A magnetic field generating device

Abstract

The embodiment of the present application discloses a magnetic field generating device, including: a first coil assembly and a second coil assembly, the first coil assembly and the second coil assembly are arranged on the same side of a first reference plane; the first coil assembly includes at least three first coil units, the second coil assembly includes at least three second coil units, the projections of the at least three first coil units on the first reference plane and the projections of the at least three second coil units on the first reference plane are arranged alternately, the axes of the at least three first coil units and the at least three second coil units intersect at a point on the first reference plane, the axis of the first coil unit forms a first angle with the first reference plane, the axis of the second coil unit forms a second angle with the first reference plane, and the angle values ​​of the first angle and the second angle are different. In the above manner, the present application can generate an efficient gradient magnetic field and provide a more convenient operating platform for medical workers.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electromagnetic technology, and in particular, to a magnetic field generating device. Background Art

[0002] With the development of science and technology, micro medical robot technology is increasingly used in the treatment of diseases in the human body cavity, which can greatly reduce the pain caused by medical devices to patients. The working environment of micro robots in the body is human blood vessels, intestines and even more fragile human eyeballs. In order to avoid causing damage to soft tissues in complex fluid environments, micro robots need to be driven by magnetic fields without cables to achieve minimally invasive treatment. Therefore, various magnetic fields are of great value in driving micro robots in medical applications.

[0003] There are many ways to achieve the driving magnetic field. Some use the rotating permanent magnet of the mechanical structure to generate a rotating magnetic field in a single rotating plane, such as the rotating magnetic field of the motor and the magnetic stirrer; some use the energized coil method to achieve the rotating magnetic field, generally one or more fixed rotating planes. However, at present, almost all rotating magnetic fields generate uniform magnetic fields, rather than gradient magnetic fields, which cannot well meet the requirements of the controlled substances for the magnetic field. Moreover, the structure of the existing magnetic field generating device is complex and the workbench provided is extremely inconvenient for medical treatment. Summary of the invention

[0004] The main technical problem solved by the embodiments of the present application is to provide a magnetic field generating device, which can solve the problems in the prior art that a gradient magnetic field cannot be generated and the provided workbench is inconvenient for medical workers to operate.

[0005] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present application is: a magnetic field generating device is provided, comprising: a first coil assembly and a second coil assembly, the first coil assembly and the second coil assembly are arranged on the same side of a first reference plane; the first coil assembly includes at least three first coil units, the second coil assembly includes at least three second coil units, the projections of the at least three first coil units on the first reference plane and the projections of the at least three second coil units on the first reference plane are alternately arranged, the axes of the at least three first coil units and the at least three second coil units intersect at a point on the first reference plane, the axis of the first coil unit forms a first angle with the first reference plane, the axis of the second coil unit forms a second angle with the first reference plane, and the angle values ​​of the first angle and the second angle are different.

[0006] The beneficial effect of the embodiment of the present application is: in the method of the embodiment of the present application, the magnetic field generating device includes: a first coil assembly and a second coil assembly, the first coil assembly and the second coil assembly are arranged on the same side of the first reference plane; the first coil assembly includes at least three first coil units, the second coil assembly includes at least three second coil units, the projections of the at least three first coil units on the first reference plane and the projections of the at least three second coil units on the first reference plane are arranged alternately, the axes of the at least three first coil units and the at least three second coil units intersect at a point on the first reference plane, the axis of the first coil unit forms a first angle with the first reference plane, the axis of the second coil unit forms a second angle with the first reference plane, and the angle values ​​of the first angle and the second angle are different. Since the magnetic field generating device has at least six coil units, a gradient magnetic field with five degrees of freedom can be generated by superposition of the magnetic fields generated by the at least six coil units, and since the angle values ​​of the first angle and the second angle are different, it is convenient to obtain the magnetic field intensity component of the desired direction by controlling the current of the coil units with different angles, which is conducive to improving the efficiency of magnetic field generation. In addition, since the first coil assembly and the second coil assembly are arranged on the same side of the first reference plane, that is, the magnetic field generating device does not have a coil on the other side of the first reference plane, the space on the other side of the first reference plane can be used to accommodate the medical body where the magnetically controlled robot is located. Therefore, the workbench provided by the magnetic field generating device is more convenient for medical workers to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a side structural schematic diagram of the first embodiment of the magnetic field generating device of the present application;

[0008] Figure 2 is a schematic diagram of a top view of the structure of the first embodiment of the magnetic field generating device of the present application;

[0009] Figure 3 It is a schematic diagram of the principle of generating a magnetic field by the magnetic field generating device of the present application;

[0010] Figure 4 yes Figure 2 A schematic diagram of a projection of the magnetic field generating device on a first reference plane is shown;

[0011] Figure 5 is a schematic side view of the first embodiment of the magnetic field generating device of the present application from another angle;

[0012] Figure 6 yes Figure 1 A schematic cross-sectional structure diagram of the magnetic field generating device shown;

[0013] Figure 7 is a schematic diagram of the cross-sectional structure of each first coil unit and second coil unit of the present application;

[0014] Figure 8 It is a structural schematic diagram of the second embodiment of the magnetic field generating device of the present application. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0016] like Figure 1 As shown, in the first embodiment of the magnetic field generating device of the present application, the magnetic field generating device comprises: a first coil component 101 and a second coil component 102 , and the first coil component 101 and the second coil component 102 are arranged on the same side of a first reference plane 103 .

[0017] Specifically, in an application example, Figure 1 As shown, the first reference plane 103 is a plane (such as a horizontal plane). Since the first coil assembly 101 and the second coil assembly 102 are both arranged on the same side of the first reference plane 103, and no coil is arranged on the other side, the other side of the first reference plane 103 can be used to accommodate the medical object (such as a human body) where the magnetic control robot is located. Therefore, the workbench provided by the magnetic field generating device is more convenient for medical workers to operate. Of course, in another application example, the first reference plane 103 can also be a curved surface with an arc, etc., which can be specifically set according to actual needs.

[0018] In order to generate a magnetic field with five degrees of freedom, the magnetic field generating device comprises a first coil assembly 101 including at least three first coil units 1011, and a second coil assembly 102 including at least three second coil units 1021. After a current is passed through each of the first coil units 1011 and the second coil units 1021, a magnetic field can be generated. By controlling the current passed through each coil unit, the magnetic field generated by each coil unit can be controlled, and then a magnetic field with five degrees of freedom can be generated by superposition of at least six magnetic fields. At the same time, in order to improve the control efficiency of the magnetic field, the projections of the at least three first coil units 1011 on the first reference plane 103 and the projections of the at least three second coil units 1021 on the first reference plane 103 are alternately arranged, and the axes of the at least three first coil units 1011 and the at least three second coil units 1021 intersect at a point O on the first reference plane 103. Among them, the size and number of coil turns of each coil unit in the first coil unit 1011 and the second coil unit 1021 are the same.

[0019] Specifically, Figure 1 and Figure 2As shown, in an application example, the first coil assembly 101 includes four first coil units 1011, and the second coil assembly 102 includes four second coil units 1021, and the projections of the four first coil units 1011 on the first reference plane 103 and the projections of the four second coil units 1021 on the first reference plane 103 are alternately arranged.

[0020] Among them, Figure 2 As shown, in order to generate a five-degree-of-freedom gradient magnetic field, for example, a magnetically controlled robot can be generated in the following manner: Figure 3 The magnetic field generating device can generate a magnetic field that moves in three directions of the three axes X, Y, and Z of the three-dimensional space coordinate axis and rotates around any two coordinate axes. The magnetic field generating device alternately arranges four first coil units 1011 and four second coil units 1021 at intervals, so that the projections of the four first coil units 1011 on the first reference plane 103 and the projections of the four second coil units 1021 on the first reference plane 103 are alternately arranged, that is, Figure 4 As shown, projections M1-M4 of the axes of the four first coil units 1011 on the first reference plane 103 and projections N1-N4 of the axes of the four second coil units 1021 on the first reference plane 103 are arranged alternately. At this time, since there are eight coil units, each coil unit can generate a magnetic field, and the spatial magnetic field can be obtained by superposition of the eight magnetic fields.

[0021] In this embodiment, the magnetic field generating device can generate a gradient magnetic field to directly generate force on particles (such as a magnetically controlled robot) to control the movement of the magnetically controlled robot. The specific principle is as follows:

[0022] In the magnetic field, the torque and force on the magnetically controlled robot are as follows:

[0023] T=M×B

[0024]

[0025] in,

[0026]

[0027] T is the magnetic moment, F is the force, M is the magnetic moment, and B is the magnetic field strength vector.

[0028] Since the current in the coil unit does not pass through the body of the magnetron robot, the Maxwell coils provide confinement:

[0029] The magnetic field generated by the hollow coil can be linearly superimposed, but this is not the case for the magnetic field of the coil with an iron core, because the coil with an iron core will produce hysteresis. However, when the current passed through the coil with an iron core is within a given range, that is, does not exceed the set value, the hysteresis can be ignored, and the magnetic field generated by the coil can be linearly superimposed. Among them, the set value can be set according to parameters such as the number of coil turns and the size of the iron core. In the magnetic field generating device of this embodiment, the first coil unit 1011 and the second coil unit 1021 can use hollow coils or coils with iron cores, as long as the current passed through the coil with an iron core is controlled not to exceed the set value.

[0030] Among multiple coil units, the magnetic field strength generated by the e-th coil unit at a point P in space can be expressed as the magnetic field strength generated by the unit current at point P Multiply by the current I e ,as follows:

[0031]

[0032] The magnetic field strength generated by each coil unit can be superimposed. The superposition of the magnetic field strength generated by n coil units at point P can be expressed as:

[0033]

[0034] It can also be expressed as:

[0035]

[0036] In the gradient magnetic field, the components on each axis can be decomposed, and the components on the x-axis are as follows:

[0037]

[0038] The components on the y-axis and the z-axis are similar to those on the x-axis above, as follows:

[0039]

[0040] The relationship between the torque, force and current of the magnetic control robot can be expressed as the following matrix:

[0041]

[0042] in:

[0043]

[0044] When the magnetic field is required to generate a specific magnetic torque and force, the following formula can be used to find the inverse of the matrix and calculate the required current I.

[0045]

[0046] The magnetic field generating device of this embodiment can realize a spatial rotating magnetic field of any axis, and its principle and implementation method are as follows:

[0047] From the spatial analytic geometry, we know that the vector in space can be expressed by azimuth. The magnetic field generated by the magnetic field generating device is as follows: Figure 3 As shown, let the azimuth angle of the rotating axial direction n of the magnetic field be Among them, θ is the angle between the magnetic field rotation axis direction n and the positive direction of the OZ axis, is the angle between the projection of the magnetic field rotation axis n on the XOY plane and the positive direction of OX. The three-coordinate components of the magnetic field rotation axis n can be expressed as The other two vectors n1 and n2 that are perpendicular to n are:

[0048]

[0049] make

[0050] Assume that η is the rotation angle of the rotating magnetic field, η=ωt, ω is the rotation angular frequency of the rotating magnetic field, and t is time. Then the rotating magnetic field with the rotation axis n and amplitude B0 can be expressed as:

[0051] B0(n1cosη+n2sinη)

[0052] The three components of the rotating magnetic field in the rectangular coordinate system [B x B y B z ] is expressed as:

[0053]

[0054] According to the three components of the rotating magnetic field calculated by the above equations, eight magnetic field components can be obtained by controlling the current passed through each coil unit. When hysteresis is ignored, the contribution of the magnetic field generated by a single coil unit to the overall magnetic field is linearly superimposed. Therefore, the required rotating magnetic field can be obtained by synthesizing the eight magnetic field components in space.

[0055] When the magnetic field amplitude and frequency need to be changed, B0 and ω can be changed. When the magnetic field rotation axis is changed, the azimuth of the magnetic field rotation axis is changed. Since the magnetic field generated by each coil unit is related to the current passed through it, its magnetic field can be changed by changing the current passed through it, thereby realizing a rotating magnetic field in any axial direction.

[0056] Optionally, in order to facilitate the control of the magnetic field, the projections of the at least three first coil units 1011 on the first reference plane 103 and the projections of the at least three second coil units 1021 on the first reference plane 103 are evenly alternated, that is, the angles of the projections of the axes of two adjacent coil units on the first reference plane 103 (horizontal plane) are the same.

[0057] For example Figure 2 As shown, the four first coil units 1011 and the four second coil units 1021 are spaced apart and evenly arranged, so that Figure 4 As shown, the projection angles of the eight coil units on the first reference plane 103 (horizontal plane) are 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, respectively, and the axes of the eight coil units intersect at a point O. Since the coil units in each coil assembly are symmetrically arranged, when it is necessary to adjust the magnetic field intensity component in a certain direction, it can be obtained by adjusting the current after performing simple calculations through the symmetrical coil units without performing complex calculations, thereby reducing the amount of calculations and facilitating the generation of an efficient gradient magnetic field.

[0058] Optionally, in order to further improve the control efficiency of the magnetic field, the angles between the coil units in the first coil assembly 101 and the second coil assembly 102 and the first reference plane 103 can be set to different angles, so that when the magnetic field is used to generate forces in different axes to control the magnetically controlled robot, the current of the coil units closer to the axis can be dispatched or adjusted to generate a larger magnetic field intensity component to generate a larger force component on the axis.

[0059] Specifically, Figure 1 and Figure 5 As shown, the axis of the first coil unit 1011 forms a first angle α (such as 20°) with the first reference plane 103, and the axis of the second coil unit 1021 forms a second angle β (such as 45°) with the first reference plane 103, and the angle values ​​of the first angle α and the second angle β are different. Since the angle values ​​of the first angle α and the second angle β are different, that is, the first coil unit 1011 is closer to the first reference plane 103 (horizontal plane), and the second coil unit 1021 is closer to the axis perpendicular to the horizontal plane, therefore, when it is necessary to generate a force toward the axis perpendicular to the horizontal plane, such as when it is necessary to control the magnetic control robot to move in the direction of the axis perpendicular to the horizontal plane, the second coil unit 1021 can be called more, so that the current of the coil unit can be adjusted in a targeted manner, so as to generate a corresponding magnetic field, which is conducive to generating an efficient gradient magnetic field.

[0060] In this embodiment, in order to generate a controllable magnetic field more accurately, the magnetic field generating device can also be provided with a third coil assembly or more groups of coil assemblies, and the number of coil units in each coil assembly and the angle formed with the first reference plane 103 can be adjusted according to actual needs.

[0061] Optionally, in order to provide a more convenient workbench for medical workers, the at least three first coil units 1011 and the at least three second coil units 1021 are located on the same second reference plane 104 at one end facing the first reference plane 103. Figure 6 As shown, the first reference surface 103 is a plane, and the second reference surface 104 is an arc surface (such as a hemispherical surface). Since the arc surface is more in line with the design of the head, shoulders and other parts of the human body, it is also convenient for medical personnel to use the magnetic field generating device to perform a series of precision surgeries such as eye surgery. Of course, the size of the magnetic field generating device can also be designed according to the size of the in vivo treatment that the medical personnel need to perform. If it is to control the intraocular retinal surgery, the magnetic field generating device can be reduced and miniaturized. If it is to perform abdominal surgery, the magnetic field generating device can be enlarged.

[0062] In this embodiment, in order to enhance the strength of the magnetic field and facilitate the control of the micro-robot, each coil unit in the magnetic field generating device is configured as a coil with an iron core.

[0063] Specific as Figure 7 As shown, each of the first coil unit 1011 and the second coil unit 1021 includes an iron core 201, a first coil layer 202 and a second coil layer 203. The first coil layer 202 is wound on the surface of the iron core 201, and the second coil layer 203 is wound on the surface of the first coil layer 202. Each of the first coil unit 1011 and the second coil unit 1021 adopts a double-layer nested structure of the first coil layer 202 and the second coil layer 203, so that when opposite currents are passed through the first coil unit 1011 and the second coil unit 1021, the hysteresis generated by the first coil unit 1011 and the second coil unit 1021 can cancel each other, thereby eliminating the hysteresis phenomenon caused by the iron core, and achieving the effect of immediately reducing the magnetic field generated outside each of the first coil unit 1011 and the second coil unit 1021 to zero.

[0064] The second coil layer 203 exposes a portion of the first coil layer 202 adjacent to one end of the first coil unit 1011 or the second coil unit 1021, that is, Figure 7 As shown, the height H2 of the second coil layer 203 is less than the height H1 of the first coil layer 202, so that a portion of the first coil layer 202 adjacent to one end of the first coil unit 1011 or the second coil unit 1021 is exposed. Moreover, one end of the first coil unit 1011 or the second coil unit 1021 adjacent to a portion of the first coil layer 202 faces the first reference plane 103.

[0065] In order to facilitate the elimination of hysteresis, the number of turns of the first coil layer 202 and the second coil layer 203 can be set to be the same. At this time, it is only necessary to pass currents with the same amplitude but opposite directions into the first coil layer 202 and the second coil layer 203 respectively, so that the hysteresis generated by the first coil unit 1011 and the second coil unit 1021 can cancel each other.

[0066] In order to input current to the coil units in the first coil assembly and the second coil assembly and control the input current, the magnetic field generating device of the present application may further include a DC power supply and a control circuit.

[0067] Specific as Figure 8 As shown, in the second embodiment of the magnetic field generating device of the present application, the magnetic field generating device includes: a first coil component 101, a second coil component 102, a DC power supply 110 and a control circuit 120, wherein the DC power supply 110 is connected to the first coil component 101 and the second coil component 102, and the control circuit 120 is connected to the DC power supply 110.

[0068] The structures of the first coil assembly 101 and the second coil assembly 102 are the same as those of the magnetic field generating device in the aforementioned embodiment, and are not repeated here.

[0069] Specifically, the DC power supply 110 is connected to each of the first coil units 1011 and the second coil units 1021 to provide current to each of the first coil units 1011 and the second coil units 1021 , and the control circuit 120 is connected to the DC power supply 110 to control the current output by the DC power supply 110 .

[0070] The control circuit 120 may be a central processing unit (CPU), a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The general purpose processor may be a microprocessor or the processor may be any conventional processor.

[0071] In order to reduce hysteresis, the Figure 7 As shown, the control circuit 120 can control the DC power supply 110 to provide opposite currents to the first coil layer 202 and the second coil layer 203 in each first coil unit 1011 and the second coil unit 1021, so that the magnetic fields generated by the first coil layer 202 and the second coil layer 203 cancel each other.

[0072] Furthermore, if Figure 8As shown, the magnetic field generating device includes a plurality of DC power supplies 110, each of which is connected to the corresponding first coil unit 1011 or the second coil unit 1021, so as to provide current to each first coil unit 1011 and the second coil unit 1021 separately, so that the control circuit 120 can control the current input to each first coil unit 1011 and the second coil unit 1021 separately, so as to generate the required magnetic field.

[0073] Of course, in other embodiments, the DC power supply 110 may also be integrated with multiple DC branches, and the control circuit 120 may control the output current of each DC branch separately, so that each DC branch can provide current to each first coil unit 1011 and second coil unit 1021 separately.

[0074] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A magnetic field generating device, characterized in that: include: A first coil assembly and a second coil assembly, wherein the first coil assembly and the second coil assembly are arranged on the same side of a first reference plane; The first coil assembly includes at least three first coil units, and the second coil assembly includes at least three second coil units. The projections of the at least three first coil units on the first reference plane and the projections of the at least three second coil units on the first reference plane are arranged alternately. The axes of the at least three first coil units and the at least three second coil units intersect at a point on the first reference plane. The axis of the first coil unit forms a first angle with the first reference plane, and the axis of the second coil unit forms a second angle with the first reference plane. The angle values ​​of the first angle and the second angle are different. Each of the first coil unit and the second coil unit includes an iron core, a first coil layer and a second coil layer. The first coil layer is wound on the surface of the iron core, and the second coil layer is wound on the surface of the first coil layer. The size and number of coil turns of each coil unit in the first coil unit and the second coil unit are the same. A direct current power supply and a control circuit, wherein the control circuit can control the direct current power supply to provide opposite currents to the first coil layer and the second coil layer, so that the magnetic fields generated by the first coil layer and the second coil layer cancel each other out.

2. The magnetic field generating device according to claim 1, characterized in that The at least three first coil units and one end of the at least three second coil units facing the first reference plane are located on the same second reference plane.

3. The magnetic field generating device according to claim 2, characterized in that The first reference surface is a plane, and the second reference surface is a hemispherical surface.

4. The magnetic field generating device according to claim 1, characterized in that The projections of the at least three first coil units on the first reference plane and the projections of the at least three second coil units on the first reference plane are evenly and alternately arranged.

5. The magnetic field generating device according to claim 1, characterized in that: There are multiple DC power supplies, and each of the DC power supplies is connected to the corresponding first coil unit or the second coil unit to provide current to each of the first coil unit and the second coil unit separately.

Images