Joint structure and robot arm Number:7,367,245 from the United States Patent and Trademark Office (PTO) owispatent A joint structure includes a rotating guide pulley, a fixed guide, and a rotating guide pulley. The rotating guide pulley is coaxial with a rotating shaft of a revolute joint, and is arranged so as to be rotatable about the rotating shaft. The fixed guide is arranged in a first structure, and has an arc portion. The arc portion has the same radius as the rotating guide pulley and is coaxial with the rotating guide pulley. The rotating guide pulley is arranged in a second structure so as to be relatively movable. A wire is put round the rotating guide pulley, the movable rotating guide pulley, and the fixed guide in the order of them.<H structure, robot, Joint, structure, 7367245.html, Patent, pto, 7367245

Title: Joint structure and robot arm

Abstract: A joint structure includes a rotating guide pulley, a fixed guide, and a rotating guide pulley. The rotating guide pulley is coaxial with a rotating shaft of a revolute joint, and is arranged so as to be rotatable about the rotating shaft. The fixed guide is arranged in a first structure, and has an arc portion. The arc portion has the same radius as the rotating guide pulley and is coaxial with the rotating guide pulley. The rotating guide pulley is arranged in a second structure so as to be relatively movable. A wire is put round the rotating guide pulley, the movable rotating guide pulley, and the fixed guide in the order of them.

Patent Number: 7,367,245 Issued on 05/06/2008 to Okazaki, et al.

Inventors: Okazaki; Yasunao (Shiga, JP), Asai; Katsuhiko (Nara, JP)
Assignee: Matsushita Electric Industrial Co., Ltd. (Osaka, JP)

Appl. No.: 11/785,366

Filed: April 17, 2007

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
PCT/JP2005/021239	Nov., 2005

Foreign Application Priority Data


Nov 22, 2004 [JP]			2004-337067

Current U.S. Class: 74/490.04 ; 74/490.05; 74/490.06; 901/21; 901/28

Current International Class: B25J 17/00 (20060101)

Field of Search: 74/490.01,490.04,490.05,490.06 901/21,27,28

References Cited [Referenced By]

U.S. Patent Documents


5046375	September 1991	Salisbury et al.
5778730	July 1998	Solomon et al.
6077027	June 2000	Kawamura et al.
2004/0250644	December 2004	Gosselin et al.
2005/0053453	March 2005	Wilson
2007/0193398	August 2007	Kawabuchi et al.
2007/0256513	November 2007	Forslund et al.

Foreign Patent Documents


61-249292	Nov., 1986	JP
3-26476	Feb., 1991	JP
6-77914	Oct., 1994	JP
3290709	Jun., 2002	JP
2004-306224	Nov., 2004	JP
2005-46980	Feb., 2005	JP

Primary Examiner: Fenstermacher; David M.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack, L.L.P.

Parent Case Text

This is a continuation application of International Application No. PCT/JP2005/021239, filed Nov. 18, 2005.

Claims

What is claimed is:

1. A joint structure comprising: a first structure; a second structure; a revolute joint for connecting the first structure and the second structure; a rotating guide pulley which is coaxial with a rotating shaft of the revolute joint and arranged so as to be rotatable about the rotating shaft; a fixed guide which is arranged in the first structure, the fixed guide having an arc portion; a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable; a wire which is put round the rotating guide pulley, the movable rotating guide pulley, and the fixed guide in an order of the rotating guide pulley, the movable rotating guide pulley, and the fixed guide; a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; and a second drive apparatus, which is included in the first structure, for driving the wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire, wherein the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the rotating guide pulley.

2. A joint structure according to claim 1, wherein the fixed guide is formed as a part of a member fixed to the first structure.

3. A joint structure according to claim 1, wherein the movable rotating guide pulley has a structure in which a first movable rotating guide pulley whose guide groove is located in a same plane as a plane including a guide groove of the rotating guide pulley and a second movable rotating guide pulley whose guide groove is located in a same plane as a plane including a guide groove of the fixed guide are integrally formed.

4. A joint structure according to claim 1, wherein the movable rotating guide pulley has a first guide groove located in a same plane as a plane including a guide groove of the rotating guide pulley and a second guide groove located in a same plane as a plane including a guide groove of the fixed guide.

5. A joint structure comprising: a first structure; a second structure; a revolute joint for connecting the first structure and the second structure; a first rotating guide pulley and a second rotating guide pulley which are coaxial with a rotating shaft of the revolute joint, the first rotating guide pulley and the second rotating guide pulley being arranged in the first structure or the second structure so as to be rotatable about the rotating shaft respectively, the first rotating guide pulley and the second rotating guide pulley being capable of rotating relative to each other; a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable; an auxiliary rotating guide pulley which is provided in the first structure while freely rotated; a wire which is put round the first rotating guide pulley, the movable rotating guide pulley, the second rotating guide pulley, and the auxiliary rotating guide pulley in an order of the first rotating guide pulley, the movable rotating guide pulley, the second rotating guide pulley, and the auxiliary rotating guide pulley, both end portions of the wire being fixed to the second drive apparatus; a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the first and second rotating guide pulleys; and a second drive apparatus, which is included in the first structure, for driving the wire, and moving the movable rotating guide pulley to change the distance to the first and second rotating guide pulleys by driving the wire, wherein the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the first and second rotating guide pulleys.

6. A joint structure comprising: a first structure; a second structure; a revolute joint for connecting the first structure and the second structure; a third rotating guide pulley which is coaxial with a rotating shaft of the revolute joint, and arranged so as to be rotatable about the rotating shaft; a fourth rotating guide pulley which is arranged in the second structure while freely rotated; a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable; a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; and a second drive apparatus, which is included in the first structure, for driving a wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire; and the wire which is put round the third rotating guide pulley, the movable rotating guide pulley, and the fourth rotating guide pulley in an order of the third rotating guide pulley, the movable rotating guide pulley, and the fourth rotating guide pulley, one end portion of the wire being fixed to the second drive apparatus, the other end portion being fixed to the fourth rotating guide pulley; a first parallel link whose one end portion is supported by the first structure while freely rotated; and a second parallel link in which one end portion is connected to the other end portion of the first parallel link so as to be freely rotated and the other end portion is fixed to the fourth rotating guide pulley, wherein a four-node parallel link structure is formed so as to have four fulcrums of a portion where the one end portion of the first parallel link is supported to the first structure, a portion where the other end portion of the first parallel link and the one end portion of the second parallel link are connected to each other, a portion where the other end portion of the second parallel link is fixed to the fourth rotating guide pulley, and a portion which is arranged in the second structure of the fourth rotating guide pulley while freely rotated, and the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the third rotating guide pulley.

7. A joint structure comprising: a first structure; a second structure; a rotating guide pulley which is coaxial with a rotating shaft of the revolute joint, and arranged so as to be rotatable about the rotating shaft; a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable; a first drive apparatus which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; a second drive apparatus which is included in the first structure, for driving a wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire; the wire which is put round the rotating guide pulley and the movable rotating guide pulley in an order of the rotating guide pulley and the movable rotating guide pulley, one end portion of the wire being fixed to the second drive apparatus, the other end portion being fixed to the movable rotating guide pulley; a first parallel link whose one end portion is supported by the first structure while freely rotated; and a second parallel link in which one end portion is connected to the other end portion of the first parallel link while being freely slidable and rotatable and the other end portion is fixed to the movable rotating guide pulley, wherein a four-node parallel link structure is formed while having four fulcrums of a portion where the one end portion of the first parallel link is supported to the first structure, a portion where the other end portion of the first parallel link and the one end portion of the second parallel link are connected to each other, a portion where the other end portion of the second parallel link is fixed to the movable rotating guide pulley, and a portion which is arranged in the second structure of the rotating guide pulley while freely rotated, and the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the rotating guide pulley.

8. A robot arm comprising: a joint structure as in claim 1; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

9. A robot arm comprising: a joint structure as in claim 2; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

10. A robot arm comprising: a joint structure as in claim 3; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

11. A robot arm comprising: a joint structure as in claim 4; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

12. A robot arm comprising: a joint structure as in claim 5; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

13. A robot arm comprising: a joint structure as in claim 6; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

14. A robot arm comprising: a joint structure as in claim 7; a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and a hand driving wire for connecting the movable rotating guide pulley and the hand, wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a joint structure which can be applied to a joint mechanism of a mechanical apparatus such as a robot arm, and the robot arm including the joint structure.

Conventionally, in a structure of a multiple-joint robot arm, an actuator which drives a joint is usually arranged in a joint portion or near the joint portion. However, in such a structure, hand inertia becomes large, because a heavy motor or the like is arranged near a hand such as a wrist of a human-like arm. This may hinder an improvement of hand position control performance, or may generate a large impact in collision, which requires a consideration in terms of safety.

In response to the above issue, a wire drive type robot arm has been developed, in which the actuator is arranged near a base end position away from the driven joint and driving force is transmitted by wire. Because the hand can be slimmed down in the wire drive type robot arm, the wire drive type robot arm has excellent characteristics such as high-speed drive.

However, in the wire drive type robot arm, in the case where the wrist portion is driven by arranging the actuator in a body portion which is of a base portion to which the arm is attached in order to reduce the hand-side inertia, namely, in the case where a run distance of the wire is made longer, it is necessary that the wire be arranged beyond the joint such as an elbow of the human-like arm. In this case, when driving the joint located in the midway of the wire, a wire path length changes, which causes an issue that the change in wire path length influences on joint movement of the end portion, such as the wrist, which is driven by the wire.

In order to solve the issue, Patent Document 1 (Japanese Patent No. 3290709) discloses a configuration in which a pair of pulleys is arranged so as to be displaced from a rotation center of the joint. Further, Patent Document 2 (Japanese Examined Patent Publication No. H6-77914) discloses a configuration having a wire guide pulley the rotation center is rotated in accordance with the joint movement.

However, in the configuration disclosed in the Patent Document 1, the change in wire path length by the joint movement cannot completely be eliminated, so that the change in wire path length is increased as a rotation angle of the joint located in the midway is increased. Further, in the configuration disclosed in the Patent Document 2, when the rotational movement of the wire guide pulley is generated in accordance with the joint rotation, in the state where the joint is bent, the wire path is bent toward a direction opposite to the direction of a front end-side arm member before the wire is bent toward the direction of the front end-side arm member. Therefore, the wire path cannot be kept completely constant irrespective of the joint movement.

An object of the present invention is to provide, in order to solve the above issues, a joint structure which can transmit driving force without being influenced by rotating movement at the revolute joint at all, and the robot arm including the joint structure.

SUMMARY OF THE INVENTION

In order to achieve the above object, the present invention is configured as follows.

According to a first aspect of the present invention, there is provided a joint structure comprising:

a first structure;

a second structure;

a revolute joint for connecting the first structure and the second structure;

a rotating guide pulley which is coaxial with a rotating shaft of the revolute joint and arranged so as to be rotatable about the rotating shaft;

a fixed guide which is arranged in the first structure, the fixed guide having an arc portion;

a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable;

a wire which is put round the rotating guide pulley, the movable rotating guide pulley, and the fixed guide in an order of the rotating guide pulley, the movable rotating guide pulley, and the fixed guide;

a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; and

a second drive apparatus, which is included in the first structure, for driving the wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire,

wherein the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the rotating guide pulley.

According to the present invention, the driving force of the second drive apparatus (for example, translation actuator) arranged in the first structure can be transmitted to an end portion (for example, hand) such as a wrist beyond the revolute joint without being influenced by rotating movement at the revolute joint.

Accordingly, the second drive apparatus such as the actuator which drives the movement of the wrist or the like of the robot arm can be arranged on a bottom side of the robot arm, and inertia on a front end of the robot arm is decreased, so that high-speed operation can be performed while control performance is improved with respect to positional control and force control. Because the inertia is small, kinetic energy also becomes small and safety in collision may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1A is a plan view showing an almost entirety of a robot arm in a case where a joint structure according to a first embodiment of the present invention is applied to the robot arm;

FIG. 1B is a bottom view showing the almost entirety of the robot arm in the case where the joint structure according to the first embodiment of the present invention is applied to the robot arm;

FIG. 2 is a perspective view showing a detailed structure of the joint structure according to the first embodiment of the present invention;

FIG. 3 is a view showing a structure of a pneumatic artificial muscle which can form a group of translation actuators as an example of a drive apparatus of the joint structure according to the first embodiment of the present invention;

FIG. 4 is a view showing a configuration of a pneumatic supply and drive system for drives the pneumatic artificial muscle;

FIG. 5A is a side view showing an operation of a robot arm in the case where the joint structure according to the first embodiment of the present invention is applied to the robot arm;

FIG. 5B is a side view showing the robot arm operation in the case where the joint structure according to the first embodiment of the present invention is applied to the robot arm;

FIG. 6A is a view showing a wire guidance operation of the joint structure according to the first embodiment of the present invention in operating a first translation actuator;

FIG. 6B is a view showing the wire guidance operation of the joint structure according to the first embodiment of the present invention in operating a second translation actuator;

FIG. 7 is a perspective view showing a detailed structure of a joint structure according to a second embodiment of the present invention;

FIG. 8 is a perspective view showing a detailed structure of a joint structure according to a third embodiment of the present invention;

FIG. 9A is a side view showing an almost entirety of a robot arm in a case where a joint structure according to a fourth embodiment of the present invention is applied to the robot arm;

FIG. 9B is a side view showing the almost entirety of the robot arm in the case where the joint structure according to the fourth embodiment of the present invention is applied to the robot arm;

FIG. 10 is a perspective view showing a detailed structure of the joint structure according to the fourth embodiment of the present invention;

FIG. 11 is a view showing an operation of the joint structure according to the fourth embodiment of the present invention;

FIG. 12 is a plan view showing an almost entirety of a robot arm in the case where a joint structure according to a fifth embodiment of the present invention is applied to the robot arm;

FIG. 13 is a perspective view showing a detailed structure of the joint structure according to the fifth embodiment of the present invention;

FIG. 14 is a view showing an operation of the joint structure according to the fifth embodiment of the present invention;

FIG. 15 is a plan view showing an almost entirety of a robot arm in the case where a joint structure according to a sixth embodiment of the present invention is applied to the robot arm;

FIG. 16 is a perspective view showing a detailed structure of the joint structure according to the sixth embodiment of the present invention;

FIG. 17 is a view showing an operation of the joint structure according to the sixth embodiment of the present invention;

FIG. 18A is a side view showing an almost entirety of a robot arm in the case where a joint structure according to another embodiment of the present invention is applied to the robot arm;

FIG. 18B is a bottom view showing the almost entirety of the robot arm in the case where the joint structure according to another embodiment of the present invention is applied to the robot arm;

FIG. 19A is an overall view showing a structure of a wire guidance mechanism while a gripper is opened in a joint mechanism according to a seventh embodiment of the present invention;

FIG. 19B is an overall view showing the structure of the wire guidance mechanism while the gripper is closed in the joint mechanism according to the seventh embodiment of the present invention;

FIG. 19C is an overall view showing the structure of the wire guidance mechanism while the gripper is swung in the joint mechanism according to the seventh embodiment of the present invention; and

FIG. 20 is a perspective view showing the structure of the wire guidance mechanism in the joint mechanism according to the seventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings.

Various aspects of the present invention will be described before preferred embodiments of the present invention are described in detail with reference to the drawings.

According to a first aspect of the present invention, there is provided a joint structure comprising:

a first structure;

a second structure;

a revolute joint for connecting the first structure and the second structure;

a rotating guide pulley which is coaxial with a rotating shaft of the revolute joint and arranged so as to be rotatable about the rotating shaft;

a fixed guide which is arranged in the first structure, the fixed guide having an arc portion;

a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable;

a wire which is put round the rotating guide pulley, the movable rotating guide pulley, and the fixed guide in an order of the rotating guide pulley, the movable rotating guide pulley, and the fixed guide;

a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; and

a second drive apparatus, which is included in the first structure, for driving the wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire,

wherein the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the rotating guide pulley.

According to a second aspect of the present invention, there is provided a joint structure according to the first aspect, wherein the fixed guide is formed as a part of a member fixed to the first structure.

According to a third aspect of the present invention, there is provided a joint structure according to the first aspect, wherein the movable rotating guide pulley has a structure in which a first movable rotating guide pulley whose guide groove is located in a same plane as a plane including a guide groove of the rotating guide pulley and a second movable rotating guide pulley whose guide groove is located in a same plane as a plane including a guide groove of the fixed guide are integrally formed.

According to a fourth aspect of the present invention, there is provided a joint structure according to the first aspect, wherein the movable rotating guide pulley has a first guide groove located in a same plane as a plane including a guide groove of the rotating guide pulley and a second guide groove located in a same plane as a plane including a guide groove of the fixed guide.

According to a fifth aspect of the present invention, there is provided a joint structure comprising:

a first structure;

a second structure;

a revolute joint for connecting the first structure and the second structure;

a first rotating guide pulley and a second rotating guide pulley which are coaxial with a rotating shaft of the revolute joint, the first rotating guide pulley and the second rotating guide pulley being arranged in the first structure or the second structure so as to be rotatable about the rotating shaft respectively, the first rotating guide pulley and the second rotating guide pulley being capable of rotating relative to each other;

a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable;

an auxiliary rotating guide pulley which is provided in the first structure while freely rotated;

a wire which is put round the first rotating guide pulley, the movable rotating guide pulley, the second rotating guide pulley, and the auxiliary rotating guide pulley in an order of the first rotating guide pulley, the movable rotating guide pulley, the second rotating guide pulley, and the auxiliary rotating guide pulley, both end portions of the wire being fixed to the second drive apparatus;

a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the first and second rotating guide pulleys; and

a second drive apparatus, which is included in the first structure, for driving the wire, and moving the movable rotating guide pulley to change the distance to the first and second rotating guide pulleys by driving the wire,

wherein the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the first and second rotating guide pulleys.

According to a sixth aspect of the present invention, there is provided a joint structure comprising:

a first structure;

a second structure;

a revolute joint for connecting the first structure and the second structure;

a third rotating guide pulley which is coaxial with a rotating shaft of the revolute joint, and arranged so as to be rotatable about the rotating shaft;

a fourth rotating guide pulley which is arranged in the second structure while freely rotated;

a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable;

a first drive apparatus, which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley; and

a second drive apparatus, which is included in the first structure, for driving a wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire; and

the wire which is put round the third rotating guide pulley, the movable rotating guide pulley, and the fourth rotating guide pulley in an order of the third rotating guide pulley, the movable rotating guide pulley, and the fourth rotating guide pulley, one end portion of the wire being fixed to the second drive apparatus, the other end portion being fixed to the fourth rotating guide pulley;

a first parallel link whose one end portion is supported by the first structure while freely rotated; and

a second parallel link in which one end portion is connected to the other end portion of the first parallel link so as to be freely rotated and the other end portion is fixed to the fourth rotating guide pulley,

wherein a four-node parallel link structure is formed so as to have four fulcrums of a portion where the one end portion of the first parallel link is supported to the first structure, a portion where the other end portion of the first parallel link and the one end portion of the second parallel link are connected to each other, a portion where the other end portion of the second parallel link is fixed to the fourth rotating guide pulley, and a portion which is arranged in the second structure of the fourth rotating guide pulley while freely rotated, and

the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the third rotating guide pulley.

According to a seventh aspect of the present invention, there is provided a joint structure comprising:

a first structure;

a second structure;

a rotating guide pulley which is coaxial with a rotating shaft of the revolute joint, and arranged so as to be rotatable about the rotating shaft;

a movable rotating guide pulley which is arranged in the second structure so as to be relatively movable;

a first drive apparatus which is included in the first structure, for rotating the second structure about the revolute joint without changing a distance from the movable rotating guide pulley to the rotating guide pulley;

a second drive apparatus which is included in the first structure, for driving a wire, and moving the movable rotating guide pulley to change the distance to the rotating guide pulley by driving the wire;

the wire which is put round the rotating guide pulley and the movable rotating guide pulley in an order of the rotating guide pulley and the movable rotating guide pulley, one end portion of the wire being fixed to the second drive apparatus, the other end portion being fixed to the movable rotating guide pulley;

a first parallel link whose one end portion is supported by the first structure while freely rotated; and

a second parallel link in which one end portion is connected to the other end portion of the first parallel link while being freely slidable and rotatable and the other end portion is fixed to the movable rotating guide pulley,

wherein a four-node parallel link structure is formed while having four fulcrums of a portion where the one end portion of the first parallel link is supported to the first structure, a portion where the other end portion of the first parallel link and the one end portion of the second parallel link are connected to each other, a portion where the other end portion of the second parallel link is fixed to the movable rotating guide pulley, and a portion which is arranged in the second structure of the rotating guide pulley while freely rotated, and

the second structure is rotated about the revolute joint by driving the first drive apparatus without changing the distance from the movable rotating guide pulley to the rotating guide pulley.

According to an eighth aspect of the present invention, there is provided a robot arm comprising:

a joint structure as in any one of the first to seventh aspects;

a hand which is arranged at an front end on a side opposite to a revolute joint side of the second structure; and

a hand driving wire for connecting the movable rotating guide pulley and the hand,

wherein the movable rotating guide pulley is movable relative to the second structure, and thereby the hand driving wire rotates and drives the hand with respect to the second structure.

The embodiments of the present invention will be described in detail below with reference to the drawings.

First Embodiment

FIGS. 1A and 1B are overall views showing a joint structure according to a first embodiment of the present invention. FIGS. 1A and 1B show, by way of example, a structure of a case in which the joint structure of the first embodiment is applied to a robot arm 100.

In FIGS. 1A and 1B, numeral 1 designates a rod-shape first structure which forms an upper arm portion of the robot arm 100. Numeral 2 designates a rod-shape second structure which forms a front arm portion of the robot arm 100. The first structure 1 and the second structure 2 are connected to each other by a first revolute joint 3, and the first structure 1 and the second structure 2 can relatively forwardly and reversely be rotated about a joint shaft 3a of the first revolute joint 3. As an example shown in FIG. 1B, branch portions 2a into which a first revolute joint side-end portion of the second structure 2 is branched are formed, a lower end portion of the first structure 1 is sandwiched between the branch portions 2a, and the first structure 1 is connected so as to be relatively rotatable with respect to the joint shaft 3a.

Numerals 4-1 and 4-2 designate two first translation actuators, such as pneumatic artificial muscles, each capable of constituting a first translation actuator as an example of the first drive apparatus. Each of upper end portions of the two first translation actuators 4-1 and 4-2 is fixed to a support plate 1a fixed to the upper end portion of the first structure 1. Lower end portions of the two first translation actuators 4-1 and 4-2 are rotatably coupled to rotating ends of revolute joints 5-1 and 5-2 whose base end portions are fixed to the second structure 2, connecting the two first translation actuators 4-1 and 4-2 to the first structure 1 and the second structure 2 to drive the normal and reverse rotations of the first structure 1 and second structure 2 at the first revolute joint 3. That is, the base end portions of the rod-shape revolute joints 5-1 and 5-2 are fixed to the second structure 2, and the lower end portions of the first translation actuators 4-1 and 4-2 are rotatably coupled to the front end portion of the joints 5-1 and 5-2. Because the revolute joints 5-1 and 5-2 are symmetrically arranged in relation to the rotating shaft 3a of the first revolute joint 3, the second structure 2 is rotated clockwise about the rotating shaft 3a of the first revolute joint 3 when the lower end portion of the first translation actuator 4-1 is ascended while the lower end portion of the first translation actuator 4-2 is lowered. On the contrary, when the lower end portion of the first translation actuator 4-1 is lowered while the lower end portion of the first translation actuator 4-2 is ascended, the second structure 2 is rotated counterclockwise about the rotating shaft 3a of the first revolute joint 3.

Numerals 6-1 and 6-2 designate two second translation actuators, such as the pneumatic artificial muscles, motors, or cylinders, each capable of constituting a second translation actuator as an example of the second drive apparatus (the second translation actuators in FIG. 1A are shown overlapping each other, and the second translation actuator on the front side designates 6-1 and the second translation actuator on the rear side designates 6-2). The two second translation actuators 6-1 and 6-2 pull and drive arm flexure wires 7-1 and 7-2 whose end portions are fixed to lower ends of the second translation actuators 6-1 and 6-2.

In the structure of each of the pneumatic artificial muscles constituting the translation actuators 4-1, 4-2, 6-1, and 6-2, as shown in FIG. 3, a constraint member 16 formed by fiber cords is arranged on an outer surface of a tubular elastic body 15 made of a rubber material, and both end portions of the tubular elastic body 15 are hermetically sealed by sealing members 17. When internal pressure is imparted to an internal space of the tubular elastic body 15 by supplying compressible fluid such as air into the tubular elastic body 15 through a fluid injection and evacuation member 18 which is provided in the sealing member 17 located at one end portion of the tubular elastic body 15, although the tubular elastic body 15 expands mainly in a radial direction, the expansion is converted into movement in a center axis direction of the tubular elastic body 15 by an action of the constraint member 16, which contracts an overall length of the tubular elastic body 15. On the contrary, when the internal pressure is reduced in the internal space of the tubular elastic body 15 by evacuating the compressible fluid such as air from the tubular elastic body 15 through the fluid injection and evacuation member 18, although the tubular elastic body 15 contracts mainly in the radial direction, the contraction is converted into the movement in the center axis direction of the tubular elastic body 15 by the action of the constraint member 16, which stretches the overall length of the tubular elastic body 15. Because the pneumatic artificial muscle is mainly made of an elastic material, the pneumatic artificial muscle has flexibility and a characteristic that the pneumatic artificial muscle is a safe and light actuator.

Numerals 8-1 and 8-2 designate rotating guide pulleys each having a guide groove 8a. The rotating guide pulleys 8-1 and 8-2 are coaxial with the rotating shaft 3a of the first revolute joint 3 at positions where the rotating guide pulleys 8-1 and 8-2 face each other across the second structure 2, and the rotating guide pulleys 8-1 and 8-2 are arranged in the second structure 2 while being freely rotatable about the rotating shaft 3a through bearings or the like. That is, the rotating guide pulleys 8-1 and 8-2 can freely be rotated about the rotating shaft 3a with respect to the second structure 2. In FIG. 1A, the rear-side rotating guide pulley 8-2 is not shown because the rotating guide pulley 8-2 is hidden behind the front-side rotating guide pulley 8-1. However, the rotating guide pulley 8-2 is shown in FIG. 1B.

Numerals 9-1 and 9-2 designate fixed guide pulleys each having a guide groove 9a which are of an example of the fixed guide. The fixed guide pulleys 9-1 and 9-2 have the same radiuses as those of the rotating guide pulleys 8-1 and 8-2. At the positions where the fixed guide pulleys 9-1 and 9-2 face each other across the second structure 2, the fixed guide pulleys 9-1 and 9-2 are arranged outside the rotating guide pulleys 8-1 and 8-2 respectively so as to be coaxial with the rotating shaft 3a of the first revolute joint 3. Because the fixed guide pulleys 9-1 and 9-2 are fixed to the first structure 1 with the rotating shaft 3a, the relative rotational movement is not generated between the fixed guide pulleys 9-1 and 9-2 and the first structure 1. In FIG. 1A, the rear-side fixed guide pulley 9-2 is not shown because the fixed guide pulley 9-2 is hidden behind the front-side fixed guide pulley 9-1. However, the fixed guide pulley 9-2 is shown in FIG. 1B. The rotating shaft 3a is fixed to the second structure 2.

Numerals 10-1 and 10-2 designate movable rotating pulleys each having a guide groove 10a which are arranged in an intermediate portion of the second structure 2. The movable rotating pulley 10-1 and 10-2 are arranged in an upper end portion of a lever 11-1 and a lower end portion of a lever 11-2, and the movable rotating pulley 10-1 and 10-2 can be rotated about rotating axes 10-1a and 10-2a respectively. The upper end portion of the lever 11-1 and the lower end portion of the lever 11-2 are arranged at respective positions so as to face each other across the second structure 2, and the upper end portion of the lever 11-1 and the lower end portion of the lever 11-2 can be swung about fulcrums 11-1a and 11-2a.

Numeral 12 designates a hand for holding goods and the like. The hand 12 is connected to the second structure 2 with a second revolute joint 13, and the hand 12 can relatively be swung about the joint shaft 13a with respect to the second structure 2.

Numerals 14-1 and 14-2 designate wires for driving the hand 12. In the hand drive wires 14-1 and 14-2, each of end portions are fixed to each of the rotating shafts 10-1a and 10-2a of the movable rotating pulleys 10-1 and 10-2, and the other end portions are fixed to positions which are symmetrically located in relation to the joint shaft 13a of the hand 12.

A path of the arm flexure wire 7-1 with respect to the rotating guide pulley 8-1, the fixed guide pulley 9-1, and the movable rotating pulley 10-1 will be described below with reference to FIG. 2. Although the wire is put round each pulley for the purpose of accommodating the wire in each guide groove (see FIG. 1B), the description of the guide groove will be omitted in the following description.

The arm flexure wire 7-1 whose one end is fixed to the lower end of the second translation actuator 6-1 is guided to the rotating guide pulley 8-1, and the path of the arm flexure wire 7-1 is bent by the rotating guide pulley 8-1 (see arrow (1)). Then, the arm flexure wire 7-1 is guided to the movable rotating pulley 10-1, under the movable rotating pulley 10-1 from under the joint shaft 3a of the first revolute joint 3 in the drawing sheet surface of FIG. 2 (see arrow (2)). Then, the arm flexure wire 7-1 is bent so as to turn the direction by the movable rotating pulley 10-1 (see arrow (3)), and the arm flexure wire 7-1 is guided to the upper side of the fixed guide pulley 9-1 from the upper side of the movable rotating pulley 10-1 in the drawing sheet surface of FIG. 2 (see arrow (4)). After the arm flexure wire 7-1 runs along an outer periphery of the fixed guide pulley 9-1 (see arrow (5)), the end portion of the arm flexure wire 7-1 is fixed to the fixed guide pulley 9-1 with a wire fixing pin 7P.

The path of the arm flexure wire 7-2 with respect to the rotating guide pulley 8-2, the fixed guide pulley 9-2, and the movable rotating pulley 10-2 is similar to the path of the arm flexure wire 7-1, so that the detailed description will be omitted.

FIG. 4 is a view showing a configuration of a pneumatic supply and drive system for driving the pneumatic artificial muscle. In FIG. 4, numeral 19 designates a pneumatic source, for example, such as a compressor, and numeral 20 designates a pneumatic adjustment unit formed by a set of a pneumatic filter 20a, a pneumatic reducing valve 20b, and a pneumatic lubricator 20c. Numeral 21 designates a five-port flow rate control electromagnetic valve for controlling a flow rate by driving, e.g., a spool valve or the like using force of an electro magnet. Numeral 22 designates a control computer which is formed by, e.g., a general personal computer, and a D/A board 22a is mounted on the control computer 22. The flow rate of the air passing through each of the fluid injection and evacuation members 18 can be controlled by outputting a voltage instruction value to the five-port flow rate control electromagnetic valve 21.

According to the pneumatic supply and drive system shown in FIG. 4, the high-pressure air generated by the pneumatic source 19 is reduced and adjusted to, for example, a constant pressure of 600 kPa by the pneumatic adjustment unit 20, and the air is supplied to the five-port flow rate control electromagnetic valve 23. A valve opening degree of the five-port flow rate control electromagnetic valve 21 is controlled in proportion to the voltage instruction value outputted from the control computer 22 through the D/A board 22a. The fluid injection and evacuation members 18 of the tubular elastic bodies 15 of a pair of pneumatic artificial muscles 201-1 and 201-2 are connected to the five-port flow rate control electromagnetic valve 21. The pair of pneumatic artificial muscles 201-1 and 201-2 is arranged in substantially parallel with a support rod 203, and the end portions on the fluid injection and evacuation members-18-side of the tubular elastic bodies 15 are fixed to a support plate 202 fixed to the end portion of the support rod 203. A T-shaped rotating member 204 is supported on the other end portion side of each of the tubular elastic bodies 15 of the pair of pneumatic artificial muscles 201-1 and 201-2. The rotating member 204 is rotatably supported at the revolute joint shaft 200 by the support rod 203, and the other end portions of the respective tubular elastic bodies 15 of the pair of pneumatic artificial muscles 201-1 and 201-2 are rotatably supported by the rotating member 204. Accordingly, as described below, the rotating member 204 is rotated forwardly and reversely about the revolute joint shaft 200 by stretching and contracting the tubular elastic bodies 15 of the pair of pneumatic artificial muscles 201-1 and 201-2.

In the case where the control computer 22 causes the D/A board 22a to input the positive voltage instruction value to the five-port flow rate control electromagnetic valve 21, a pneumatic circuit becomes the state shown by the sign A in FIG. 4, a flow channel is opened from the pneumatic source-19-side to the fluid injection and evacuation member-18-side of the tubular elastic body 15 of the pneumatic artificial muscle 201-1 through the five-port flow rate control electromagnetic valve 21, and the air is supplied to the pneumatic artificial muscle-201-1-side at the flow rate proportional to an absolute value of the voltage instruction value. On the pneumatic artificial muscle 201-2-side, a flow channel is opened to an atmospheric air side from the fluid injection and evacuation member 18 of the tubular elastic body 15 through the five-port flow rate control electromagnetic valve 21, and the air is evacuated into the atmosphere from pneumatic artificial muscle 201-2-side at the flow rate proportional to the absolute value of the voltage instruction value. Accordingly, as shown in FIG. 4, the overall length of the pneumatic artificial muscle 201-1 is contracted while the overall length of the pneumatic artificial muscle 201-2 is stretched, which allows the joint shaft 200 to perform the clockwise rotational movement at a speed proportional to the absolute value of the voltage instruction value as shown by an arrow in FIG. 4.

On the other hand, in the case where the control computer 22 causes the D/A board 22a to input the negative voltage instruction value to the five-port flow rate control electromagnetic valve 21, the pneumatic circuit becomes the state shown by the sign B in FIG. 4 by switching the five-port flow rate control electromagnetic valve 21, the pneumatic artificial muscle 201-2 is reversely operated, and the joint shaft 200 perform the counterclockwise rotational movement. That is, the flow channel is opened from the pneumatic source-19-side to the fluid injection and evacuation member-18-side of the tubular elastic body 15 of the pneumatic artificial muscle 201-2 through the five-port flow rate control electromagnetic valve 21, and the air is supplied to the pneumatic artificial muscle 201-2-side at the flow rate proportional to the absolute value of the voltage instruction value. On the side of the pneumatic artificial muscle 201-1, the flow channel is opened to the atmospheric air side from the fluid injection and evacuation members 18 of the tubular elastic body 15 through the five-port flow rate control electromagnetic valve 21, and the air is evacuated into the atmosphere from the side of pneumatic artificial muscle 201-1 at the flow rate proportional to the absolute value of the voltage instruction value. Accordingly, the overall length of the pneumatic artificial muscle 201-2 is contracted while the overall length of the pneumatic artificial muscle 201-1 is stretched, which allows the joint shaft 200 to perform the counterclockwise rotational movement shown by the reverse direction of the arrow in FIG. 4 at a speed proportional to the absolute value of the voltage instruction value.

An operation of the joint structure having the wire guidance mechanism of the above-described configuration will be described below.

FIGS. 5A and 5B are views showing the robot arm operation in the case where the joint structure according to the first embodiment of the present invention is applied to the robot arm.

As described above, in the two first translation actuators 4-1 and 4-2 of the first translation actuator 4, the first translation actuator 4-1 located on the left side of FIG. 1A and the first translation actuator 4-2 located on the right side of FIG. 1A are connected to the second structure 2 through the revolute joints 5-1 and 5-2 so as to face each other across the first structure 1 with respect to the first revolute joint 3. Accordingly, when the first translation actuator 4-1 located on the left side of FIG. 1A is stretched while the first translation actuator 4-2 located on the right side of FIG. 1A is contracted, as shown in FIG. 5A, the counterclockwise rotational movement is generated about the rotating shaft 3a of the first revolute joint 3. On the contrary, when the first translation actuator 4-1 located on the left side of FIG. 1A is contracted while the first translation actuator 4-2 located on the right side of FIG. 1A is stretched, the clockwise rotational movement is generated about the rotating shaft 3a of the first revolute joint 3.

At this point, the first embodiment of the present invention has a feature in that the arm flexure wires 7-1 and 7-2 are induced by the rotating guide pulleys 8-1 and 8-2, the fixed guide pulleys 9-1 and 9-2, and the movable rotating pulleys 10-1 and 10-2. The action will be described below with reference to FIGS. 6A and 6B.

In the case where the counterclockwise rotational movement of the second structure 2 is generated about the rotating shaft 3a of the first revolute joint 3 by the operations of the first translation actuators 4-1 and 4-2 as shown in FIG. 5A, the relatively rotational movement of the movable rotating pulley 10-1 relative to the rotating guide pulley 8-1 and the fixed guide pulley 9-1 is generated about the rotating shaft 3a of the first revolute joint 3 as shown by an arrow A of FIG. 6A. At this point, an amount in which the arm flexure wire 7-1 is put round the circumferential portion of the rotating guide pulley 8-1 is increased by a part of a circumference corresponding to an angle .alpha. and decreased by a part of the circumference corresponding to an angle .beta.. The arm flexure wire 7-1 is induced by the clockwise rotational movement about the rotating shaft 10-1a of the movable rotating pulley 10-1 as shown by an arrow B, and the increase which is of the part of the circumference corresponding to the angle .alpha. and the decrease which is of the part of the circumference corresponding to the angle .beta. cancel each other. A distance L between the rotating guide pulley 8-1 and the movable rotating pulley 10-1 is not changed because of angle .alpha.=angle .beta.. Accordingly, the relatively rotational movement relative to the second structure 2 is not generated about the fulcrum 11-1a of the lever 11-1.

The same wire guidance operation is performed in the guidance of the arm flexure wire 7-2 by the rotating guide pulley 8-2, the fixed guide pulley 9-2, and the movable rotating pulley 10-2.

Accordingly, the relatively rotational movement of the hand 12, connected to the levers 11-1 and 11-2, about the second revolute joint 13 relative to the second structure 2 by a hand driving wire 14-1 and a hand driving wire 14-2 is not generated by the rotational movement about the rotating shaft 3a of the first revolute joint 3 of the second structure 2 by the operation of the first translation actuator 4.

On the other hand, in the case where the second translation actuator 6-1 is contracted while the second translation actuator 6-2 is stretched, the arm flexure wire 7-1 is pulled as shown by an arrow C of FIG. 6B, the rotating guide pulley 8-1 is rotated clockwise about the rotating shaft 3a of the first revolute joint 3 as shown by an arrow D, and the arm flexure wire 7-1 is delivered toward the second translation actuator 6-1-side. However, the arm flexure wire 7-1 is fixed to the fixed guide pulley 9-1 (see FIG. 2), the movable rotating pulley 10-1 is brought close to the rotating guide pulley 8-1 as shown by an arrow F while rotated clockwise about the rotating shaft 10-1a as shown by an arrow E, and the distance L between the rotating guide pulley 8-1 and the movable rotating pulley 10-1 is shortened, such that the distance is shortened from a distance L1 of pre-movement to a distance L2 (L1>L2). Accordingly, as shown in FIG. 5B, the lever 11-1 is relatively rotated counterclockwise about the fulcrum 11-1a relative to the second structure 2. On the contrary, the guidance of the arm flexure wire 7-2 by the rotating guide pulley 8-2, the fixed guide pulley 9-2, and the movable rotating pulley 10-2, as shown in FIG. 5B, the lever 11-2 is relatively rotated clockwise about the fulcrum 11-2a relative to the second structure 2.

Accordingly, as shown in FIG. 5B, the hand 12 connected to the levers 11-1 and 11-2 with the hand driving wire 14-1 and the hand driving wire 14-2 is relatively rotated counterclockwise about the second revolute joint 13 relative to the second structure 2.

Thus, according to the joint structure of the first embodiment of the present invention, the arm flexure wires 7-1 and 7-2 are configured to be induced by the rotating guide pulleys 8-1 and 8-2, the fixed guide pulleys 9-1 and 9-2, and the movable rotating pulleys 10-1 and 10-2, which allows the driving force of the second translation actuator 6 arranged in the first structure 1 to be transmitted to the front end-side of the robot arm 100 beyond the first revolute joint 3 without being influenced by rotating movement about the rotating shaft 3a of the first revolute joint 3.

Accordingly, the actuator which drives the movement about the second revolute joint 13 can be arranged on the base end side of the robot arm 100 like the second translation actuator 6, the front end-side inertia of the robot arm 100 becomes small, so that the high-speed operation can be performed while the control performance concerning the position control and force control is improved. Because the inertia becomes small, the kinetic energy is also small, and the safety in collision is improved.

In the first embodiment, as an example, the second structure 2 can be rotated clockwise and counterclockwise about the rotating shaft 3a from the orientation shown in FIG. 1A by about 60 degrees with respect to the first structure 1. The hand 12 can also be rotated clockwise and counterclockwise about the rotating shaft 3a from the orientation shown in FIG. 1A by about 60 degrees with respect to the first structure 2.

Second Embodiment

FIG. 7 is a perspective view showing a detailed structure of a joint structure according to a second embodiment of the present invention. In FIG. 7, only main components will be described, and other configurations will be omitted because other configurations are similar to those of the First embodiment shown in FIGS. 1A and 1B. Although the wire is put round each pulley so as to be accommodated in each guide groove (similarly to FIG. 1B), the guide groove will be omitted in the following description and the corresponding drawing for the purpose of simplification.

In FIG. 7, numeral 23-1 designates a first movable rotating guide pulley, and numeral 24-1 designates a second movable rotating guide pulley. The first movable rotating guide pulley 23-1 and the second movable rotating guide pulley 24-1 have the same radius. The first movable rotating guide pulley 23-1 and the second movable rotating guide pulley 24-1 are fixed to each other, and the first movable rotating guide pulley 23-1 and the second movable rotating guide pulley 24-1 are rotated about the rotating shaft 10-1a, and the first movable rotating guide pulley 23-1 and the second movable rotating guide pulley 24-1 are provided instead of the movable rotating pulley 10-1 of the first embodiment. The first movable rotating guide pulley 23-1 is arranged in the same plane as the rotating guide pulley 8-1, and the second movable rotating guide pulley 24-1 is arranged in the same plane as the fixed guide pulley 9-1.

Then, the wire path of the joint structure in the second embodiment will be described. In this case, the arm flexure wire 7-1 of the first embodiment is configured to be d