WO2009104853A1

WO2009104853A1 - Curved rcm of surgical robot arm

Info

Publication number: WO2009104853A1
Application number: PCT/KR2008/005870
Authority: WO
Inventors: Jong Seok Won; Seung Wook Choi; William Peine
Original assignee: Meerecompany
Priority date: 2008-02-20
Filing date: 2008-10-07
Publication date: 2009-08-27
Also published as: KR20090089928A

Abstract

Disclosed is a linkage structure for a surgical robot arm. The linkage structure for a surgical robot arm comprises a robot arm, a first linkage unit forming an axis combination with a fore-end of the robot arm through a first axis, a second linkage unit forming an axis combination with the first linkage unit through a second axis and an instrument forming an axis combination with the second linkage unit through a third axis, the first, second and third axes being formed such that extended lines of the three axes are concentrated on a predetermined point of a fore-end of the instrument. An active type RCM of robot arm according to the present invention allows a fore-end of an instrument to freely pivot around an incision point of the instrument without injuring tissues and to perform precise spherical motion.

Description

Description CURVED RCM OF SURGICAL ROBOT ARM

Technical Field

[1] The present invention relates to a linkage structure of a surgical robot arm.

Background Art

[2] Surgery refers to a medical specialty that uses operative manual and instrumental techniques on the tissues of a patient to treat a pathological condition. Surgical robots have been proposed as an alternative for performing an excision surgery, which needs cutting tissues to treat or remove the organ within the body, to reduce blood loss, pain and improve precision.

[3] The surgical robot consists of a master robot generating and transmitting signals according to manipulations of a surgeon and a slave robot applying the manipulation directly to the patient according to the signals from the master robot. The master robot may be integrated with the slave robot or may be separated from the slave robot.

[4] The slave robot has a robot arm in order for surgery manipulation, and an instrument is disposed at a fore-end of the robot arm. Accordingly, a movement of the robot arm causes the instrument to move together, which may lead to unnecessary injury while the instrument performs a surgery. Also, when the surgical area is wide, tissues of the patient should be incised as much as the moving path of the instrument, which weakens the advantage of the robotic surgery.

[5] In order to overcome this weakness, the instrument sets a virtual pivot center point at a predetermined location on a fore-end, so that the robot arm is controlled such that the instrument pivots around this point. Such a virtual point is referred to as a remote center of motion or RCM.

[6] Prior methods for controlling the RCM of the robot arm may be classified into a passive type and an active type. The passive type controls such that the fore-end of the instrument moves against a moving direction of the robot arm by adopting tissues incised for inserting the instrument as a confronting point.

[7] However, because the tissues confront the moving force of the instrument, undesired damage may be applied to the tissues, which may occasionally become a cause of a surgical accident.

[8] A method has been introduced as the active type in which an RCM determination unit 23 having a 4-bar linkage is formed to determine a predetermined area of the fore- end of the instrument as the RCM 8.

[9] However, such an active type requires many parts, increasing the robot arm in volume and size. A large volume surgical robot is space consuming and inconvenient for moving. Also, the large volume robot makes it difficult for an assistant surgeon to access the patient, which in an emergency may threaten the life of the patient. Disclosure of Invention

Technical Problem

[10] The present invention aims to provide a linkage structure of a surgical robot arm that can decrease the size and weight of a surgical robot by using less parts to form an RCM of a robot arm. Technical Solution

[11] According to one aspect of the present invention is provided a linkage structure for a surgical robot arm comprising a robot arm, a first linkage unit forming an axis combination with a fore-end of the robot arm through a first axis, a second linkage unit forming an axis combination with the first linkage unit through a second axis and an instrument forming an axis combination with the second linkage unit through a third axis, the first, second and third axes being formed such that extended lines of the three axes are concentrated on a predetermined point of a fore-end of the instrument.

[12] The first linkage unit may be formed by perforating the first axis and the second axis in a sub linkage unit that is curved to a degree such that the first axis and the second axis are concentrated on the predetermined point

[13] The second linkage unit may be formed by perforating the second and the third axes in a sub linkage unit that is curved to a degree such that the second axis and the third axis are concentrated on the predetermined point

[14] The second linkage unit may be overlapped with the first linkage unit by rotating the second linkage unit about the second axis.

[15] The first linkage unit may be deposited on the robot arm by rotating the first linkage unit about the first axis.

[16] Additional aspects, features, and advantages will be elucidated from the following drawings, claims, and specification.

Advantageous Effects

[17] An active type RCM of robot arm according to the present invention allows a fore- end of an instrument to freely pivot around an incision point of the instrument without injuring tissues and to perform precise spherical motion.

[18] Also, the present invention provides a compact size robot arm by forming an RCM with two overlappable linkage units. Since fewer parts are required for forming the RCM, failure rate may decrease. Brief Description of Drawings

[19] Fig.1 is a side view of an RCM mechanism according to a prior art.

[20] Fig.2 is a side view of linkage structure of a robot arm according to an embodiment of the present invention.

[21] Fig.3 shows a driving mechanism of a linkage structure of a surgical robot arm according to an embodiment of the present invention. Mode for the Invention

[22] Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. Also, specific descriptions on related prior art will be omitted in order to concentrate on the gist of the present invention.

[23] The terms first, second, third and the like in the description and in the claims, are use d for distinguishing between similar elements and not necessarily for describing a sequential or chronological order.

[24] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto only by the claims. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated.

[25] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof.

[26] Hereinafter, same reference characters designate the same or similar parts throughout the drawings and the repeated description about the same reference characters is omitted.

[27] Fig.2 is a side view of linkage structure of a robot arm according to an embodiment of the present invention. Fig.3 shows a driving mechanism of a linkage structure of a surgical robot arm according to an embodiment of the present invention. In Figs.2 and 3 are illustrated a robot arm 1, a first axis 3, a second axis 5, a third axis 7, a remote center of motion 9, a first linkage unit 10, a second linkage unit 20, and an instrument 30.

[28] This embodiment presents an active type linkage structure for controlling an RCM of the robot arm 1. This embodiment presents a serial type linkage structure in which linkage units are, unlike the parallel type having a 4-bar linkage as shown in Fig.l, serially linked to realize the RCM. [29] Also, unlike the prior art in which an RCM determination device is installed on a fixed base as shown in Fig.l, this embodiment realizes an RCM by linking linkage units in a serial type at an end of the moving robot arm 1.

[30] A linkage part for implementing the serial type RCM may comprise a single linkage unit, but if necessary, several sub linkage units may be assembled to form a linkage part functioning as a single linkage unit. While this embodiment describes an example in which each linkage unit is formed of a single unit, the present invention is not limited thereto.

[31] The linkage structure of the robot arm 1 according to this embodiment comprises the first linkage unit 10 forming an axial combination with a fore-end of the robot arm 1, the second linkage unit 20 forming an axial combination with an fore-end of the first linkage unit 10, and the instrument 30 forming an axial combination with a fore-end of the second likage unit 20.

[32] The first axis 3 refers to an axis combining the robot arm 1 with the first linkage unit, the first axis refers to an axis combining the first linkage unit 10 with the second linkage unit 20, and the third axis 7 refers to an axis combining the second linkage unit 20 with the instrument 30. In order to realize an RCM, the first axis 3, the second axis 5, and the third axis 7 are designed to concentrate on the remote center of motion 9, a predetermined point of the fore-end of the instrument 30, as shown in Fig.2.

[33] Accordingly, as shown in Figs. 3(b) and 3(c), even if the first linkage unit 10 is rotated with respect to the fore-end of the robot arm 1 about the first axis 3, a manipulation part on an end of the instrument 30 rotates about the first axis 3 without changing the remote center of motion 9. On the same principle, as shown in Figs. 3(d) and 3(e), even if the second linkage unit 20 is rotated with respect to the first linkage unit 10 about the second axis 5, the remote center of motion 9 remains unchanged, and even if the instrument 30 is rotated with respect to the second linkage unit 20 about the third axis 7, the remote center of motion 9 remains unchanged.

[34] As a result, this embodiment employs two linkage units and designs the combination axes to focus on the remote center of motion 9, thereby realizing an RCM and allowing the manipulation part disposed on the end of the instrument 30 to perform a spherical motion.

[35] This embodiment introduces an example that employs two linkage units, but additional linkage units may be added if necessary.

[36] While in the above description each linkage unit is formed of a single unit, it is also true that several sub units may also form one linkage unit. However, it is still true that in any case the combination axes of the linkage units should be designed to focus on the remote center of motion 9.

[37] In order to concentrate the first 3, the second 5, and the third 7 axes on the remote center of motion 9, the combination axes of the units may be perforated in the direction of the remote center of motion 9, or the first linkage unit 10 may be formed to be curved as shown in Fig.2. In this case, the first linkage unit 10 and the fore end of the robot arm 1 are jointed perpendicular to the surface, and the degree of curve of the first linkage unit 10 may be adjusted to concentrate the first axis 3 and the second axis 5 on the remote center of motion 9.

[38] Likewise, the second linkage unit 20 may be formed to be curved so that the second

5 and the third axes 7 concentrate on the remote center of motion 9. In this case, the first linkage unit 10 and the second linkage unit 20 are jointed perpendicular to the surface, the instrument 30 is combined perpendicular to the fore end of the second linkage unit 20, and the degree of curve of the second linkage unit 20 may be adjusted to concentrate the second axis 5 and the third axis 7 on the remote center of motion 9.

[39] Through the above configuration, a 'curve RCM' with two curved units is generated.

[40] Meanwhile, when the instrument 30 is removed, the second linkage unit 20 may be rotated about the second axis 5 to be overlapped with the first linkage unit 10, thereby saving the occupying space of the robot arm 1.

[41] In the same principle, the first linkage unit 10 and/or the first linkage unit 10 overlapped with the second linkage unit 20 may be rotated about the first axis 3 to be deposited on the robot arm 1, which may be materialized by forming a storage or forming the curve of the linkage units corresponding to the fore end of the robot arm 1. Industrial Applicability

[42] Although the present invention is described by referring to one of preferable embodiments, it will be appreciated by those skilled in the art that changes may be made without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

[1] A linkage structure for a surgical robot arm comprising: a robot arm; a first linkage unit forming an axis combination with a fore-end of the robot arm through a first axis; a second linkage unit forming an axis combination with the first linkage unit through a second axis; and an instrument forming an axis combination with the second linkage unit through a third axis, the first, second and third axes being formed such that extended lines of the three axes are concentrated on a predetermined point of a fore-end of the instrument. [2] The linkage structure for a surgical robot arm of Claim 1, wherein the first linkage unit is formed by perforating the first axis and the second axis in a sub linkage unit that is curved to a degree such that the first axis and the second axis are concentrated on the predetermined point [3] The linkage structure for a surgical robot arm of Claim 1, wherein the second linkage unit is formed by perforating the second and the third axes in a sub linkage unit that is curved to a degree such that the second axis and the third axis are concentrated on the predetermined point [4] The linkage structure for a surgical robot arm of Claim 1, wherein the second linkage unit is overlapped with the first linkage unit by rotating the second linkage unit about the second axis. [5] The linkage structure for a surgical robot arm of Claim 4, wherein the first linkage unit is deposited on the robot arm by rotating the first linkage unit about the first axis.