KR102456895B1 - Microrobot driving system including weight current control function and driving method of microrobot through the same - Google Patents

Abstract

The present invention relates to a microrobot driving system including a weighted current control function and a method of driving a microrobot through the same. By controlling the temperature of the coil, it is possible to effectively and efficiently control the electromagnetic field system and the temperature of the coil included in the electromagnetic field system.

Description

{Microrobot driving system including weight current control function and driving method of microrobot through the same}

The present invention relates to a microrobot driving system including a weighted current control function and a method for driving a microrobot through the same, and more particularly, to a coil included in an electromagnetic field system by controlling the temperature of the coil through weighted current control, It relates to an apparatus and method for efficiently managing the temperature of a coil and an electromagnetic field system without a separate cooling device.

Micro-robot surgery, for example, minimally invasive surgery, is a surgical method that can reduce the patient's pain and shorten the recovery period by enabling precise targeting of diseases and minimization of incisions. is in progress

Methods for controlling the movement of micro-robots can be divided into external driving and self driving methods. The self-driving method includes a method of propelling using the pressure of gas generated by a mutual chemical reaction between an external fluid and a microrobot body, a method of using biological propulsion such as movement of bacteria, and the like. However, the self-driving method has limitations in that it is difficult to apply in the human body due to low control freedom, low control precision, and chemical/biological toxicity for driving the microrobot.

The micro-robot driving method using a magnetic field is a representative external driving method with high safety in the human body, and can be classified into a method using a permanent magnet or an electromagnetic driving coil device. In particular, compared to the method using a permanent magnet, the micro-robot control method using an electromagnetic driving coil has a wide range of applications and is the most active due to the advantage that the strength and direction of the magnetic field can be precisely controlled by controlling the current applied to the coil. It is one of the areas in which research is being conducted. In particular, there are many studies that use an external magnetic field to propel microrobots or drive them for treatment. Most studies are conducted on a two-dimensional plane or a study that can simply move a three-dimensional space. In order to control the electromagnetic driving coil device using a magnetic field, the medical device is partially or entirely composed of a magnetic material without a battery or a separate actuator.

The electromagnet-driven medical device can be controlled with a magnetic field generated by applying a current to a coil fixedly arranged outside. In this case, by controlling the intensity and direction of the current applied to each coil, the desired driving of the medical device can be realized. The method using the electromagnet is easier to control than the method using the permanent magnet, and the movement of the medical device can be quickly controlled according to the characteristics of the coil.

However, heat is generated from the electromagnet when the microrobot is controlled using the electromagnet, and as the generated heat is significant, the operating time of the microrobot driving system is limited. Currently, as a method for cooling an electromagnet, a method of cooling the electromagnet using a water cooling type, an air cooling type, a heat pipe and an oil flow is known.

However, electromagnet cooling through water cooling and conventional methods has many considerations such as heat and noise, and the system is complicated and the device is large, so the maintenance cost is high. are greatly affected And, in the case of the heat pipe, an additional liquid cooling device is inevitably required, the weight of the entire system increases, and the magnetic field is attenuated due to the material properties and volume of the heat pipe. In addition, the method of cooling the electromagnet through the oil flow has a disadvantage in that it is necessary to manufacture an additional device for a channel for cooling and a hollow shaft for cooling the rotor.

Against this background, there is a need for a temperature control method that can reduce the size of the microrobot driving system, do not cause attenuation of the magnetic field, and efficiently manage the temperature of the electromagnet.

Republic of Korea Patent No. 10-1830088 US Patent Publication US2015/0188391 A1

Accordingly, the present inventors invented a microrobot driving system capable of controlling the temperature of each coil by weighting it according to the temperature of each coil, and it was confirmed that the temperature control effect thereof was very excellent.

Accordingly, it is an object of the present invention to provide a microrobot driving system that controls the power supply so that a current of a specific value is applied to each coil by weighting according to the temperature of each coil.

Another object of the present invention is to provide a method of driving a microrobot for controlling a power supply unit so that a current of a specific value is applied to each coil by weighting according to the temperature of each coil.

Another object of the present invention is to provide a method of controlling an electromagnetic field system for driving a microrobot that adjusts the temperature of each coil by weighting it according to the temperature of each coil.

The present invention relates to a microrobot driving system including a weighted current control function and a method of driving a microrobot through the same. The coil temperature can be adjusted.

The present inventors have confirmed that the temperature control effect of the coil and electromagnetic field system of the microrobot driving system according to the present invention and the method of driving the microrobot through this is remarkably excellent.

Hereinafter, the present invention will be described in more detail.

One aspect of the present invention includes an electromagnetic field system comprising one or more coils receiving independent current from a power source and applying an electromagnetic field to the microrobot through each of the coils; a temperature sensing unit for measuring a temperature of the electromagnetic field system or the coil; a processing unit for receiving the location information and direction information of the microrobot, receiving temperature information from the temperature sensing unit, and controlling the power supply unit so that a current of a specific value is applied to each of the coils; It is a microrobot driving system that controls the power supply so that a current ( I ) of a specific value is applied to each coil by weighting according to the temperature of each coil.

As used herein, the term “micro-robot” is a type of implantable medical device, a mechanical/electronic micro-robot and a DDS micro-robot including a permanent magnet or an elongated body as a millimeter-scale magnetic material such as a blood vessel robot and an active capsule endoscope. , can be classified into polymer/cell-based microrobots containing magnetic nanoparticles as micro/nano-scale magnetic materials such as micro-scaffolds for cell therapy delivery, nano-robots, and macrophage robots, and others Other types of micro-robots may be included.

The microrobot according to the present invention may further include one or more selected from the group consisting of a camera module, a location information providing unit, a driving unit, a treatment unit, a robot control unit, a data transmitting/receiving unit, and a wireless power receiving unit.

In one embodiment of the present invention, the coil may be one or more types of coils selected from a solenoid coil, a circular coil, a square coil, a Maxwell coil, a Helm-Heltz coil, and a saddle coil.

As used herein, the term “circular coil” may be interpreted as a circular electromagnet, and the circular electromagnet refers to a ring-shaped magnet, that is, an endless magnet that does not show the effect of a demagnetizing force at the end.

In one embodiment of the present invention, one or more temperature sensing units may be included in each coil.

In one embodiment of the present invention, the electromagnetic field system may include a cooling unit for cooling each coil.

In one embodiment of the present invention, the processing unit may derive the current ( I ) of the specific value applied to each of the coils by the following <Equation 1>.

<수식 1>

<Formula 1>

In the above formula,

E is an identity matrix;

D is a required magnetic force matrix and is defined as in Equation 2 below;

<수식 2>

<Formula 2>

(B _d is the desired torque, F _d is the desired magnetic force)

Q ₀ is a weight matrix and is defined as in Equation 3 below;

<수식 3>

<Equation 3>

( W _i is the weight of the i-th coil)

X(P) is a unit magnetic field matrix, which is defined as in Equation 4 below,

<수식 4>

<Formula 4>

는 마이크로로봇의 구동방향에 대한 자화크기이고, V는 마이크로로봇의 자성체 부피임)(B _U (P) is the unit magnetic flux density of each coil at the center point of the region of interest (ROI), and B _Ux (P), B _Uy (P), B _Uz (P) are the x, y, and z axes is the partial derivative of B _U (P) with respect to the direction,

is the magnetization magnitude with respect to the driving direction of the microrobot, and V is the volume of the microrobot's magnetic material)

In the present invention, <Equation 1> is a formula for deriving the required coil current, and it can be derived by configuring the following <Equation 5> in the form of a pseudo-inverse matrix.

<수식 5>

<Formula 5>

Another aspect of the present invention is a method of driving a microrobot, which is driven by a microrobot driving system, comprising the following steps:

A control step of controlling to apply a current of a specific value to each coil of the electromagnetic field system; and a driving step in which each of the coils drives the microrobot through a magnetic field.

The control step may include a first receiving step of receiving temperature information of each coil of the electromagnetic field system; a second receiving step of receiving location information and direction information of the microrobot; a first calculation step of calculating a weight for each coil from the temperature information; a second calculation step of calculating a required torque and a required magnetic force from the position information and the direction information; and calculating a current value to be applied to each coil through the weight, the required torque, and the required magnetic force.

In one embodiment of the present invention, the calculating step calculates the current value ( I ) to be applied to each coil by the following <Equation 1>,

<수식 1>

<Formula 1>

In the above formula,

E is an identity matrix;

D is a required magnetic force matrix and is defined as in Equation 2 below;

<수식 2>

<Formula 2>

(B _d is the desired torque, F _d is the desired magnetic force)

Q ₀ is a weight matrix and is defined as in Equation 3 below;

<수식 3>

<Equation 3>

( W _i is the weight of the i-th coil)

X(P) is a unit magnetic field matrix, which is defined as in Equation 4 below,

<수식 4>

<Formula 4>

는 마이크로로봇의 구동방향에 대한 자화크기이고, V는 마이크로로봇의 자성체 부피임)(B _U (P) is the unit magnetic flux density of each coil at the center point of the region of interest (ROI), and B _Ux (P), B _Uy (P), B _Uz (P) are the x, y, and z axes is the partial derivative of B _U (P) with respect to the direction,

is the magnetization magnitude with respect to the driving direction of the microrobot, and V is the volume of the microrobot's magnetic material)

Another aspect of the present invention is a method for controlling an electromagnetic field system for driving a microrobot, comprising the steps of:

a first receiving step of receiving temperature information of each coil of the electromagnetic field system; a second receiving step of receiving location information and direction information of the microrobot; a first calculation step of calculating a weight for each coil from the temperature information; a second calculation step of calculating a required torque and a required magnetic force from the position information and the direction information; and calculating a current value to be applied to each coil through the weight, the required torque, and the required magnetic force.

Since the method for controlling the electromagnetic field system for driving the microrobot according to the present invention includes the same calculation step as the above-described method for driving the microrobot of the present invention, the overlapping content between the two avoids excessive complexity of the present specification. omit to do

The present invention relates to a microrobot driving system including a weighted current control function and a method of driving a microrobot through the same. By controlling the temperature of the coil, it is possible to effectively and efficiently control the electromagnetic field system and the temperature of the coil included in the electromagnetic field system.

1 is a view showing an operation flow of a microrobot driving system according to an embodiment of the present invention.
2 is a view showing an electromagnetic field system according to an embodiment of the present invention.
3 is a diagram illustrating a process of deriving a magnetic field necessary for driving a microrobot according to an embodiment of the present invention.
4 is a view showing the operation of the processing unit in driving the microrobot according to an embodiment of the present invention, and is a view showing a process of deriving a coil current required for driving the microrobot.
5 is a graph showing an input current to each electromagnet coil when a weighted current control function according to an embodiment of the present invention is not applied.
6 is a graph showing an input current to each electromagnet coil when a weighted current control function according to an embodiment of the present invention is applied.
7 is a graph showing the amount of heat generated by each electromagnet coil when a weighted current control function according to an embodiment of the present invention is not applied.
8 is a graph showing the amount of heat generated by each electromagnet coil when a weighted current control function according to an embodiment of the present invention is applied.

The above-described objects, features and advantages will become more clear through the detailed description to be described later with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains to easily implement the technical idea of the present invention You can do it. In addition, in the description of the present invention, if it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

Throughout the specification, when a part is said to "comprising or including" a certain component, it does not exclude other components unless otherwise stated, meaning that other components may be further included. do. In addition, the term “…unit” described in the specification means a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software. Furthermore, "a or an", "one", and like related terms in the context of describing the present invention are used in both the singular and the plural unless otherwise indicated herein or otherwise clearly contradicted by the context. It can be used in the meaning of including.

In addition, when a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but other components may exist in between. It should be understood that there is On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Other expressions describing the relationship between elements, such as "between" and "immediately between" or "neighboring to" and "directly adjacent to", etc., should be interpreted similarly.

1 is a view showing an operation flow of a microrobot driving system according to an embodiment of the present invention.

Referring to FIG. 1 , a microrobot driving system according to an embodiment includes a processing unit 100 , a power supply unit 200 , an electromagnetic field system 300 , a microrobot 400 , a temperature sensing unit 500 , and a location information system 600 . ) may be included.

The electromagnetic field system 300 may include one or more coils, and each coil may receive current independently from the power supply unit 200 .

The coil may be one or more types of coils selected from a solenoid coil, a circular coil, a square coil, a Maxwell coil, a Helmheltz coil, and a saddle coil.

The electromagnetic field system 300 may generate a magnetic field for driving the microrobot 400 .

The microrobot 400 may include a magnetic material, and thus may be moved to a position desired by the user by the magnetic field generated by the electromagnetic field system 300 .

The location information system 600 may be included in the micro-robot 400, or is disposed outside the micro-robot to measure the location and direction of the micro-robot 400, and generate location information and direction information to the processing unit 100 can be sent to

The temperature sensing unit 500 may measure the temperature of the electromagnetic field system 300 or a coil included in the electromagnetic field system, and may generate temperature information and transmit it to the processing unit. For example, one or more temperature sensing units 500 may be included in each coil, but the present invention is not limited thereto.

The processing unit 100 may receive temperature information from the temperature sensing unit 500 , and may receive position information and direction information of the microrobot 400 from the location information system 600 .

2 is a view showing an electromagnetic field system according to an embodiment of the present invention.

Referring to FIG. 2 , an electromagnetic field capable of generating a magnetic field by an electromagnet current may include an electromagnet coil composed of a plurality of coils.

Electromagnet coils include a number of coils, namely, a Maxwell coil (MC _y1 , MC _y2 , MCz ₁ , MC _z2 ), a Helmholtz coil (HC _y1 , HC _y2 ) and a Rectangular coil (RC). _{xz_L1} , RC _{xz_L2} , RC _{xz_R1} , RC _{xz_r2} ).

The Maxwellian coil pairs (MC _y1 , MC _y2 , MCz ₁ , MC _z2 ) may be disposed with a distance of √3 times (√3R) of the radius of each Maxwellian coil.

The Helmholtz coil pairs HC _y1 and HC _y2 may be arranged to form a pair by being spaced apart by a distance of a radius of each Helmholtz coil.

The square coil (RC _{xz_L1} , RC _{xz_L2} , RC _{xz_R1} , RC _{xz_r2} ) is as shown in FIG. 2 , and the square coil pair is arranged at an angle of 45 degrees with respect to the Maxwellian coil pair (MCz ₁ , MC _z2 ), when viewed from the front It may be arranged to form a square.

In particular, each coil pair constituting the electromagnet coil may be installed to generate a uniform magnetic field and a gradient magnetic field in each axis in order to move the microrobot in a space with three degrees of freedom.

In addition, in the present invention, ten coils are arranged to form an electromagnet coil, but the arrangement method and the number of coils may be variously changed depending on the applied system.

3 is a view showing a process of deriving a magnetic field necessary for driving a microrobot according to an embodiment of the present invention, and FIG. 4 is a view showing the operation of the processing unit in driving the microrobot according to an embodiment of the present invention, It is a diagram showing a process of deriving a coil current required for driving a microrobot.

Referring to FIG. 3, as shown in Equation 5 below, the current ( I ) input to the electromagnetic field system is multiplied by the unit magnetic field matrix (X(P)) at the center point of the region of interest (ROI). It is possible to calculate the magnetic field for driving the robot.

<수식 5>

<Formula 5>

In Equation 5, B _d is the desired torque, and F _d is the desired magnetic force.

는 마이크로로봇의 구동방향에 대한 자화크기이고, V는 마이크로로봇의 자성체 부피이다.In Equation 5, B _U (P) is the unit magnetic flux density of each coil at the center point of the region of interest, and B _Ux (P), B _Uy (P), B _Uz (P) are B _U in the x, y, and z-axis directions. is the partial derivative of (P),

is the magnetization magnitude with respect to the driving direction of the microrobot, and V is the volume of the microrobot's magnetic material.

And, as shown in Fig. 4, the required coil current (Desired current, I ) can be derived by configuring the equation in <Equation 5> in the form of a pseudo-inverse matrix, and the relation for the derived coil current is the following <Equation 1> is the same as

<수식 1>

<Formula 1>

Here, E is an identity matrix.

And, D is a required magnetic force matrix and is defined as in <Equation 2>, in <Equation 2>, B _d is a desired torque and F _d is a desired magnetic force.

<수식 2>

<Formula 2>

Q ₀ is a weight matrix and is defined as in Equation 3 below, where W _i is the weight of the i-th coil.

<수식 3>

<Equation 3>

X(P) is a unit magnetic field matrix, which can be derived from <Equation 5>, and is defined as <Equation 4> below.

<수식 4>

<Formula 4>

Therefore, referring to FIG. 4 , the processing unit receives the temperature information from the temperature sensing unit, sets the current weight ( W _i ) based on the temperature information, and the electromagnetic field system receives the temperature information from the temperature sensing unit, and the magnetic force required for driving the microrobot through the location information system ( Bd, Fd) can be received and the calculation of the coil current ( I ) can be performed.

At this time, the weight Wi is always a positive value, and has the same number as the number of electromagnet coils. The weight Wi is configured in the form of a diagonal matrix in the weight matrix Q ₀ as shown in Equation 3 above. In addition, the weighting matrix (Q ₀ ) increases the weight ( Wi ) for a specific coil having a high temperature ( Wi > 1 ) so that the power supply unit can control the current to supply an optimal current to the corresponding coil.

Therefore, the processing unit can control the temperature by lowering the heating value of the coil expected to overheat or overheat the electromagnet, and according to the above process, the microrobot driving system according to the present invention generates a desired magnetic field and weights the temperature of the electromagnet coil It can be controlled by regulating.

Example 1: Confirmation of temperature control effect according to weighted current control

The experiment shows the arrangement of Maxwell coils (MCy1, MCy2, MCz1, MCz2), Helmholtz coils (HCy1, HCy2) and Rectangular coils (RCxz_L1, RCxz_L2, RCxz_R1, RCxz_r2) of FIG. It was carried out using a conventional electromagnetic field system.

At this time, the control group input the required magnetic field in the z-axis direction to the processing unit (required torque (Bd) 0.01T, required magnetic force (Fd) 0.1T/m), and the required current ( I in each coil) through the following <Equation 5> ), the calorific value was measured for 10 seconds.

<수식 5>

<Formula 5>

And, the required current in each coil is shown in Tables 1 and 5, and the amount of heat generated by each coil for 10 seconds is shown in Tables 3 and 7.

On the other hand, the experimental group input the required magnetic field in the z-axis direction in the same way as the control group (required torque (Bd) 0.01T, required magnetic force (Fd) 0.1T/m), and using the current value induced through <Equation 5>, Calculate the amount of heat generated in each coil, set a weight of 2.5 to the electromagnet coil with the highest heat output and a weight of 1 to the remaining coils, and then derive the required current ( I ) to which the weighting matrix is applied based on the following <Equation 1> did.

<수식 1>

<Formula 1>

After that, the amount of heat generated in each coil for 10 seconds was calculated. At this time, the required current in each coil is shown in Tables 2 and 6, and the amount of heat generated in each coil for 10 seconds is shown in Tables 4 and 8. .

HC _y1 HC _y2 RC _xz-R1 RC _xz-R2 RC _xz-L1 RC _xz-L2 MC _z1 MC _z2 mc _y1 mc _y2 Input current [A] -2.14 2.14 1.62 0.88 1.62 0.88 13.89 -4.46 1.49 -1.49

HC _y1 HC _y2 RC _xz-R1 RC _xz-R2 RC _xz-L1 RC _xz-L2 MC _z1 MC _z2 mc _y1 mc _y2 Input current [A] -7.27 7.27 8.05 5.55 8.05 5.55 9.11 -5.56 5.08 -5.08

time (sec) Heat output per coil (kJ) HC _y1 HC _y2 RC _xz-R1 RC _xz-R2 RC _xz-L1 RC _xz-L2 MC _z1 MC _z2 mc _y1 mc _y2 One 18.25 18.25 10.45 3.11 10.45 3.11 772.12 79.67 8.90 8.90 2 36.51 36.51 20.89 6.22 20.89 6.22 1544.23 159.34 17.80 17.80 3 54.76 54.76 31.34 9.33 31.34 9.33 2316.35 239.02 26.69 26.69 4 73.02 73.02 41.79 12.44 41.79 12.44 3088.46 318.69 35.59 35.59 5 91.27 91.27 52.23 15.55 52.23 15.55 3860.58 398.36 44.49 44.49 6 109.52 109.52 62.68 18.66 62.68 18.66 4632.69 478.03 53.39 53.39 7 127.78 127.78 73.12 21.77 73.12 21.77 5404.81 557.70 62.28 62.28 8 146.03 146.03 83.57 24.88 83.57 24.88 6176.92 637.38 71.18 71.18 9 164.29 164.29 94.02 27.99 94.02 27.99 6949.04 717.05 80.08 80.08 10 182.54 182.54 104.46 31.10 104.46 31.10 7721.15 796.72 88.98 88.98

time (sec) Heat output per coil (kJ) HC _y1 HC _y2 RC _xz-R1 RC _xz-R2 RC _xz-L1 RC _xz-L2 MC _z1 MC _z2 mc _y1 mc _y2 One 211.36 211.36 259.19 123.26 259.19 123.26 331.61 123.49 103.03 103.03 2 422.72 422.72 518.38 246.53 518.38 246.53 663.22 246.97 206.05 206.05 3 634.08 634.08 777.58 369.79 777.58 369.79 994.83 370.46 309.08 309.08 4 845.44 845.44 1036.77 493.05 1036.77 493.05 1326.44 493.94 412.11 412.11 5 1056.80 1056.80 1295.96 616.32 1295.96 616.32 1658.04 617.43 515.13 515.13 6 1268.16 1268.16 1555.15 739.58 1555.15 739.58 1989.65 740.91 618.16 618.16 7 1479.52 1479.52 1814.34 862.85 1814.34 862.85 2321.26 864.40 721.19 721.19 8 1690.88 1690.88 2073.54 986.11 2073.54 986.11 2652.87 987.88 824.21 824.21 9 1902.24 1902.24 2332.73 1109.37 2332.73 1109.37 2984.48 1111.37 927.24 927.24 10 2113.60 2113.60 2591.92 1232.64 2591.92 1232.64 3316.09 1234.85 1030.27 1030.27

As can be seen from the experimental results, as can be seen in FIG. 5 , when the weighted current control was not applied, a high input current of 13A or more was applied to the MC _z1 coil, and as can be seen in FIG. 7 , the temperature of the MC _z1 coil also changed over time. It was found that the temperature increased significantly.

On the other hand, when weighted current control is applied, as can be seen in FIG. 6 , as the weight is given to the MC _z1 coil, the input current of the MC _z1 coil was applied to 10A or less, and the temperature of the MC _z1 coil also decreased relatively significantly. Confirmed.

Claims (8)

an electromagnetic field system including one or more coils receiving an independent current from a power source and applying an electromagnetic field to the microrobot through each of the coils;
a temperature sensing unit for measuring a temperature of the electromagnetic field system or the coil;
a processing unit for receiving position information and direction information of the microrobot, receiving temperature information from the temperature sensing unit, and controlling the power supply unit so that a current of a specific value is applied to each of the coils;
including,
The processing unit controls the power supply unit so that a current ( I ) of a specific value is applied to each of the coils by weighting them according to the temperature of each coil,
microrobot drive system. According to claim 1, wherein the processing unit derives the current ( I ) of the specific value applied to each of the coils by the following <Equation 1>,

<Formula 1>
In the above formula,
E is an identity matrix;
D is a required magnetic force matrix and is defined as in Equation 2 below;

<Formula 2>
(B _d is the desired torque, F _d is the desired magnetic force)
Q ₀ is a weight matrix and is defined as in Equation 3 below;

<Equation 3>
( W _i is the weight of the i-th coil)
X(P) is a unit magnetic field matrix, which is defined as in Equation 4 below,

<Formula 4>
(B _U (P) is the unit magnetic flux density of each coil at the center point of the region of interest (ROI), and B _Ux (P), B _Uy (P), B _Uz (P) are the x, y, and z axes is the partial derivative of B _U (P) with respect to the direction,

is the magnetization magnitude with respect to the driving direction of the microrobot, and V is the volume of the microrobot's magnetic material)
microrobot drive system. The microrobot driving system according to claim 1, wherein the coil is one or more types of coils selected from a solenoid coil, a circular coil, a square coil, and a saddle coil. The microrobot driving system according to claim 1, wherein at least one temperature sensing unit is included in each of the coils. delete delete delete delete

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