field signal in the Y-axis direction is B Y , the magnetic field signal in the Z-axis direction is B Z ; The calibration module applies a unidirectional uniform magnetic field to the sensing modules respectively; The frequency sampling range of the calibration module and the sampling time of each sampling frequency are set, and the sensing module obtains the corresponding magnetic field signal B and magnetic gradient signal G based on each sampling frequency; The phase of the magnetic field signal B corresponding to each sampling frequency is used as the initial phase, and the eddy current signal is obtained from the corresponding magnetic gradient signal G through separation and extraction operations; The magnetic field strength of the eddy current signal of each sampling frequency is fitted with the sampling frequency to obtain the corresponding eddy current coefficient e. Based on each eddy current coefficient e, the eddy current coefficient e of the X axis is obtained. x , eddy current coefficient e of Y axis y and the eddy current coefficient e of the Z axis z ; By obtaining the e x 、e y and e z , realize the eddy current interference compensation of the magnetic gradient signal G in the application environment, and obtain the compensation signal G of the magnetic gradient signal G 补偿 ,in, .

2. The eddy current interference compensation method according to claim 1, characterized in that: The test environment is a ground environment; the application environment is an aviation environment.

3. The eddy current interference compensation method according to claim 1, characterized in that: The sensing module and the calibration module are strictly aligned in the X-axis, Y-axis and Z-axis directions respectively.

4. The eddy current interference compensation method according to claim 3, characterized in that: The steps of applying unidirectional uniform magnetic fields are as follows: when applying a uniform magnetic field in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions; when applying a uniform magnetic field in the Y-axis direction, no magnetic field is applied in the X-axis and Z-axis directions; when applying a uniform magnetic field in the Z-axis direction, no magnetic field is applied in the X-axis and Y-axis directions.

5. The eddy current interference compensation method according to claim 4, characterized in that: Through the dual-phase lock-in amplification operation, the eddy current coefficient e of the eddy current signal is obtained from the magnetic gradient signal B through separation and extraction operations, including: Based on the uniform magnetic field, the induction module obtains a magnetic field signal B and a magnetic gradient signal G, wherein B=A*sin(ω*t+Φ0), A is the amplitude of the magnetic field signal B, Φ0 is the initial phase, t is the time, ω is the angular frequency, wherein ω=2π×sampling frequency; G=u* A*sin(ω*t+Φ0)+ e*A*ω*cos(ω*t+Φ0), where u is the unbalance coefficient of the magnetic gradient signal G, and the magnetic field strength of the eddy current signal is B e , B e = e*A*ω* cos(ω*t+Φ0); Construct a pair of zero-phase unit signals sin(ω*t) and cos(ω*t), multiply them with the magnetic field signal B to find the average value, and solve to get the initial phase, where, , where mean represents the average value operation; Construct a pair of unit signals sin(ω*t+Φ0) and cos(ω*t+Φ0), multiply them with the magnetic gradient signal G to get the average value, and get: u* A=2*mean(G* sin(ω*t+Φ0)), e*A*ω=2*mean(G* cos(ω*t+Φ0)); The eddy current coefficient e is obtained by solving the problem.

6. The eddy current interference compensation method according to claim 5, characterized in that: Get the eddy current coefficient e of the X axis x , eddy current coefficient e of Y axis y and the eddy current coefficient e of the Z axis z The process is as follows: when a uniform magnetic field is applied in the X-axis direction, no magnetic field is applied in the Y-axis and Z-axis directions, the magnetic field strength and sampling frequency of the eddy current signal are fitted, and based on the operations of step 41) to step 44), the corresponding eddy current coefficient e is obtained, the eddy current coefficient e of each sampling frequency is averaged, and the average value is used as the eddy current coefficient e of the X-axis. x ; And so on, we get the eddy current coefficient e of the Y axis y and the eddy current coefficient e of the Z axis z .

7. An eddy current interference compensation device, used to implement the eddy current interference compensation method according to any one of claims 1 to 6, characterized in that: The eddy current interference compensation device at least includes: the sensing module, the dewar, the calibration module, the signal generator and the power amplifier, wherein: The sensing module is disposed in the low-temperature environment medium inside the dewar, and obtains a magnetic field signal B and a magnetic gradient signal G based on a uniform magnetic field; The Dewar is placed inside the calibration module, wherein the Dewar is placed inside the calibration module by being placed on a non-magnetic turntable below; The calibration module is used to generate a uniform magnetic field; The power amplifier is connected to the calibration module, and the signal generator is connected to the power amplifier, wherein the test signal output by the signal generator is amplified by the power amplifier and then output to the calibration module, so that the calibration module generates a uniform magnetic field.

8. The eddy current interference compensation device according to claim 7, characterized in that: The induction module is a full tensor magnetic gradient component, and the calibration module is a three-dimensional Helmholtz coil.

9. The eddy current interference compensation device according to claim 8, characterized in that: The full tensor magnetic gradient component includes: 1 three-axis magnetometer and 6 SQUID plane gradiometers. The three-axis magnetometer is arranged on the side of the cube module to obtain the magnetic field signal B; the SQUID plane gradiometer is arranged on the side of the hexagonal pyramid module to obtain the magnetic gradient signal G; the upper surface and the lower surface of the hexagonal pyramid module are both regular hexagons, and the side surface is an isosceles trapezoid; the lower surface of the cube module is in contact with the upper surface of the hexagonal pyramid module.

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