Calibration system and method for installation errors of superconducting full-tensor magnetic gradient measurement assembly

Abstract

The application provides a kind of superconducting full tensor magnetic gradient measurement component installation error calibration system and method, comprising: calibration source and the Dewar being set in calibration source working area, full tensor magnetic gradient measurement component, measurement and control component, rotating device, attitude adjustment device;Full tensor magnetic gradient measurement component is fixedly arranged in Dewar, including at least 5 measuring units, each measuring unit is symmetrically distributed based on central axis;Measurement and control component is used to read the output signal of full tensor magnetic gradient measurement component;Rotating device is used to control full tensor magnetic gradient measurement component rotates around central axis;Attitude adjustment device is used to control full tensor magnetic gradient measurement component adjusts attitude.The application adopts the mode of time division multiplexing, in specific circumstances, a single measuring unit can measure the full tensor magnetic gradient generated by known calibration source, so as to reduce the number of single calibration of symmetric configuration full tensor magnetic gradient measurement component installation error parameters, improve calibration accuracy.

Description

Technical Field

[0001] This invention relates to the field of magnetic field detection, and in particular to a calibration system and method for the installation error of a superconducting full tensor magnetic gradient measurement component. 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. Compared with traditional magnetic measurement, the full tensor magnetic gradient can effectively reduce the multiple solutions in the inversion and has the advantages of improving the resolution and positioning accuracy of anomaly detection. It has important application value in resource exploration, military, archaeology and other fields.

[0003] Magnetic sensors composed of superconducting quantum interference devices (SQUIDs) are currently the most sensitive magnetic sensors known for practical application, capable of measuring extremely weak magnetic signals. Airborne superconducting full-tensor magnetic gradient measurement systems, with SQUIDs as the core components, have significant advantages and epoch-making significance compared to traditional total field and total field gradient aeromagnetic measurements. They represent an important development direction and international research frontier in airborne magnetic geophysical exploration technology.

[0004] The full tensor magnetic gradient measurement component built with SQUID as the core device needs to be constructed using multiple magnetometers or plane gradiometers in a certain configuration. Among them, the solution based on plane gradiometer is currently the best, and the commonly used physical configuration is a hexagonal pyramid. Therefore, obtaining the full tensor magnetic gradient inevitably involves the fusion of information from multiple sensors. The installation error of the plane gradiometer in the physical configuration becomes an important factor restricting the accuracy of the full tensor magnetic gradient measurement.

[0005] Existing technology discloses a calibration system for a full-tensor magnetic gradient measurement component. The calibration system includes an excitation source, a calibration source, a non-magnetic turntable, a mounting bracket, a full-tensor magnetic gradient measurement component, a measurement and control component, and an attitude adjustment device. Its characteristic is that after establishing an error model regarding structural installation error and sensitivity error coefficients, based on the characteristic that the invariants of the eigenvalues ​​and characteristic equations of the full-tensor magnetic gradient matrix do not change with attitude, the structural installation error and sensitivity error coefficients are solved according to the calibration theoretical values ​​and multiple sets of calibration measurements to complete the calibration of the full-tensor magnetic gradient measurement component. Given that each plane gradiometer has three unknown attitude installation errors and one sensitivity error coefficient, and a single conventional hexagonal pyramidal full-tensor magnetic gradient measurement component requires six plane gradiometers to construct, this scheme requires simultaneously solving for 24 unknown parameters when calibrating the installation error of the full-tensor magnetic gradient measurement component. Although this scheme is feasible, the large number of unknown parameters that need to be solved simultaneously leads to less than ideal repeatability and larger errors in the related calibration.

[0006] In summary, when building a high-precision full-tensor magnetic gradient measurement instrument, it is necessary to further improve the calibration accuracy of the installation error of the superconducting full-tensor magnetic gradient measurement component. Therefore, providing an efficient method and device for calibrating the installation error of the full-tensor magnetic gradient measurement component is crucial for the strategically important airborne superconducting magnetic measurement system. 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 calibration system and method for the installation error of a superconducting full tensor magnetic gradient measurement component, in order to solve the problem of low calibration accuracy of the installation error of the superconducting full tensor magnetic gradient measurement component in the prior art.

[0008] To achieve the above and other related objectives, the present invention provides a calibration system for the installation error of a superconducting full-tensor magnetic gradient measurement assembly, wherein the calibration system for the installation error of the superconducting full-tensor magnetic gradient measurement assembly includes at least:

[0009] The calibration source and the Dewar, full tensor magnetic gradient measurement component, measurement and control component, rotation device, and attitude adjustment device set in the working area of ​​the calibration source;

[0010] The full tensor magnetic gradient measurement assembly is fixedly installed inside the Dewar and includes at least 5 measurement units located on different planes. Each measurement unit is symmetrically distributed based on the central axis and is used to measure the magnetic field generated by the calibration source.

[0011] The measurement and control component is connected to the full tensor magnetic gradient measurement component and is used to read the output signal of the full tensor magnetic gradient measurement component.

[0012] The rotating device is used to control the rotation of the full tensor magnetic gradient measurement component around the central axis;

[0013] The attitude adjustment device is used to control the attitude adjustment of the full tensor magnetic gradient measurement component.

[0014] Optionally, the calibration source is a standard magnetic dipole or a gradient coil.

[0015] Optionally, the rotating device is a single-axis non-magnetic turntable, and the Dewar is fixed on the single-axis non-magnetic turntable to drive the Dewar and the full tensor magnetic gradient measurement component to rotate around the central axis.

[0016] Alternatively, the attitude adjustment device is disposed at the bottom of the single-axis non-magnetic turntable and is fixedly connected to the single-axis non-magnetic turntable, and the attitude of the full tensor magnetic gradient measurement component is adjusted by three-dimensional rotation.

[0017] Optionally, the rotation device and the attitude adjustment device are implemented using a three-axis non-magnetic turntable. The Dewar is fixed on the three-axis non-magnetic turntable, and the three-dimensional rotation drives the full tensor magnetic gradient measurement component to rotate around the central axis and adjust the attitude of the full tensor magnetic gradient measurement component.

[0018] Optionally, the rotating device is disposed inside the Dewar and includes a non-magnetic rotating component and a non-magnetic rotating shaft; the rotating component is fixed to the top of the Dewar; one end of the non-magnetic rotating shaft is connected to the non-magnetic rotating component, and the other end is connected to the full tensor magnetic gradient measurement component; the non-magnetic rotating component drives the non-magnetic rotating shaft to drive the full tensor magnetic gradient measurement component to rotate.

[0019] Alternatively, the calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component further includes a base and an annular protrusion disposed at the bottom of the full tensor magnetic gradient measurement component; the base is fixed to the bottom inner wall of the Dewar, and an annular groove is disposed on the upper surface of the base; the annular protrusion at the bottom of the full tensor magnetic gradient measurement component is disposed in the annular groove on the upper surface of the base, and the annular protrusion is slidably connected to the annular groove.

[0020] Alternatively, the attitude adjustment device is fixedly connected to the Dewar and the attitude of the Dewar and the full tensor magnetic gradient measurement component is adjusted by three-dimensional rotation.

[0021] Optionally, the measuring unit is a plane gradient meter or a magnetometer.

[0022] To achieve the above and other related objectives, the present invention also provides a method for calibrating the installation error of a superconducting full-tensor magnetic gradient measurement assembly, wherein the method for calibrating the installation error of the superconducting full-tensor magnetic gradient measurement assembly includes at least the following:

[0023] 1) providing a full tensor magnetic gradient measurement assembly, wherein the full tensor magnetic gradient measurement assembly comprises at least 5 measurement units located on different planes, and each measurement unit is symmetrically distributed based on a central axis;

[0024] 2) placing the full tensor magnetic gradient measurement assembly in the working area of a calibration source, measuring the magnetic field generated by the calibration source, and reading the output signal of each measurement unit in the full tensor magnetic gradient measurement assembly; rotating the full tensor magnetic gradient measurement assembly around the central axis to cyclically shift each measurement unit, so that the measurement units mutually replace the measurement positions in the time dimension, and reading the measurement value output by each measurement unit in each time dimension;

[0025] 3) adjusting the attitude of the full tensor magnetic gradient measurement assembly, and repeating step 2) to obtain the measurement values of each measurement unit at each measurement position in a time-division multiplexing manner under different attitudes, wherein the attitudes of the full tensor magnetic gradient measurement assembly include at least 3;

[0026] 4) solving the residuals under different attitudes, and taking the installation error of the full tensor magnetic gradient measurement assembly when the minimum value is obtained as the final calibration result.

[0027] Optionally, the residual is calculated based on the modulus of the full tensor, which satisfies the following relational expression:

[0028]

[0029]

[0030] wherein, H0 is the residual, CT i is the modulus of the full tensor under different attitudes, CTm is the standard modulus, n is the number of attitude adjustment measurements of the full tensor magnetic gradient measurement assembly; Gxx, Gyy, Gzz, Gxy, Gxz and Gyz are the components of the full tensor magnetic gradient.

[0031] Optionally, the residual is calculated based on invariants, which satisfies the following relational expression:

[0032]

[0033]

[0034] wherein, H0 is the residual, I 1i is the first full tensor invariant under different attitudes, I1m is the standard value of the first full tensor invariant, n is the number of attitude adjustment measurements of the full tensor magnetic gradient measurement assembly; Gxx, Gyy, Gzz, Gxy, Gxz and Gyz are the components of the full tensor magnetic gradient; λ1, λ2 and λ3 are the eigenvalues of the symmetric matrix of the full tensor magnetic gradient.

[0035] Optionally, the residuals are calculated based on the invariants, satisfying the following relationship:

[0036]

[0037]

[0038] Where H0 is the residual; I 2i Let be the second full tensor invariant under different attitudes; I2m be the standard value of the second full tensor invariant; n be the number of attitude measurements adjusted by the full tensor magnetic gradient measurement component; Gxx, Gyy, Gzz, Gxy, Gxz, and Gyz be the components of the full tensor magnetic gradient; λ1, λ2, and λ3 are the eigenvalues ​​of the full tensor magnetic gradient symmetric matrix.

[0039] Alternatively, the installation error of the full tensor magnetic gradient measurement assembly can be solved based on the following relationship:

[0040]

[0041] G our =K*V out ;

[0042] Among them, G out denoted as , where is the physical quantity of the gradient magnetic field; K is the sensitivity coefficient of the measurement unit; Vout is the output voltage of the full tensor magnetic gradient measurement component; Gxx, Gyy, Gzz, Gxy, Gxz, and Gyz are the components of the full tensor magnetic gradient; α is the tilt angle of the plane where the measurement unit is located, and α is the installation error of the full tensor magnetic gradient measurement component corresponding to α. Let be the angle between the plane containing the measurement unit and the corresponding reference side, and b be the angle between the plane and the reference side. The corresponding installation error of the full tensor magnetic gradient measurement component; d is the installation error of the full tensor magnetic gradient measurement component in the heading direction.

[0043] Alternatively, the sensitivity coefficient of the measurement unit can be obtained by a publicly available calibration method.

[0044] Alternatively, the calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component further includes:

[0045] In step 2), the attitude of the full tensor magnetic gradient measurement component is adjusted, and the attitude of the full tensor magnetic gradient measurement component includes at least 4 attitudes;

[0046] In step 4), the sensitivity coefficient error of the measurement unit when the residual is minimized under different attitudes is calculated to obtain the sensitivity coefficient of the measurement unit.

[0047] As described above, the calibration system and method for the installation error of the superconducting full tensor magnetic gradient measurement component of the present invention have the following beneficial effects:

[0048] The calibration system and method for the installation error of the superconducting full tensor magnetic gradient measurement component of the present invention adopts a time-division multiplexing approach. By rotating the full tensor magnetic gradient measurement component multiple times in a known calibration source, each measurement unit can replace other measurement units in the time dimension. Under specific conditions, a single measurement unit can measure the full tensor magnetic gradient generated by a known calibration source, thereby reducing the number of installation error parameters of the symmetrical configuration full tensor magnetic gradient measurement component that need to be calibrated at one time, and thus improving the calibration accuracy of the installation error of the full tensor magnetic gradient measurement component. Attached Figure Description

[0049] Figure 1 The diagram shows a structural schematic of a calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to the present invention.

[0050] Figure 2 The diagram shown is a structural schematic of the full tensor magnetic gradient measurement component of the present invention.

[0051] Figure 3 This is a schematic diagram of another structure of the calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component of the present invention.

[0052] Figure 4 This is another structural schematic diagram of the calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component of the present invention.

[0053] Figure 5 The diagram shows a perspective view of the base and the full tensor magnetic gradient measurement assembly of the present invention.

[0054] Figure 6 The diagram shown is a cross-sectional view of the base and the full tensor magnetic gradient measurement assembly of the present invention.

[0055] Figure 7 The figures show the installation error of the full tensor magnetic gradiometer corresponding to the inclination angle of the hexagonal pyramid of the present invention and the installation error of the full tensor magnetic gradiometer in the heading direction.

[0056] Figure 8 The figure shows the installation error of the full tensor magnetic gradient meter corresponding to the angle between the side of the hexagonal pyramid and the reference side of the present invention.

[0057] Component designation explanation

[0058] 1. Calibration system for installation error of superconducting full tensor magnetic gradient measurement assembly

[0059] 11 Calibration Source

[0060] 111 Power Signal Source

[0061] 111a signal source

[0062] 111b power amplifier

[0063] 112 High linearity gradient coils

[0064] 12 Duwa

[0065] 13 Full Tensor Magnetic Gradient Measurement Component

[0066] 131 Circular protrusion

[0067] 132 threaded hole

[0068] 14 Measurement and Control Components

[0069] 15 Rotating device

[0070] 151 Non-magnetic rotating parts

[0071] 152 Non-magnetic rotating shaft

[0072] 16 Attitude Adjustment Device

[0073] 17. Base

[0074] 171 Circular groove Detailed Implementation

[0075] 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 described 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.

[0076] Please see Figures 1 to 8 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.

[0077] Example 1

[0078] like Figure 1 and Figure 2 As shown, this embodiment provides a calibration system 1 for the installation error of a superconducting full tensor magnetic gradient measurement component. The calibration system 1 for the installation error of the superconducting full tensor magnetic gradient measurement component includes:

[0079] The calibration source 11 and the Dewar 12, full tensor magnetic gradient measurement component 13, measurement and control component 14, rotation device 15, and attitude adjustment device 16 disposed within the working area of ​​the calibration source 11.

[0080] like Figure 1 As shown, the calibration source 11 is used to generate a gradient magnetic field.

[0081] Specifically, the calibration source 11 is a standard magnetic dipole or a gradient coil. In this embodiment, the calibration source 11 is a gradient coil, including but not limited to Maxwell coils. As an example, the calibration source 11 is preferably a gradient coil capable of generating five independent components of the full tensor magnetic gradient. Figure 1 As shown, the calibration source 11 includes a power signal source 111 and a high-linearity gradient coil 112. The power signal source 111 includes a signal source 111a and a power amplifier 111b; the signal source 111a generates an excitation signal; the power amplifier 111b is connected to the output terminal of the signal source 111a, amplifies the excitation signal, and provides it to the high-linearity gradient coil 112. The high-linearity gradient coil 112 is connected to the power signal source 111 and is used to generate a sinusoidal magnetic field.

[0082] It should be noted that the calibration source 11 generates a standard gradient magnetic field for calibration at the location of the full tensor magnetic gradient measurement component 13, preferably an AC gradient magnetic field generated by a sinusoidal excitation signal of fixed frequency. In practical use, any calibration source capable of generating a magnetic field is applicable to this invention, and will not be described in detail here.

[0083] like Figure 1 As shown, the Dewar 12 is disposed within the working area of ​​the calibration source 11. The Dewar 12 is used to contain liquid helium to provide a cryogenic working environment for the full tensor magnetic gradient measurement assembly 13.

[0084] like Figure 1 As shown, the full tensor magnetic gradient measurement component 13 is fixedly installed inside the Dewar 12 and includes at least 5 measurement units located on different planes. Each measurement unit is symmetrically distributed based on the central axis and is used to measure the magnetic field generated by the calibration source 11.

[0085] Specifically, the full tensor magnetic gradient measurement component 13 is immersed in liquid helium within the Dewar 12. The measurement units include, but are not limited to, plane gradiometers and magnetometers, and the number of measurement units is no less than five. Figure 2As shown, in this embodiment, the full tensor magnetic gradient measurement component 13 includes 6 plane gradient meters, each plane gradient meter being attached to 6 sides of a hexagonal pyramid physical configuration; each plane gradient meter is symmetrically distributed with respect to the central axis, which is the line connecting the center of the regular hexagon on the top and bottom surfaces of the hexagonal pyramid physical configuration.

[0086] It should be noted that in actual use, any measurement unit with a number of 5 or more, and a full tensor magnetic gradient measurement component in which each measurement unit is symmetrically distributed based on the central axis, is applicable to this invention and is not limited to this embodiment.

[0087] Specifically, in this embodiment, the full tensor magnetic gradient measurement component 13 is fixed to the bottom of the Dewar 12. In actual use, the full tensor magnetic gradient measurement component 13 can be fixedly connected to the inside of the Dewar 12 as needed, and is not limited to this embodiment.

[0088] like Figure 1 As shown, the measurement and control component 14 is connected to the full tensor magnetic gradient measurement component 13 and is used to read the output signal of the full tensor magnetic gradient measurement component 13.

[0089] Specifically, the measurement and control component 14 is located outside the low-temperature environment and reads the measurement results of the full tensor magnetic gradient measurement component 13. Any structure of the measurement and control component 14 that can achieve signal readout is applicable to this invention, and is not limited thereto.

[0090] like Figure 1 As shown, the rotating device 15 is used to control the rotation of the full tensor magnetic gradient measurement assembly 13 around the central axis.

[0091] Specifically, in this embodiment, the rotating device 15 is a single-axis non-magnetic turntable, and the Dewar 12 is fixed on the single-axis non-magnetic turntable to drive the Dewar 12 and the full tensor magnetic gradient measurement component 13 to rotate around the central axis. The rotation plane of the single-axis non-magnetic turntable is parallel to the base of the hexagonal pyramid of the full tensor magnetic gradient measurement component 13. Every 60° rotation of the single-axis non-magnetic turntable allows each plane gradient meter to replace the measurement position of the adjacent plane gradient meter in the rotation direction, achieving the effect of time-division multiplexing.

[0092] It should be noted that the central axis of the full tensor magnetic gradient measurement component 13 is made as parallel or coincident as possible with the central axis of the single-axis non-magnetic turntable through machining and assembly precision. This allows the full tensor magnetic gradient measurement component 13 to rotate around its central axis by rotating the Dewar 12 and its internal components as a whole.

[0093] like Figure 1As shown, the attitude adjustment device 16 is used to control the attitude adjustment of the full tensor magnetic gradient measurement component 13.

[0094] Specifically, in this embodiment, the attitude adjustment device 16 is disposed at the bottom of the single-axis non-magnetic turntable and is fixedly connected to the single-axis non-magnetic turntable. The attitude of the full tensor magnetic gradient measurement component 13 is adjusted by three-dimensional rotation to obtain measurement data under different attitudes.

[0095] The hexagonal pyramidal full-tensor magnetic gradient measurement assembly consists of six planar gradiometers distributed on the surface of the hexagonal pyramid. Obtaining the full-tensor magnetic gradient requires the fusion of information from multiple sensors. This process inevitably involves the impact of the installation errors of the planar gradiometers in the physical configuration on the accuracy of the full-tensor magnetic gradient measurement. Each planar gradiometer has three unknown attitude installation errors in three-dimensional space. Therefore, the hexagonal pyramidal full-tensor magnetic gradient measurement assembly has a total of 18 installation error parameters. It should be noted that even with the simplest configuration of the full-tensor magnetic gradient measurement assembly, five planar gradiometers are required, resulting in 15 installation error parameters, making precise calibration very difficult.

[0096] The calibration system for the installation error of the superconducting full-tensor magnetic gradient measurement component of the present invention adopts a time-division multiplexing approach. Within a known calibration source, the full-tensor magnetic gradient measurement component is rotated multiple times in space. For example, for a hexagonal pyramidal full-tensor magnetic gradient measurement component, it is rotated 60° around its central axis each time, for a total of 5 rotations. This allows each plane gradiometer to replace other plane gradiometers in the time dimension, thereby enabling a single plane gradiometer to measure the full-tensor magnetic gradient generated by a known calibration source under specific conditions. In other words, by using time-division multiplexing, the number of installation error parameters for a single calibration of the hexagonal pyramidal full-tensor magnetic gradient measurement component is reduced from 18 to 3, and then the calibration of the 18 installation error parameters is completed in 6 separate calibrations, thereby improving the calibration accuracy of the installation error of the full-tensor magnetic gradient measurement component.

[0097] Example 2

[0098] like Figure 3 As shown, this embodiment provides a calibration system 1 for the installation error of a superconducting full tensor magnetic gradient measurement component. The difference from Embodiment 1 is that the rotating device 15 and the attitude adjustment device 16 are implemented using a three-axis non-magnetic turntable.

[0099] Specifically, the Dewar 12 is fixed on the three-axis non-magnetic turntable, and the three-dimensional rotation drives the full tensor magnetic gradient measurement component 13 to rotate around the central axis and adjust the attitude of the full tensor magnetic gradient measurement component 13.

[0100] The structure and working principle of the remaining parts of the calibration system 1 for the installation error of the superconducting full tensor magnetic gradient measurement component in this embodiment are the same as those in Embodiment 1, and will not be described in detail here.

[0101] Example 3

[0102] like Figure 4 As shown, this embodiment provides a calibration system 1 for the installation error of a superconducting full tensor magnetic gradient measurement component. The difference from embodiments one and two is that the rotating device 15 is disposed inside the Dewar 12 and includes a non-magnetic rotating component 151 and a non-magnetic rotating shaft 152.

[0103] Specifically, the non-magnetic rotating component 151 is fixed above the top of the Dewar 12. One end of the non-magnetic rotating shaft 152 is connected to the non-magnetic rotating component 151, and the other end is connected to the full tensor magnetic gradient measurement assembly 13. The non-magnetic rotating component 151 drives the non-magnetic rotating shaft 152 to drive the full tensor magnetic gradient measurement assembly 13 to rotate.

[0104] More specifically, the non-magnetic rotating component 151 is rigidly connected to the Dewar 12 via an RF shielded housing. The non-magnetic rotating component 151 is preferably a piezoelectric rotating component constructed from a piezoelectric motor. The control component of the piezoelectric rotating component can be integrated with the measurement and control component 14 or be an external, independent control component; details are omitted here. The non-magnetic rotating shaft 152 adopts a high-rigidity structure; for example, the non-magnetic rotating shaft 152 is a ceramic rod. In this embodiment, the non-magnetic rotating shaft 152 is fixedly connected to the full tensor magnetic gradient measurement component 13 via a threaded hole 132 at the center of the top surface of the full tensor magnetic gradient measurement component 13. The non-magnetic rotating component 151 and the non-magnetic rotating shaft 152 can allow the full tensor magnetic gradient measurement component 13 to rotate around its central axis by any specific angle while ensuring that the Dewar 12 remains stationary. This embodiment ensures that the central axis of the full tensor magnetic gradient measurement component 13 coincides with the central axis of the rotating device 15.

[0105] like Figure 5 and Figure 6As shown, as another implementation of this embodiment, to avoid a cantilever beam structure fixed at one end, the calibration system 1 for the installation error of the superconducting full tensor magnetic gradient measurement component further includes a base 17 and an annular protrusion 131 disposed at the bottom of the full tensor magnetic gradient measurement component 13, for improving the installation strength of the full tensor magnetic gradient measurement component 13. Specifically, the base 17 is fixed to the bottom inner wall of the Dewar 12, and an annular groove 171 is provided on the upper surface of the base 17. The annular protrusion 131 at the bottom of the full tensor magnetic gradient measurement component 13 is disposed in the annular groove 171 on the upper surface of the base 17, and the annular protrusion 131 is slidably connected to the annular groove 171. The annular protrusion 131 coincides with the center of the annular groove 171. When the full tensor magnetic gradient measurement component 13 rotates, the range of motion of the annular protrusion 131 is restricted in the annular groove 171, thereby ensuring that the central axis of the rotating device 15 and the full tensor magnetic gradient measurement component 13 coincides.

[0106] Specifically, the attitude adjustment device 16 is fixedly connected to the Dewar 12, and the attitude of the Dewar 12 and the full tensor magnetic gradient measurement component 13 is adjusted by three-dimensional rotation. As an example, the attitude adjustment device 16 is disposed below the Dewar 12. In actual use, the relative positional relationship between the attitude adjustment device 16 and the Dewar 12 can be set as needed to adjust the attitude of the Dewar 12 and the full tensor magnetic gradient measurement component 13, and is not limited to this embodiment.

[0107] The structure and working principle of the remaining parts of the calibration system 1 for the installation error of the superconducting full tensor magnetic gradient measurement component in this embodiment are the same as those in Embodiment 1, and will not be described in detail here.

[0108] Example 4

[0109] like Figure 7 and Figure 8 As shown, this embodiment provides a calibration method for the installation error of a superconducting full-tensor magnetic gradient measurement component. As an example, the calibration method is implemented based on the calibration system 1 for the installation error of the superconducting full-tensor magnetic gradient measurement component in Embodiments 1, 2, or 3. In practical use, any system capable of implementing this method is applicable and is not limited to this example. The calibration method for the installation error of the superconducting full-tensor magnetic gradient measurement component includes at least the following:

[0110] 1) Provide a full tensor magnetic gradient measurement assembly, the full tensor magnetic gradient measurement assembly including at least 5 measurement units located in different planes, each measurement unit being symmetrically distributed based on a central axis.

[0111] Specifically, the physical configuration of the full tensor magnetic gradient measurement component 13 is not limited, and will not be described in detail here.

[0112] 2) Place the full tensor magnetic gradient measurement component in the working area of ​​the calibration source, measure the magnetic field generated by the calibration source, and read the output signal of each measurement unit in the full tensor magnetic gradient measurement component; rotate the full tensor magnetic gradient measurement component around the central axis, so that each measurement unit is cyclically shifted, and the measurement positions of each measurement unit are replaced in the time dimension, and read the measurement value output by each measurement unit in each time dimension.

[0113] Specifically, the full tensor magnetic gradient measurement component 13 is placed within the working area of ​​the calibration source 11, and the working parameters of the calibration source 11 are set based on the measurement and control component 14 to generate a standard gradient magnetic field for calibration at the location of the full tensor magnetic gradient measurement component 13. After acquiring the output of each plane gradiometer at the measurement point, the full tensor magnetic gradient measurement component 13 is rotated around its central axis by a specific angle using the rotation device 15, causing each plane gradiometer to shift cyclically, and the output of all plane gradiometers at each measurement point is measured. In this embodiment, for the hexagonal pyramidal full tensor magnetic gradient measurement component 13, it is rotated 60° around the central axis each time, for a total of 5 rotations, requiring the measurement of the output of all plane gradiometers at 6 measurement points, thereby using a time-division multiplexing method to measure the full tensor magnetic gradient generated by a known calibration source using a single plane gradiometer.

[0114] 3) Adjust the attitude of the full tensor magnetic gradient measurement component and repeat step 2) to obtain the measurement values ​​of each measurement unit at each measurement position in a time-division multiplexing manner under different attitudes, wherein the attitude of the full tensor magnetic gradient measurement component includes at least 3.

[0115] Specifically, the attitude of the full tensor magnetic gradient measurement component 13 is adjusted multiple times by the attitude adjustment device 16. After each attitude adjustment, the rotation device 15 is used in a time-division multiplexing manner according to the method in step 2) so that each plane gradiometer can replace other plane gradiometers in the time dimension, and the output of all plane gradiometers at each measurement point is measured. This yields a series of calibration system values ​​corresponding to the installation error of the superconducting full tensor magnetic gradient measurement component at different attitudes, with each plane gradiometer measuring at each cone surface of the hexagonal pyramid in a time-division multiplexing manner.

[0116] Specifically, in this embodiment, the sensitivity coefficient of the plane gradient meter in the full tensor magnetic gradient measurement component is a known quantity, which can be pre-calibrated by a known precise calibration method, thereby further reducing the complexity of calibrating the installation error of the full tensor magnetic gradient measurement component; therefore, the unknown quantities are the three installation error quantities, and the attitude of the full tensor magnetic gradient measurement component can be set to three.

[0117] 4) Solve for the installation error of the full tensor magnetic gradient measurement component when the residual is minimized under different attitudes, and use it as the final calibration result.

[0118] Specifically, the full tensor magnetic gradient is a 3x3 symmetric matrix with 9 components. In a space where both magnetic field divergence and curl are zero, it has only 5 independent components: Gxx, Gyy, Gxy, Gxz, and Gyz. In this embodiment, there may be installation errors when the full tensor magnetic gradient meter is installed on a hexagonal pyramidal full tensor measurement assembly. For example... Figure 7 and Figure 8 As shown, α is the tilt angle of the hexagonal pyramid, and a is the installation error of the full tensor magnetic gradient meter corresponding to α; It is the angle between the six lateral faces of a hexagonal pyramid and the reference lateral face, where b is the angle with respect to the reference lateral face. The corresponding installation error of the full tensor magnetic gradiometer; d is the installation error of the full tensor magnetic gradiometer in the heading direction. When measuring the full tensor magnetic gradient using a single planar gradiometer in a time-division multiplexing manner, its corresponding error model can be derived based on the installation error of the hexagonal pyramidal full tensor magnetic gradient measurement component, satisfying the following relationship:

[0119]

[0120] Among them, G out α is the physical quantity of the gradient magnetic field; α is the inclination angle of the plane where the measurement unit is located; and a is the installation error of the full tensor magnetic gradient measurement component corresponding to α. Let be the angle between the plane containing the measurement unit and the corresponding reference side, and b be the angle between the plane and the reference side. The corresponding installation error of the full tensor magnetic gradient measurement component; d is the installation error of the full tensor magnetic gradient measurement component in the heading direction.

[0121] It should be noted that, as an example, any of the following includes the tilt angle α of the plane where the measurement unit is located, the installation error a of the full tensor magnetic gradient measurement component corresponding to α, and the angle between the plane where the measurement unit is located and the corresponding reference side. and The error models for the installation error b of the full tensor magnetic gradient measurement component and the installation error d of the full tensor magnetic gradient measurement component in the heading direction are applicable to the present invention (including but not limited to various variations of formula (1) in this embodiment), and are not limited to this embodiment; in actual use, any model that can describe the error of the full tensor magnetic gradient measurement component (including but not limited to one or more combinations of the errors listed in this embodiment) is applicable to the present invention, and will not be elaborated here.

[0122] Specifically, after using a single plane gradiometer to rotate around the central axis of a hexagonal pyramid in a time-division multiplexing manner to obtain its output at each pyramidal face position, denoted as G1, G2, G3, G4, G5, and G6, the plane gradiometer outputs at any 5 different measuring points or their algebraic sum can be converted into matrix expressions according to formula (1). The following formula is the matrix expression for selecting the first 5 measuring points G1, G2, G3, G4, and G5:

[0123] [G1 G2 G3 G4 G s I T =M sxs ×[G xx G xy G xz G yy G yz ] T (2)

[0124] Among them, M 5×5 It is a 5x5 matrix composed of the installation error coefficients of the full tensor measurement components.

[0125] It should be noted that in the hexagonal pyramidal full tensor magnetic gradient measurement component, one plane gradient meter is redundant, that is, the outputs of the six plane gradient meters are linearly correlated. Therefore, when constructing the matrix representation shown in formula (2), only a 5x5 matrix can be selected.

[0126] Specifically, after establishing the corresponding error mathematical model based on the installation error of the hexagonal pyramidal full tensor magnetic gradient measurement component and the sensitivity coefficient of the plane gradient meter, one of the full tensor modulus or full tensor invariant of formula (3), formula (4) or formula (5) is selected. Then, based on the optimization calculation methods such as the cuckoo algorithm and the genetic algorithm, the optimal value of the installation error of the full tensor magnetic gradient measurement component when the residual H0 is minimized under different postures is solved, and it is used as the final calibration result.

[0127] More specifically, 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, and the modulus and invariants of the full tensor can be obtained from its characteristic equation, satisfying the following relationship:

[0128]

[0129]

[0130]

[0131] Where CT is the modulus of the full tensor; I1 is the first full tensor invariant; I2 is the second full tensor invariant; and λ1, λ2 and λ3 are the eigenvalues ​​of the full tensor magnetic gradient symmetric matrix.

[0132] The residual H0 is calculated based on the modulus CT of the full tensor, and satisfies the following relationship:

[0133]

[0134] Alternatively, the residual H0 can be calculated based on the first full tensor invariant I1, satisfying the following relationship:

[0135]

[0136] Alternatively, the residual H0 can be calculated based on the second full tensor invariant I2, satisfying the following relationship:

[0137]

[0138] Among them, CT i is the modulus of the full tensor under different orientations; CTm is the standard modulus; I 1i I1 represents the first full tensor invariant under different postures; I1m represents the standard value of the first full tensor invariant; I1 represents the standard value of the first full tensor invariant. 2i I2m represents the second full tensor invariant under different postures; I2m represents the standard value of the second full tensor invariant; and n represents the number of posture measurements adjusted by the full tensor magnetic gradient measurement component.

[0139] Specifically, G out It is a physical quantity of the gradient magnetic field, while the plane gradiometer in the full tensor magnetic gradient measurement system outputs voltage, which needs to be converted into a gradient magnetic field through a sensitivity coefficient, satisfying the following relationship:

[0140] G out =K*V out (9)

[0141] Where K is the sensitivity coefficient of the measurement unit; Vout is the output voltage of the full tensor magnetic gradient measurement component.

[0142] In another implementation of the present invention, the sensitivity coefficient of the measurement unit is unknown, therefore, it includes four unknowns (three installation error quantities and one sensitivity coefficient error quantity). The calibration method for the installation error of the superconducting full-tensor magnetic gradient measurement component further includes:

[0143] In step 2), the attitude of the full tensor magnetic gradient measurement component 13 is adjusted, and the attitude of the full tensor magnetic gradient measurement component 13 includes at least 4 attitudes.

[0144] In step 4), the sensitivity coefficient error of the measurement unit when the residual is minimized under different attitudes is calculated to obtain the sensitivity coefficient of the measurement unit.

[0145] Specifically, by solving four sets of equations for four unknowns, the installation errors a, b, and d, and the sensitivity coefficient error K are obtained. e ,in,

[0146] K = K e *K r (10),K r This is the sensitivity coefficient of the initially calibrated measurement unit.

[0147] The calibration system and method for the installation error of the superconducting full-tensor magnetic gradient measurement component of the present invention are based on time-division multiplexing calibration using a non-magnetic turntable and a single gradient meter. It can easily solve the calibration of the installation error of the superconducting full-tensor magnetic gradient measurement component through a set calibration process and experimental data, while improving the calibration accuracy.

[0148] In summary, this invention provides a calibration system and method for the installation error of a superconducting full tensor magnetic gradient measurement component, comprising: a calibration source and a Dewar, a full tensor magnetic gradient measurement component, a measurement and control component, a rotation device, and an attitude adjustment device disposed within the working area of ​​the calibration source; the full tensor magnetic gradient measurement component is fixedly disposed within the Dewar and includes at least 5 measurement units, each symmetrically distributed based on a central axis, for measuring the magnetic field generated by the calibration source; the measurement and control component is connected to the full tensor magnetic gradient measurement component and is used to read the output signal of the full tensor magnetic gradient measurement component; the rotation device is used to control the full tensor magnetic gradient measurement component to rotate around the central axis; and the attitude adjustment device is used to control the attitude adjustment of the full tensor magnetic gradient measurement component. The calibration system and method for the installation error of the superconducting full-tensor magnetic gradient measurement component of this invention adopts a time-division multiplexing approach. By repeatedly rotating the full-tensor magnetic gradient measurement component in space within a known calibration source, each measurement unit can replace other measurement units in the time dimension. Under specific conditions, a single measurement unit can measure the full-tensor magnetic gradient generated by a known calibration source, thereby reducing the number of calibrations required for the installation error parameters of the symmetrical configuration full-tensor magnetic gradient measurement component in a single operation, and thus improving the calibration accuracy of the installation error of the full-tensor magnetic gradient measurement component. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0149] 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 calibrating the installation error of a superconducting full tensor magnetic gradient measurement assembly, characterized in that, The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component includes at least the following steps: 1) Provide a full tensor magnetic gradient measurement assembly, the full tensor magnetic gradient measurement assembly comprising at least 5 measurement units located in different planes, each measurement unit being symmetrically distributed based on a central axis; 2) Place the full tensor magnetic gradient measurement component in the working area of ​​the calibration source, measure the magnetic field generated by the calibration source, and read the output signal of each measurement unit in the full tensor magnetic gradient measurement component; rotate the full tensor magnetic gradient measurement component around the central axis to make each measurement unit shift cyclically, and replace the measurement position of each measurement unit in the time dimension, and read the measurement value output by each measurement unit in each time dimension; 3) Adjust the attitude of the full tensor magnetic gradient measurement component and repeat step 2) to obtain the measurement values ​​of each measurement unit at each measurement position in a time-division multiplexing manner under different attitudes, wherein the attitude of the full tensor magnetic gradient measurement component includes at least 3. 4) Solve for the residuals of the modulus or invariants of the full tensor under different attitudes, and take the installation error of the full tensor magnetic gradient measurement component when the residual is the minimum value, and use it as the final calibration result.

2. The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 1, characterized in that: The residual is calculated based on the modulus of the full tensor, satisfying the following relationship: ， ； in, For residuals, CT i Here, CTm represents the modulus of the full tensor under different postures, n represents the standard modulus, and g represents the number of posture measurements adjusted by the full tensor magnetic gradient measurement component. Gxx, Gyy, Gzz, Gxy, Gxz, and Gyz are the components of the full tensor magnetic gradient.

3. The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 1, characterized in that: The residuals, calculated based on the invariants, satisfy the following relationship: ， ； in, For residuals, I 1i Let I1m be the standard value of the first full tensor invariant under different postures, and n be the number of posture measurements adjusted by the full tensor magnetic gradient measurement component; Gxx, Gyy, Gzz, Gxy, Gxz and Gyz are the components of the full tensor magnetic gradient. , and These are the eigenvalues ​​of the full tensor magnetic gradient symmetric matrix.

4. The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 1, characterized in that: The residuals, calculated based on the invariants, satisfy the following relationship: ， ； in, For residuals; I 2i I²m represents the second full tensor invariant under different postures; n represents the standard value of the second full tensor invariant; Gxx, Gyy, Gzz, Gxy, Gxz, and Gyz represent the components of the full tensor magnetic gradient. , and These are the eigenvalues ​​of the full tensor magnetic gradient symmetric matrix.

5. The method for calibrating the installation error of the superconducting full tensor magnetic gradient measurement component according to any one of claims 2-4, characterized in that: The installation error of the full tensor magnetic gradient measurement component is solved based on the following relationship: ， ； in, This is a physical quantity representing the gradient magnetic field. Vout is the sensitivity coefficient of the measurement unit; Gxx, Gyy, Gzz, Gxy, Gxz, and Gyz are the components of the full tensor magnetic gradient; The angle of inclination of the plane containing the measurement unit. To and The installation error of the corresponding full tensor magnetic gradient measurement component; The angle between the plane containing the measurement unit and the corresponding reference side surface. To and The installation error of the corresponding full tensor magnetic gradient measurement component; This represents the installation error of the full tensor magnetic gradient measurement assembly in the heading direction.

6. The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 5, characterized in that: The sensitivity coefficient of the measurement unit is known.

7. The method for calibrating the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 5, characterized in that: The calibration method for the installation error of the superconducting full tensor magnetic gradient measurement component also includes: In step 3), the attitude of the full tensor magnetic gradient measurement component is adjusted, and the attitude of the full tensor magnetic gradient measurement component includes at least 4 attitudes; In step 4), the sensitivity coefficient error of the measurement unit when the residual is minimized under different attitudes is calculated to obtain the sensitivity coefficient of the measurement unit.

8. A calibration system for the installation error of a superconducting full-tensor magnetic gradient measurement assembly, used to implement the calibration method for the installation error of the superconducting full-tensor magnetic gradient measurement assembly as described in any one of claims 1-7, characterized in that, The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component includes at least the following: The calibration source and the Dewar, full tensor magnetic gradient measurement component, measurement and control component, rotation device, and attitude adjustment device set in the working area of ​​the calibration source; The full tensor magnetic gradient measurement assembly is fixedly installed inside the Dewar and includes at least 5 measurement units located on different planes. Each measurement unit is symmetrically distributed based on the central axis and is used to measure the magnetic field generated by the calibration source. The measurement and control component is connected to the full tensor magnetic gradient measurement component and is used to read the output signal of the full tensor magnetic gradient measurement component. The rotating device is used to control the rotation of the full tensor magnetic gradient measurement component around the central axis; The attitude adjustment device is used to control the attitude adjustment of the full tensor magnetic gradient measurement component.

9. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 8, characterized in that: The calibration source is a standard magnetic dipole or gradient coil.

10. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 8, characterized in that: The rotating device is a single-axis non-magnetic turntable, and the Dewar is fixed on the single-axis non-magnetic turntable to drive the Dewar and the full tensor magnetic gradient measurement component to rotate around the central axis.

11. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 10, characterized in that: The attitude adjustment device is located at the bottom of the single-axis non-magnetic turntable and is fixedly connected to the single-axis non-magnetic turntable. It adjusts the attitude of the full tensor magnetic gradient measurement component by three-dimensional rotation.

12. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 8, characterized in that: The rotating device and the attitude adjustment device are implemented using a three-axis non-magnetic turntable. The Dewar is fixed on the three-axis non-magnetic turntable. The three-dimensional rotation drives the full tensor magnetic gradient measurement component to rotate around the central axis and adjusts the attitude of the full tensor magnetic gradient measurement component.

13. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 8, characterized in that: The rotating device is disposed inside the Dewar and includes a non-magnetic rotating component and a non-magnetic rotating shaft; the non-magnetic rotating component is fixed to the top of the Dewar; one end of the non-magnetic rotating shaft is connected to the non-magnetic rotating component, and the other end is connected to the full tensor magnetic gradient measurement component; the non-magnetic rotating component drives the non-magnetic rotating shaft to drive the full tensor magnetic gradient measurement component to rotate.

14. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 13, characterized in that: The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component also includes a base and an annular protrusion disposed at the bottom of the full tensor magnetic gradient measurement component; the base is fixed to the bottom inner wall of the Dewar, and an annular groove is provided on the upper surface of the base; the annular protrusion at the bottom of the full tensor magnetic gradient measurement component is disposed in the annular groove on the upper surface of the base, and the annular protrusion is slidably connected to the annular groove.

15. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 13 or 14, characterized in that: The attitude adjustment device is fixedly connected to the Dewar and adjusts the attitude of the Dewar and the full tensor magnetic gradient measurement component by three-dimensional rotation.

16. The calibration system for the installation error of the superconducting full tensor magnetic gradient measurement component according to claim 8, characterized in that: The measuring unit is a plane gradient meter or a magnetometer.

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