Robot

A robot includes a link portion including a plurality of link members and a drive portion to rotate the link members, and axes of rotation of the drive portion extending from end portions of the link members is positioned at an identical point.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2014-0041386, filed on Apr. 7, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field of the Invention

Embodiments of the present invention relate to a robot, and more particularly, to a robot that may aim at a target more accurately and rapidly.

2. Description of the Related Art

Radiation therapy is a form of treatment to kill cancer cells using high-energy radiation. Radiation refers to a material mediating propagation or a phenomenon of energy propagating through a space, and an X-ray is a typical example of the radiation.

Radiation therapy is one of the three most prevalent cancer treatments, in company with surgery and chemotherapy. In general, radiation therapy may not require hospitalization, take a few to about 30 minutes per day, and be painless during treatment.

As radiation therapy apparatuses, X-Knife (Radionics, U.S.A.), Novalis Tx (BrainLAB, Germany), Peacok (NOMOS Corp., U.S.A.), Trilogy (Varian Medical System, U.S.A.), and CyberKnife (Accuray Inc., U.S.A.) are known. Many of the radiation therapy apparatuses are evolving to reduce an error occurring during treatment and increase an accuracy based on technology of Image Guided Radiotherapy (IGRT) and a linear accelerator.

CyberKnife is a high-precision stereotactic radiation therapy exclusive apparatus that may intensively irradiate a tumor portion in various directions by providing a small linear accelerator to a robot arm freely moving with six joints.

CyberKnife may provide a precise treatment by tracking coordinates of a gold marker inserted into a body and a skeleton image using real-time image guided technology, without an invasive fixing device. In addition, contrary to Gamma Knife used to treat brain tumors, CyberKnife may be used to treat cancer throughout a human body. Further, CyberKnite may be used for fractionated radiation therapy administered a few times, rather than once.

Recently, varied research is being conducted on CyberKnife. For example, Korean Patent Application No. 2009-0038051, filed on Apr. 30, 2009, discloses “System for radiotherapy planning information viewer”.

SUMMARY

An aspect of the present invention provides a robot that may be provided in a compact design to reduce an overall weight.

Another aspect of the present invention also provides a robot that may increase a directivity with respect to a target through easy control.

Still another aspect of the present invention also provides a robot that may aim at a target more accurately and rapidly, thereby reducing a treatment or surgery time.

Yet another aspect of the present invention also provides a robot that may prevent a mutual collision between link members during an operation of a drive portion.

Further another aspect of the present invention also provides a robot including an additional angle adjustment element disposed at an end portion of a second link member or an emitting member to efficiently adjust an angle at which the emitting member faces a target.

According to an aspect of the present invention, there is provided a robot including a link portion comprising a plurality of link members, and a drive portion to rotate the link members. Axes of rotation of the drive portion extending from end portions of the link members may be positioned at an identical point.

The link portion may include a first link member, and a second link member connected to an end portion of the first link member.

The first link member and the second link member may be provided in a form of arcs and disposed on concentric spheres, respectively.

The drive portion may include a first drive member disposed at one end of the first link member to rotate the first link member on a first axis of rotation, and a second drive member disposed at another end of the first link member to rotate the second link member on a second axis of rotation.

An emitting member may be disposed at another end of the second link member to face a target.

According to another aspect of the present invention, there is also provided a robot including a first link member, a first drive member disposed at one end of the first link member to rotate the first link member on a first axis of rotation, a second link member connected to another end of the first link member, a second drive member disposed between the other end of the first link member and one end of the second link member to rotate the second link member on a second axis of rotation, and an emitting member disposed at another end of the second link member. The first axis of rotation and the second axis of rotation may be positioned at an identical location of a target.

The first link member and the second link member may be provided in a form of arcs and disposed on concentric spheres on which the target is centered, respectively.

An angle adjustment element may be disposed at the second link member or the emitting member to adjust an angle at which the emitting member faces the target.

DETAILED DESCRIPTION

FIG. 1is a front view illustrating a robot10according to an embodiment of the present invention.FIG. 2is a view illustrating axes of rotation being positioned at an identical point in the robot10.FIG. 3is a view illustrating an angle adjustment element provided at an emitting member300of the robot10.FIG. 4is a view illustrating a radiation range of the emitting member300of the robot10.

Referring toFIG. 1, the robot10may include a link portion100and a drive portion200.

The link portion100may include a plurality of link members. The plurality of link members may include a first link member110and a second link member120.

The first link member110and the second link member120may be connected to each other.

The first link member110and the second link member120may be connected to each other, with the drive portion200disposed therebetween.

The first link member110and the second link member120may be provided in a form of arcs and disposed on concentric spheres, respectively.

For example, the first link member110may correspond to an arc disposed on a large concentric sphere, and the second link member120may correspond to an arc disposed on a small concentric sphere. The first link member110and the second link member120may be disposed away from a location at which the first link member110and the second link member120are radially spaced from each other.

The first link member110and the second link member120may be provided in different lengths. For example, the first link member110may have a greater length than the second link member120. Thus, when the second link member120rotates inside the first link member110, a mutual collision between the first link member110and the second link member120may be prevented.

However, the shape and the disposition of the first link member110and the second link member120are not limited thereto. The first link member110and the second link member120may be provided in any shape and disposition in which the first link member110and the second link member120may not mutually collide while being rotated in response to an operation of the drive portion200.

The drive portion200may be disposed on the first link member110and the second link member120to rotate the first link member110and the second link member120.

The drive portion200may include a first drive member210and a second drive member220.

The first drive member210may be disposed at one end of the first link member110. For example, the first link member110may be disposed in an upper portion of the first drive member210.

Referring toFIG. 2, the first drive member210may rotate the first link member110on a first axis of rotation X1. When a longitudinal central axis of the first drive member210matches the first axis of rotation X1, the first link member110may rotate on the longitudinal central axis of the first drive member210.

The second drive member220may be disposed at another end of the first link member110.

When a connection element112is provided to compensate for a level difference between the first link member110and the second drive member220, the second drive member220may be disposed on the connection element112.

In this example, the connection element112and the second drive member220may be disposed on an identical axis, and the connection element112may be disposed to be in contact with an upper end of the second drive member220.

The second drive member220may be disposed at one end of the second link member120. For example, the second link member120may be disposed in a lower portion of the second drive member220.

The second drive member220may rotate the second link member120on a second axis of rotation X2. When a longitudinal central axis of the second drive member220matches the second axis of rotation X2, the second link member120may rotate on the longitudinal central axis of the second drive member220.

The first axis of rotation X1and the second axis of rotation X2may extend to be positioned at an identical point.

When the first axis of rotation X1is formed in a vertical direction, the second axis of rotation X2may be formed to tilt at a degrees (°) with respect to the first axis of rotation X1. Thus, an angle between the first axis of rotation X1and the second axis of rotation X2may correspond to α°.

The identical point at which the first axis of rotation X1and the second axis of rotation X2, provided at both end portions of the first link member110, are positioned may correspond to a central point O of the concentric spheres on which the first link member110and the second link member120are disposed.

When the emitting member300, which will be described later, is disposed on the second link member120, the emitting member300may be easily aimed at a target.

The drive portion200may have two degrees of freedom by means of the first drive member210and the second drive member220, thereby spherically moving the emitting member300. In this example, two motors may be used. Since a relatively few motors are used, an overall weight of the robot10may decrease.

The first link member110and the second link member120may rotate on the first axis of rotation X1and the second axis of rotation X2in different areas, respectively. Thus, an area accessed by the first link member110and the second link member120may be extended by the first drive member210and the second drive member220, whereby a directivity of the link portion100with respect to a target may increase.

The emitting member300may be disposed at another end of the second link member120.

Hereinafter, the emitting member300will be described based on a linear accelerator that emits radiation for radiation therapy.

However, the emitting member300is not limited thereto. The emitting member300may emit another material including a liquid or gas.

The second link member120may be disposed at a center of the emitting member300. The emitting member300may be disposed to be perpendicular to a tangential direction of an end portion of the second link member120.

Radiation or other materials may be emitted from a lower end of the emitting member300. An angle at which radiation or other materials are emitted may be changed based on a tilting angle of the emitting member300.

Referring toFIG. 2again, the emitting member300may be disposed to tilt β° with respect to the second axis of rotation X2, and disposed to tilt α°+β° with respect to the first axis of rotation X1.

Angles α and β may be determined so that the first link member110and the second link member120may be smoothly rotated by the first drive member210and the second drive member220and the emitting member300may aim at a target over a relatively broader area.

A portion of the emitting member300at which radiation is emitted may be disposed on a third axis X3. Thus, the radiation may be emitted from the emitting member300along the third axis X3.

Similar to first axis of rotation X1and the second axis of rotation X2, the third axis X3may also be positioned at the central point O of the concentric spheres.

That is, the first axis of rotation X1, the second axis of rotation X2, and the third axis X3may intersect at the central point O of the concentric spheres of the first link member110and the second link member120.

Thus, a point at which radiation is to be emitted through the emitting member300may be adjusted by the link portion100and the drive portion200.

Referring toFIG. 3, an angle adjustment element310may be additionally provided at an end portion of the second link member120or the emitting member300.

The angle adjustment element310may be disposed at a point at which the emitting member300and the second link member120meet. The emitting member300may move in a direction of an arrow on the third axis X3, and have a yaw movement.

As described above, the emitting member300including the angle adjustment element310may perform a small-angle movement. Thus, the angle adjustment element310may be useful when a minute angle adjustment is required after the emitting member300aims at a target by means of the drive portion200.

The robot10may further include a controller (not shown). The first drive member210and the second drive member220may be easily controlled by the controller.

In detail, the controller may selectively or simultaneously operate the first drive member210or the second drive member220to dispose the emitting member300to face the target, and operate the angle adjustment element310, as necessary.

The controller may control an operation of the first drive member210or the second drive member220to adjust a rotation velocity or a rotation direction of the first link member110or the second link member120. Thus, a radiation surgery or treatment time may be reduced.

The robot10configured as described above according to an embodiment of the present invention may operate as follows. By operating the first drive member210or the second drive member220, the first link member110or the second link member120may rotate.

The first link member110and the second link member120may be disposed on concentric spheres, and relatively rotate on different axes of rotation X1, and X2, respectively. Thus, the first link member110and the second link member120may smoothly rotate without a collision.

In addition, the first drive member210and the second drive member220may operate simultaneously or selectively. Thus, by operating the first drive member210and the second drive member220simultaneously, the first link member110and the second link member120may rotate simultaneously. Also, after the first link member110rotates by operating the first drive member210, the second link member120may rotate by operating the second drive member220.

In response to the rotation of the first link member110and the second link member120, the emitting member300disposed at an end portion of the second link member120may move in a spherical pattern.

The angle adjustment element310may selectively operate.

The angle adjustment element310may minutely adjust an angle since the emitting member300may have a yaw movement on the third axis X3.

Radiation may be emitted through the emitting member300.

The radiation may be used to treat a target T, for example, an affected area of a patient.

Referring toFIG. 4, the emitting member300may emit radiation within an area A.

The area A may include an area in which the first link member110is rotated on the first axis of rotation X1by the first drive member210, and an area in which the second link member120is rotated on the second axis of rotation X2by the second drive member220.

When the first drive member210and the second drive member220operate simultaneously, a position of the emitting member300may be freely adjusted within the area A.

By operating the first drive member210and the second drive member220, the emitting member300may aim at the target T or the affected area to be treated, and radiation emitted from the emitting member300may be concentrated on the target T.

When the emitting member300is to be relocated during treatment, by controlling the first drive member210, the second drive member220, or the angle adjustment element310through the controller, the emitting member300may be relocated more rapidly and accurately. When minute adjustment is required after the emitting member300is relocated, the minute adjustment may be performed by controlling the angle adjustment element310.

As described above, a robot10according to an embodiment of the present invention may reduce a treatment or surgery time by aiming at a target more rapidly and accurately, increase a directivity with respect to the target through easy control, and reduce an overall weight through a compact design. In addition, the robot10may prevent a mutual collision between link members110and120during an operation of a drive portion200, and adjust an angle at which a material is emitted from an emitting member300or an angle at which the emitting member300faces the target through an additional angle adjustment element310disposed at an end portion of a second link member120or the emitting member300.

Hereinafter, a kinematical analysis on a structure of the robot10will be described in detail. Forward kinematics of a robot arm may be expressed as follows.
x=f(θ)  [Equation 1]

In the Equation 1, θ denotes a joint angle, and x denotes a location and direction of an end-effector. Coordinates of an emitting member may be estimated based on an angle at which link members are connected to each other.

In addition, when a Denavit-Hartenberg (D-H) convention is used, the kinematics of the robot may include four parameters, for example, a link length a of a line member, a link offset d, a link distortion α, and a joint angle θ. In this example, when a joint rotates around a z axis, transformation matrices may be expressed as follows.

In Transformation Matrices 1 and 2, s denotes sine, and c denotes cosine. Through the above transformation matrices, a transformation matrix may be derived as follows.

The above transformation matrix may represent a case in which two link members are provided. A point to which relocation is to be performed by a translation, an offset, a scale, or a rotation on a three-dimensional (3D) coordinate system may be estimated using the transformation matrix.

In addition, a location and direction of the emitting member300or the end-effector may be expressed as follows.

In this example, the location of the emitting member300or the end-effector may be constantly uniform.

FIG. 5illustrates a direction of the emitting member300in the robot10. Referring toFIG. 5, the emitting member300may face a z axis, and have a roll movement of rotating on the z axis, a yaw movement of oscillating up and down based on the z axis, and a pitch movement of rotating up and down based on the z axis. In this example, a roll direction may be insignificant in the emitting member300. Only a z-vector may be considered for a direction of the emitting member300. Thus, Transformation Matrix 2 may be arranged as follows.

A desired direction of the emitting member300may be designated as spherical coordinates α and β ofFIG. 6. When the direction of the emitting member300is given as a and β ofFIG. 6, rotation matrices corresponding to the direction may be expressed as follows.

Based on α and β from Rotation Matrices 1 and 2,0x2=[x1, x2, x3]T,0y2=[y1, y2, y3]T, and0z2=[z1, z2, z3]Tmay be determined, and θ1and θ2may also be determined. Such a relationship may be expressed by inverse kinematics as follows.
θ=f(x)−1[Equation 2]

In Equation 2, x denotes a vector0z2=[z1, z2, z3]Tand, θ denotes a vector including θ1and θ2. Equation 2 may be an inverse function of Equation 1.

The joints angles θ1and θ2may be calculated based on orthonormal vectors0x2,0y2, and0z2. An intuitive method of calculating such vectors may be performed using spherical coordinates. When a direction is given as α and β, a rotation matrix corresponding to the direction may be expressed as follows.

The following Equations may be extracted from Transformation Matrix 3.
x3=sα1sθ2
z3=cα1cα2−cθ2sα1sα2[Equation 3]

In Equation 3, θ2may be induced as follows.

A function arctan 2, an arctangent function including two input variables, may be used due to a stability of being close to zero input values and a characteristic of a final angle returning to an appropriate quadrant. θ1may be calculated as follows. The following Equations 5 through 7 may be obtained from Transformation Matrix 4.

In addition, the following may be assumed.
a=cα2sα1+sα2cα1
b=sα2sθ2[Equation 8]

Through Equations 7 and 8, the following may be calculated.

Through Equations 6 and 9, θ1may be calculated as follows.

From Equations 4 and 10, the two joint angles θ1and θ2may be determined. A Jacobian matrix will be described hereinafter. A linear mapping between a θ-space and an x-space may be as follows. Equation 1 may be differentiated as follows.

The Transformation Matrix 1 may be expressed as follows.

Thus, the Jacobian matrix may be expressed as follows.

Thus, the Jacobian matrix may be expressed as follows.

Through Jacobian Matrix 4, when only an angular velocity is considered and a translational velocity is not considered, a singularity may not be achieved except for a case in which α=nπ and nεN are satisfied.

As described above, a relationship between a joint velocity of a link member and a velocity of an emitting member may be determined through a Jacobian matrix. Thus, a moving velocity of the emitting member may be estimated based on the joint velocity of the link member. In addition, when a desired velocity of the emitting member is given, a joint velocity of the link member that may achieve the desired velocity of the emitting member may be inversely calculated.

In detail, a location of the emitting member may be estimated based on a current location of a link member. Conversely, to enable the emitting member to face a central point or a target, an operation of a link member may be controlled based on a current location of the emitting member.