CONTINUUM ROBOT, MODIFICATION METHOD OF KINEMATIC MODEL OF CONTINUUM ROBOT, AND CONTROL METHOD OF CONTINUUM ROBOT

• US 20190321976A1
• Filed: 07/05/2017
• Published: 10/24/2019
• Est. Priority Date: 07/13/2016
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: TAKAGI, Kiyoshi
• Granted Patent: US 11,331,797 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2034/301 for introducing or steering flexible instruments inserted into the body, e.g. catheters or endoscopes
• CPC Class Codes: A61B 34/30 Surgical robots
• CPC Class Codes: A61B 34/71 Manipulators operated by drive cable mechanisms
• CPC Class Codes: A61M 25/0116 self-propelled, e.g. autonomous robots A61M25/0122 takes precedence
• CPC Class Codes: B25J 18/06 flexible
• CPC Class Codes: B25J 9/1625 Truss-manipulator for snake-like motion
• CPC Class Codes: G05B 2219/40234 Snake arm, flexi-digit robotic manipulator, a hand at each end

Abstract

A continuum robot includes a curvable first curvable portion, a curvable second curvable portion provided adjacent to the first curvable portion, a first wire connected to the first curvable portion, a second wire connected to the second curvable portion, and a control unit which controls curves of the first curvable portion and the second curvable portion by controlling driving of the first wire and the second wire. The control unit controls driving of the first wire and the second wire on the basis of a kinematic model in consideration of a curve of the second curvable portion accompanying driving the first wire and a curve of the first curvable portion accompanying driving of the second wire. Alternatively, the control unit controls driving of the first wire and the second wire so that a curve target value of the first curvable portion is achieved by the sum of curved amounts of the first curvable portion and the second curvable portion.

Claims

1. A continuum robot, comprising:

a first curvable portion capable of curving;

at least one second curvable portion provided adjacent to the first curvable portion and capable of curving;

a first wire connected to the first curvable portion;

a second wire connected to the second curvable portion; and

a control unit configured to control curves of the first curvable portion and the second curvable portion by controlling driving of the first wire and the second wire,

wherein the control unit controls driving of the first wire and the second wire on the basis of a kinematic model in consideration of a curve of the second curvable portion accompanying driving of the first wire in order to curve the first curvable portion and a curve of the first curvable portion accompanying driving of the second wire in order to curve the second curvable portion.

3. The continuum robot according to claim 1, wherein the control unit performs follow-the-leader control.

2. A continuum robot, comprising:

a first curvable portion capable of curving;

at least one second curvable portion provided adjacent to the first curvable portion and capable of curving;

a first wire connected to the first curvable portion;

a second wire connected to the second curvable portion; and

a control unit configured to control curves of the first curvable portion and the second curvable portion by controlling driving of the first wire and the second wire,

wherein the control unit controls driving of the first wire and the second wire so that a curve target value of the first curvable portion is achieved by the sum of curved amounts of the first curvable portion and the second curvable portion.

17. The continuum robot according to claim 2, wherein the control unit performs follow-the-leader control.

4. A modification method of a kinematic model of a continuum robot, which includes a first curvable portion capable of curving, at least one second curvable portion provided adjacent to the first curvable portion and capable of curving, a first wire connected to the first curvable portion, and a second wire connected to the second curvable portion, the method comprising modifying the kinematic model by using a model in consideration of a curve of the second curvable portion accompanying driving of the first wire in order to curve the first curvable portion and a curve of the first curvable portion accompanying driving of the second wire in order to curve the second curvable portion.

6. The modification method according to claim 4, wherein a modification value for modifying a kinematic model which represents a relationship between data of a target position of the curvable portion and a position of the curvable portion by a driven displacement of the first wire and the second wire derived from the data in accordance with a mechanism of the continuum robot is obtained by an algorithm using an optimization technique to reduce a difference between data of the target position of the curvable portion when the continuum robot obtains a predetermined position and a measurement value related to an actual position of the curvable portion.

7. The correcting method according to claim 6, wherein a measurement displacement of the curvable portion controlled by a driven displacement of the wire in accordance with data of a first predetermined representative position of the continuum robot is obtained, a modification coefficient with respect to the first predetermined representative position is obtained by a steepest descent method by using the measurement displacement, the data of the first predetermined representative position, and an initial value of the modification coefficient, this method is used similarly to a second predetermined representative position to obtain a modification coefficient with respect to the second predetermined representative position, so that the modification coefficient is obtained with respect to each of a plurality of predetermined representative positions, and the modification value is obtained.

8. The modification method according to claim 7, wherein the modification coefficient obtained with respect to the first predetermined representative position is used as an initial value of the modification coefficient of the steepest descent method with respect to the second predetermined representative position.

9. The modification method according to claim 7, wherein the iterative optimization technique is used, and a modification coefficient obtained in a first previous time is used as an initial value of a modification coefficient of each time.

10. The modification method according to claim 7, wherein a mean value of all the modification coefficients is obtained and is defined as the modification value.

11. The modification method according to claim 6, wherein the modification value is obtained by using a model in which an angle obtained by multiplying the curve relative angle in the i-th curvable portion by a coefficient γ

p[i] is added to the curve relative angle in the adjacent (i−

1)th curvable portion, an angle obtained by multiplying the curve relative angle in the i-th curvable portion by another coefficient γ

d[i] is added to the curve relative angle in the adjacent (i+1)th curvable portion, and an angle obtained by multiplying the curve relative angle in the i-th curvable portion by (γ

p[i]+yd[i]) is subtracted from the curve relative angle in the i-th curvable portion (i is 2 or greater and equal to or smaller than (the number of curvable portions)−

1).

12. The modification method according to claim 11, wherein the modification value is obtained from a modification matrix.

13. The modification method according to claim 12, wherein in the modification matrix, i-th row, i-th column is defined as 1−

γ

d[i]−

γ

p[i], i-th row, (i−

1)th column is defined as γ

d[i−

1], and i-th row, (i+1)th column is defined as γ

p[i+1].

14. A control method of a continuum robot, which includes a first curvable portion capable of curving, at least one second curvable portion provided adjacent to the first curvable portion and capable of curving, a first wire connected to the first curvable portion, and a second wire connected to the second curvable portion, the method comprising:

obtaining a target position modified by multiplying data of the target position of the curvable portion by an inverse of a modification value by using the modification method according to claim 6 and,

controlling the curvable portion by a driven displacement of the wire calculated in accordance with the modified target position.

15. The control method according to claim 14, wherein not only control of a previously set curvature, but also control of a curvature by a real-time operation is performed by adding an additional target value of the curvature to data of the target position.

16. The control method according to claim 14, wherein follow-the-leader control with respect to a trajectory of inconstant curvature is performed by multiplying an inverse of the modification value by an additional gain.

19. The control method according to claim 15, wherein follow-the-leader control with respect to a trajectory of inconstant curvature is performed by multiplying an inverse of the modification value by an additional gain.

5. A modification method of a kinematic model of a continuum robot, which includes a first curvable portion capable of curving, at least one second curvable portion provided adjacent to the first curvable portion and capable of curving, a first wire connected to the first curvable portion, and a second wire connected to the second curvable portion, the method comprising modifying the kinematic model by using a model for controlling driving of the first wire and the second wire so that a curve target value of the first curvable portion is achieved by the sum of curved amounts of the first curvable portion and the second curvable portion.

18. The modification method according to claim 5, wherein a modification value for modifying a kinematic model which represents a relationship between data of a target position of the curvable portion and a position of the curvable portion by a driven displacement of the first wire and the second wire derived from the data in accordance with a mechanism of the continuum robot is obtained by an algorithm using an optimization technique to reduce a difference between data of the target position of the curvable portion when the continuum robot obtains a predetermined position and a measurement value related to an actual position of the curvable portion.