US-12617077-B2 - Continuum robot control system and continuum robot control method

US12617077B2US 12617077 B2US12617077 B2US 12617077B2US-12617077-B2

Abstract

A control unit that controls the motion of a continuum robot including a bendable unit having a plurality of bending sections, defines a predetermined position on a wire guide located most distal from a base in the second bending section, which is a follower bending section, as an origin, sets reference axes for a direction in which the wire guide is facing, and causes a drive unit in the base to drive a wire of the third bending section so that the third bending section, which is a distal bending section, is bent on the basis of a relative coordinate system in which the origin and the reference axes relating to the wire guide vary in accordance with the movement of the continuum robot.

Inventors

Kiyoshi Takagi

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20240812
Priority Date: 20220214

Claims (19)

1 . A continuum robot control system comprising: a continuum robot including a bendable body having a plurality of bending sections each configured to be bent by a linear member that is driven, a base configured to support the bendable body, and a drive driver configured to drive the linear member, wherein the plurality of bending sections of the bendable body include a distal bending section that is located distal from the base and that includes a distal fixed member located most distal from the base in the distal bending section and a distal linear member serving as the linear member fixed to the distal fixed member and driven by the driver and at least one follower bending section that is located between the distal bending section and the base and that includes a follower fixed member located most distal from the base in the at least one follower bending section and a follower linear member serving as the linear member fixed to the follower fixed member and driven by the driver; and a controller configured to control a motion of the continuum robot, wherein the controller defines a predetermined position on the follower fixed member as an origin, sets reference axes for a direction in which the follower fixed member is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the follower fixed member, and causes the driver to drive the distal linear member so that the distal bending section is bent based on a relative coordinate system in which the origin and the reference axes relating to the follower fixed member vary in accordance with the movement of the continuum robot, and wherein the controller operates to: (i) determine a bend angle between a reference axis extending orthogonally from a predetermined position on the distal fixed member of the distal bending section and a reference axis extending from the predetermined position on the distal fixed member of the distal bending section and corresponding to or being parallel to the one orthogonal reference axis of the follower fixed member; and (ii) use the determined bend angle to drive the distal linear member and bend the distal bending section.
2 . The continuum robot control system according to claim 1 , wherein the at least one follower bending section includes a first follower bending section and a second follower bending section, wherein the first follower bending section is located between the distal bending section and the second follower bending section and includes a first follower fixed member that is located most distal from the base in the first follower bending section and a first follower linear member serving as the linear member that is fixed to the first follower fixed member and that is driven by the driver, wherein the second follower bending section is located between the first follower bending section and the base and includes a second follower fixed member that is located most distal from the base in the second follower bending section and a second follower linear member serving as the linear member that is fixed to the second follower fixed member and that is driven by the driver, wherein the controller defines the predetermined position on the first follower fixed member as the origin, sets the reference axes for a direction in which the first follower fixed member is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the first follower fixed member, and causes the driver to drive the distal linear member so that the distal bending section is bent based on a first relative coordinate system serving as the relative coordinate system in which the origin and the reference axes relating to the first follower fixed member vary in accordance with the movement of the continuum robot, the bend angle being used to drive the distal linear member and to bend the distal bending section being determined to be between the reference axis extending orthogonally from the predetermined position on the distal fixed member of the distal bending section and a reference axis extending from the predetermined position on the distal fixed member of the distal bending section and corresponding to or being parallel to the one orthogonal reference axis of the first follower fixed member, wherein the controller defines the predetermined position on the second follower fixed member as an origin, sets reference axes for a direction in which the second follower fixed member is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the second follower fixed member, and causes the driver to drive the first follower linear member so that the first follower bending section is bent following a bending motion of the distal bending section based on a second relative coordinate system serving as the relative coordinate system in which the origin and the reference axes relating to the second follower fixed member vary in accordance with the movement of the continuum robot, and wherein the controller further operates to (i) determine a bend angle between a reference axis extending orthogonally from the predetermined position on the first follower fixed member of the first follower bending section and a reference axis extending from the predetermined position on the first follower fixed member of the first follower bending section and corresponding to or being parallel to the one orthogonal reference axis of the second follower fixed member; and (ii) use the determined bend angle to drive the first follower linear member and bend the first follower bending section.
3 . The continuum robot control system according to claim 2 , wherein the controller includes one or more processors that operate to: (i) calculate a driving amount of the distal linear member and a driving amount of the follower linear member in the relative coordinate system based on an input target bending angle of the distal bending section and an input target bending angle of the at least one follower bending section in the relative coordinate system, and (ii) transform the driving amount of the distal linear member and the driving amount of the follower linear member in the relative coordinate system into, and to obtain, a driving amount of the distal linear member and a driving amount of the follower linear member in an absolute coordinate system, and wherein the controller controls the driver based on the driving amount of the distal linear member and the driving amount of the follower linear member in the absolute coordinate system so that the bend angle of the distal bending section becomes or matches the input target bending angle of the distal bending section and so that the bend angle of the first follower bending section becomes or matches the input target bending angle of the first follower bending section.
4 . The continuum robot control system according to claim 2 , wherein the controller further operates to: (i) define a predetermined position on the base as an origin, set reference axes for a direction in which the base is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the base, and cause the driver to drive the second follower linear member so that the second follower bending section is bent following a bending motion of the distal bending section and/or the first follower bending section based on a third relative coordinate system serving as the relative coordinate system in which the origin and the reference axes relating to the base vary in accordance with the movement of the continuum robot, and the controller further operates to (i) determine a bend angle between a reference axis extending orthogonally from the predetermined position on the second follower fixed member of the second follower bending section and a reference axis extending from the predetermined position on the second follower fixed member of the second follower bending section and corresponding to or being parallel to the one orthogonal reference axis of the base; and (ii) use the determined bend angle to drive the second follower linear member and bend the second follower bending section.
5 . The continuum robot control system according to claim 4 , wherein the absolute coordinate system is equivalent to the third relative coordinate system.
6 . The continuum robot control system according to claim 2 , wherein the controller includes one or more processors that operate to: (i) determine and use a respective turning angle for the distal bending section, the first follower bending section, and/or the second follower bending section to cause the driver to drive and turn one or more of the distal bending section, the first follower bending section, and/or the second follower bending section; (ii) determine and use a respective radius of curvature for the distal bending section, the first follower bending section, and/or the second follower bending section to cause the driver to drive and cause to curve one or more of the distal bending section, the first follower bending section, and/or the second follower bending section; and/or (iii) determine and use a respective phase angle for the distal bending section, the first follower bending section, and/or the second follower bending section to cause the driver to drive the respective distal linear member, the first follower linear member, and/or the second follower linear member.
7 . The continuum robot control system according to claim 1 , wherein the controller includes one or more processors that operate configured to: (i) calculate a driving amount of the distal linear member and a driving amount of the follower linear member in the relative coordinate system based on an input target bending angle of the distal bending section and an input target bending angle of the at least one follower bending section in the relative coordinate system, and (ii) transform the driving amount of the distal linear member and the driving amount of the follower linear member in the relative coordinate system into, and to obtain, a driving amount of the distal linear member and a driving amount of the follower linear member in an absolute coordinate system, and wherein the controller controls the driver based on the driving amount of the distal linear member and the driving amount of the follower linear member in the absolute coordinate system so that the bend angle of the distal bending section becomes or matches the input target bending angle of the distal bending section.
8 . The continuum robot control system according to claim 7 , wherein the one or more processors further operate to calculate a target bending angle of the at least one follower bending section in the relative coordinate system based on the input target bending angle of the distal bending section in the relative coordinate system, a displacement of the base, and a length of the at least one follower bending section, and wherein the one or more processors perform-performs the calculation using the calculated target bending angle of the at least one follower bending section in the relative coordinate system.
9 . The continuum robot control system according to claim 8 , wherein when calculating the target bending angle of the at least one follower bending section in the relative coordinate system, the one or more processors further operate to divide the at least one follower bending section into a plurality of sections and perform a process to superimpose the target bending angles of the plurality of sections in the relative coordinate system when the at least one follower bending section bends following the bending motion of the distal bending section.
10 . The continuum robot control system according to claim 9 , wherein when calculating the target bending angle of the at least one follower bending section in the relative coordinate system, the one or more processors further operate to divide the at least one follower bending section into a plurality of virtual bending sections and perform the process to superimpose the target bending angles of the plurality of virtual bending sections in the relative coordinate system when the at least one follower bending section bends following the bending motion of the distal bending section.
11 . The continuum robot control system according to claim 7 , wherein when obtaining the driving amount of the distal linear member in the absolute coordinate system, the one or more processors add the driving amount of the follower linear member to the driving amount of the distal linear member in the relative coordinate system.
12 . The continuum robot control system according to claim 1 , wherein: (i) the controller operates to receive a target bending angle of the distal bending section from an input device; (ii) the controller operates to receive a target bending angle of the at least one follower bending section from an input device; (iii the controller operates to receive a displacement of the base from an input device; (iv) the controller operates to receive additional information from an input device, the additional information including one or more of the following: a length of the distal bending section and/or a length of the at least one follower section; and/or (v) the controller operates to drive the continuum robot using one or more of the following: the target bending angle of the distal bending section, the target bending angle of the at least one follower bending section, the displacement of the base, and/or the additional information.
13 . The continuum robot control system according to claim 1 , wherein a relationship between a driving displacement l p1 of a linear member and a bending angle θ 1 is given by the following equation: l p1 = 3 / 2 r 1 θ 1 (1).
14 . The continuum robot control system according to claim 1 , wherein a relationship between a driving displacement or amount l pn of a linear member in an n-th bending section is a sum of the driving displacements or amounts of a linear member for driving the n-th bending section in the relative coordinate system in a first bending section to the (n−1)th bending section, and is expressed by the following equations (4) and (5): l pn ={tilde over (l)} pn +{tilde over (l)} pn-1 + . . . +{tilde over (l)} p1 (4) =3/2 r n ({tilde over (θ)} n +{tilde over (θ)} n-1 + . . . +θ 1 )=3/2 r n θ n (5).
15 . The continuum robot control system according to claim 1 , wherein a relationship between a bending angle θ 1 of a first bending section at a distal end and coordinates (x t1 , z t1 ) of the distal end is expressed by the following equations (6) and (7): x t1 =l 1 /θ 1 (1−cos θ 1 ) (6) z t1 =l 1 /θ 1 sin θ 1 (7).
16 . The continuum robot control system according to claim 15 , wherein, when using a rotation transformation matrix, the coordinates (x t1 , z t1 ) of the distal end are expressed using the following equation (10): [ x tn z tn ] = [ x t ⁢ 1 z b + z t ⁢ 1 ] + ∑ m = 2 n [ cos ⁢ θ ~ m - 1 sin ⁢ θ ~ m - 1 - sin ⁢ θ ~ m - 1 cos ⁢ θ ~ m - 1 ] [ l m θ ~ m ⁢ ( 1 - cos ⁢ θ ~ m ) l m θ ~ m ⁢ sin ⁢ θ ~ m ] . ( 10 )
17 . The continuum robot control system according to claim 1 , wherein the controller further includes a storage or memory that operates to store one or more reference tables each indicating a relationship between a pair of a target bending angle of the distal bending section and a target bending angle of the at least one follower bending section; and the controller includes one or more processors that operate to: (i) rewrite one or more of the reference tables and (ii) input to the one or more reference tables information regarding a length of the distal bending section or of the at least one follower bending section and information specifying the reference table of the one or more reference tables to be used to rewrite the selected reference table in accordance with a change in the target bending angle of the distal bending section and the displacement of the base.
18 . A continuum robot control method for use of a continuum robot control system, the system including a continuum robot including a bendable body having a plurality of bending sections each configured to be bent by a linear member that is driven, a base configured to support the bendable body, and a driver configured to drive the linear member, wherein the plurality of bending sections of the bendable body include a distal bending section that is located distal from the base and that includes a distal fixed member located most distal from the base in the distal bending section and a distal linear member serving as the linear member fixed to the distal fixed member and driven by the driver and at least one follower bending section that is located between the distal bending section and the base and that includes a follower fixed member located most distal from the base in the at least one follower bending section and a follower linear member serving as the linear member fixed to the follower fixed member and driven by the driver, and a controller configured to control a motion of the continuum robot, the continuum robot control method comprising: defining, by the controller, a predetermined position on the follower fixed member as an origin; setting, by the controller, reference axes for a direction in which the follower fixed member is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the follower fixed member; determining, by the controller, a bend angle between a reference axis extending orthogonally from a predetermined position on the distal fixed member of the distal bending section and a reference axis extending from the predetermined position on the distal fixed member of the distal bending section and corresponding to or being parallel to the one orthogonal reference axis of the follower fixed member; and causing, by the controller, the driver to drive the distal linear member so that the distal bending section is bent based on a relative coordinate system in which the origin and the reference axes relating to the follower fixed member vary in accordance with the movement of the continuum robot and using the determined bend angle to drive the distal linear member and bend the distal bending section.
19 . A non-transitory computer-readable storage medium storing one or more control programs that operate to cause a computer to perform a continuum robot control method for use of a continuum robot control system, the system including a continuum robot including a bendable body having a plurality of bending sections each configured to be bent by a linear member that is driven, a base configured to support the bendable body, and a driver configured to drive the linear member, wherein the plurality of bending sections of the bendable body include a distal bending section that is located distal from the base and that includes a distal fixed member located most distal from the base in the distal bending section and a distal linear member serving as the linear member fixed to the distal fixed member and driven by the driver and at least one follower bending section that is located between the distal bending section and the base and that includes a follower fixed member located most distal from the base in the at least one follower bending section and a follower linear member serving as the linear member fixed to the follower fixed member and driven by the driver, and a controller configured to control a motion of the continuum robot, the continuum robot control method comprising: defining, by the controller, a predetermined position on the follower fixed member as an origin; setting, by the controller, reference axes for a direction in which the follower fixed member is facing where one reference axis of the reference axes extends orthogonally from the predetermined position on the follower fixed member; determining, by the controller, a bend angle between a reference axis extending orthogonally from a predetermined position on the distal fixed member of the distal bending section and a reference axis extending from the predetermined position on the distal fixed member of the distal bending section and corresponding to or being parallel to the one orthogonal reference axis of the follower fixed member; and causing, by the controller, the driver to drive the distal linear member so that the distal bending section is bent based on a relative coordinate system in which the origin and the reference axes relating to the follower fixed member vary in accordance with the movement of the continuum robot and using the determined bend angle to drive the distal linear member and bend the distal bending section.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Continuation of International Patent Application No. PCT/JP2023/001645, filed Jan. 20, 2023, which claims the benefit of Japanese Patent Application No. 2022-020491, filed Feb. 14, 2022, both of which are hereby incorporated by reference herein in their entireties. TECHNICAL FIELD The present disclosure relates to a continuum robot control system and a continuum robot control method for controlling the motion of a continuum robot. BACKGROUND ART A continuum robot has a bendable unit including a plurality of bending sections with a flexible structure. The shape of the continuum robot is controlled by deforming the bending sections. A continuum robot has mainly two advantages over a robot configured with rigid links. The first advantage is that the continuum robot can move along a curve in a narrow space or in an environment with scattered objects in which the rigid-link robot may get stuck. The second advantage is that since the continuum robot has intrinsic softness, the continuum robot can be operated without damaging a fragile object. Continuum robots do not necessarily have to detect an external force, which is required for rigid-link robots. Taking advantage of this feature, continuum robots are expected to be applied to the field of healthcare, such as an endoscope sheath and a catheter, and to extreme work robots, such as rescue robots. PTL 1 describes a control method for controlling a bendable unit of a continuum robot used as an endoscope when the bendable unit enters a narrow space. More specifically, in PTL 1, for all pairs of neighboring bending sections in the bendable unit, control (leader following control) is performed so that the bending shape of a following bending section follows the bending shape of the leading bending section as a base of an endoscope moves forward and, thus, the shape of the endoscope is continuously propagated. In this case, according to PTL 1, the bending angle of the most distal (forward) bending section is continuously propagated to the following bending section over a virtual section length smaller than the actual bending section length. Thus, a command is sent so that the bending angle of the following bending section gets closer to the bending angle of the leading bending section. As a result, contact with a surrounding obstacle is less likely to occur in a narrow space and, therefore, entry into a narrow space path is facilitated. CITATION LIST Patent Literature PTL 1 U.S. Pat. No. 11,103,992 In PTL 1, in the above-mentioned leader following control, a coordinate system is established on a slide stage that has a continuum robot fixed thereon and that moves forward and backward, and the bending angles of all bending sections are determined based on the coordinate system. The technique described in PTL 1 facilitates the operation performed by the operator, because when the operator can look down on the continuum robot, they can grasp the correspondence between the coordinate system for the operation of a bendable unit having a plurality of bending sections and the coordinate system for the front end of the continuum robot. In addition, the amount of calculation in a control system is reduced. However, according to the technique described in PTL 1, for example, when a camera is mounted at the most distal end of the continuum robot, and then, the operator who cannot look down on the continuum robot operates the bendable unit while observing a camera image, it is difficult for the operator to intuitively operate the bendable unit because it is difficult to grasp the bending conditions of the following bending section. SUMMARY OF INVENTION Accordingly, it is at least one object of the present disclosure to provide a mechanism that enables the operator to intuitively operate the bendable unit of the continuum robot. According to at least one aspect of the present disclosure, a continuum robot control system includes a continuum robot including a bendable unit having a plurality of bending sections each configured to be bent by a linear member that is driven, a base configured to support the bendable unit, and a drive unit configured to drive the linear member, where the plurality of bending sections of the bendable unit include a distal bending section that is located distal from the base and that includes a distal fixed member located most distal from the base in the distal bending section and a distal linear member serving as the linear member fixed to the distal fixed member and driven by the drive unit and a follower bending section that is located between the distal bending section and the base and that includes a follower fixed member located most distal from the base in the follower bending section and a follower linear member serving as the linear member fixed to the follower fixed member and driven by the drive unit, and a control unit configured to control the motion of the continuum robot. The co