Magnetic positioning method, system, equipment and medium for magnetic soft robot

Abstract

The invention discloses a magnetic positioning method, system and device for a magnetic soft robot and a medium. The method comprises the steps that a driving magnetic field generated by the magnetic soft robot at the position where each magnetic sensor is located is calculated; wherein the magnetic soft robot is driven by a rectangular electromagnetic coil group, and a permanent magnet is embedded in the head of the magnetic soft robot; calculating the theoretical magnetic induction intensity of the position of each magnetic sensor; based on the difference value between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the position of each magnetic sensor, constructing a magnetic induction intensity error function which takes the position and the attitude of the permanent magnet as variables and eliminates an environment magnetic field and a driving magnetic field; and solving the error function to obtain the position and attitude of the permanent magnet.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and in particular relates to a magnetic positioning method, system, electronic equipment, and medium for a magnetic soft robot. Background Art

[0002] In the medical field, osteochondral defect is a very common type of clinical disease. Compared with other tissues in the human body, articular cartilage has a more complex structure and lacks nerves and blood vessels inside, and its repair and regeneration ability is very limited. Among all cases of articular cartilage defects, knee cartilage defect is the most common type. The repair of knee cartilage defects has become one of the most challenging clinical problems faced by orthopedic surgeons.

[0003] With the cross-development of medicine and engineering, magnetic soft robots have shown great application potential in minimally invasive repair of knee cartilage. Magnetic soft robots for minimally invasive repair of knee cartilage can alleviate patients' treatment pain, reduce their treatment costs, and shorten their recovery time. At the same time, they can accurately anchor biomaterials at the knee cartilage defects through in situ printing, which provides a minimally invasive, directional, efficient and precise treatment method for knee cartilage repair.

[0004] When the magnetic soft robot for minimally invasive repair of knee cartilage works in the body, the premise for achieving high-precision and high-robust control is to be able to obtain its accurate position information and have good position perception. Because the internal environment of the human body is unknown and complex, the magnetic soft robot for minimally invasive repair of knee cartilage may stagnate at a certain position or deviate from the expected route due to environmental restrictions, resulting in surgical failure or even secondary injury to the patient.

[0005] Among the existing soft robot in vivo positioning methods, positioning based on ultrasonic signals is affected by the heterogeneity of human tissue and the positioning accuracy varies greatly; positioning based on medical images requires complex three-dimensional reconstruction and has radiation hazards; optical fiber shape sensing positioning is costly and the equipment technology is complex; the permanent magnet positioning method has the advantages of not consuming energy, not being blocked by the human body, fast positioning speed, and high positioning accuracy, but there is no design of a magnetic soft robot for minimally invasive repair of knee cartilage. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a magnetic positioning method, system, equipment and medium for a magnetic soft robot.

[0007] In a first aspect, an embodiment of the present invention provides a magnetic positioning method for a magnetic soft robot, the method comprising:

[0008] Calculating the driving magnetic field generated by the magnetic soft robot at the location of each magnetic sensor; wherein the magnetic soft robot is driven by a rectangular electromagnetic coil group and has a permanent magnet embedded in its head;

[0009] Calculate the theoretical magnetic induction intensity at the location of each magnetic sensor;

[0010] Based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor, a magnetic induction intensity error function is constructed with the position and posture of the permanent magnet as variables and the ambient magnetic field and the driving magnetic field eliminated;

[0011] Solve the error function to obtain the position and attitude of the permanent magnet.

[0012] In a second aspect, an embodiment of the present invention provides a magnetic positioning system for a magnetic soft robot, which is used to implement the magnetic positioning method of the magnetic soft robot, and the system includes:

[0013] The magnetic source to be tested is a magnetic soft robot, which is driven by a rectangular electromagnetic coil group and has a permanent magnet embedded in its head;

[0014] A magnetic sensor is arranged near the magnetic source to be measured to detect the ambient magnetic field during the initialization phase and to detect the driving magnetic field generated by the magnetic source to be measured at the location of each magnetic sensor;

[0015] The magnetic positioning processing module constructs a magnetic induction intensity error function with the position and posture of the permanent magnet as variables and eliminates the ambient magnetic field and the driving magnetic field based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor; solves the error function to obtain the position and posture of the permanent magnet.

[0016] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory is coupled to the processor; wherein the memory is used to store program data, and the processor is used to execute the program data to implement the above-mentioned magnetic positioning method of the magnetic soft robot.

[0017] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned magnetic positioning method of the magnetic soft robot.

[0018] In a fifth aspect, an embodiment of the present invention provides a computer program product, including a computer program / instruction, which implements the above-mentioned magnetic positioning method of the magnetic soft robot when executed by a processor.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a magnetic positioning method for a magnetic soft robot. Compared with traditional imaging positioning technologies such as X-rays and computer tomography (CT), this positioning method does not generate radiation, and will avoid the health risks of patients being exposed to radiation environments for a long time. The present invention calculates the driving magnetic field generated by the magnetic soft robot at the location of each magnetic sensor, and based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor, constructs a magnetic induction intensity error function with the position and posture of the permanent magnet as variables, and eliminates the environmental magnetic field and the driving magnetic field; solves the error function to obtain the position and posture of the permanent magnet. The present invention provides a new technical means for the research on the positioning of magnetic soft robots under driving conditions, and can realize the simultaneous driving and positioning of magnetic soft robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0022] Figure 1 A flow chart of a magnetic positioning method for a magnetic soft robot provided by an embodiment of the present invention;

[0023] Figure 2 A mathematical integral model diagram of a rectangular electromagnetic coil provided in an embodiment of the present invention;

[0024] Figure 3 A magnetic dipole model diagram of a permanent magnet provided in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that, in the absence of conflict, the features in the following embodiments and implementations may be combined with each other.

[0028] like Figure 1As shown, an embodiment of the present invention provides a magnetic positioning method for a magnetic soft robot, thereby converting magnetic field data acquired by a magnetic sensor into position and posture information of a permanent magnet, the method comprising:

[0029] Step S1, calculating the driving magnetic field generated by the magnetic soft robot at the location of each magnetic sensor; wherein the magnetic soft robot is driven by a rectangular electromagnetic coil group and a permanent magnet is embedded in its head.

[0030] Furthermore, in this example, the magnetic soft robot takes the magnetic soft robot for minimally invasive repair of knee cartilage as an example. For the magnetic soft robot for minimally invasive repair of knee cartilage with a permanent magnet embedded in the head, a magnetic sensor array is arranged outside the patient's body in order to accurately detect the magnetic field information around the magnetic soft robot. The magnetic sensor array is composed of multiple (generally greater than or equal to 5) single-axis magnetic sensors, and the distance from the permanent magnet on the head of the magnetic soft robot is greater than 10 times the size of the permanent magnet itself, to ensure that the magnetic dipole model can be applied and can accurately detect the magnetic field around the robot.

[0031] Furthermore, the magnetic soft robot includes an elastomeric hose and an optical fiber from the outside to the inside; the elastomeric hose is made of polydimethylsiloxane (PDMS), which has good biocompatibility and low Young's modulus. The permanent magnet is an axially magnetized annular permanent magnet, whose material is nebium iron boron, and the outer diameter and height dimensions are less than 5mm; in this example, the dimensions are set to an outer diameter of 3.1mm, an inner diameter of 1.9mm, and a height of 5mm. This size design ensures that the permanent magnet can be subjected to a large magnetic force in a spatial gradient magnetic field, while meeting the requirements of being sensed by a magnetic sensor array and the robot's spatial volume. The magnetic soft robot is driven by an electromagnetic coil group, and the number of coils is greater than or equal to 3. The change of the magnetic field is controlled by changing the size of the current configuration of the electromagnetic coil group, thereby controlling the torque and magnetic force of the soft robot.

[0032] Specifically, the step S1 includes the following steps:

[0033] Step S101, calculating the magnetic induction intensity generated by each side of each rectangular electromagnetic coil at the location of each magnetic sensor.

[0034] like Figure 2 As shown, the length of the rectangular electromagnetic coil is 2L, the width is 2w, and the height is 2h. The magnetic induction intensity generated by a rectangular current loop at any point P (a, b, c) in space is generated by the superposition of four sides. The expression of the magnetic induction intensity generated by each side is as follows:

[0035]

[0036] in, , represents the vacuum permeability, J s represents the current density, Indicates the real-time position of the current, represents a unit vector in three-dimensional space, θ is the angle between the current direction and the z-axis at a certain moment. C represents the current flow path, and I represents the surface current (I= J s dx).

[0037] Step S102, based on the superposition principle, superimpose the magnetic induction intensity generated by the four sides of each rectangular electromagnetic coil at the location of each magnetic sensor to obtain the magnetic induction intensity of each rectangular electromagnetic coil at the location of each magnetic sensor.

[0038] Assume that the magnetic induction intensity generated by the entire rectangular electromagnetic coil at any point P(a,b,c) in space is , which is generated by the superposition of four parts on each side. Assume that the magnetic induction intensity generated by each part is (i=1, 2, 3, 4), then the three-axis components are:

[0039]

[0040] By using numerical analysis method to solve the above equation, we can get:

[0041]

[0042]

[0043]

[0044] Step S103 , superimposing the product of the magnetic induction intensity of each rectangular electromagnetic coil at the location of each magnetic sensor and the current flowing therein, to obtain the driving magnetic field generated by the rectangular electromagnetic coil group at the location of each magnetic sensor.

[0045] For a drive system consisting of n rectangular electromagnetic coils, each electromagnetic coil is fed with a different current. Assume that the magnetic induction intensity generated by the e-th electromagnetic coil when a unit current is fed is expressed as Indicates that the current flowing through the e-th electromagnetic coil is expressed as Indicates that the driving magnetic field generated by the driving system at any point P(a, b, c) in space is:

[0046] .

[0047] It can be seen that as long as the size, position, and current of the rectangular electromagnetic coil are known, the magnetic induction intensity it generates can be calculated.

[0048] Step S2, calculating the theoretical magnetic induction intensity at the location of each magnetic sensor.

[0049] like Figure 3 (A) and Figure 3 As shown in (B), the head of the magnetic soft robot is embedded with a hollow cylindrical permanent magnet, and the center of the permanent magnet is denoted as P0= , the unit vector in the direction of magnetic dipole moment is denoted as H0= , length is L, outer diameter is r1, inner diameter is r2, permanent magnet is at the detection point The magnetic induction intensity generated at can be regarded as the magnetic induction intensity generated by the solid cylindrical permanent magnet with a radius of r1 and a length of L minus the magnetic induction intensity generated by the solid cylindrical permanent magnet with a radius of r2 and a length of L. The three-axis component form is:

[0050]

[0051]

[0052]

[0053] In the formula, , , They respectively represent the theoretical values ​​of the magnetic induction intensity on the x, y, and z components of the kth magnetic sensor.

[0054] in, , represents the remanence of permanent magnets, .

[0055] Furthermore, for an axially magnetized cylindrical permanent magnet, when it moves along its axis, the magnetic induction intensity at the detection point is is unchanged, therefore, only the five-dimensional pose information of the permanent magnet can be calculated, but there are the following constraints:

[0056]

[0057] Step S3, based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor, a magnetic induction intensity error function is constructed with the position and posture of the permanent magnet as variables and the ambient magnetic field and the driving magnetic field eliminated.

[0058]

[0059]

[0060]

[0061] In the formula, , , They represent the magnetic induction intensity errors at the x, y, and z components of the magnetic sensor location, respectively. N represents the number of magnetic sensors. , , They respectively represent the magnetic induction intensity of the x, y, and z components at the location detected by the k-th magnetic sensor; , , They represent the ambient magnetic field at the x, y, and z components of the kth magnetic sensor location, respectively. represents the location of the kth magnetic sensor, , , They represent the driving magnetic field at the x, y, and z components of the kth magnetic sensor location, respectively. , , They represent the theoretical values ​​of magnetic induction intensity on the x, y, and z components assuming the kth magnetic sensor is located;

[0062]

[0063] Where P(a, b, c) is the rectangular electromagnetic coil at any point in space, H0= is the unit vector in the direction of the magnetic dipole moment.

[0064] Step S4, solving the error function to obtain the position and posture of the permanent magnet.

[0065] Specifically, in this example, the Newton method, Gauss-Newton method, LM algorithm, and particle swarm algorithm can be used to solve the error function.

[0066] Exemplarily, a particle swarm algorithm is selected for solution. The overall idea is: by designing a massless particle to simulate the birds in a flock, the particle has only two attributes: speed and position. The speed represents the speed of movement, and the position represents the direction of movement. Each particle searches for the optimal solution in the search space individually, and records it as the current individual extreme value, and shares the individual extreme value with other particles in the entire particle swarm. The best individual extreme value is found as the current global optimal solution of the entire particle swarm. All particles in the particle swarm adjust their speed and position according to the current individual extreme value they find and the current global optimal solution shared by the entire particle swarm, so that the movement of the entire group evolves and moves towards the optimal goal in the problem-solving space, gradually evolving from a disordered state to an ordered state, thereby obtaining the optimal solution.

[0067] Specifically, when using the particle swarm algorithm to solve the problem, the particle swarm size, particle position and moving speed are initialized, the fitness value of each particle is calculated according to the overall error function, and it is compared with the fitness value of the individual optimal position and the global optimal position of the group and updated, and the maximum number of iterations or the minimum fitness threshold is set as the end condition of the iteration, and finally the optimized position and posture information of the magnetic soft robot is output.

[0068] On the other hand, an embodiment of the present invention further provides a magnetic positioning system for a magnetic soft robot, which is used to implement the magnetic positioning method for the magnetic soft robot, and the system includes:

[0069] The magnetic source to be tested is a magnetic soft robot, which is driven by a rectangular electromagnetic coil group and has a permanent magnet embedded in its head;

[0070] A magnetic sensor is arranged near the magnetic source to be measured to detect the ambient magnetic field during the initialization phase and to detect the driving magnetic field generated by the magnetic source to be measured at the location of each magnetic sensor;

[0071] The magnetic positioning processing module constructs a magnetic induction intensity error function with the position and posture of the permanent magnet as variables and eliminates the ambient magnetic field and the driving magnetic field based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor; solves the error function to obtain the position and posture of the permanent magnet.

[0072] Regarding the system in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0073] For the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The system embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application. A person of ordinary skill in the art can understand and implement it without creative work.

[0074] Accordingly, the present application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the magnetic positioning method of the magnetic soft robot as described above. Figure 4As shown, it is a hardware structure diagram of any device with data processing capability in which the magnetic positioning method of the magnetic soft robot provided by the embodiment of the present invention is located, except Figure 4 In addition to the processor, memory and network interface shown, any device with data processing capability in which the apparatus in the embodiment is located may also include other hardware, generally based on the actual functions of the device with data processing capability, which will not be described in detail.

[0075] Accordingly, the present application also provides a computer-readable storage medium on which computer instructions are stored, and when the instructions are executed by the processor, the magnetic positioning method of the magnetic soft robot as described above is implemented. The computer-readable storage medium can be an internal storage unit of any device with data processing capabilities described in any of the aforementioned embodiments, such as a hard disk or a memory. The computer-readable storage medium can also be an external storage device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), an SD card, a flash card (Flash Card), etc. equipped on the device. Furthermore, the computer-readable storage medium can also include both an internal storage unit and an external storage device of any device with data processing capabilities. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capabilities, and can also be used to temporarily store data that has been output or is to be output.

[0076] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only.

[0077] It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A magnetic positioning method for a magnetic soft robot, characterized in that: The method comprises: Calculating the driving magnetic field generated by the magnetic soft robot at the location of each magnetic sensor; wherein the magnetic soft robot is driven by a rectangular electromagnetic coil group and has a permanent magnet embedded in its head; Calculate the theoretical magnetic induction intensity at the location of each magnetic sensor; Based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor, a magnetic induction intensity error function is constructed with the position and posture of the permanent magnet as variables and the ambient magnetic field and the driving magnetic field eliminated; Solve the error function to obtain the position and attitude of the permanent magnet.

2. The magnetic positioning method of a magnetic soft robot according to claim 1, characterized in that: The process of calculating the driving magnetic field generated by the magnetic soft robot at each magnetic sensor location includes: Calculate the magnetic induction intensity generated by each side of each rectangular electromagnetic coil at the location of each magnetic sensor; Based on the superposition principle, the magnetic induction intensity generated by the four sides of each rectangular electromagnetic coil at the location of each magnetic sensor is superimposed to obtain the magnetic induction intensity of each rectangular electromagnetic coil at the location of each magnetic sensor; The driving magnetic field generated by the rectangular electromagnetic coil group at the location of each magnetic sensor is obtained by superimposing the product of the magnetic induction intensity of each rectangular electromagnetic coil at the location of each magnetic sensor and the current flowing therein.

3. The magnetic positioning method of a magnetic soft robot according to claim 2, characterized in that: The process of calculating the driving magnetic field generated by the rectangular electromagnetic coil group at the location of each magnetic sensor specifically includes: The length of the rectangular electromagnetic coil is 2L, the width is 2w, and the height is 2h. The magnetic induction intensity generated by a rectangular current loop at any point P (a, b, c) in space is generated by the superposition of the four sides. The expression of the magnetic induction intensity generated by each side is as follows: ； in, , represents the vacuum permeability, J s represents the current density, Indicates the real-time position of the current, represents a unit vector in three-dimensional space, θ is the angle between the current direction and the z-axis at a certain moment; Assume that the magnetic induction intensity generated by the entire rectangular electromagnetic coil at any point P(a,b,c) in space is , generated by the superposition of each edge, assuming that the magnetic induction intensity generated by each edge is , i=1,2,3,4, then the three-axis components are: ； For a drive system consisting of n rectangular electromagnetic coils, each electromagnetic coil is fed with a different current. Assume that the magnetic induction intensity generated by the e-th electromagnetic coil when a unit current is fed is expressed as Indicates that the current flowing through the e-th electromagnetic coil is expressed as Indicates that the driving magnetic field generated by the driving system at any point P(a, b, c) in space is: 。 4. The magnetic positioning method of a magnetic soft robot according to claim 1, characterized in that: The process of calculating the theoretical magnetic induction intensity at each magnetic sensor location includes: The head of the magnetic soft robot is embedded with a hollow cylindrical permanent magnet, and the center of the permanent magnet is denoted as P0= , the unit vector in the direction of magnetic dipole moment is denoted as H0= , length is L, outer diameter is r1, inner diameter is r2, permanent magnet is at the detection point The three-axis component form of the magnetic induction intensity generated at is: ； ； ； In the formula, , , They represent the theoretical values ​​of the magnetic induction intensity at the x, y, and z components assuming the kth magnetic sensor is located. , , represents the remanence of permanent magnets, .

5. The magnetic positioning method of a magnetic soft robot according to claim 1, characterized in that: Based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor, a magnetic induction intensity error function is constructed with the position and posture of the permanent magnet as variables and the ambient magnetic field and the driving magnetic field eliminated, including: ； ； ； In the formula, , , They represent the magnetic induction intensity errors at the x, y, and z components of the magnetic sensor location, respectively. N represents the number of magnetic sensors. , , They respectively represent the magnetic induction intensity of the x, y, and z components at the location detected by the k-th magnetic sensor; , , They represent the ambient magnetic field at the x, y, and z components of the kth magnetic sensor location, respectively. represents the location of the kth magnetic sensor, , , They represent the driving magnetic field at the x, y, and z components of the kth magnetic sensor location, respectively. , , They represent the theoretical values ​​of the magnetic induction intensity on the x, y, and z components assuming the kth magnetic sensor is located; ； Where P(a, b, c) is the rectangular electromagnetic coil at any point in space, H0= is the unit vector in the direction of the magnetic dipole moment.

6. The magnetic positioning method of a magnetic soft robot according to claim 1, characterized in that: The process of solving the error function includes: using Newton's method, Gauss-Newton method, LM algorithm, and particle swarm algorithm to solve the error function.

7. A magnetic positioning system for a magnetic soft robot, characterized in that: A magnetic positioning method for implementing the magnetic soft robot according to any one of claims 1 to 6, the system comprising: The magnetic source to be tested is a magnetic soft robot, which is driven by a rectangular electromagnetic coil group and has a permanent magnet embedded in its head; A magnetic sensor is arranged near the magnetic source to be measured to detect the ambient magnetic field during the initialization phase and to detect the driving magnetic field generated by the magnetic source to be measured at the location of each magnetic sensor; The magnetic positioning processing module constructs a magnetic induction intensity error function with the position and posture of the permanent magnet as variables and eliminates the ambient magnetic field and the driving magnetic field based on the difference between the actual magnetic induction intensity detected by each magnetic sensor and the theoretical magnetic induction intensity at the location of each magnetic sensor; solves the error function to obtain the position and posture of the permanent magnet.

8. An electronic device comprising a memory and a processor, characterized in that: The memory is coupled to the processor; wherein the memory is used to store program data, and the processor is used to execute the program data to implement the magnetic positioning method of the magnetic soft robot as described in any one of claims 1-6 above.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the magnetic positioning method of the magnetic soft robot as described in any one of claims 1-6 is implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the magnetic positioning method of the magnetic soft robot described in any one of claims 1-6 is implemented.

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