Slave Device and Control Method Therefor, and Eye Surgery Device and Control Method Therefor

A slave device according to an example embodiment may comprise: a lower shaft; an upper shaft connected to the lower shaft so as to be able to slide with a single degree of freedom; a lower gripper rotatably supporting the lower shaft; an upper gripper rotatably supporting the upper shaft; a lower delta robot movably supporting the lower gripper; and an upper delta robot movably supporting the upper gripper.

TECHNICAL FIELD

The following description relates to a slave device and a control method therefor, and an eye surgery device and a control method therefor.

BACKGROUND ART

A master device and a slave device electrically transmit and receive signals with each other. A user may directly drive the master device, and the slave device may be remotely controlled based on a movement of the master device. For example, the master device and the slave device are used in a surgical field that requires detailed work.

An eye surgery device includes a surgical instrument that penetrates a surface of an eye to be inserted into the eye. There is a need for a technique that does not damage the surface of the eye while the surgical instrument is moved. In addition, an internal region of the eye that may be observed through a pupil thereof is limited, and thus, there is an issue that it is difficult to observe the inside of the eye.

DISCLOSURE OF THE INVENTION

Technical Goals

An object of an example embodiment is to provide a slave device and a method of controlling the slave device.

Technical Solutions

According to an aspect, there is provided a lower shaft; an upper shaft slidably connected to the lower shaft in one degree of freedom; a lower gripper configured to rotatably support the lower shaft; an upper gripper configured to rotatably support the upper shaft; a lower delta robot configured to movably support the lower gripper; and an upper delta robot configured to movably support the upper gripper.

The lower shaft may be configured to maintain a position relative to the lower gripper irrespective of a change in a distance between the lower gripper and the upper gripper in an axial direction of the lower shaft.

Each of the lower shaft and the upper shaft may be rotatably supported in two degrees of freedom by the lower gripper and the upper gripper.

Each of the lower delta robot and the upper delta robot may include three support rods; three movement parts, each of the three movement parts configured to move in a longitudinal direction of each of the three support rods; and three arms connecting the three movement parts and a gripper.

Each of the lower delta robot and the upper delta robot may further include three guide rods arranged in parallel with the three support rods and guiding movements of the three movement parts.

The three support rods of the lower delta robot may be in parallel with the three support rods of the upper delta robot.

The three support rods of the lower delta robot may be separated from the three support rods of the upper delta robot.

The slave device may further include a surgical instrument including a surgical tip having a smaller thickness than the lower shaft and a rotation module which is placed at a lower end of the lower shaft and configured to rotate the surgical tip.

A distance between the lower gripper and the upper gripper may be adjusted while the surgical instrument maintains a position separated from the lower gripper in an axial direction of the lower shaft.

According to another aspect, there is provided a method of controlling a slave device including a lower shaft, an upper shaft slidably connected to the lower shaft in one degree of freedom, a lower gripper configured to rotatably support the lower shaft, an upper gripper configured to rotatably support the upper shaft, and a surgical instrument provided at a lower end of the lower shaft, and the method may include determining a remote rotation center of the surgical instrument; receiving a target point of a tip of the surgical instrument; determining a reaching point of the lower gripper for placing the tip of the surgical instrument at the target point based on the remote rotation center and the target point of the tip of the surgical instrument; determining a reaching point of the upper gripper based on the remote rotation center and the reaching point of the lower gripper; and moving the lower gripper to the reaching point of the lower gripper and moving the upper gripper to the reaching point of the upper gripper in a state in which at least one point of the surgical instrument is set to pass through the remote rotation center.

The method of controlling the slave device may further include determining whether the tip of the surgical instrument is able to reach the target point.

The method of controlling the slave device may further include determining whether the tip of the surgical instrument is able to reach the target point based on a size of a surgical operation object.

The method of controlling the slave device may further include calculating a position closest to the target point based on a state in which a distance between the lower gripper and the upper gripper is shortest, if the tip of the surgical instrument is determined to be unable to reach the target point.

In the determining of the reaching point of the upper gripper, the reaching point of the upper gripper may be determined on an imaginary extension line passing through the remote rotation center and the reaching point of the lower gripper.

In the determining of the reaching point of the upper gripper, a point that is in a movable region of the upper gripper and separated by the longest distance from the lower gripper may be determined as the reaching point of the upper gripper.

According to another aspect, there is provided an eye surgery device including a support frame; a first slave device connected to one end of the support frame; a second slave device connected to the other end of the support frame; and a microscope module placed between the first slave device and the second slave device and capable of moving on the support frame.

Each of the first slave device and the second slave device may include a lower shaft; an upper shaft slidably connected to the lower shaft in one degree of freedom; a lower gripper rotatably supporting the lower shaft; an upper gripper rotatably supporting the upper shaft; a lower delta robot movably supporting the lower gripper; an upper delta robot movably supporting the upper gripper; and a surgical instrument provided at a lower end of the lower shaft and capable of penetrating the eye.

Each of the lower delta robot and the upper delta robot may include three support rods; three movement parts that move in a longitudinal direction of the three support rods;

and three arms connecting the three movement parts to the gripper.

The eye surgery device may further include a controller configured to detect a position of a surgical instrument of each of the first slave device and the second slave device and control a position of the microscope module based on the position of the surgical instrument.

According to another aspect, there is provided a method of controlling an eye surgery device including a support frame, a first slave device connected to one end of the support frame and configured to drive a first surgical instrument, a second slave device connected to the other end of the support frame and configured to drive a second surgical instrument, and a microscope module placed between the first slave device and the second slave device, and the method may include receiving rotation amount information of an eye from a master device; setting, on a surface of the eye, an initial remote rotation center of each of the first surgical instrument and the second surgical instrument; calculating a target remote rotation center of each of the first surgical instrument and the second surgical instrument based on the rotation amount information of the eye; and moving the remote rotation center of the first surgical instrument from the initial remote rotation center to the target remote rotation center and moving the remote rotation center of the second surgical instrument from the initial remote rotation center to the target remote rotation center, on the surface of the eye.

The rotation amount information of the eye may include first rotation amount information on a rotation about a first rotation axis passing through a center of the eye, and second rotation amount information on a rotation about a second rotation axis that passes through the center of the eye and is orthogonal to the first rotation axis.

The method of controlling the eye surgery device may further include generating a first movement speed profile required while the first surgical instrument reaches the target remote rotation center from the initial remote rotation center in a state in which a distance between the remote rotation center of the first surgical instrument and the remote rotation center of the second surgical instrument is maintained; and generating a second movement speed profile required while the second surgical instrument reaches the target remote rotation center from the initial remote rotation center in a state in which the distance between the remote rotation center of the first surgical instrument and the remote rotation center of the second surgical instrument is maintained.

The calculating of the target remote rotation center of each of the first surgical instrument and the second surgical instrument may include setting a spherical coordinate system based on a center of the eye; calculating, on the spherical coordinate system, an angular change from the initial remote rotation center of the first surgical instrument to the target remote rotation center the first surgical instrument; and calculating, on the spherical coordinate system, an angular change from the initial remote rotation center of the second surgical instrument to the target remote rotation center of the second surgical instrument.

The method of controlling the eye surgery device may further include moving the microscope based on the rotation amount information of the eye.

The method of controlling the eye surgery device may further include moving the microscope based on a target remote rotation center of each of the first surgical instrument and the second surgical instrument.

Advantageous Effects

A slave device according to an example embodiment may include two delta robots of a three-point support structure arranged in parallel and increases precision by adjusting a distance between upper and lower delta robots or enlarge a work area as needed without changing a position of a surgical instrument.

A slave device according to an example embodiment may receive a desired position of a tip of a surgical instrument received from a master device and drives the surgical instrument while maintaining a remote rotation center, thereby operating the master device intuitively and comfortably without considering the remote rotation center.

According to a method for controlling a slave device of an example embodiment, the slave device may be driven to a remote rotation center based on a movement signal received from a master device, and distances between grippers of upper and lower delta robots may be set as long as possible in order to increase accuracy of the slave device.

According to an eye surgery device and a method for controlling the eye surgery device of an example embodiment, two surgical instruments are moved while maintaining a distance, on a surface of an eye, between portions where the two surgical instruments come into contact with the surface of the eye, and thus, the surface of the eye may not be damaged.

According to an eye surgery device and a method for controlling the eye surgery device of an example embodiment, even when an eye rotates, it is possible to easily observe the inside of the eye by changing a position of a microscope according to a change in a position of a pupil of the eye.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, example embodiments will be described in detail with reference to example drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though the components are illustrated in different drawings. In addition, in describing the example embodiment, when it is determined that detailed descriptions of a related known configuration or function interferes with understanding of the example embodiment, the detailed descriptions thereof are omitted.

In addition, in describing components of the example embodiment, terms such as first, second, A, B, (a), (b), and so on may be used. The terms are only for distinguishing the components from other components, and attributes, an order, or a sequence of the components are not limited by the terms. When it is described that one component is “connected” or “coupled” to the other component, the component may be directly connected or coupled to the other component, but it will be understood that another component may also be “connected” or “coupled” therebetween.

A component included in one example embodiment and a component having a common function will be described by using the same name in other example embodiments. Unless otherwise stated, descriptions made in one example embodiment may be applied to other example embodiments, and redundant descriptions thereof are omitted.

FIG.1is a perspective view illustrating an eye surgery system according to an example embodiment.

Referring toFIG.1, an eye surgery system100may be used by a user U to observe on or operate a patient's eye. The eye surgery system100may include a master device1, slave devices2and2′, a microscope3, a support portion6, and a display8.

The master device1may generate signals for moving the slave devices2and2′ according to a manipulation of the user U.

The slave devices2and2′ a first slave device2that passes through a first portion of a patient's eye to observe on the inside of an eye or operate the eye, and a second slave device2′ that passes through the second portion of the eye to observe on the inside of the eye or operate the eye. For example, the first portion and the second portion of the eye may be opposite to each other about the pupil of the eye.

The microscope3may observe on an eye through the pupil of the eye.

The support portion6may support the slave devices2and2′ and the microscope3.

The display8may display an image observed by the microscope3and provide the image to the user U in real time.

FIG.2is a perspective view illustrating the slave devices2and2′ and the microscope according to an example embodiment.

Referring toFIG.2, the first slave device2and the second slave device2′ may be connected to a lower portion of the support portion6. The microscope3may be connected to an upper portion of the support portion6. The support portion6may include a first support frame61for supporting the first slave device2, a second support frame62for supporting the second slave device2′, and a support base63for supporting the microscope3. For example, the support base63may be hinge-connected to be relatively rotatable and may have a plurality of link structures provided in series.

The first support frame61and the second support frame62may have holes formed through a lower side of the microscope3, and the microscope3may observe on a patient's eye through the holes. The microscope3may be movably mounted on the support portion6. For example, the microscope3is movable on the first support frame61and the second support frame62while maintaining an angle of a lens. The microscope3is movable on a plane. For example, the microscope3is movable along a first path P1parallel to the first support frame61and a second path P2perpendicular to the first path P1(seeFIGS.12and13). For example, at least one of the first support frame61, the second support frame62, and the support base63may accommodate the microscope3and provide a movable space for the microscope3. For example, the support portion6may include a first linear actuator (not illustrated) for moving the microscope3along the first path P1, and a second linear actuator (not illustrated) for moving the microscope3along the second path P2.

The first slave device2may include a first surgical instrument250, and the second slave device2′ may include a second surgical instrument250′. The first surgical instrument250may include a rotation module251and a surgical tip252inserted into a patient's eye and rotated by the rotation module251. The second surgical instrument250′ may include a rotation module251′ and a surgical tip252′ inserted into a patient's eye and rotated by the rotation module251′. For example, only one of the first surgical instrument250and the second surgical instrument250′ may be inserted into the eye to perform observation or surgery.

FIG.3is a perspective view schematically illustrating an internal structure of a slave device according to an example embodiment.

Referring toFIG.3, the slave device may include a lower delta robot210, an to upper delta robot220, a lower shaft231, an upper shaft232, a lower gripper241, an upper gripper242, a surgical instrument250, a lower frame280, and an upper frame290.

The lower delta robot210may movably support the lower gripper241. The upper delta robot220may movably support the upper gripper242. The lower delta robot210and the upper delta robot220may respectively include three support rods211and three support rods221, three movement parts212and three movement parts222that respectively move along longitudinal directions of the support rods211and221, three arms213and three arms223that respectively connect the movement parts212and the movement parts222to the lower grippers241and the upper grippers242, and three drive sources214and three drive sources224that respectively provide power for moving the three movement parts212and the three movement parts222. The lower delta robot210and the upper delta robot220may be driven according to a linear actuator method and may perform a precise movement with little vibration and backlash. The three support rods211and221may be arranged between the lower frame280and the upper frame290.

The arms213and223may be rotatably connected to the corresponding movement parts212and222, and the arms213and223may be relatively rotatably connected to the corresponding grippers241and242.

The support rods211of the lower delta robot210may be parallel to the support rods221of the upper delta robot220. For example, each of the support rods211of the lower delta robot210and each of the support rods221of the upper delta robot220may be respectively a lower portion of any one support rod and an upper portion of any one support rod. In other words, the support rods211of the lower delta robot210may be respectively bonded to the support rods221of the upper delta robot220without boundaries. According to this structure, only three support rods may guide six movement parts, and thus, the structure may be simply designed. Meanwhile, the support rods211of the lower delta robot210may be separated from the support rods221of the upper delta robot220(seeFIG.10).

The lower shaft231may be driven by the lower delta robot210. The lower shaft231may be rotatably connected to the lower gripper241in two degrees of freedom. For example, the lower shaft231may include a joint, which is rotatably connected to the lower gripper241in two degrees of freedom, for example, a ball joint or a universal joint. The lower shaft231may be fixed to the lower gripper241at a point in which the joint is placed. One point of the lower shaft231may be fixed to the lower gripper241.

Hereinafter, a point of the lower gripper241at which the lower shaft231is fixed may be referred to as a central point of the lower gripper241.

The upper shaft232may be driven by the upper delta robot220. The upper shaft232may be rotatably connected to the upper gripper242in two degrees of freedom. For example, the upper shaft232may include a joint, which is rotatably connected to the upper gripper242in two degrees of freedom, for example, a ball joint or a universal joint. The upper shaft232may be fixed to the upper gripper242at a point in which the joint is placed. One point of the upper shaft232may be fixed to the upper gripper242. Hereinafter, a point of the upper gripper242at which the upper shaft232is fixed may be referred to as a central point of the upper gripper242.

The lower shaft231and the upper shaft232are relatively slidable. For example, while driving the lower delta robot210and/or the upper delta robot220to change a position of the lower gripper241and/or a position of the upper gripper242, the lower shaft231and the upper shaft232are slidable in one degree of freedom. The lower shaft231is rotatable in two degrees of freedom with respect to the lower gripper241, and the rotation of the lower shaft231is independent of a change in a distance between the lower gripper241and the upper gripper242in an axial direction of the lower shaft231. According to this structure, the slave device may move only the upper shaft232while the lower shaft231is fixed.

For example, any one of the lower shaft231and the upper shaft232may include a hollow, and the other may include a slider which is slidable while being inserted into the hollow. For example, as illustrated inFIG.3, the lower shaft231may include a hollow accommodating at least a part of the upper shaft232, and the upper shaft232may include a slider which is slidable while being inserted into the hollow of the lower shaft231. For example, the slider may slide in one degree of freedom while in surface contact with an inner wall of the lower shaft231.

The lower gripper241may rotatably support the lower shaft231. The lower gripper241may be supported by the three arms213of the lower delta robot210, and a position thereof may be changed based on movements of the three movement parts212.

The upper gripper242may rotatably support the upper shaft232. The upper gripper242may be supported by the three arms223of the upper delta robot220, and a position thereof may be changed based on movements of the three movement parts222.

While the surgical instrument250maintains a position separated from the central point of the lower gripper241in an axial direction (a longitudinal direction) of the lower shaft231, a distance between the lower gripper241and the upper gripper242may be adjusted. In this case, the lower gripper241is fixed, and the upper gripper242moves along a path parallel to the longitudinal direction of the lower shaft231.

The surgical instrument250may include a rotation module251and a surgical tip252. The surgical tip252may be a longitudinal member. For example, the surgical tip252may be parallel to the lower shaft231and upper shaft232. For example, a central axis of the surgical tip252may pass through central axes of the lower shaft231and the upper shaft232. The surgical tip252may have a less thickness than the lower shaft231and may be inserted into an eye through a surface of the eye. The rotation module251may be mounted on the lower shaft231and may rotate the surgical tip252. For example, the surgical tip252may rotate about an axis parallel or parallel to a longitudinal axis of lower shaft231.

FIG.4is a plan view schematically illustrating a surgical instrument according to an example embodiment, andFIG.5is a front view schematically illustrating a lower shaft and a surgical instrument according to an example embodiment.FIG.4illustrates an internal mechanism of the rotation module251schematically illustrated inFIG.5.

Referring toFIGS.4and5, the rotation module251may be installed at a lower end of the lower shaft231. Unlike this, the rotation module251may also be installed elsewhere on the lower shaft231.

The rotation module251may include a main body2511, a first gear2512installed on a side of the main body2511, a gear shaft2513for rotating the first gear2512, and a second gear2514meshing with the first gear2512. The surgical tip252may be rotated along with a rotation of the second gear2514. For example, a rotation axis of the second gear2514may be parallel to or coincident with a central axis of the lower shaft231.

A drive source installed in the rotation module251first rotates the gear shaft2513, and thus, the first gear2512rotates the second gear2514, and then the surgical tip252rotates. Accordingly, a yaw rotation in which a longitudinal direction of the lower shaft231is used as a gear axis may be achieved.

FIG.6is a diagram illustrating a relationship between movements of a lower gripper and an upper gripper and movements of a lower shaft and an upper shaft according to the movements of the lower and upper grippers, according to an example embodiment.

Inverse kinematics, forward kinematics, and Jacobian of a dual delta structure constituting a slave device are described in detail with reference toFIG.6. The dual delta robot uses two delta robots (a lower delta robot and an upper delta robot) that move only in an x-axis direction, a y-axis direction, and a z-axis direction by connecting the two delta robots to each other with a passive joint.

Variables used in the kinematics of the double delta structure are defined as follows.

pointuppdelta(Xupp,Yupp,Zupp) orthocenter of moving plate of Upper delta
pointlowdelta(Xlow,Ylow,Zlow) orthocenter of moving plate of Lower delta
pointenddelta(Xend,Yend,Zend) end point of surgical instrument
linkupp, linklowlink length of Upper/Lower delta
HA, HB, HC, LA, LB, LCvertex of moving plate of Upper/Lower delta
BA, BB, BCvertex of Base structure
H1, H2, H3, L1, L2, L3joint displacement of Upper/Lower delta
Len1distance from end point of surgical instrument to orthocenter of Lower delta
Len2distance from end point of surgical instrument to orthocenter of Upper delta
BNlength of edge of Base structure
HS, LSlength of edge of Upper/Lower Moving Plate
Bwdistance from orthocenter of Base structure to edge
Hw, Lwdistance from orthocenter of Upper, Lower Moving Plate to edge
BUdistance from orthocenter of Base structure to vertex
HU, LUdistance from orthocenter of Upper, Lower Moving Plate to vertex

pointuppdelta(Xupp,Yupp,Zupp) is an orthocenter of an upper gripper and indicates a point in which an upper shaft is fixed. The upper shaft is rotatable in two degrees of freedom while one point thereof is fixed to the upper gripper. Here, the orthocenter of the upper gripper indicates an orthocenter of points (HA, HB, HC) in which three arms of an upper delta robot are connected to the upper gripper. In the present application, pointuppdelta(Xupp,Yupp,Zupp) is also referred to as a central point of the upper gripper.

pointlowdelta(Xlow,Ylow,Zlow) is an orthocenter of a lower gripper and indicates a point in which a lower shaft is fixed. The lower shaft is rotatable in two degrees of freedom while one point thereof is fixed to the lower gripper. Here, the orthocenter of the lower gripper indicates an orthocenter of points (LA, LB, LC) in which three arms of a lower delta robot are connected to the lower gripper. Because the lower shaft is fixed to the lower gripper, a distance from pointlowdelta(Xlow,Ylow,Zlow) to a surgical instrument may be constant. In the present application, pointlowdelta(Xlow,Ylow,Zlow) is also referred to as a central point of the lower gripper.

linkuppindicates a length of an arm of the upper delta robot, and linklowindicates a length of an arm of the lower delta robot. HA, HB, HC, LA, LB, LCindicate points in which each of the upper gripper and the lower gripper is connected to the arm. BA, BB, BCindicate points connected to three support rods of a lower frame. H1, H2, H3, L1, L2, L3indicate displacements of movement parts of upper and lower delta structures. Len1indicates a distance from an end point of a surgical instrument to pointlowdelta(Xlow,Ylow,Zlow). Len2indicates a distance from the end point of the surgical instrument to pointuppdelta(Xupp,Yupp,Zupp). BSindicates a length between any two of BA,BB,BCEach of HS,LSindicates a length between any two of HA,HB,HCand a length between any two of LA, LB, LC. Bwindicates a distance from an orthocenter of BA, BB, BCto an edge thereof. Hw,Lwrespectively indicate a distance from a line connecting any two of HA,HB,HCto pointuppdelta(Xupp,Yupp,Zupp) and a distance from a line connecting any two of LA, LB, LCof the lower gripper to pointlowdelta(Xlow,Ylow,Zlow). BUindicates a distance from an orthocenter of BA, BB, BCto any one ofBA, BB, BC. HU,LUrespectively indicate a distance from pointuppdelta(Xupp,Yupp,Zupp) to any one of HA,HB,HCand a distance from pointlowdelta(Xlow,Ylow,Zlow) to any one of LA, LB, LC.

Inverse Kinematics

Positions of the lower and upper grippers are determined through a spherical coordinate system based on rotation information received from a master device, and displacement of a surgical instrument may be obtained through this. The full inverse kinematics may be calculated by calculating kinematics of a lever and kinematics of a delta robot and then combining the kinematics. In order to adjust a hardware scale that is characteristics of a proposed structure, a distance between an end point (an end portion of a surgical tip) of the surgical instrument and the upper gripper is referred to as a variable Lenz.

In a first operation, central positions of the lower and upper gripper are obtained from a position of the end point of the surgical instrument by using the kinematics of the lever. Here, it is assumed that the position and an inclination value of the end point of the surgical instrument are given from the master device. Len2is assumed to be a constant. In a second operation, the positions of the lower and upper grippers are calculated by using kinematics of a double delta structure.

Kinematics of a lever structure shows a relationship between an end point pointenddelta(Xend,Yend,Zend) of the surgical instrument, a central point, pointlowdelta(Xlow,Ylow,Zlow) of the lower gripper, and a central point pointuppdelta(Xupp,Yupp,Zupp) of the upper gripper. Len2indicates a distance from the end point of the surgical instrument to the central point of the upper gripper and is used as a variable for adjusting the hardware scale. Φ indicates a pitch axis azimuth, and Θ indicates a roll axis azimuth.

The azimuth expressed in a spherical coordinate system is expressed in the following form by a Cartesian coordinate system.

Xupp=Xend+Len2·?·cos⁡(θ)(1)Yupp=Yend+Len2·?·sin⁡(θ)(2)Zupp=Zend+Len3·?(3)Xlow=Xend+Len1·?·cos⁡(θ)(4)Ylow=Yend+Len1·?·sin⁡(θ)(5)Zlow=Zend+Len1·?(6)Len2=?+(Yupp-Yend)2+?ϕ=arccos⁡(Zupp-ZendLen2)θ=arc⁢tan⁡(Yupp-YendXupp-Xend)?indicates text missing or illegible when filed

By using a principle of a lever, a central point of a lower delta robot may be obtained through Xend,Yend,Zend, Ø, θ of a tip of a surgical instrument and Len1that is a distance between the tip of the surgical instrument and a lower gripper. Len1is a constant value that does not change because Len1is a distance determined by a length of the mounted surgical instrument. Likewise, a central point of the upper gripper may be obtained through Len2that is a distance between the tip of the surgical instrument and the upper gripper.

Next, a relationship between the central points of the upper and lower grippers to and a prismatic joint is obtained through kinematics of a delta robot as follows. The previously determined central point of each delta determines values of six prismatic joints which are H1, H2, H3, L1, L2, L3. The relationship between the central points of the upper and lower grippers and the prismatic joint is as follows.

Xupp3+Yupp3+Zupp3+aupp2+bupp2+2·aupp·Xupp+2·bupp·Yupp+2·Zupp·H1+?-linkupp2=0(7)Xupp2+Yupp2+Zupp2+aupp1+bupp2-2·aupp·Xupp+2·bupp·Yxpp+2·Zupp·H2+H22-?=0(8)Xupp2+?+?+cupp3+2·cupp·?+2·?·H3+H32-linkupp2=0(9)Xlow3+Ylow3+?+alow2+blow3+2·alow·Xlow+2·blow·Ylow+2·?·L1+L12-?=0(10)Xlow3+Ylow3+Zlow2+alow2+?-2·alow·Xlow+2·blow·Ylow+2·?·?+?-?=0(11)Xlow3+Ylow3+Zlow2+clow2+2·clow·Ylow+2·Zlow·?+?-linklow3=0(12)Where:aupp=RS2-HS2,bupp=BW-HW,cupp=HU-BU⁢alow=BS2-LS2,blow=BW-LW,clow=LU-BU?indicates text missing or illegible when filed

As a result, the values of the prismatic joints of double delta are as follows.

Kinematically, each prismatic joint may have two solutions, and thus, various combinations may occur, but a slave device according to an example embodiment is designed to have only positive solutions through structural constraints.

Forward Kinematics

First, pointuppdelta(Xupp,Yupp,Zupp) that is a central point of the upper gripper is obtained as follows. A following equation may be obtained by subtracting Equation (8) from Equation (7).

This may be expressed in terms of Xuppas follows.

The following equation may be obtained by subtracting Equation (9) from Equation (7) and then inserting Equation (20) thereinto.

A solution is obtained by expressing Equation (9) in terms of Zuppand using a quadratic equation.

Inserting Equation (23) into Equations (20) and (21),

Possible solutions according to Equations (23) to Equation (25) are represented by two sets according to signs thereof. Just like finding a single solution in inverse kinematics, structural constraint conditions are used to have only positive solutions in forward kinematics. When the same method is also applied to the lower gripper, a value of pointlowdelta(Xlow,Ylow,Zlow) may be obtained. Coordinates pointend(Xend,Yend,Zend) of the tip of the surgical instrument based on positions of the upper gripper and the lower gripper may be obtained as follows.

A first operation of finding Jacobian of a double delta structure is to perform partial differentiation of an inverse kinematic relation of a lever structure. A state variable is obtained by combining Xend′, Yend′, Zend′ that is a speed component of a tip of a surgical instrument based on a Cartesian coordinate system and {dot over (Ø)}, {dot over (θ)}, Lėn2that is a speed component based on a spherical coordinate system. Through differential inverse kinematic constraints, relationships between Velupp(Xupp′, Yupp′, Zupp′), Vellow(Xlow′, Ylow′,Zlow′), Xend, Yend′, Zend′, {dot over (Ø)}, {dot over (θ)}, Lėn2are expressed as follows.

The relationship may be expressed as a matrix and expressed as follows.

In a second operation, a relationship between speeds of the upper and lower grippers in the Cartesian coordinate system and speeds of the prismatic joints previously calculated through the partial differentiation of the inverse kinematic relation of the delta structure may be found. A relationship between {dot over (H)}1and Xupp′, Yupp′, Zupp′ through a constraint equation of H1(1,2)may be expressed as follows.

In the above equation, partial differentiation of H1, Xupp, Yupp, Zuppwith respect to time is performed.

Equation (40) may be obtained by dividing Equation (39) by 2·(Zupp+H1).

?=-??·Xupp.-??·Yupp.-??·Zupp.(40)?indicates text missing or illegible when filed

By calculating speeds of the remaining prismatic joints, a matrix B6x6may be defined as follows.

Finally, a Jacobian matrix between a tip of a surgical instrument and an actuator joint may be obtained by multiplying B6x6, and A6x6together.

FIG.7is a front view schematically illustrating a state in which a lower shaft and an upper shaft rotate when a lower gripper and an upper gripper are relatively close to each other, according to an example embodiment.FIG.8is a front view schematically illustrating a state in which a lower shaft and an upper shaft rotate when a lower gripper and an upper gripper are relatively far apart from each other, according to an example embodiment.

Referring toFIGS.7and8, when a distance between the lower gripper241and the upper gripper242is relatively short (seeFIG.7), an angle is referred to as Θ1at which the lower gripper241and the upper gripper242are inclined as the upper gripper242moves to the right by a distance d from an initial state in which the lower gripper241and the upper gripper242are perpendicular to the ground, and when the distance between the lower gripper241and the upper gripper242is relatively long (seeFIG.8), an angle is referred to as Θ2at which the lower gripper241and the upper gripper242are inclined as the upper gripper242moves to the right by the distance d from the initial state in which the lower gripper241and the upper gripper242are perpendicular to the ground, and in this case, Θ1may be greater than Θ2.

A user may maximize the distance between the lower gripper241and the upper gripper242within a movable range, thereby increasing precision of a slave device. In addition, even while a distance between a central point C1of the lower gripper241and a central point C2of the upper gripper242is adjusted, a position of the surgical instrument250may be fixed to the central point C1of the lower gripper241. According to this structure, precision may be adjusted without changing the position of the surgical instrument250even while the surgical instrument250does a surgery on a part of an eye.

FIG.9is a block diagram of a slave device according to an example embodiment.

Referring toFIG.9, operations of the lower delta robot210, the upper delta robot220, and the rotation module251are controlled by a controller270. The lower delta robot210controls a position of the lower gripper241, and the upper delta robot220controls a position of the upper gripper242.

The controller270may separately control operations of the three drive sources214of the lower delta robot210. The movement parts212move according to the operations of the drive sources214, and then the arms213connected to the movement parts212move, thereby moving the lower gripper241. The lower gripper241finally moves a lower shaft.

In addition, the controller270may separately control the operations of the three drive sources224of the upper delta robot220. The movement parts222move according to the operations of the drive sources224, and then the arms223connected to the movement parts222move, thereby moving the upper gripper242. The upper gripper242finally moves an upper shaft.

The surgical tip252may move in conjunction with the movement of the lower and upper shafts. The surgical tip252may rotate in a total of three degrees of freedom. The controller270may control a two-degree-of-freedom rotation of the surgical tip252through the lower delta robot210and the upper delta robot220and control the remaining one-degree-of-freedom rotation through the rotation module251.

According to the example embodiment described above, a precise movement with less vibration and backlash may be performed by using a robust structure called a delta robot, and by using a double delta robot, a limitation of a small movable range of to the existing delta robot may be overcome.

In addition, by utilizing a precise delta robot structure used throughout the existing industry, precision and an operable range may be adjusted as needed, and thus, the structure may be applied not only to a medical robot, but also to all fields that need to control a precise movement and a wide range of movement as needed.

FIG.10is a perspective view of a slave device according to an example embodiment.

Referring toFIG.10, the lower delta robot210and the upper delta robot220may respectively include the three support rods211and the three support rods221, the three movement parts212and the three movement parts222, the three arms213and the three arms223, the three drive sources214and the three drive sources224, and three guide rods215and three guide rods225.

The support rods211and221and the movement parts212and222may have, for example, a ball-screw linear sliding structure. The drive sources214and224may cause the movement parts212and222to move in a longitudinal direction of the support rods211and221by rotating the support rods211and221. According to this structure, a more precise manipulation may be performed, and a structure resistant to an external impact may be implemented.

The support rods211of the lower delta robot210may be separated from the support rods221of the upper delta robot220. For example, any one of the support rods211of the lower delta robot210may be arranged between two adjacent support rods221of the upper delta robot220. In this way, when the support rods211of the lower delta robot210are separated from the support rods221of the upper delta robot220, movable ranges of the movement parts212and222may be increased, compared with a state in which the support rods211and221of the lower delta robot210and the upper delta robot220are arranged side by side.

The guide rods215and225are parallel to the support rods211and221and may guide movements of the movement parts212and222. The movement parts212and222may move up and down more stably by moving along the guide rods215and225and the support rods211and221. The guide rods215and225may increase position control accuracy of the movement parts212and222, and as a result, position control accuracy of the surgical instrument250may be increased.

The movement parts212and222may move along the support rods211and221and the guide rods215and225to control a position of the surgical tip252. The rotation module251may rotate the surgical tip252about a central axis of the surgical tip252. A roll, a pitch, and a yaw rotation of the surgical tip252may be performed by the movement parts212and222and the rotation module251.

FIG.11is a flowchart illustrating a method of controlling a slave device, according to an example embodiment.

Referring toFIG.11, the method of controlling the slave device may include operation S110of determining a remote rotation center of the surgical instrument, operation S120of receiving a target point of a tip of the surgical instrument, operation S130of determining a reaching point of the lower gripper for placing the tip of the surgical instrument at a target point based on the remote rotation center and the target point of the tip of the surgical instrument, operation S140of determining a reaching point of the upper gripper based on the remote rotation center and the reaching point of the lower gripper, operation S150of determining whether the tip of the surgical instrument is able to reach the target point, operation S160of calculating a position closest to the target point based on a state in which a distance between the lower gripper and the upper gripper is shortest, if the tip of the surgical instrument is determined to be unable to reach the target point, operation S170of modifying the target point of the tip of the surgical instrument based on the position and modifying the reaching point of the lower gripper based on the modified target point of the tip of the surgical instrument, and operation S180of moving the lower gripper to the reaching point of the lower gripper and moving the upper gripper to the reaching point of the upper gripper in a state in which at least one point of the surgical instrument is set to pass through the remote rotation center.

In operation S110, a controller may determine a remote rotation center of a surgical instrument. First, the controller moves movement parts of upper and lower delta robots to change positions of lower and upper grippers such that the tip of a surgical instrument comes into contact with a surface of a patient's eye. When the tip of the surgical instrument is in contact with the surface of the eye, the controller may determine a position of the tip of the surgical instrument in the corresponding position as the remote rotation center.

In operation S120, the controller may receive a target point of the tip of the surgical instrument. The target point of the tip of the surgical instrument may be received from the master device1(seeFIG.1). The master device1may transmit an operation signal to the controller. The controller may operate a slave device based on the operation signal. For example, the target point may be any position in the eye.

In operation S130, the controller may determine a reaching point of the lower gripper for placing the tip of the surgical instrument at the target point, based on the remote rotation center and the target point of the tip of the surgical instrument. The controller may control the position of the surgical tip while maintaining a state in which at least a part of a surgical tip of the surgical instrument passes through the remote rotation center. For example, the surgical tip is a longitudinal member, one point has to pass through the remote rotation center, and when a position (target point) of the tip is determined, a reaching point of the lower gripper may be determined as a single value.

In operation S140, the controller may determine a reaching point of the upper gripper based on the remote rotation center and the reaching point of the lower gripper. Because the reaching point of the lower gripper is determined in operation S130and the target point of the surgical instrument is determined in operation S120, a position and an angle of a lower shaft are determined, and thus, the reaching point of the upper gripper may be determined as any point of a path parallel to a longitudinal direction of the lower gripper. In other words, the reaching point of the upper gripper may be determined on an imaginary extension line passing through the remote rotation center and the reaching point of the lower gripper. A target point of the tip of the surgical instrument may be determined as any one point as the remote rotation center is determined, and a reaching point of the lower gripper may also be determined as any one position as the position and angle of the surgical instrument are determined. In addition, a position of the upper gripper may be determined as a preset region. The reaching point of the upper gripper in the preset region may be determined as a point separated by the longest distance from the lower gripper. According to this structure, precision of the slave device may be increased (seeFIG.8).

In operation S150, the controller may determine whether the tip of the surgical instrument may reach the target point. For example, when the target point of the tip of the surgical instrument is determined, a position of the lower gripper is determined as any one point, and the lower gripper may not actually reach the corresponding point due to a structural limitation. For example, although the lower gripper may reach the reaching point, the upper gripper may not reach the reaching point due to the structural limitation. As such, if the lower gripper and/or the upper gripper may not reach the reaching point due to the structural limitation, the processing may proceed to operation S160. If the lower gripper and/or the upper gripper may not reach the reaching point, the processing may proceed to operation S180.

In operation S150, the controller may determine whether the tip of the surgical instrument may reach the target point based on a size such as a diameter of, for example, a surgical operation object such as an eye. In other words, by determining that the tip of the surgical instrument may not reach the target point when out of an internal space of the eye even at a position that may be implemented on the slave device, surgical stability may be increased. Here, a boundary surface of the internal space of the eye may be set as, for example, a value received from a user or may also be automatically determined by detecting a diameter of the eye through processing of an image observed through a microscope. For example, when the size of the eye is large, a size of the region reachable by the tip of the surgical instrument may be relatively large.

In operation S160, the controller may calculate a position closest to a target point based on a state in which a distance between the lower gripper and the upper gripper is the shortest. When the distance between the lower gripper and the upper gripper is the shortest, constraints due to a structural limitation of the upper gripper may be reduced. For example, when an initial position of the surgical instrument is referred to as S1and a target position thereof is referred to as S2, a position closest to the target point may indicate a point closest to S2on an imaginary line segment region connecting S1to S2.

In operation S170, the controller may modify the target point of the tip of the surgical instrument based on the position calculated in operation S160and modify the reaching point of the lower gripper based on the modified target point of the tip of the surgical instrument.

In operation S180, in a state in which at least one point of the surgical instrument is set to pass through a remote rotation center, the controller may move the lower gripper to the reaching point of the lower gripper and move the upper gripper to the reaching point of the upper gripper. While the lower gripper moves from the initial position to the reaching point, the upper gripper may be controlled to adjust an angle of the lower to gripper such that at least one point of the surgical instrument passes through the remote rotation center.

Because the slave device controls the surgical instrument in real time by receiving a signal from the master device in real time, the initial position and the target point of the tip of the surgical instrument may be located substantially adjacent to each other. In a case in which the slave device operates by receiving a signal from the master device in real time at short time intervals, when it is determined in operation S150that the tip of the surgical instrument is unable to reach the target point, the modified target point of the tip of the surgical instrument may be the same as the target point of the tip of the surgical instrument prior to the modification, and the surgical instrument may not move any more.

FIGS.12and13are views schematically illustrating a state in which an eye rotates according to driving of first and second slave devices and a microscope moves according to a rotation of the eye.

Referring toFIGS.12and13, the microscope3may be placed between the first slave device2and the second slave device2′ and is movable on the support frames61and62. The microscope3is movable along two paths P1and P2that are orthogonal to each other. The two paths P1and P2include a first path P1and a second path P2each orthogonal to a certain perpendicular line of a lens of the microscope3. The microscope3is movable on a plane including the first path P1and the second path P2. For example, the microscope3may include two linear actuators that are orthogonal to each other.

The first slave device2and the second slave device2′ may respectively include a first surgical instrument250and a second surgical instrument250′ which pass through a surface of the eye E. The first slave device2and the second slave device2′ may rotate the eye E by changing angles of the first surgical instrument250and the second surgical instrument250′. The eye E is rotatable about a first rotation axis A1passing through the center of the eye and is rotatable about a second rotation axis A2(seeFIG.15) that is perpendicular to the first rotation axis A1and passes through the center of the eye. The first rotation axis A1and the second rotation axis A2may be orthogonal to, for example, an imaginary extension line passing through the center of a pupil P from the center of the eye E.

The microscope3may move based on the rotation of the eye E. The microscope3may cause a lens to be parallel to the pupil P by moving in response to a change in a position of the pupil P. For example, the amount of movement of the microscope3may be determined by the amount of change in a position where the central position of the pupil P is projected onto a movable plane of the microscope3. According to this method, a region that may be observed inside the eye E may be increased as illustrated inFIGS.12and13.

For example, as illustrated inFIG.13, the slave devices2and2′ rotate the eye E while relative positions and angles of the surgical instruments250and250′ with respect to the eye E are fixed. According to this control method, a distance between the two surgical instruments250and250′ does not change, and thus, it is possible to prevent the eye E from being damaged during rotation of the eye E.

FIG.14is a flowchart illustrating a method of controlling an eye surgery device, according to an example embodiment,FIGS.15to17are plan views illustrating a state in which an eye is rotated by an eye surgery device, andFIG.18is a flowchart illustrating operations of calculating a target rotation center of each of first and second surgical instruments, according to an example embodiment.

Referring toFIGS.14to18, a method of controlling an eye surgery device may include operation S210of receiving rotation amount information of an eye from a master device, operation S220of setting, on a surface of the eye, an initial remote rotation center of each of the first surgical instrument and the second surgical instrument, operation S230of calculating a target remote rotation center of each of the first surgical instrument and the second surgical instrument based on the rotation amount information of the eye, operation S240of generating a first movement speed profile required while the first surgical instrument reaches the target remote rotation center from the initial remote rotation center in a state in which a distance between the remote rotation centers of the first surgical instrument and the second surgical instrument is maintained, operation S250of generating a second movement speed profile required while the second surgical instrument reaches the target remote rotation center from the initial remote rotation center in a state in which the distance between the remote rotation centers of the first surgical instrument and the second surgical instrument is maintained, operation S260of moving the remote rotation center of the first surgical instrument from the initial remote rotation center to the target remote rotation center and moving the remote rotation center of the second surgical instrument from the initial remote rotation center to the target remote rotation center, on the surface of the eye, and operation S270of moving a microscope.

In operation S210, a controller may receive rotation amount information of an eye from a master device. The rotation amount information of the eye may include first rotation amount information on a rotation about a first rotation axis A1passing through the center of the eye E, and second rotation amount information on a rotation about a second rotation axis A2that passes through the center of the eye E and is orthogonal to the first rotation axis A1.

In operation S220, the controller may set initial remote rotation centers of a first surgical instrument and a second surgical instrument on a surface of the eye E. For example, when a tip of the first surgical instrument comes into contact with the surface of the eye E, the controller may determine a position of the tip of the first surgical instrument as an initial remote rotation center RCM1. Likewise, when a tip of the second surgical instrument comes into contact with the surface of the eye E, the controller may determine a position of the tip of the second surgical instrument as an initial remote center RCM1′.

In operation S230, the controller may calculate target remote rotation centers RCM3and RCM3′ of the first surgical instrument and the second surgical instrument, based on rotation amount information of the eye E. Operation S230may include operation S231of setting a spherical coordinate system based on the center of the eye E, operation S232of calculating an angular change from an initial remote rotation center of the first surgical instrument to a target remote rotation center on the spherical coordinate system, and operation S233of calculating an angular change from an initial remote rotation center of the second surgical instrument to a target remote rotation center on the spherical coordinate system.

In operation S231, the controller may set the spherical coordinate system based on the center of the eye E. The controller may reset the initial remote rotation centers RCM1and RCM1′ determined to be a Cartesian coordinate system as the spherical coordinate system. The initial remote rotation centers RCM1and RCM1′ may be represented by two angles.

In operation S232, the controller may calculate an angular change from the initial remote rotation center RCM1to the target remote rotation center RCM3of the first surgical instrument on the spherical coordinate system. For example, the remote rotation center may move to RCM2by rotating from the initial remote rotation center RCM1by θ about the first rotation axis A1, and in this state, by further rotating by ϕ about the second rotation axis A2, the remote rotation center may move to the target remote rotation center RCM3. The controller may respectively calculate θ and ϕ.

In operation S233, the controller may calculate an angular change from the initial remote rotation center RCM1′ of the second surgical instrument to the target remote rotation center RCM3′ on the spherical coordinate system. The controller may calculate an angular change from the initial remote rotation center RCM1′ of the second surgical instrument to the target remote rotation center RCM3′ on the spherical coordinate system. For example, a remote rotation center may move to RCM2′ by rotating by θ about the first rotation axis A1from the initial remote rotation center RCM1′, and in this state, the remote rotation center may move to the target remote rotation center RCM3′ by further rotating by ϕ about the second rotation axis A2. The controller may respectively calculate θ and ϕ.

In operation S240, the controller may generate a first movement speed profile required while the first surgical instrument reaches a target remote rotation center from an initial remote rotation center in a state in which a distance between the remote rotation centers of the first and second surgical instruments is maintained. In operation S250, the controller may generate a second movement speed profile required while the second surgical instrument reaches a target remote rotation center from an initial remote rotation center in a state in which the distance between the remote rotation centers of the first and second surgical instruments is maintained. For example, when the eye E rotates in a direction toward the initial remote rotation center RCM1′ of the second surgical instrument about the first rotation axis A1from the pupil P and then rotates about the rotation axis A2based on a plan view as illustrated inFIGS.15to17, a distance on a surface of the eye E from the initial remote rotation center RCM1of the first surgical instrument to the target remote rotation center RCM3may be longer than a distance on the surface of the eye E from the initial remote rotation center RCM1′ of the second surgical instrument to the target remote rotation center RCM3′. In this case, when a movement speed of the first surgical instrument is faster than a movement speed of the second surgical instrument, a distance between the remote rotation centers of the first surgical instrument and the second surgical instrument may be maintained. In operation S240, the distance between the remote rotation centers of the first and second surgical instruments is maintained, and thus, the eye E may be prevented from being damaged while the remote rotation centers of the first and second surgical instruments changes.

In operation S260, the controller may move the remote rotation center of the first surgical instrument from the initial remote rotation center to the target rotation remote center and may move the remote rotation center of the second surgical instrument from the initial remote rotation center to the target rotation remote center, on a surface of the eye E.

In operation S270, the controller may move a microscope. For example, a position of the microscope may be moved from a first position L1to a second position L2as the remote rotation centers of the first surgical instrument and the second surgical instrument are moved. For example, the controller may move the microscope based on rotation amount information of an eye. For example, the controller may control the position of the microscope based on the rotation amount information of the eye received from a master device. In another example, the controller may move the microscope based on the remote rotation centers of the first surgical instrument and the second surgical instrument. For example, the controller may project a position change of the pupil P onto a plane parallel to a plane including the first path P1(seeFIG.13) and the second path P2(seeFIG.13) through a change in remote rotation centers of the first surgical instrument and the second surgical instrument, and then set the position of the microscope based on the change in the position of the pupil P in the corresponding plane.

As described above, although example embodiments are described with reference to the limited drawings, those skilled in the art may perform various modifications and changes from the above description. For example, even when the described techniques are performed in a different order from the described method, and/or even when components of the described structure and device are coupled or combined in a different form from the described method or replaced or substituted with other components or equivalents, appropriate results may be achieved.