Enhanced electromagnetic driving system, device and method capable of generating various electromagnetic fields

Abstract

The invention relates to an electromagnetic driving system which is used for solving the problem that different magnetic field modes are needed clinically to assist in drug delivery, but in the prior art, it is difficult to use one electromagnetic driving system to generate different magnetic field modes. According to the micro-robot magnetic control system with the extensible spherical large working space, modular mechanical design is adopted, and an enhanced gradient magnetic field, a uniform magnetic field, a rotating magnetic field, an oscillating magnetic field and a dispersed gradient magnetic field can be generated in the spherical space; therefore, the micro-robots in any form and number can be conveniently controlled to deform and move, and the medicine is conveyed to the corresponding position of the human body.

Description

Technical Field

[0001] The present disclosure relates to an electromagnetic drive system for a micro-robot, and more particularly to an electromagnetic drive system, device and method capable of generating multiple electromagnetic fields, which can provide a large operating space required for magnetizing a drug delivery within a robot body. Background Art

[0002] With the development of biomedical engineering, electromagnetic drive has become a safe and efficient driving method. Electromagnetic drive robots have advantages such as remote control and non-invasive / minimally invasive, and have important application values in magnetic robot operations. The development of clinical surgery is closely linked to the progress of engineering technology. Specifically, in the field of non-invasive or minimally invasive surgery, it is particularly manifested in the use of magnetic drive devices to drive magnetic robots to deliver drugs or perform surgeries. The internal environment of the human body includes different regions, such as the easily accessible intraocular space to the complex and difficult-to-access intravascular system, or large natural cavities and channels within the human body, such as joint cavities or gastrointestinal tracts, which are ideal working spaces for the movement of magnetic robots. Summary of the Invention

[0003] The purpose of the present disclosure is to propose a micro-robot magnetic manipulation system with an expandable spherical large working space, which can generate enhanced gradient magnetic fields, uniform magnetic fields, rotating magnetic fields, oscillating magnetic fields, and dispersed gradient magnetic fields within a spherical space, so as to manipulate the deformation and movement of micro-robots of any shape and quantity, and deliver drugs to corresponding positions in the human body.

[0004] To achieve the above object, an electromagnetic drive system proposed by the present disclosure includes 4 closed-loop magnetic bridges, and a first electromagnetic device and a second electromagnetic device are connected to each magnetic bridge; the first electromagnetic device and the second electromagnetic device are the same, and each includes a conical head, a first anti-magnetic dissipation device, an iron core, an electromagnetic coil, and a second anti-magnetic dissipation device, wherein: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located within the electromagnetic coil, and the first anti-magnetic dissipation device is sandwiched between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second or fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is sandwiched between the electromagnetic coil and the magnetic bridge; the working space size is adjusted and the magnetic field gradient is enhanced between the center of the conical head and the iron core through an extension rod, and the shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space.

[0005] In an implementation manner of the above system technical solution, the magnetic bridges are installed on a base, and there are holes on the base capable of adjusting the installation position. By simultaneously moving the four groups of magnetic bridges outward, the working space can be increased.

[0006] In an embodiment of the above system technical solution, the magnetic bridge includes a first section, a second section, an intermediate section, a third section, and a fourth section connected in sequence. The first section and the fourth section are parallel, the second section and the third section are of equal length, and both the second section and the third section form an angle with the intermediate section. A first electromagnetic device is connected to the second section, and a second electromagnetic device is connected to the third section; the first section and the fourth section ensure an enhanced gradient magnetic field in the vertical direction.

[0007] In an embodiment of the above system technical solution, the length of the extension rod is 20 mm - 30 mm.

[0008] In an embodiment of the above system technical solution, the weight of the electromagnetic drive system is less than 70 kg, and the height is less than 500 mm.

[0009] As can be seen from the above system technical solution, the present disclosure also proposes an electromagnetic device, which includes a conical head, a first anti-magnetic dissipation device, an iron core, an electromagnetic coil, and a second anti-magnetic dissipation device, wherein: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is sandwiched between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second section or the fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is sandwiched between the electromagnetic coil and the magnetic bridge; the working space size is adjusted between the conical head and the center of the iron core through an extension rod and the gradient of the magnetic field is enhanced. The shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space.

[0010] As can be seen from the above system technical solution, the present disclosure also proposes a method for generating a magnetic field in the working space of an electromagnetic drive system. The electromagnetic drive system includes 4 closed-loop magnetic bridges, and a first electromagnetic device and a second electromagnetic device are connected to each magnetic bridge. The first electromagnetic device and the second electromagnetic device are the same, and both include a conical head, a first anti-magnetic dissipation device, an iron core, an electromagnetic coil, and a second anti-magnetic dissipation device, wherein: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is sandwiched between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second section or the fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is sandwiched between the electromagnetic coil and the magnetic bridge; the working space size is adjusted between the conical head and the center of the iron core through an extension rod and the gradient of the magnetic field is enhanced. The shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space; the method includes: generating a preset magnetic field pattern by making the first electromagnetic device and / or the second electromagnetic device at a preset position work, and the magnetic field pattern includes an enhanced gradient magnetic field, a uniform magnetic field, a rotating magnetic field, an oscillating magnetic field, and a dispersed gradient magnetic field.

[0011] In the above method technical solution, generating a preset magnetic field pattern by operating the first electromagnetic device and / or the second electromagnetic device at a preset position includes: generating a magnetic circuit by driving a pair of electromagnetic devices on a magnetic bridge to conduct currents in opposite directions, so as to generate a gradient magnetic field with enhanced horizontal direction; dividing the four electromagnetic devices in the upper half or the lower half into two groups, taking two adjacent electromagnetic devices as a group, and driving the two groups of electromagnetic devices to make the current directions on one group of electromagnetic devices opposite to those on the other group, so as to generate a gradient magnetic field with enhanced vertical direction; generating a uniform magnetic field by configuring two electromagnetic devices that meet a preset distance to operate, and the two electromagnetic devices that meet the preset distance are two electromagnetic devices located in the second section and the third / second section on the opposite magnetic bridges, or two electromagnetic devices located in the second section and the third section on the adjacent magnetic bridges; generating the rotating magnetic field by time-sharing exciting four preset electromagnetic devices to operate, and the four preset electromagnetic devices are the electromagnetic devices in the second section of each magnetic bridge, or the electromagnetic devices in the third section of each magnetic bridge, or four electromagnetic devices on the opposite magnetic bridges, or four electromagnetic devices on two adjacent magnetic bridges; generating the oscillating magnetic field by making the operating currents of four preset electromagnetic devices satisfy the following excitation function: , , , , where is the current amplitude, and the constant parameter , is the oscillation frequency, is the time, and the oscillation angle . By adjusting the constant parameter , the oscillation angle can be changed; the four preset electromagnetic devices are the four electromagnetic devices in the second section of each magnetic bridge, or the four electromagnetic devices in the third section of each magnetic bridge, or four electromagnetic devices on two opposite magnetic bridges, or four electromagnetic devices on two adjacent magnetic bridges; generating the dispersed gradient magnetic field by driving two pairs of electromagnetic devices on the opposite magnetic bridges to make the magnetic circuit directions generated by one pair of electromagnetic devices opposite to those of the other pair; or dividing two adjacent pairs of the four pairs of electromagnetic devices into a group, and driving the two groups of electromagnetic devices to make the magnetic circuit directions formed by the two pairs of electromagnetic devices in one group opposite to those in the other group, so as to generate the dispersed gradient magnetic field.

[0012] Advantageous technical effects of the present disclosure: (1) It can generate a variety of specific magnetic field patterns, including a uniform magnetic field, a dispersed gradient magnetic field, and an enhanced gradient magnetic field. (2) It can achieve a large magnetic field gradient (16 T / m) under the drive of a small current (10 A), drive micro-robots of any shape, and cooperate with a large space for medical applications. For example, it can be used for the treatment of knee joint injuries by configuring the system at the knee joint so that the working space of the system is located at the knee joint. (3) The gradient force in the vertical direction is considered in three-dimensional space, and the gradient force in the vertical direction is enhanced without affecting the gradient force in the horizontal direction. (4) The electromagnetic drive system under the structure of the present disclosure can generate a large magnetic field at a small size (the height can be less than 500 mm). BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0014] Figure 1 It is a side view of the structure of the electromagnetic drive system in an embodiment.

[0015] Figure 2 It is a schematic diagram of the installation of the electromagnetic device on a magnetic bridge in an embodiment.

[0016] Figure 3 It is an exploded view of an electromagnetic device in an embodiment.

[0017] Figure 4 It is a schematic diagram of the oscillating magnetic field generated by the electromagnetic drive system exemplified in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The magnetic drive methods include magnetic torque drive and magnetic force gradient drive. Although the torque drive method is more energy-efficient than the magnetic drive method, the torque drive method highly depends on the design of magnetic robots. The structural design of torque-driven micro-robots must meet the requirement of converting the applied torque into translational force. A typical design is a helical structure, imitating bacterial flagella. Another is a fish-like structure, which makes full use of the torque generated by an oscillating magnetic field to move forward. Due to the limitations of the structural design, it is difficult to achieve drug loading solely by the torque drive method. A typical magnetic robot design for drug delivery uses a burr-like porous spherical structure driven under a magnetic field gradient. Classical designs, such as Octomag (Kummer, Michael P., et al. "OctoMag: An electromagnetic system for 5-DOF wireless micromanipulation." IEEE Transactions on Robotics 26.6 (2010): 1006-1017), are intended for ophthalmic surgery and can generate a 3D gradient field. However, due to the low efficiency characteristics of the gradient field, this design is difficult to be used in medical scenarios that require large gradient forces.

[0019] Based on this, the present disclosure proposes an electromagnetic drive system, which includes a first electromagnetic device, a second electromagnetic device, and 4 magnetic bridges; each magnetic bridge includes a first section, a second section, an intermediate section, a third section, and a fourth section connected in sequence, the first section and the fourth section are parallel, the second section and the third section are of equal length, and both the second section and the third section form an angle with the intermediate section. A first electromagnetic device is connected to the second section, and a second electromagnetic device is connected to the third section; the first electromagnetic device and the second electromagnetic device are the same, and each includes a conical head, a first magnetic leakage prevention device, an iron core, an electromagnetic coil, and a second magnetic leakage prevention device, where: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first magnetic leakage prevention device is sandwiched between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second section or the third section of the magnetic bridge, and the second magnetic leakage prevention device is sandwiched between the electromagnetic coil and the magnetic bridge; by energizing the first electromagnetic device and / or the second electromagnetic device at a preset position, a preset magnetic field pattern can be generated, and the magnetic field pattern includes an enhanced gradient magnetic field, a uniform magnetic field, a rotating magnetic field, an oscillating magnetic field, and a dispersed gradient magnetic field.

[0020] Next, the implementation of the technical solution of this case will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described implementation manners are only a part of the implementation manners of this case, rather than all of the implementation manners. Based on the implementation manners in this case, all other implementation manners obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of this application.

[0021] The entire electromagnetic drive system can have 4 pairs of identical electromagnetic devices. Figure 1 A side view showing the structure of the electromagnetic drive system. Figure 2 It shows a schematic diagram of the installation of the electromagnetic device on a magnetic bridge. Each electromagnetic device is installed on the magnetic bridge, and each pair of electromagnetic devices is located on one magnetic bridge. The magnetic bridge is installed on the base, and the base includes a lower base 400 and a large base 402. Each magnetic bridge is installed on the lower base 400 belonging to that magnetic bridge, and the 4 lower bases 400 are installed on the large base 402 of the entire system. There are holes 401 on the large base and the lower base that can adjust the installation position of the magnetic bridge.

[0022] Each of the magnetic bridges includes a first section 301, a second section 302, an intermediate section 303, a third section 304, and a fourth section 305 connected in sequence. The first section and the fourth section are parallel, the second section and the third section are of equal length, and both the second section and the third section form an angle with the intermediate section. A first electromagnetic device 100 is connected to the second section, and a second electromagnetic device 200 is connected to the third section. The structures of the first section and the fourth section are square blocks, which can make the gradient in the vertical direction slightly larger than that in the horizontal direction and ensure gradient enhancement.

[0023] See Figure 3 The exploded view of the first electromagnetic device 100 or the second electromagnetic device 200 shown in. The first electromagnetic device and the second electromagnetic device are the same, and both include a conical head 101, a first anti-magnetic dissipation device 102, an iron core 104, an electromagnetic coil 103, and a second anti-magnetic dissipation device 105, where: the tip radius of the conical head is greater than zero, which can determine the working space of the magnetic field as the magnetic field edge. The bottom of the cone is fixed to the first end of the iron core. The iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is clamped between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second section or the third section of the magnetic bridge, and the second anti-magnetic dissipation device is clamped between the electromagnetic coil and the magnetic bridge. The outer diameter of the first anti-magnetic dissipation device and the second anti-magnetic dissipation device is the same as the diameter of the electromagnetic coil; the inner diameter of the first anti-magnetic dissipation device and the second anti-magnetic dissipation device is the same as the diameter of the iron core.

[0024] By energizing the first electromagnetic device and / or the second electromagnetic device at a preset position to work, a spherical magnetic field working space can be formed in the middle of the entire electromagnetic drive system. The tip of the conical head is on the boundary of the working space, and by adjusting the position of the conical head, the size of the working space can be adjusted.

[0025] Energize a preset electromagnetic device, including setting which electromagnetic device or which groups of electromagnetic devices, and setting working parameters (including setting the excitation current value, current direction of the electromagnetic coil, and the distance between the magnetic core and the center of the working space). The set working parameters can be one group or multiple groups. The first and second magnetic leakage prevention devices adopt a disc design and can reduce magnetic field leakage. A terminal is arranged on the side of the second magnetic leakage prevention device, which can reduce the space occupied by the whole system.

[0026] In the exemplified embodiment, an extension rod is provided between the conical head and the center of the iron core. The shortest length of the extension rod is determined by the minimum length of the end for fixing the conical head, and the longest length is determined by the minimum working space. The optional length range of the extension rod is 20 mm - 30 mm.

[0027] In some embodiments, the conical bottom of the conical head has a protruding threaded frustum. Correspondingly, the first end of the iron core has a threaded concave hole adapted to the frustum. In the embodiment with an extension rod, the first end of the extension rod has a threaded concave hole adapted to the bottom of the conical head, and the second end of the extension rod has a threaded frustum adapted to the first end of the iron core. The shortest length of the extension rod is determined by the minimum length of the concave hole for fixing.

[0028] Since a pair of electromagnetic devices are connected by a closed-loop support iron column magnetic bridge to form a closed loop of magnetic flux, the gradient in the working space can be significantly enhanced with lower magnetic flux leakage, that is, the magnetic field gradient is enhanced based on the closed magnetic loop. Among them, all the magnetic conduction iron columns are made of DT4C material with extremely high magnetic permeability.

[0029] Since passing currents in opposite directions through a pair of electromagnetic coils on a magnetic bridge can make the magnetic field directions at the heads of each electromagnetic coil opposite, thus forming an electromagnetic circuit and establishing a connection between two conductors to enhance the magnetic flux. On this basis, it can be further assumed that using a high magnetic permeability material to connect the two electromagnetic coils can enhance the magnetic flux effect, but the deflection effect caused by the interaction between the two electromagnets is often regarded as an error that needs to be corrected, and using this effect can not only enhance the magnetic field gradient but also create new types of magnetic fields.

[0030] In the driving and control of the magnetic field, in order to reflect the magnetic field gradient enhancement effect, two electromagnets connected by a magnetic bridge are used as a pair to control the magnetic field, and magnetic fields in four mutually perpendicular directions can be generated on a plane ( x+ ), ( x- ), ( y+ ), ( y- ). In addition, according to the design of the first and fourth sections on the magnetic bridge, the four magnetic heads on the upper side, two by two as a group, can also generate a closed magnetic circuit to generate an upward magnetic field gradient (z+ ). Similarly, for the following four magnetic heads, taking two as a group, a closed magnetic circuit can also be generated to produce a downward magnetic field gradient ( z- ).

[0031] The specific example electromagnetic drive system adopted by each of the following magnetic field modes is as follows: 4 magnetic bridges are installed on the large base 402, and electromagnetic devices are installed on the second and third sections of each magnetic bridge. The electromagnetic device installed on the second section is above the electromagnetic device on the third section. The four electromagnetic devices above are respectively marked as 1, 3, 5, 7 clockwise (when looking down), and the marks of their corresponding lower electromagnetic devices are 2, 4, 6, 8.

[0032] The magnetic field intensity at any point in the working space generated by a single electromagnetic coil can be expressed by the following formula:

[0033] Among them, represents the distance from the coil, is the magnetic permeability in vacuum, is the current, is the minimum distance on the coil, d is the distance from a point on the electromagnetic coil to the middle of the magnetic field, is the length of a section of the electromagnetic coil taken, and c is the integral length of the coil.

[0034] For a pair of electromagnetic coils, the magnetic field intensity in space is approximately twice the calculated magnetic field intensity.

[0035] The torque and force generated at any point in space can be expressed as:

[0036] Among them, taking the coordinate axis o-xyz as the space coordinate system and the center point of the working space as the origin: the positive direction of the x-axis is perpendicular to the palm of the right hand, the direction in which the four fingers are straightened is the positive direction of the y-axis, and the direction of the thumb is the z-axis direction. is the torque, is the magnetic force, is the skew-symmetric matrix, is the magnetic field intensity at point, is the dipole moment, is the gradient of point p along the x direction, is the gradient of point p along the y direction, is the gradient of point p along the z direction, is the required current.

[0037] According to the above formula, if the required torque and force are given, or pThe magnetic field intensity and magnetic field gradient of the point, the required current can be calculated.

[0038] In one embodiment, according to the dynamic model of the controlled robot, the required torque / force can be known, and the required current can be obtained according to the known torque / force.

[0039] It can be obtained from the simulation experiment of Ansys EM that the optimized design with a closed-loop support iron column can double the magnetic field and magnetic field gradient.

[0040] The enhanced gradient magnetic field can be generated by driving a pair of electromagnetic devices on a magnetic bridge. By making the electromagnetic polarities of a pair of electromagnetic devices opposite, a magnetic path can be achieved.

[0041] Specifically, by driving a pair of electromagnetic devices on a magnetic bridge to pass currents in opposite directions to generate a magnetic circuit, thereby generating the enhanced gradient magnetic field in the horizontal direction; dividing the four electromagnetic devices in the upper half or the lower half into two groups, taking two adjacent electromagnetic devices as a group, and by driving the two groups of electromagnetic devices, making the current directions on one group of electromagnetic devices opposite to those on the other group to generate the enhanced gradient magnetic field in the vertical direction.

[0042] For example, in the example electromagnetic drive system, by making the electromagnetic device marked as 1 and the electromagnetic device marked as 2 pass currents in opposite directions, an enhanced gradient magnetic field in the horizontal direction can be generated in the working space.

[0043] For example, in the example electromagnetic drive system, for the four electromagnetic devices marked as 1, 3, 5, and 7, making the electromagnetic devices marked as 1 and 3 as the first group, and the remaining ones as the second group. By making the current directions of the two electromagnetic devices in the first group the same and opposite to the current direction of the second group, an enhanced gradient magnetic field in the vertical direction can be generated in the working space.

[0044] On the premise of ensuring the generation of the gradient magnetic field, this design also considers the generation of a uniform magnetic field. The magnetic field intensity along the distance z from the center extension line of the conical head of the electromagnetic device to the center of the working space can be expressed as:

[0045] is the number of turns of the electromagnetic coil, is the radius of the electromagnetic coil.

[0046] It can be seen from the above formula that when the distance between two electromagnetic coils is equal to the radius of the coil, a uniform magnetic field can be generated in the middle of the two electromagnetic coils.

[0047] In the classical theory, it can be obtained from the above formula that when the distance between the coils of two relative electromagnetic devices is equal to the radius of the electromagnetic device coil, the most uniform magnetic field can be generated in the working space. However, in this design, due to the magnetic field enhancement effect of the closed magnetic circuit, the distance between the coils of two relative electromagnetic devices should be much greater than the radius of the electromagnetic coil. Since the magnetic field enhancement effect can generate a magnetic field intensity approximately twice that of the original magnetic field, when the radius of an electromagnetic coil is 53 mm as in the example, the distance between the coils of two relative electromagnetic devices here should be approximately 106 mm. Further, from the simulation results, the optimal distance is 100 mm. In this example, a sphere with a diameter of 100 mm is used as the working space for analysis.

[0048] Therefore, by configuring two preset electromagnetic devices to meet the preset distance requirement for operation, a uniform magnetic field can be generated by this device. The two preset electromagnetic devices can be the two electromagnetic devices located in the second and third sections on the relative magnetic bridge, or the two electromagnetic devices located in the second section on the relative magnetic bridge, or the two electromagnetic devices located in the third section on the relative magnetic bridge, or the two electromagnetic devices located in the second and third sections on the adjacent magnetic bridges.

[0049] For example, in the example electromagnetic drive system, the current directions passed through the two electromagnetic devices are opposite. By making the two electromagnetic devices labeled 1 and 6 meet the preset distance, a uniform magnetic field can be generated. Or by making the two electromagnetic devices labeled 1 and 5 meet the preset distance, a uniform magnetic field can also be generated. Or by making the two electromagnetic devices labeled 2 and 6 meet the preset distance, a uniform magnetic field can also be generated. Or by making the two electromagnetic devices labeled 1 and 4 meet the preset distance, a uniform magnetic field can be generated, etc.

[0050] According to the ability of the coil to generate a uniform magnetic field, a rotating magnetic field can be achieved by time-sharing excitation of the preset electromagnetic devices. For example, in the counterclockwise direction, the current inputs to the preset four electromagnetic devices are the following excitation functions respectively: 、 、 、 , where: is the amplitude of the excitation function, is the frequency of the excitation function, is the phase difference of the excitation function. Exemplarily, .

[0051] The above preset electromagnetic devices can be the electromagnetic devices in the second section of each magnetic bridge, or the electromagnetic devices in the third section of each magnetic bridge, or 4 electromagnetic devices on two adjacent magnetic bridges, or 4 electromagnetic devices on the relative magnetic bridges.

[0052] For example, in the exemplary electromagnetic drive system, by driving the four electromagnetic devices labeled 1, 3, 5, and 7, or by driving the four electromagnetic devices labeled 2, 4, 6, and 8, or by driving the four electromagnetic devices labeled 1, 2, 3, and 4, or by driving the four electromagnetic devices labeled 1, 2, 5, and 6, a rotating magnetic field can be generated, etc. The currents of the four electromagnetic devices satisfy the above four excitation functions.

[0053] By making the preset electromagnetic devices work to form two magnetic circuits with opposite directions. In space, the two magnetic induction lines are equal in magnitude and opposite in direction, and cancel each other out at a point in the working space, forming the minimum point of the magnetic field intensity in space, so that a dispersed gradient magnetic field is formed in all directions with this point as the center.

[0054] For example, in the exemplary electromagnetic drive system, use to represent the electromagnetic intensity that activates the coils indicated by the corresponding subscripts. If the electromagnetic devices labeled 1 and 2 and the electromagnetic devices labeled 5 and 6 are made to work, and the direction of the magnetic induction lines generated by the electromagnetic devices labeled 1 and 2 is opposite to the direction of the magnetic induction lines generated by the electromagnetic devices labeled 5 and 6, then the calculation formula for the center point of the dispersed gradient magnetic field is:

[0055] It can be understood that the electromagnetic devices labeled 3 and 4 and the electromagnetic devices labeled 7 and 8 can also be made to work, and the direction of the magnetic induction lines generated by the electromagnetic devices labeled 3 and 4 is opposite to the direction of the magnetic induction lines generated by the electromagnetic devices labeled 7 and 8, then the calculation formula for the center point of the dispersed gradient magnetic field is:

[0056] Using the above formulas, the positions of the dispersed points in the horizontal direction and the x - y direction are calculated respectively, so as to determine the positions of the dispersed points in space. Through the design of the dispersed field and the design of the extension rod, the electromagnetic gradient of the whole system can be increased to 16 T / m.

[0057] In the vertical direction, if the four upper electromagnetic devices 1, 3, 5, and 7 are taken as a group, and the corresponding four lower electromagnetic devices 2, 4, 6, and 8 are taken as a group. In the same group, adjacent two electromagnetic devices (such as 1 and 3) pass the current in the same direction, and the other two electromagnetic devices (such as 5 and 7) pass the current in the opposite direction. In different groups, the current directions of the four lower electromagnetic devices are opposite to those of the corresponding four upper electromagnetic devices. Then, in the z direction, the calculation formula for the center point of the dispersed gradient magnetic field is:

[0058] Using the above formula, the positions of the dispersed points in the vertical direction and the z direction are calculated.

[0059] The oscillating magnetic field is another type of magnetic field formed based on a uniform magnetic field. It can be achieved by applying a current to the four electromagnetic devices in the second section of each magnetic bridge, or the four electromagnetic devices in the third section of each magnetic bridge, or the four electromagnetic devices on two adjacent magnetic bridges, or the four electromagnetic devices on two diagonals, in a clockwise or counterclockwise direction according to the following excitation function: , , , . Among them, is the current amplitude, a constant parameter , is the oscillation frequency, is the time, and the oscillation angle . The oscillation angle can be adjusted by changing the constant parameter .

[0060] The oscillating magnetic field in the local coordinate system i-j-k can be expressed as:

[0061] Among them, is the rotation matrix, where represents the local coordinate system , represents the global coordinate system .

[0062] For example, in the example electromagnetic drive system, a rotating magnetic field can be generated by driving the four electromagnetic devices labeled 1, 3, 5, and 7, or by driving the four electromagnetic devices labeled 2, 4, 6, and 8, or by driving the four electromagnetic devices 1, 2, 3, and 4, or by driving the four electromagnetic devices 1, 2, 5, and 6. The currents of the four electromagnetic devices satisfy the above four excitation functions.

[0063] Figure 4 is a schematic diagram of the oscillating magnetic field generated by the electromagnetic drive system in the above example. Figure 4 1, 2, 5, and 6 in Figure 4 respectively indicate the electromagnetic device labeled 1, the electromagnetic device labeled 2, the electromagnetic device labeled 5, and the electromagnetic device labeled 6. , , , , etc. The magnetic flux density generated by these four electromagnetic devices at different times is shown in Figure 4 . (d) in is a function schematic diagram of Figure 4 . The horizontal axis is the time t-axis, with the unit of seconds (s). It can be seen from Figure 4 that at the moment and when the maximum magnetic flux density appears. The relationship between the maximum magnetic flux density and the current is (mT).

[0064] By keeping the magnetic core and the closed-loop supporting iron column unsaturated to optimize and enhance the effective electromagnetic flux, and through the limitations of weight, overall size, and the shape of the working space, the height, width, and thickness of the middle section of the electromagnetic drive system are designed.

[0065] In one embodiment, the enhanced gradient magnetic field or rotating magnetic field of the electromagnetic drive system is used to deliver drugs. In another embodiment, such as drug diffusion in the treatment of osteoarthritis (OA), platelet-rich plasma (PRP) or other drugs loaded on the magnetic robot are directly injected into the joint cavity through a syringe. After injection, the drugs must be evenly dispersed in the joint cavity to ensure effective treatment of the drugs. Therefore, the dispersed gradient magnetic field is the key in this application. The viscosity in the inflamed joint is as high as 20 cp or higher. Since the blood viscosity is between 3.5 cp and 5.5 cp, the required gradient is much higher than most of the currently existing gradient magnetic fields applied to blood vessels. To implement such an application, the designed magnetic bridge has a height of 430 mm, a thickness of 25 mm, a width of 40 mm, a length of 215 mm for the middle section, and lengths of 150 mm for the second and third sections. The radius of the tip of the conical head is 3.5 mm, and the conical height is 40 mm. The radius of the iron core in the first electromagnetic device and the second electromagnetic device is 25 mm, the radius of the electromagnetic coil is 53 mm, and the length of the iron core and the electromagnetic coil is 110 mm. The number of turns of the copper coil in the electromagnetic coil is 566 turns, and the cross-sectional ellipse of the copper wire is 1.6 mm × 3 mm. The resistance of a single electromagnetic device is 0.7 ohm, and the inductance is 13.7 mH. The overall weight is less than 70 kg. The rated working current during the operation of the electromagnetic device is 10 A, and the maximum current is 20 A. In the rated current dispersed magnetic working mode, the gradient at the center of the working space can reach 16 T / m. The minimum working space is a sphere with a diameter of 40 mm, and the commonly used working space is a sphere with a diameter of 100 mm. The working space can be further expanded according to the modular base design. Both the large base and the lower base in the base preferably have pores, and the working space is further expanded by moving four pairs of magnetic bridges along the positions of the pores. As can be seen from the above, the overall electromagnetic drive system can use relatively less material than the materials of the prior art, require less physical space, but still maintain a high level of performance.

[0066] In another embodiment, an extension rod is provided between the conical head and the center of the iron core. Although the extension rod makes the overall space smaller, the magnetic field gradient of the entire system is further enhanced at the same time. This modular mechanical design makes the entire system more suitable for applications that require stronger gradients and smaller spaces. When the length of the extension rod is 30 mm, the gradients in the horizontal and vertical directions can reach 8.55 T / m and 9.7 T / m respectively.

[0067] In summary, the electromagnetic drive system proposed in the present disclosure adopts a modular design and various magnetic field enhancement and drive methods, which can enhance the flexibility and scalability of clinical research and applications. Compared with the existing method of using an electromechanical system to change the space size, the method of pure mechanical design improves the safety of the electromagnetic drive system.

[0068] Although the embodiments of the present disclosure have been described above in conjunction with the accompanying drawings, the present disclosure is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present disclosure, and these all belong to the scope of protection of the present disclosure.

Claims

1. An electromagnetic drive system, characterized in that, The system includes four closed-loop magnetic bridges, and a first electromagnetic device and a second electromagnetic device are connected to each magnetic bridge; The first electromagnetic device and the second electromagnetic device are the same, and each includes a conical head, a first anti-magnetic dissipation device, an iron core, an electromagnetic coil, and a second anti-magnetic dissipation device, where: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is clamped between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second or fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is clamped between the electromagnetic coil and the magnetic bridge; The size of the working space is adjusted between the conical head and the center of the iron core through an extension rod, and the gradient of the magnetic field is enhanced. The shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space.

2. The electromagnetic drive system according to claim 1, characterized in that The magnetic bridge is installed on a base, and there are holes on the base that can adjust the installation position. By simultaneously moving the four groups of magnetic bridges outward, the working space can be increased.

3. The electromagnetic drive system according to claim 1, wherein The magnetic bridge includes a first section, a second section, an intermediate section, a third section, and a fourth section connected in sequence. The first section and the fourth section are parallel, the second section and the third section are of equal length, and both the second section and the third section form an angle with the intermediate section. A first electromagnetic device is connected to the second section, and a second electromagnetic device is connected to the third section; the enhanced gradient magnetic field in the vertical direction is ensured through the first section and the fourth section.

4. The electromagnetic drive system according to claim 1, wherein, The length of the extension rod is 20 mm - 30 mm.

5. The electromagnetic drive system according to claim 1, characterized in that, The weight of the electromagnetic drive system is less than 70 kg, and the height is less than 500 mm.

6. An electromagnetic device, characterized in that: The electromagnetic device includes a conical head, a first anti-magnetic dissipation device, an iron core, an electromagnetic coil, and a second anti-magnetic dissipation device, where: the tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is clamped between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second or fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is clamped between the electromagnetic coil and the magnetic bridge; The size of the working space is adjusted between the conical head and the center of the iron core through an extension rod, and the gradient of the magnetic field is enhanced. The shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space.

7. A method for generating a magnetic field in the working space of an electromagnetic drive system, the electromagnetic drive system comprising four closed-loop magnetic bridges, with a first electromagnetic device and a second electromagnetic device connected to each magnetic bridge, the first electromagnetic device and the second electromagnetic device being identical and each comprising a conical head, a first magnetic leakage prevention device, an iron core, an electromagnetic coil, and a second magnetic leakage prevention device, wherein: The tip radius of the conical head is greater than zero, the bottom of the cone is fixed to the first end of the iron core, the iron core is located inside the electromagnetic coil, and the first anti-magnetic dissipation device is clamped between the conical head and the electromagnetic coil; the second end of the iron core is fixed to the second or fourth section of the magnetic bridge, and the second anti-magnetic dissipation device is clamped between the electromagnetic coil and the magnetic bridge; the size of the working space is adjusted between the conical head and the center of the iron core through an extension rod, and the gradient of the magnetic field is enhanced. The shortest length of the extension rod is determined by the minimum length of the end fixing the conical head, and the longest length is determined by the minimum working space; characterized in that the method includes: By making the first electromagnetic device and / or the second electromagnetic device at a preset position work, a preset magnetic field pattern is generated, and the magnetic field pattern includes an enhanced gradient magnetic field, a uniform magnetic field, a rotating magnetic field, an oscillating magnetic field, and a dispersed gradient magnetic field.

8. The method according to claim 7, wherein Generating a preset magnetic field pattern by operating the first electromagnetic device and / or the second electromagnetic device at a preset position, including: Generating a magnetic circuit by driving a pair of electromagnetic devices on a magnetic bridge to conduct currents in opposite directions, thereby generating an enhanced gradient magnetic field in the horizontal direction; dividing the four electromagnetic devices in the upper half or the lower half into two groups, taking two adjacent electromagnetic devices as a group, and driving the two groups of electromagnetic devices so that the current directions on one group of electromagnetic devices are opposite to those on the other group, to generate an enhanced gradient magnetic field in the vertical direction; Generating a uniform magnetic field by operating two electromagnetic devices that satisfy a preset distance, where the two electromagnetic devices that satisfy the preset distance are two electromagnetic devices on opposite magnetic bridges located in the second section and the third / second section, or two electromagnetic devices on adjacent magnetic bridges located in the second section and the third section; Generating the rotating magnetic field by time-division exciting four preset electromagnetic devices, where the four preset electromagnetic devices are the electromagnetic devices in the second section of each magnetic bridge, or the electromagnetic devices in the third section of each magnetic bridge, or four electromagnetic devices on opposite magnetic bridges, or four electromagnetic devices on two adjacent magnetic bridges; The oscillating magnetic field is generated by making the operating currents of four preset electromagnetic devices satisfy the following excitation function: , , , , where is the current amplitude, and the constant parameter , is the oscillation frequency, is the time, and the oscillation angle . By adjusting the constant parameter , the oscillation angle can be changed; the four preset electromagnetic devices are the four electromagnetic devices in the second section of each magnetic bridge, or the four electromagnetic devices in the third section of each magnetic bridge, or the four electromagnetic devices on two opposite magnetic bridges, or the four electromagnetic devices on two adjacent magnetic bridges; Generating the dispersed gradient magnetic field by driving two pairs of electromagnetic devices on opposite magnetic bridges so that the magnetic circuit directions generated by one pair of electromagnetic devices are opposite to those of the other pair; or dividing two adjacent pairs of the four pairs of electromagnetic devices into a group, and driving the two groups of electromagnetic devices so that the magnetic circuit directions formed by the two pairs of electromagnetic devices in one group are opposite to those in the other group, to generate the dispersed gradient magnetic field.

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