KR102495396B1 - Medical multi-dof robot - Google Patents

Abstract

A medical multi-degree-of-freedom robot according to an embodiment includes a first link arm having a first front end and a first rear end; a first actuator installed on the first front end to rotate the first front end about a first rotation axis; a second link arm having a second front end and a second rear end; a second actuator installed at the first rear end to rotate the second front end about a second rotation axis; and a stimulation unit connected to the second rear end, wherein the stimulation unit includes: a linear movement device connected to the second rear end; A posture control device connected to the linear movement device to provide two or more degrees of freedom; and a magnetic stimulator connected to the posture control device.

Description

Medical multi-degree-of-freedom robot {MEDICAL MULTI-DOF ROBOT}

The present invention relates to a medical multi-degree-of-freedom robot capable of providing six-degree-of-freedom movement to a magnetic stimulator.

The brain is an organ located inside the head and is the highest central organ of the nervous system. The brain is divided into cerebrum, cerebellum, midbrain, mesencephalon, pons, and medulla, and generates brainwaves. EEG, also called electroencephalography (EEG), refers to the flow of electricity generated when signals are transmitted from the nervous system to cranial nerves. EEG appears differently when the brain processes various information and is the most important index for measuring the activity of the brain.

Applying electrical stimulation to the brain can treat or alleviate neurological symptoms such as hand tremor. Methods of applying electrical stimulation to the brain include an invasive brain electrical stimulation method and a non-invasive brain electrical stimulation method. The invasive brain electrical stimulation method is a method of surgically inserting electrodes into the brain and applying electrical signals to the electrodes. In contrast, the non-invasive brain electrical stimulation method is a method in which electrodes are attached to the scalp and then electrical signals are applied to the electrodes. The non-invasive brain electrical stimulation method has the advantage of lower cost and risk compared to the invasive brain electrical stimulation method. Accordingly, research and development on an electrical stimulation device capable of applying electrical stimulation to the brain in a non-invasive manner has been conducted.

Non-invasive brain stimulation is in the limelight in terms of treatment of various neuro/psychiatric diseases, and typical technologies include transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and transcranial ultrasound stimulation (TUS). there is. In fact, treatment cases such as dementia, epilepsy, and depression have been reported by stimulating specific parts of the patient's brain.

Most of the non-invasive stimulation brain stimulation methods use a method of adjusting the position and angle of the stimulation by human hands, making it difficult to accurately apply the stimulation to the desired location, which has a disadvantage in that the reproducibility of the stimulation effect is poor. Therefore, despite its high expected performance, it has not yet been widely used.

In order to overcome these problems, efforts have been made to increase the accuracy of brain stimulation using robots. For example, in studies using ① existing 6-DOF serial robot arm, ② serial spherical mechanism, and ③ 6-DOF parallel mechanism, brain stimulation performance could be greatly improved through precise stimulation. However, serial type robots have a problem in that safety is low and a large impact can be applied to a person's head if control fails. It may be possible, but there is a problem in that the size of the equipment increases and expensive manufacturing costs are required.

Therefore, it is required to develop a brain stimulation device that secures high safety and has high accuracy (that is, can smoothly compensate for the patient's motion), and can perform accurate and repetitive stimulation with low-cost and simple installation and operation. equipment needs to be developed.

A medical multi-degree-of-freedom robot according to an embodiment of the present invention includes a first link arm having a first front end and a first rear end; a first actuator installed on the first front end to rotate the first front end about a first rotation axis; a second link arm having a second front end and a second rear end; a second actuator installed at the first rear end to rotate the second front end about a second rotation axis; and a stimulation unit connected to the second rear end, wherein the stimulation unit includes: a linear movement device connected to the second rear end; a posture control device connected to the linear movement device to provide two or more degrees of freedom; and a magnetic stimulator connected to the posture control device.

According to one embodiment, the posture control device may include a third link arm installed in a linear movement device and having a third front end and a third rear end; a fourth link arm having a fourth front end and a fourth rear end; a third actuator installed at the third rear end to rotate the fourth front end about a third rotation axis; a fifth link arm having a fifth front end and a fifth rear end; a fourth actuator installed at the fourth rear end to rotate the fifth front end about a fourth rotational axis perpendicular to the third rotational axis; a sixth link arm having a sixth front end and a sixth rear end; and a fifth actuator installed at the fifth rear end to rotate the sixth front end about a fifth rotational axis perpendicular to the third and fourth rotational axes, and a magnetic stimulator may be connected to the sixth rear end.

According to one embodiment, a torsion spring may be installed between the first actuator and the first front end and between the second actuator and the second front end, respectively.

According to one embodiment, a stand installed on the ground; And a height adjustment unit installed on the top of the stand and connected to the first actuator, wherein the height adjustment unit adjusts the height of the first actuator so that the intersection point of the first and second rotation axes coincides with the center of the head of the pizza pole. there is.

According to one embodiment, the stimulation unit may include a torque sensor installed at the sixth rear end; and a moving platform connected to the torque sensor.

According to one embodiment, the first actuator includes a first motor and a first reducer, the second actuator includes a second motor and a second reducer, and the first and second reducers may each be configured as a harmonic drive. there is.

According to one embodiment, the first actuator may further include a first brake to prevent free rotation of the first link arm, and the second actuator may further include a second brake to prevent free rotation of the second link arm. there is.

According to one embodiment, the distance between the first link arm and the center of the head of the pizza pole may be longer than the distance between the second link arm and the center of the head.

According to one embodiment, the extension lines of the third to fifth rotation shafts may be configured to intersect at one intersection point.

According to one embodiment, the intersection point may be configured to move along a linear axis of the linear movement device when the third link arm moves.

According to one embodiment, the first and second link arms are each configured as a spherical frame to enclose the head of a pizza stimulator, and the magnetic stimulator may be a non-invasive brain stimulator.

According to one embodiment, the posture adjusting device may be configured to control the posture of the magnetic stimulator by adjusting roll, pitch, and yaw angles of the magnetic stimulator.

A control method for a medical multi-degree-of-freedom robot according to an embodiment of the present invention, comprising: setting a position and direction of a stimulation focus for an angiostimulator; Calculating input values of the first to fifth actuators and the linear movement device by performing inverse kinematic analysis; moving first and second link arms according to input values; fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to input values; and fixing the stimulation focus by moving the third link arm according to the input value.

According to an embodiment, a step of calibrating the stimulation focus and the contact force by moving the third link arm may be further included.

According to one embodiment, the method further comprises changing a stimulation focus, wherein changing the stimulation focus comprises: resetting to a position and orientation of another stimulation focus; calculating secondary input values of the first to fifth actuators and the linear movement device by performing inverse kinematic analysis according to the reset stimulus focus; moving the first to sixth link arms to initial positions; moving the first and second link arms according to the secondary input value; fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to the secondary input value; and fixing the stimulation focus by moving the third link arm according to the second input value.

Since the medical multi-degree-of-freedom robot according to an embodiment of the present invention has two spherical arms, it is possible to secure a wider work area than existing devices based on a specific effective work area corresponding to the vicinity of a human head, The potential collision between the human head and the robot is minimized, maximizing the safety of the pizza stimulator.

In addition, since the medical multi-degree-of-freedom robot can stimulate the brain at a desired position and angle, it can enable safe and precise brain stimulation. In addition, since equipment can be manufactured at low cost, the equipment penetration rate can be increased, and the effect of brain stimulation treatment can be maximized by designing the device to enable self-treatment, and the reliability of related research can be greatly improved.

1 is a perspective view showing a multi-degree-of-freedom medical robot according to an embodiment of the present invention.
2 is a perspective view showing a driving part of a multi-degree-of-freedom medical robot according to an embodiment of the present invention.
Figure 3a is a perspective view showing the stimulation unit in Figure 2;
FIG. 3B is a perspective view of the stimulation unit shown in FIG. 2 viewed from a direction different from that of FIG. 2 .
FIG. 4 is a view showing a rotational movable range of the first rotary joint shown in FIG. 2 .
FIG. 5 is a view showing a rotational movable range of the second rotary joint shown in FIG. 2 .
FIG. 6 is a diagram showing a linear movable range of the linear joint shown in FIG. 2 .
7 is a view for explaining an embodiment in which a torque sensor is installed in the stimulation unit shown in FIG. 2;
FIG. 8 is a view showing the operation of the linear movement device shown in FIG. 2 .
9 is a view showing an operation of the posture control device shown in FIG. 2 .
FIG. 10 is a view showing a state in which a 'T' shape is applied to the link arm shown in FIG. 2 .
11 is a view for explaining the operation of the first rotary joint shown in FIG. 2;
FIG. 12 is a view for explaining the operation of the second rotary joint shown in FIG. 2;
FIG. 13 is a diagram for explaining the operation of the stimulation unit shown in FIG. 2 .
14 is a diagram for explaining the movable range of the medical multi-degree-of-freedom robot.
15 is a flowchart illustrating a control method of a medical multi-degree-of-freedom robot according to an embodiment of the present invention.
FIG. 16 is a flowchart illustrating the steps of changing the stimulus focus shown in FIG. 15 .
17 is a diagram for explaining inverse kinematics analysis.
18 is a block diagram for explaining the control and compensation process of the multi-degree-of-freedom medical robot.

Embodiments of the present invention are presented by way of example to explain the technical idea of the present invention. The scope of rights according to the present invention is not limited to the following embodiments or specific descriptions of these embodiments.

1 is a perspective view showing a medical multi-degree-of-freedom robot 1 according to an embodiment of the present invention.

The medical multi-degree-of-freedom robot 1 has a serial mechanism structure in which a linear joint and a rotary joint with two or more degrees of freedom are additionally attached to a main link part having a spherical frame, and the overall size can be minimized.

The multi-DOF medical robot 1 is driven with a total of 6 degrees of freedom, and may be composed of one 2-DOF spherical frame, a linear actuator connected thereto, and an orientation mechanism module with 2 or more DOFs. The direction conversion modules with more than 2 degrees of freedom are each connected at right angles and can be connected to the moving platform while inducing only the direction change at the end. A stimulator for brain stimulation may be attached to the moving platform.

The medical multi-degree-of-freedom robot 1 may include a stand 10, a first rotary joint 100, a second rotary joint 200, and a stimulation unit 300. The first rotary joint 100 may include a first actuator 130 that rotates the first link arm 120 about the first link arm 120 and the first rotation axis 110 . The second rotary joint 200 may include a second actuator 230 that rotates the second link arm 220 about the first link arm 220 and the second rotation shaft 210 . The stimulation unit 300 may include a linear joint having a linear movement axis 315 and third to fifth rotational joints, details of which will be described later.

An angle between the extension line of the first rotation axis 110 and the extension line of the second rotation axis 120 may be approximately 50°. Also, an angle formed by an extension of the second rotation axis 120 and an extension of the linear movement axis 315 may be approximately 65°.

The stand 10 may be installed on the ground and may be composed of a lower part 11 and an upper part 12. A height adjustment unit 13 may be installed on the upper part 12 . A rail 14 may be formed on the upper part 12 , and an actuator 15 may be installed on the upper end of the rail 14 . The frame 16 may be installed on the rail 14 and moved up and down along the rail 14 by the actuator 15 . The first actuator 130 may be installed on the frame 16 .

The height adjustment unit 13 moves the first actuator 130 so that the intersection point P ₁ of the first and second rotational axes 110 and 210 is at the center of the head of the pizza pole stimulated by the stimulation unit 300. It is possible to adjust the height of the first rotary joint 100 to match.

In this way, the height adjustment unit 13 can make it possible to position the rotational center of the positioning device at the center of the head of the pizza stimulator by providing one degree of freedom between the ground and the device.

2 is a perspective view showing a driving part of a medical multi-degree-of-freedom robot 1 according to an embodiment of the present invention.

In the first rotary joint 100 , the first link arm 120 may have a first front end 121 and a first rear end 122 . The first actuator 130 may be installed on the first front end 121 to rotate the first front end 121 around the first rotational shaft 110 .

In the second rotary joint 200 , the second link arm 220 may have a second front end 221 and a second rear end 222 . The second actuator 230 may be installed on the first rear end 122 to rotate the second front end 221 around the second rotation shaft 210 . The stimulation unit 300 may be connected to the second rear end 222 .

The stimulation unit 300 includes a linear movement device 310 connected to the second rear end 222, a posture control device 400 connected to the linear movement device 310 and providing two or more degrees of freedom, and a posture control device. It may include a magnetic stimulator 500 connected to (400).

The linear movement device 310 is driven by being connected to a ball screw to adjust the depth of focus of the stimulator, and may include a rotation conversion module actuator with two or more degrees of freedom, a reducer, and a sensor for position feedback of the driving module.

The linear movement device 310 may include a linear frame 311 , an actuator 312 , and a third link arm 313 . The third link arm 313 may be installed on the linear frame 311 and moved along the longitudinal direction of the linear frame 311 by the actuator 312 .

The linear joint 301 may include a linear movement device 310 and a third link arm 313 . The third rotation joint 401 may include a third actuator 420 and a fourth link arm 410 . The fourth rotation joint 402 may include a fourth actuator 440 and a fifth link arm 430 . The fifth rotation joint 403 may include a fifth actuator 460 and a sixth link arm 450 .

The linear movement device 310 may include a rail 311 , an actuator 312 , and a third link arm 313 . The third link arm 313 may linearly move along the rail 311 by the actuator 312 .

A first torsion spring 140 is installed between the first actuator 130 and the first front end 121 of the first link arm 120, and between the second actuator 230 and the second link arm 220 A second torsion spring 240 may be installed between the second front ends 211 . Since the first and second torsion springs 140 and 240 are provided in this way, even if the magnetic stimulator 500 collides with the anatomical pole, the torsion spring can absorb this impact, thereby reducing the shock applied to the polaroid pole can be minimized.

In this way, by attaching a torsion spring having high rigidity between each drive joint and the frame, physical damage applied to the test subject when the head of the test subject collides with the robot arm can be minimized.

The first actuator 130 may include a first motor 131 and a first reducer 133 , and the second actuator 230 may include a second motor 231 and a second reducer 233 . In addition, each of the first and second reducers 133 and 233 may be configured as a harmonic drive. The reduction ratio of the harmonic drive is about 100:1, so that high torque can be finally transmitted to the link arm.

The first actuator 130 further includes a first brake 132 disposed on the first motor 131 and the first reducer 133 and preventing the free rotation of the first link arm 120, and the second actuator 230 may further include a second brake 232 disposed between the second motor 231 and the second reducer 233 and preventing free rotation of the second link arm 220 . Accordingly, even when the power is turned off, the posture of the robot may be maintained without changing.

The first and second link arms 120 and 220 are each composed of a spherical frame so as to surround the head of a pizza stimulator, and the magnetic stimulator 500 may be a non-invasive brain stimulator. In this way, when the stimulator moves around the head of the anatomical exciter using the spherical frame, since the head of the anatomical exciter is excluded from the effective operating range, it has high safety and can have a wide effective operating range.

The distance between the first link arm 120 and the center of the head of the angiostimulator may be longer than the distance between the second link arm 220 and the center of the head. Since the stimulation unit 300 is installed in the second link arm 220 and more detailed manipulation is possible in the stimulation unit 300 itself, the movement of the first link arm 120 is greater than that of the second link arm 220. can provide.

The posture adjusting device 400 may be configured to control the posture of the magnetic stimulator 500 by adjusting a roll, pitch, and yaw angle of the magnetic stimulator 500 .

The multi-degree-of-freedom robot 1 for medical use can have high accuracy by adding a linear joint and a direction conversion joint with two or more degrees of freedom between the stimulator and the spherical frame, so that the depth and direction of the focus of the stimulator can be controlled in detail.

FIG. 3A is a perspective view showing the stimulation unit 300 in FIG. 2 . FIG. 3B is a perspective view showing the stimulation unit 300 shown in FIG. 2 viewed from a direction different from that of FIG. 2 .

The third link arm 313 may have a third front end 314 installed on the rail 311 and a third rear end 315 installed with the third actuator 420 . The fourth link arm 410 may have a fourth front end 411 and a fourth rear end 412, and the third actuator 420 is installed on the third rear end 315 to 411) may be rotated about the third rotation shaft 425.

The fifth link arm 430 may have a fifth front end 431 and a fifth rear end 432, and the fourth actuator 440 is installed at the fourth rear end 412 to provide a fifth front end ( 431 may be rotated around a fourth rotational axis 445 perpendicular to the third rotational axis 425 . The sixth link arm 450 may have a sixth front end 451 and a sixth rear end 452, and the fifth actuator 460 is installed at the fifth rear end 432 to provide a sixth front end ( 451) may be rotated with a fifth rotation shaft 465 perpendicular to the third and fourth rotation shafts 425 and 445. The magnetic stimulator 500 may be connected to the sixth rear end 452 .

Extension lines of the third to fifth rotation shafts 425, 445, and 465 may be configured to intersect at one intersection point P ₂ . The crossing point P ₂ may be configured to move along the linear axis 315 of the linear movement device 310 when the third link arm 313 moves.

The combination of the first and second rotary joints 100 and 200 and the linear joint 310 can efficiently move the spherical surface around the head of the angiostimulator by using a spherical link member, so that high accuracy and driving speed can be secured. there is. In addition, it is possible to work on the entire upper hemisphere area of the pizza stimulator's head. On the other hand, compared to serial robots, safety can be ensured because there is no area passing through the head of the pizza stimulator in the work area of the end-effector of the robot even in case of control failure. Meanwhile, the operation of the 1DOF linear unit may facilitate control of focus and contact force of the stimulator.

Regarding the posture adjusting device 400, it may be easy to control the focal depth and angle of the stimulator through complex driving of the fourth to sixth link arms 410, 430, and 450.

FIG. 4 is a view showing a rotational movable range of the first rotary joint 100 shown in FIG. 2 . FIG. 5 is a view showing a rotational movable range of the second rotary joint 200 shown in FIG. 2 . FIG. 6 is a diagram showing a linear movable range of the linear joint 300 shown in FIG. 2 .

The reference position of the medical multi-degree-of-freedom robot 1 is a state in which the first and second link arms 120 and 220 are aligned so that the stimulation unit 300 is at the highest position from the ground, as shown in FIG. it means.

Each joint of the multi-degree-of-freedom medical robot 1 may have its driving range limited so as to move only the entire upper hemisphere of the head of the pizzastimulator, which is a target workspace.

In one embodiment, as shown in FIG. 5 , in the first rotary joint 100, the first actuator 130 rotates the first link arm 120 between +100° and -100° from the reference position. In the second rotary joint 200, the second actuator 230 may be driven to rotate the second link arm 220 between +100° and -100° from the reference position.

In another embodiment, the driving of the first rotational joint may be limited to rotate between +180° and -180°, and the second rotational joint rotates between 0° and 180°.

In the linear joint 301, the actuator 312 may drive the third frame 313 to linearly move between 0 mm and 15 mm.

Meanwhile, in the third rotary joint 401, the third actuator 420 may drive the fourth link arm 410 to rotate between +90° and -90° from the reference position. In the fourth rotary joint 402, the fourth actuator 440 may drive the fifth link arm 430 to rotate between +90° and -90° from the reference position. In the fifth rotary joint 403, the fifth actuator 460 may drive the sixth link arm 450 to rotate between +90° and -90° from the reference position.

FIG. 7 is a view for explaining an embodiment in which a torque sensor is installed in the stimulation unit 300 shown in FIG. 2 .

The stimulation unit 300 may include a torque sensor 530 installed at the sixth rear end 452 of the sixth link arm 450 . The magnetic stimulator 500 may be connected to the torque sensor 530 . The magnetic stimulator 500 may include a moving platform 510 directly connected to the torque sensor 530 and a magnetic field generator 520 . The moving platform 510 may have a shape surrounding the magnetic field generator 520 .

The torque sensor 530 can sense the generation of 6-axis torque, and can sense the contact force when the magnetic stimulator 500 contacts the head of the pizza stimulator. In addition, when the torque sensor 530 detects a contact force equal to or greater than the reference force, the linear movement device 310 may be operated to move the magnetic stimulator 500 immediately away from the head of the pizza stimulator.

In this way, the use of the torque sensor 530 not only increases the safety of the pizza stimulator, but also makes it possible to sense the contact force, so that when stimulating the target object, it is possible to stimulate with an appropriate amount of force.

FIG. 8 is a view showing the operation of the linear movement device 310 shown in FIG. 2 . FIG. 9 is a view showing the operation of the posture adjusting device 400 shown in FIG. 2 .

8(a) shows how the linear movement device 310 operates, and FIGS. 8(b) and 8(c) show how the fifth rotary joint 403 operates. 9(a), (b), (c), and (d) show how the magnetic stimulator 500 moves while the third to fifth rotary joints 401, 402, and 403 operate. In this way, the depth and direction of the stimulation focus can be adjusted by adjusting the posture of the magnetic stimulator 500 .

FIG. 10 is a view showing a state in which a 'T' shape is applied to the link arm shown in FIG. 2 .

Since each of the first and second link arms 120 and 220 must withstand the high load of the magnetic pole unit 300, they may be configured as arms having a 'T'-shaped cross section. When the arm has a 'T'-shaped cross section, the moment of inertia is increased compared to an arm having a general rectangular cross section, thereby reducing the possibility of occurrence of deformation due to a high load.

FIG. 11 is a view for explaining the operation of the first rotary joint 100 shown in FIG. 2 . FIG. 12 is a view for explaining the operation of the second rotary joint 200 shown in FIG. 2 . FIG. 13 is a diagram for explaining the operation of the stimulation unit 300 shown in FIG. 2 . 14 is a diagram for explaining the movable range of the multi-degree-of-freedom robot 1 for medical use. For convenience of description, the drawings shown in FIGS. 1 to 3 are briefly expressed.

Referring to FIG. 11 , it is possible to check which area can be covered from the head of a pizza pole by the operation of the first rotational joint 100 . Referring to FIG. 12 , it is possible to check what area can be covered from the head of the angiostimulator beyond the movable range of the first rotation joint 100 by the operation of the second rotation joint 200 . Referring to FIG. 13 , a process of adjusting the posture of the magnetic stimulator 500 through the operation of the linear joint 301 and the third to fifth rotary joints 401 , 402 , and 403 can be confirmed.

As shown in FIG. 14, the medical multi-degree-of-freedom robot 1 can provide the magnetic stimulator 500 with a movement of 5 degrees of freedom to 6 degrees of freedom, and the target workspace is the upper hemisphere of the head of the pizza stimulator. It can cover the entire area.

15 is a flowchart illustrating a control method (S1000) of the medical multi-degree-of-freedom robot 1 according to an embodiment of the present invention.

The medical multi-degree-of-freedom robot 1 may operate in the following order.

(1) Preparation stage

- Fixed base for device assembly and use

- By using the linear actuator additionally attached to the base end, the distance value between the center of the head of the subject and the center of the sphere of the spherical frame is set to 0.

(2) Stimulation site input step

Information on the stimulation site of the pizza stimulator prescribed by the expert is input into the device.

(3) Input stage such as stimulation time and stimulation intensity

Designate the desired stimulation intensity and time.

(4) stimulation phase

- By driving a low-speed, high-output spherical frame that is responsible for large movements, the stimulator is moved to the vicinity of the working area.

- Move the stimulator to the desired brain stimulation position and angle by simultaneously driving 5 or more actuators for the posture obtained through inverse kinematics analysis.

- The stimulator is operated and brain stimulation is performed as much as the designated stimulation amount.

Next, with reference to FIG. 15, it demonstrates.

The control method of the multi-degree-of-freedom robot for medical use (S1000) includes setting the position and direction of the stimulation focus for the angiostimulator (S1100), performing inverse kinematic analysis to determine the first to fifth actuators and the linear Calculating an input value of the moving device (S1200), moving the first and second link arms according to the input value (S1300); The steps of fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to an input value (S1400), and fixing the stimulation focus by moving the third link arm according to an input value (S1500). can In addition, the control method ( S1000 ) may further include a step ( S1600 ) of calibrating the stimulation focus and the contact force by moving the third link arm. Also, the control method ( S1000 ) may further include a step ( S1700 ) of changing a stimulus focus.

In step S1100, in detail, a total of 6 degrees of freedom of position (x, y, z values) and direction (roll, pitch, yaw values) can be set.

FIG. 16 is a flowchart illustrating the step of changing the stimulus focus shown in FIG. 15 (S1700).

The step of changing the stimulation focus (S1700) is the step of resetting the position and direction of another stimulation focus (S1710), and inverse kinematic analysis is performed according to the reset stimulation focus to determine the first to fifth actuators and the linear motion. Calculating the secondary input value of the moving device (S1720), moving the first to sixth link arms to initial positions (S1730), moving the first and second link arms according to the secondary input values (S1740), fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to the secondary input value (S1750), and fixing the stimulation focus by moving the third link arm according to the secondary input value It may include a step (S1760). Meanwhile, the changing (S1700) may further include a step (S1770) of calibrating the stimulation focus and the contact force by moving the third link arm.

After that, if it is desired to further change the stimulation focus, the step of changing the stimulation focus based on the location and direction of another focus (S1700) may be performed again.

17 is a diagram for explaining inverse kinematics analysis.

As shown in FIG. 17, basic coordinates and movement coordinates O (x, y, z) and P (u, v, w) are assigned to the ground and the magnetic stimulator 500, respectively. For inverse kinematics analysis, two vector loops are used in kinematics. The first vector loop through points O, P, and Q is a transformation (T ₁ ) containing information related to the desired posture. The second vector loop is the translation from the origin (O) to the point Q (T ₂ ) via the actuator. Given the position vector of the exciter (P=[P _x P _Y P _z ] ^T ) and the rotation matrix R _p , the transformation matrix T ₁ is obtained as follows.

Equation (1):

Here, D _P is a transformation matrix from the origin to point P, and D (axis, value) is a transformation matrix that transforms along a specific axis. Then, the transformation matrix transformation (T ₂ ) composed of the input value (θ _i ) of the rotary joint and the input value (d) of the linear actuator can be expressed as follows.

Equation (2):

where R(axis, value) is a transformation matrix that rotates along a specific axis. In Equations (1) and (2), r _d and r _s are the distances between point O and the initial position of the prismatic joint and between the point Q and the stimulus focus (P), respectively, and α and β are spherical It is the design angle of the frame (ie, the first and second link arms). Since each component of T ₁ and T ₂ must be the same, the desired value (θ _i , d) of each joint is derived as follows.

Equation (3):

Here, if c is cos and s is sin,

Using the derived input values, the end-effector of the device (i.e., the magnetic stimulator 500) can be positioned in the target position and orientation. At this time, the second revolute joint may be driven in the range of -100°<θ ₂ <100°, and the driving range of the first revolute joint is also set to -100°<θ ₁ <100°. It can be.

However, in order to prevent a singularity, the second revolute joint can be driven in the range of 0°<θ ₂ <180°, and the first revolute joint is also set to -180° <θ ₁ <180°. A driving range can be set.

18 is a block diagram for explaining the control and compensation process of the multi-degree-of-freedom medical robot.

In the following, the robot can be controlled using a position-based visual servoing (PBVS) method to compensate for unexpected human movements. The PBVS technique requires a 3D pose estimation process, but the control method used in the existing Cartesian coordinate system can be used as it is.

The position and orientation errors used for feedback control can be defined as: In Euclidean geometry, the position error (e _p ) is defined using the difference between the desired position (p _d ) and the current working end position (p _e ).

Equation (4):

The rotation matrix R is a matrix that rotates the direction while maintaining the length of an arbitrary vector z as shown in Equation (5), and belongs to a special orthogonal group.

Equation (5):

Unlike Euler angles, the rotation matrix has the advantage of not having a singularity, but it is difficult to adjust the gain. Below we use a rotation matrix to represent the orientation error of the controller.

We define a new orientation error (e ₀ ) expression using a small-angle approximation of the trigonometric function. If the input angle of the trigonometric function is very small, the sine and cosine functions can be approximated and expressed as sinθ=θ and cosθ=1.

14 degrees and 8 degrees, respectively, and the error rate due to approximation is approximately 1%. Therefore, this approximation can be used because it is intended to compensate for slight movement of the subject. Given the desired orientation (R _d ) and the rotation of the working end (R _e ) determined by the measuring system, the orientation error is

Equation (6):

In Equation (6), we applied a small-angle approximation to the rotation matrix using the ZYX Euler angles. Since small angles are assumed, the quadratic and cubic terms can also be assumed to be negligibly small.

)를 구합니다. 이러한 추정을 통해 어느 지점에서도 특이점이 없는 회전 행렬의 장점이며, 방향 오차에 대한 게인을 조정하여 원하는 성능을 얻을 수 있다.Through this, the rotation error can be estimated using the component values of the matrix as they are. After multiplying the estimated error by the gain, the final error (

) is obtained. Through this estimation, it is an advantage of the rotation matrix that there is no singularity at any point, and the desired performance can be obtained by adjusting the gain for the orientation error.

Equation (7):

Since the risk of the experiment increases as the speed of compensation according to the gain value increases, the gain can be set considering the safety and performance of the experiment.

Although the technical spirit of the present invention has been described above, various substitutions, modifications, and changes can be made without departing from the technical spirit and scope of the present invention that can be understood by those skilled in the art. Also, such substitutions, modifications and alterations are within the scope of the appended claims.

1: Multi-degree-of-freedom robot for medical use
10: stand
100, 200, 401, 402, 403: rotary joint
120, 220: link arm
300: stimulation unit
310: linear movement device
400: direction control device
500: magnetic stimulator

Claims (15)

a first link arm having a first front end and a first rear end;
a first actuator installed on the first front end to rotate the first front end about a first rotation axis;
a second link arm having a second front end and a second rear end;
a second actuator installed at the first rear end to rotate the second front end about a second rotation axis; and
And a stimulation unit connected to the second rear end,
The stimulation unit,
a linear movement device connected to the second rear end;
a posture adjusting device connected to the linear movement device to provide two or more degrees of freedom; and
Including a magnetic stimulator connected to the posture control device,
Multi-degree-of-freedom robot for medical use.
According to claim 1,
The posture control device,
a third link arm installed on the linear movement device and having a third front end and a third rear end;
a fourth link arm having a fourth front end and a fourth rear end;
a third actuator installed at the third rear end to rotate the fourth front end about a third rotation axis;
a fifth link arm having a fifth front end and a fifth rear end;
a fourth actuator installed at the fourth rear end to rotate the fifth front end about a fourth rotation axis perpendicular to the third rotation axis;
A sixth link arm having a sixth front end and a sixth rear end; and
A fifth actuator installed at the fifth rear end to rotate the sixth front end to a fifth rotational axis perpendicular to the third and fourth rotational axes,
The magnetic stimulator is connected to the sixth rear end,
Multi-degree-of-freedom robot for medical use.
According to claim 1,
A torsion spring is installed between the first actuator and the first front end and between the second actuator and the second front end, respectively.
Multi-degree-of-freedom robot for medical use.
According to claim 1,
Stand installed on the ground; and
Further comprising a height adjustment unit installed on the top of the stand and connected to the first actuator,
The height adjustment unit adjusts the height of the first actuator so that the intersection point of the first and second rotation axes coincides with the center of the head of the pizza pole.
Multi-degree-of-freedom robot for medical use.
According to claim 2,
The stimulation unit,
a torque sensor installed at the sixth rear end; and
Further comprising a moving platform connected to the torque sensor,
Multi-degree-of-freedom robot for medical use.
According to claim 1,
The first actuator includes a first motor and a first reducer,
The second actuator includes a second motor and a second reducer,
The first and second reducers are each composed of a harmonic drive,
Multi-degree-of-freedom robot for medical use.
According to claim 6,
The first actuator further includes a first brake preventing free rotation of the first link arm,
The second actuator further comprises a second brake preventing free rotation of the second link arm.
Multi-degree-of-freedom robot for medical use.
According to claim 1,
The distance between the first link arm and the center of the head of the pizza pole is longer than the distance between the second link arm and the center of the head,
Multi-degree-of-freedom robot for medical use.
According to claim 2,
The extension lines of the third to fifth rotational axes are configured to intersect at one intersection,
Multi-degree-of-freedom robot for medical use.
According to claim 9,
The crossing point is configured to move along the linear axis of the linear movement device when the third link arm moves,
Multi-degree-of-freedom robot for medical use.
According to claim 1,
The first and second link arms are each composed of a spherical frame to surround the head of the pizza pole,
The magnetic stimulator is a non-invasive brain stimulator,
Multi-degree-of-freedom robot for medical use.
According to claim 1,
The posture control device is configured to control the posture of the magnetic stimulator by adjusting the roll, pitch, and yaw angle of the magnetic stimulator.
Multi-degree-of-freedom robot for medical use.
In the control method of the medical multi-degree-of-freedom robot according to claim 2,
setting the position and direction of the stimulation focus for the pizza stimulator;
Calculating input values of the first to fifth actuators and the linear movement device by performing inverse kinematic analysis;
moving the first and second link arms according to the input value;
fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to the input value; and
And fixing the stimulation focus by moving the third link arm according to the input value.
control method.
According to claim 13,
Further comprising the step of calibrating the stimulation focus and contact force by moving the third link arm.
control method.
According to claim 13,
further comprising the step of changing the stimulation focus;
The step of changing the stimulation focus,
resetting to another stimulation focus location and orientation;
calculating secondary input values of the first to fifth actuators and the linear movement device by performing inverse kinematic analysis according to the reset stimulus focus;
moving the first to sixth link arms to initial positions;
moving the first and second link arms according to the second input value;
fixing the posture of the magnetic stimulator by moving the fourth to sixth link arms according to the second input value; and
And fixing the stimulation focus by moving the third link arm according to the secondary input value.
control method.

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