High-uniformity active magnetic compensation closed-loop control system and control method thereof

Abstract

The invention relates to a high-uniformity active magnetic compensation closed-loop control system and a control method thereof, an adopted compensation coil group is a biplanar coil group consisting of three pairs of shimming coils and five pairs of gradient coils, and compared with the common three pairs of shimming coils, the problem of asymmetry of a magnetic field can be solved, and high-uniformity residual magnetism compensation is realized. In addition, high-uniformity active magnetic compensation and control thereof can be carried out through a control module based on integral sliding mode control and a composite decoupling algorithm, and high-uniformity residual magnetism compensation of the whole working area can be realized while it is ensured that the residual magnetism intensity at the compensation area of the magnetic shielding cabin is close to zero. The available uniform region range of the active magnetic compensation system can be enlarged, the coupling influence caused by a multi-coil group system can be relieved, and the problems of the robustness of the active magnetic compensation system controller and the decoupling control of the coil groups are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of active magnetic compensation systems for magnetic shielding cabins, and in particular to a high-uniformity active magnetic compensation closed-loop control system and a control method thereof. Background Art

[0002] In terms of human magnetic signal measurement, since the intensity of human heart and brain magnetic signals ranges from tens to hundreds of fT, which is several orders of magnitude lower than the Earth's magnetic field of 50μT-60μT, human magnetic signal measurement is usually performed with high-precision magnetic field measuring instruments in a magnetic shielding cabin constructed of high magnetic permeability materials such as Permalloy. Human magnetic signal measurement often requires an active magnetic compensation system outside the passive magnetic shielding cabin to obtain an extremely weak background magnetic field.

[0003] The design of common active magnetic compensation systems is often subject to various limitations, primarily due to their focus on single-point residual magnetization compensation at the center of the magnetic shielding cabin. Typically, an active magnetic compensation system consists of XYZ triaxial shimming coils, a magnetometer, a microprocessor, and a current source. A magnetometer located at the center of the shielding cabin acquires magnetic field signals and provides them to the microprocessor for calculation of the compensation value. The shimming coils then generate a compensating magnetic field in the corresponding direction, completing the closed-loop feedback loop. However, due to the influence of external magnetic gradients and defects in the shielding cabin's holes, the magnetic field distribution within the shielding cabin is asymmetric. Active magnetic compensation systems relying solely on single-point feedback and triaxial compensation struggle to achieve highly uniform residual magnetization compensation, limiting the usable uniformity zone within the cabin.

[0004] For active magnetic compensation methods that consider compensating for magnetic field gradients in shielded cabins to achieve high uniformity, the method mainly designs additional gradient coil groups in addition to the conventional three-axis shim coil group based on the Biot-Savart law, and adds sensors to achieve compensation. However, the corresponding design, especially the control method, is relatively lacking, resulting in a lack of control over the coupling effects brought by the multi-coil group system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to overcome the technical defects of the existing active magnetic compensation system, such as the limited range of the available uniform area and the lack of control capability for the coupling influence brought by the multi-coil group system. In order to overcome this technical defect, the present invention provides a high-uniformity active magnetic compensation closed-loop control system and a control method thereof, specifically including a high-uniformity active magnetic compensation closed-loop control system and a high-uniformity active magnetic compensation closed-loop control method.

[0006] The present invention provides a high-uniformity active magnetic compensation closed-loop control system, comprising:

[0007] Cubic magnetic shielding cabin, used to shield external magnetic field interference;

[0008] A dual-plane compensation coil assembly, comprising three pairs of shim coils and five pairs of gradient coils placed in the cubic magnetic shielding cabin, wherein the three pairs of shim coils are used to provide a compensating main magnetic field to the compensation area, and the five pairs of gradient coils are used to provide a compensating gradient magnetic field to the compensation area;

[0009] A magnetometer array, configured to acquire residual magnetic field data at multiple points within the compensation area in real time;

[0010] a control module electrically connected to the magnetometer array and configured to obtain a control signal using the residual magnetic field data through integral sliding mode control and a composite decoupling algorithm;

[0011] The voltage-controlled current source is electrically connected to the control module, the three pairs of shim coils and the five pairs of gradient coils, and is used to transmit compensation current corresponding to the control signal to the three pairs of shim coils and the five pairs of gradient coils.

[0012] The high-uniformity active magnetic compensation closed-loop control system disclosed in the present invention utilizes a dual-plane compensation coil assembly consisting of three pairs of shim coils and five pairs of gradient coils. Compared to the conventional three-pair shim coil assembly, this can address magnetic field asymmetry and achieve high-uniformity residual magnetism compensation. Furthermore, the control module, based on integral sliding mode control and a composite decoupling algorithm, enables high-uniformity active magnetic compensation and its control. This ensures near-zero residual magnetism intensity in the compensation area of the magnetic shielding cabin while achieving high-uniformity residual magnetism compensation for the entire working area. This not only increases the available uniformity range of the active magnetic compensation system but also mitigates the coupling effects of multi-coil system assembly, addressing the robustness of the active magnetic compensation system controller and the decoupling control of the coil assembly.

[0013] In one possible implementation, the magnetometer array is composed of (m+n+s+1) fluxgate sensors, and the positions of these fluxgate sensors are distributed as follows:

[0014] The magnetic fluxgate sensors are arranged on the coordinate axes of an XYZ three-dimensional rectangular coordinate system with the geometric center of the cubic magnetic shielding cabin as the coordinate origin and the plane parallel to the bottom surface of the cubic magnetic shielding cabin as the XY plane, wherein one of the fluxgate sensors is placed at the coordinate origin, m of the fluxgate sensors are placed on the X axis, n of the fluxgate sensors are placed on the Y axis, and s of the fluxgate sensors are placed on the Z axis;

[0015] The X coordinates of the fluxgate sensor placed at the coordinate origin and the m fluxgate sensors placed on the X-axis form an arithmetic progression with 0 as the first term, the Y coordinates of the fluxgate sensor placed at the coordinate origin and the n fluxgate sensors placed on the Y-axis form an arithmetic progression with 0 as the first term, and the Z coordinates of the fluxgate sensor placed at the coordinate origin and the t fluxgate sensors placed on the Z-axis form an arithmetic progression with 0 as the first term;

[0016] This enables real-time measurement of magnetic field data at the center of the working area of the magnetic shielding cabin, helping to achieve high-uniformity residual magnetism compensation for the entire working area while ensuring that the residual magnetism intensity at the center of the working area of the magnetic shielding cabin is close to zero.

[0017] In a possible implementation, the control module includes:

[0018] a feedforward decoupling compensator, electrically connected to all the fluxgate sensors, configured to utilize the residual magnetic field data to reduce the coupling effect of the coil group according to its operating equation and output a feedforward decoupling compensation matrix;

[0019] a disturbance observer, electrically connected to all the fluxgate sensors at the same time, configured to estimate an unknown disturbance using the residual magnetic field data according to its operating equation and output the unknown disturbance;

[0020] an integral sliding mode controller, electrically connected to all of the fluxgate sensors, and configured to obtain the control signal using a control equation and a composite decoupling control equation according to the feedforward decoupling compensation matrix and the unknown disturbance;

[0021] a dynamic compensation filter, electrically connected to the feedforward decoupling compensator, the disturbance observer, the integral sliding mode controller and the voltage-controlled current source, for offsetting coil inertia and suppressing high-frequency noise;

[0022] In this way, while achieving power supply control, the coupling influence of the coil group is reduced, unknown disturbances are estimated, and composite control decoupling is achieved, ensuring that the voltage-controlled current source drives the compensation coil group to achieve controllable high-uniformity residual magnetism compensation in the magnetic shielding cabin.

[0023] In one possible implementation, the operating equation of the feedforward decoupling compensator is:

[0024]

[0025] Where,

[0026] s represents the complex frequency;

[0027] C0 represents a decoupling matrix obtained based on the static gain matrix of the dual-plane compensation coil group;

[0028] G0 represents the static gain matrix of the coil group;

[0029] F(s) represents the output of the motion compensation filter;

[0030] λ represents the regularization term;

[0031] I represents the identity matrix;

[0032] τ i represents the time constant of compensation coil i;

[0033] K i represents the coil constant of compensation coil i;

[0034] α i represents the time constant of the dynamic compensation filter;

[0035] i=1,2,…,8。

[0036] Running the above calculation formula can reduce the coupling effect of the coil group.

[0037] In one possible implementation, the operating equation of the disturbance observer is:

[0038]

[0039] Where,

[0040] represents the unknown disturbance;

[0041] A represents the observer gain;

[0042] a derivative matrix representing measurements of the magnetometer array;

[0043] I cmd Represents the control signal output by the integral sliding mode controller last time.

[0044] Running the above calculation formula can further estimate the unknown disturbance and help achieve composite control decoupling.

[0045] In a possible implementation, the control equation is:

[0046]

[0047] e(t)=B target -B meas (t),

[0048]

[0049] Where,

[0050] u eq represents equivalent control item;

[0051] u sw (t) represents a switching control item;

[0052] s(t) represents the sliding surface function, which is defined as a linear combination of magnetic field uniformity errors;

[0053] e(t) represents the magnetic field error vector;

[0054] b represents the sliding surface parameter, which is used to control the weight of the integral term;

[0055] ∈ represents the switching gain, which determines the approach speed;

[0056] represents the boundary layer thickness;

[0057] sign(s) is the sign function.

[0058] In a possible implementation, the composite decoupling control equation is:

[0059]

[0060] Where,

[0061] represents the generalized inverse of the decoupling matrix.

[0062] Through the above calculation formula, it is possible to further realize compound control decoupling by combining the control equation and the compound decoupling control equation on the basis of estimating the unknown disturbance.

[0063] Another technical solution of the present invention is to provide a high-uniformity active magnetic compensation closed-loop control method, comprising the following steps:

[0064] S1: Obtain residual magnetic field data at multiple points in the compensation area of the cubic magnetic shielding cabin through a magnetometer array;

[0065] S2: obtaining a control signal by a control module using integral sliding mode control and a composite decoupling algorithm according to the residual magnetic field data;

[0066] S3: delivering compensation current corresponding to the control signal to three pairs of shim coils and five pairs of gradient coils via a voltage-controlled current source.

[0067] The high-uniformity active magnetic compensation closed-loop control method disclosed in the present invention utilizes a dual-plane compensation coil assembly consisting of three pairs of shim coils and five pairs of gradient coils. Compared to the conventional three-pair shim coil assembly, this method can address magnetic field asymmetry and achieve high-uniformity residual magnetism compensation. Furthermore, by acquiring data through a magnetometer array and obtaining control signals through a control module based on integral sliding mode control and a composite decoupling algorithm, high-uniformity active magnetic compensation and its control can be performed. This method ensures that the residual magnetism intensity in the compensation area of the magnetic shielding cabin is close to zero while achieving high-uniformity residual magnetism compensation for the entire working area. This method not only increases the available uniformity range of the active magnetic compensation system but also mitigates the coupling effects of multi-coil assembly systems, thereby addressing the robustness of the active magnetic compensation system controller and the decoupling control of the coil assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a schematic diagram of the external structure of a high-uniformity active magnetic compensation closed-loop control system disclosed in an embodiment of the present invention;

[0069] Figure 2 Schematic diagram of the circuit structure of a high-uniformity active magnetic compensation closed-loop control system disclosed in an embodiment of the present invention;

[0070] Figure 3 A schematic diagram of the control module structure disclosed in an embodiment of the present invention;

[0071] Figure 4 This is a schematic diagram of the high-uniformity active magnetic compensation control principle disclosed in an embodiment of the present invention.

[0072] Description of reference numerals:

[0073] 1. Cubic magnetic shielding cabin, 2. Y-axis shim coil, 3. Fluxgate sensor. DETAILED DESCRIPTION

[0074] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of the present application and are not intended to limit the scope of protection of the embodiments of the present application. Those skilled in the art may adjust them as needed to suit specific application scenarios.

[0075] In the description of the embodiments of the present application, it should be noted that, unless otherwise expressly specified or limited, the terms "electrically connected" and "establishing an electrical connection relationship" should be understood broadly, that is, it should be understood that two or more devices have an electrical relationship, which can be achieved through a wire connection, a wireless connection, or a combination of the two; and can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood in specific circumstances.

[0076] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "forming a communication link structure" refers to the multiple communication elements or modules involved forming a network structure or a network link structure through a communication connection, and communication or communication connection refers to the transmission of information between the first feature and the second feature. This information transmission can be either unidirectional or bidirectional, and the way to achieve the communication connection can be electrical connection of wires, radio connection, electrical connection of electromagnetic media (such as optical fibers, semiconductors), communication achieved by channels, etc.

[0077] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0078] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0079] See also Figures 1 to 4 The present invention discloses a high-uniformity active magnetic compensation closed-loop control system, comprising a cubic magnetic shielding cabin 1, a dual-plane compensation coil assembly, a magnetometer array, a control module, and a voltage-controlled current source. The cubic magnetic shielding cabin 1 is used to shield against external magnetic field interference; the dual-plane compensation coil assembly comprises three pairs of shim coils and five pairs of gradient coils disposed within the cubic magnetic shielding cabin 1. The three pairs of shim coils are used to provide a compensating main magnetic field to the compensation region, and the five pairs of gradient coils are used to provide a compensating gradient magnetic field to the compensation region. The control module is electrically connected to the magnetometer array, and the voltage-controlled current source is electrically connected to the control module, the three pairs of shim coils, and the five pairs of gradient coils.

[0080] In this embodiment, the compensation area is the central area of the cubic magnetic shielding cabin 1. The geometric center of the cubic magnetic shielding cabin 1 is used as the coordinate origin, and the plane parallel to the bottom surface of the cubic magnetic shielding cabin 1 is used as the XY plane to establish an XYZ three-dimensional rectangular coordinate system. The three pairs of shim coils are the X-axis shim coil, the Y-axis shim coil 2, and the Z-axis shim coil, corresponding to the six faces of the cubic magnetic shielding cabin 1. The position of the Y-axis shim coil 2 is as shown in FIG. Figure 1 As shown; the five pairs of gradient coils are XY gradient coil, XZ gradient coil, YZ gradient coil, X 2 -Y 2 Gradient coils and Z 2The gradient coils correspond to the four designated surfaces and the six surfaces of the cubic magnetic shielding cabin 1 .

[0081] See also Figure 1 In the control system, the magnetometer array is used to obtain the residual magnetic field data at multiple points in the compensation area in real time. The magnetometer array is composed of (m+n+s+1) fluxgate sensors 3, and the position distribution of these fluxgate sensors 3 is as follows: they are arranged on the coordinate axes of the XYZ three-dimensional rectangular coordinate system, with one fluxgate sensor 3 placed at the coordinate origin, m fluxgate sensors 3 placed on the X axis, n fluxgate sensors 3 placed on the Y axis, and s fluxgate sensors 3 placed on the Z axis. In addition, the X coordinates of the fluxgate sensor 3 placed at the coordinate origin and the m fluxgate sensors 3 placed on the X axis are an arithmetic progression with 0 as the first term, the Y coordinates of the fluxgate sensor 3 placed at the coordinate origin and the n fluxgate sensors 3 placed on the Y axis are an arithmetic progression with 0 as the first term, and the Z coordinates of the fluxgate sensor 3 placed at the coordinate origin and the t fluxgate sensors 3 placed on the Z axis are an arithmetic progression with 0 as the first term. As Figure 1 As shown, in this embodiment, m=n=s=1, and the tolerance of these three arithmetic progressions is 15 cm, so as to collect the residual magnetic field data of four points in real time.

[0082] See also Figure 2 、 Figure 3 and Figure 4 In the control system, the control module is configured to obtain a control signal by utilizing residual magnetic field data through integral sliding mode control and a composite decoupling algorithm.

[0083] The voltage-controlled current source is electrically connected to the control module, the three pairs of shim coils and the five pairs of gradient coils, and is used to transmit compensation current corresponding to the control signal to the three pairs of shim coils and the five pairs of gradient coils.

[0084] like Figure 3 As shown, in this embodiment, the control module includes a feedforward decoupling compensator, a disturbance observer, an integral sliding mode controller and a dynamic compensation filter, wherein the feedforward decoupling compensator is electrically connected to all the fluxgate sensors 3 at the same time, the disturbance observer is electrically connected to all the fluxgate sensors 3 at the same time, the integral sliding mode controller is electrically connected to all the fluxgate sensors 3 at the same time, and the dynamic compensation filter is electrically connected to the feedforward decoupling compensator, the disturbance observer, the integral sliding mode controller and the voltage-controlled current source at the same time.

[0085] In the control module, the feedforward decoupling compensator is configured to utilize the residual magnetic field data to reduce the effect of coil group coupling according to its operating equation and output a feedforward decoupling compensation matrix. In this embodiment, the operating equation of the feedforward decoupling compensator is:

[0086]

[0087] Where,

[0088] s represents the complex frequency;

[0089] C0 represents the decoupling matrix obtained based on the static gain matrix of the dual-plane compensation coil group; G0 represents the static gain matrix of the coil group, where the elements are driven by the constant current output of the voltage-controlled current source to drive the compensation coil, and are measured using the magnetometer array;

[0090] F(s) represents the output of the dynamic compensation filter;

[0091] λ represents the regularization term;

[0092] I represents the identity matrix;

[0093] τi 代 Table compensation coil i time constant;

[0094] K i represents the coil constant of compensation coil i;

[0095] α i Represents the time constant of the dynamic compensation filter;

[0096] i=1,2,…,8。

[0097] In the control module, the disturbance observer is configured to estimate the unknown disturbance using the residual magnetic field data according to its operating equation and output the unknown disturbance. In this embodiment, the operating equation of the disturbance observer is:

[0098]

[0099] Where,

[0100] represents unknown disturbance;

[0101] A represents the observer gain;

[0102] The derivative matrix representing the magnetometer array measurements;

[0103] I cmd The control signal representing the output of the integral sliding mode controller.

[0104] In the control module, the integral sliding mode controller is configured to obtain the control signal using a control equation and a composite decoupling control equation based on the feedforward decoupling compensation matrix and the unknown disturbance. In this embodiment, the control equation is:

[0105]

[0106] e(t)=B target -Bmeas (t),

[0107]

[0108] Where,

[0109] u eq represents equivalent control item;

[0110] u sw (t) represents a switching control item;

[0111] s(t) represents the sliding surface function, which is defined as a linear combination of magnetic field uniformity errors;

[0112] e(t) represents the magnetic field error vector;

[0113] b represents the sliding surface parameter, which is used to control the weight of the integral term;

[0114] ∈ represents the switching gain, which determines the approach speed;

[0115] represents the boundary layer thickness;

[0116] sign(s) is the sign function.

[0117] The composite decoupling control equation is:

[0118]

[0119] Where,

[0120] Represents the generalized inverse of the decoupling matrix.

[0121] In the control module, the dynamic compensation filter is used to offset the coil inertia and suppress high-frequency noise. The transfer function of its operating equation is:

[0122]

[0123] The high-uniformity active magnetic compensation closed-loop control system described in this embodiment will be further disclosed below. The method includes the following steps: S1: obtaining residual magnetic field data at multiple points in the compensation area of the cubic magnetic shielding cabin 1 through a magnetometer array; S2: obtaining a control signal through a control module using integral sliding mode control and a composite decoupling algorithm based on the residual magnetic field data; S3: transmitting compensation current corresponding to the control signal to three pairs of shim coils and five pairs of gradient coils through a voltage-controlled current source.

[0124] The high-uniformity active magnetic compensation closed-loop control system disclosed in this embodiment uses a compensation coil group consisting of three pairs of shim coils and five pairs of gradient coils, which is a dual-plane coil group. Compared with the common three pairs of shim coils, it can solve the problem of magnetic field asymmetry and achieve high-uniformity residual magnetism compensation. In addition, the control module can perform high-uniformity active magnetic compensation and its control based on integral sliding mode control and composite decoupling algorithm. It can ensure that the residual magnetism intensity in the compensation area of the magnetic shielding cabin is close to zero while achieving high-uniformity residual magnetism compensation for the entire working area. This not only increases the available uniformity range of the active magnetic compensation system, but also alleviates the coupling effect brought by the multi-coil group system, solving the robustness of the active magnetic compensation system controller and the decoupling control of the coil group.

[0125] In the description of the embodiments of the present application, it should be noted that in the description of the present application, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present application.

[0126] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0127] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A high uniformity active magnetic compensation closed-loop control system, characterized in that: include: A cubic magnetic shielding cabin (1) for shielding against external magnetic field interference; A double-plane compensation coil group is composed of three pairs of shim coils and five pairs of gradient coils placed in the cubic magnetic shielding cabin (1), the three pairs of shim coils are used to provide a compensation main magnetic field to the compensation area, and the five pairs of gradient coils are used to provide a compensation gradient magnetic field to the compensation area; A magnetometer array, configured to acquire residual magnetic field data at multiple points within the compensation area in real time; a control module electrically connected to the magnetometer array and configured to obtain a control signal using the residual magnetic field data through integral sliding mode control and a composite decoupling algorithm; The voltage-controlled current source is electrically connected to the control module, the three pairs of shim coils and the five pairs of gradient coils, and is used to transmit compensation current corresponding to the control signal to the three pairs of shim coils and the five pairs of gradient coils.

2. The high uniformity active magnetic compensation closed-loop control system according to claim 1, characterized in that: The magnetometer array is composed of (m+n+s+1) fluxgate sensors (3), and the positions of the fluxgate sensors (3) are distributed as follows: The magnetic shielding device is arranged on the coordinate axes of an XYZ three-dimensional rectangular coordinate system with the geometric center of the cubic magnetic shielding cabin (1) as the coordinate origin and the plane parallel to the bottom surface of the cubic magnetic shielding cabin (1) as the XY plane, wherein one of the fluxgate sensors (3) is placed at the coordinate origin, m of the fluxgate sensors (3) are placed on the X axis, n of the fluxgate sensors (3) are placed on the Y axis, and s of the fluxgate sensors (3) are placed on the Z axis; The X coordinates of the fluxgate sensor (3) placed at the coordinate origin and the m fluxgate sensors (3) placed on the X axis are in an arithmetic progression with 0 as the first term, the Y coordinates of the fluxgate sensor (3) placed at the coordinate origin and the n fluxgate sensors (3) placed on the Y axis are in an arithmetic progression with 0 as the first term, and the Z coordinates of the fluxgate sensor (3) placed at the coordinate origin and the t fluxgate sensors (3) placed on the Z axis are in an arithmetic progression with 0 as the first term.

3. The high uniformity active magnetic compensation closed-loop control system according to claim 2, characterized in that: The control module includes: A feedforward decoupling compensator is electrically connected to all the fluxgate sensors (3) and is configured to reduce the coupling effect of the coil group using the residual magnetic field data according to its operating equation and output a feedforward decoupling compensation matrix; A disturbance observer is electrically connected to all the fluxgate sensors (3) at the same time, and is configured to estimate an unknown disturbance using the residual magnetic field data according to its operating equation, and output the unknown disturbance; An integral sliding mode controller is electrically connected to all the fluxgate sensors (3) at the same time and is configured to obtain the control signal using a control equation and a composite decoupling control equation according to the feedforward decoupling compensation matrix and the unknown disturbance; A dynamic compensation filter is electrically connected to the feedforward decoupling compensator, the disturbance observer, the integral sliding mode controller and the voltage-controlled current source, and is used to offset coil inertia and suppress high-frequency noise.

4. The high uniformity active magnetic compensation closed-loop control system according to claim 3, characterized in that: The operating equation of the feedforward decoupling compensator is: Where, s represents the complex frequency; C0 represents a decoupling matrix obtained based on the static gain matrix of the dual-plane compensation coil group; C0 represents the static gain matrix of the coil group; F(s) represents the output of the motion compensation filter; λ represents the regularization term; I represents the identity matrix; τ i represents the time constant of compensation coil i; K i represents the coil constant of compensation coil i; α i represents the time constant of the dynamic compensation filter; i＝1,2,…,8。 5. The high uniformity active magnetic compensation closed-loop control system according to claim 4, characterized in that: The operating equation of the disturbance observer is: Where, represents the unknown disturbance; A represents the observer gain; a derivative matrix representing measurements of the magnetometer array; I cmd The control signal representing the output of the integral sliding mode controller.

6. The high uniformity active magnetic compensation closed-loop control system according to claim 5, characterized in that: The control equation is: e(t)=B target -B meas (t), Where, u eq represents equivalent control item; u sw (t) represents a switching control item; s(t) represents the sliding surface function, which is defined as a linear combination of magnetic field uniformity errors; e(t) represents the magnetic field error vector; b represents the sliding surface parameter, which is used to control the weight of the integral term; ∈ represents the switching gain, which determines the approach speed; φ represents the boundary layer thickness; sign(s) is the sign function.

7. The high uniformity active magnetic compensation closed-loop control system according to claim 6, characterized in that: The composite decoupling control equation is: Where, represents the generalized inverse of the decoupling matrix.

8. A high uniformity active magnetic compensation closed-loop control method, characterized in that: The high uniformity active magnetic compensation closed-loop control system according to any one of claims 1 to 7 comprises the following steps: S1: obtaining residual magnetic field data at multiple points within the compensation area of the cubic magnetic shielding cabin (1) through a magnetometer array; S2: obtaining a control signal by a control module using integral sliding mode control and a composite decoupling algorithm according to the residual magnetic field data; S3: delivering compensation current corresponding to the control signal to three pairs of shim coils and five pairs of gradient coils via a voltage-controlled current source.

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