Externally-driven joint structure

Patent metadata

Field	Value
Publication number	US-11325244-B2
Application number	US-201716077349-A
Country	US
Kind code	B2
Filing date	Feb 10, 2017
Priority date	Feb 10, 2016
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

A modularized externally-driven joint structure can be used for general purposes. An externally-driven joint structure: includes a shaft member that extends in an axial direction; and a number of rotatable members that are arranged along the axial direction, and are coupled with each other by the shaft member in an axially rotatable manner. Each of the rotatable members includes a pair of face portions that face each other in the axial direction, a side wall portion that is arranged along the outer circumferential edges of the pair of face portions, and at least one coupling portion that is arranged at the face portions or the side wall portion, and is coupled with a link member constituting a link of a robot.

First claim

The invention claimed is:

1. An externally-driven joint structure comprising:
a shaft member that extends in an axial direction; and
a plurality of rotatable members that are arranged along the axial direction, and are coupled with each other by the shaft member in an axially rotatable manner,
wherein each of the rotatable members comprises:
a pair of face portions that face away from each other in the axial direction,
a side wall portion that is arranged along outer circumferential edges of the pair of face portions, and
at least one coupling portion that is arranged at the face portions or the side wall portion, and is coupled with a link member constituting a link of a robot,
wherein the plurality of rotatable members include a first rotating member and a second rotating member that are adjacent to each other in the axial direction,
the pair of face portions of the first rotating member include a first face portion that is adjacent to and faces the second rotating member,
the pair of face portions of the second rotating member include a second face portion that is adjacent to and faces the first rotating member, and
both of the first face portion and the second face portion are provided with a recess portion with a shape that allows a bearing in the shape of a ring that receives a force that acts in the axial direction to be accommodated between rotatable members that are adjacent to each other in the axial direction,
wherein the rotatable members have at least one coupling portion arranged at the side wall portions,
the side wall portion of the rotatable members is formed in the shape of a cylinder, and
the at least one coupling portion arranged at the side wall portions has a shape obtained by cutting, in a tangential direction, an arc portion of the side wall portion, the tangential direction being perpendicular to a radial direction of the cylinder.

2. The externally-driven joint structure according to claim 1 , wherein at least one rotatable member of the plurality of rotatable members comprises a plurality of the coupling portions arranged at the side wall portion.

3. The externally-driven joint structure according to claim 1 ,
wherein at least one rotatable member of the plurality of rotatable members comprises at least one coupling portion arranged at either one of the pair of face portions, and
other rotatable members of the plurality of rotatable members comprise at least one coupling portion arranged at the side wall portion.

4. The externally-driven joint structure according to claim 1 , wherein an encoder for detecting a relative rotational angle between the rotatable members that are adjacent to each other in the axial direction is further accommodated between the recess portions of the adjacent rotatable members.

5. The externally-driven joint structure according to claim 1 ,
wherein the recess portions are formed in the shape of a circular ring,
bases of inner circumferential faces of the recess portions are provided with a step portion in the shape of a circular ring extending inward in a radial direction from the inner circumferential faces,
a face portion of a rotatable member that faces the recess portions, the rotatable member being adjacent to the rotatable members, is provided with a projecting portion in the shape of a circular ring with a diameter smaller than that of the recess portions,
a base of an outer circumferential face of the projecting portion is provided with a step portion in the shape of a circular ring extending outward in the radial direction from the outer circumferential face of the projecting portion, and
a cross roller bearing as the bearing in the shape of a ring is arranged so as to be supported by the inner circumferential face of the recess portion, a face along the axial direction of the step portion of the recess portion, the outer circumferential face of the projecting portion, and a face along the axial direction of the step portion of the projecting portion.

6. The externally-driven joint structure according to claim 1 , comprising two rotatable members of the plurality of rotatable members,
wherein the coupling portions of the rotatable members are arranged symmetric about the axial direction such that, even when the joint structure is reversed about an axis that is perpendicular to the axial direction, the joint structure can be used while a positional relationship between the link members is maintained,
one of the two rotatable members is formed in one piece with the shaft member,
another rotatable member of the two rotatable members has a through hole into which the shaft member is allowed to be inserted, and
a radial bearing is arranged so as to be interference-fitted to the shaft member and clearance-fitted to an inner circumferential wall of the through hole, or so as to be clearance-fitted to the shaft member and interference-fitted to the inner circumferential wall of the through hole.

7. A link mechanism comprising:
two or more joint structures according to claim 6 ; and
the link member that is coupled with two joint structures of the two or more joint structures, one end of the link member being coupled with one of the at least one coupling portion of one of the two rotating members, another end of the link member being coupled with one of the at least one coupling portion of another of the two rotating members,

wherein the two joint structures that are adjacent to each other via the link member are arranged such that one of the joint structures is used in a state of being reversed about an axis that is perpendicular to the axial direction with respect to the other joint structure so that the rotatable members face each other in the direction that is perpendicular to the axial direction.

8. The externally-driven joint structure according to claim 1 , comprising three or more rotatable members,
wherein the coupling portions of at least two rotatable members of the three or more rotatable members are coupled with a same link member.

9. The externally-driven joint structure according to claim 1 , wherein coupling between the coupling portions and the link member is constituted by a magnet.

10. The externally-driven joint structure according to claim 1 , wherein the side wall portions of the rotatable members have a height that matches a thickness of the link member, the height of the side wall portions being a length along the axial direction and the thickness of the link member being a length along the axial direction when connected to one of the side wall portions of the rotatable members.

11. The externally-driven joint structure according to claim 1 , wherein the coupling portions arranged at the side wall portions have a projecting portion projecting outward in the radial direction at a center in the tangential direction, in conformity with a recess portion provided at a center of an end face of the link member.

12. The externally-driven joint structure according to claim 1 , wherein a reinforcing plate for supporting a coupling region of the coupling portion arranged at the side wall portion of the rotatable member and the link member is provided on at least one of both sides in the axial direction of the coupling region.

13. A link mechanism comprising:
the joint structure according to claim 1 ; and
the link member that is coupled with the coupling portion arranged at the side wall portions of the rotatable members of the joint structure,
wherein at least one of the side wall portions of the rotatable members of the joint structure comprises a wire-driving groove portion,
a fixture is attached to the link member, and
a wire that is driven by an e

Assignees

• Advanced Telecommunications Res Institute International
• Univ Osaka

Inventors

• Noda Tomoyuki
• Nakata Yoshihiro
• Ishiguro Hiroshi
• Morimoto Jun

Classifications

• B25J17/02

  Wrist joints · CPC title

• B25J9/08 Primary

  characterised by modular constructions · CPC title

• B25J17/00

  Joints · CPC title

• F16C35/06

  Mounting {or dismounting} of ball or roller bearings; Fixing them onto shaft or in housing · CPC title

• B25J13/088

  with position, velocity or acceleration sensors · CPC title