GB2087837A

GB2087837A - A flecible arm for a robot

Info

Publication number: GB2087837A
Application number: GB8135007A
Authority: GB
Original assignee: Tokico Ltd
Current assignee: Tokico Ltd
Priority date: 1980-11-21
Filing date: 1981-11-20
Publication date: 1982-06-03
Also published as: WO1982001680A1; GB2087837B; SU1168089A3; DE3145891C2; JPS5789585A; DE3145891A1; FR2494618B1; FR2494618A1

Abstract

A Flexible arm for a program-controlled manipulator, having a plurality of movable arm members (19, 26, 28, 37, 39) sequentially connected to a cylindrical base (18) rotatably mounted on a non-flexible arm (4), and an operating rod (20) movably attached to the base (18) for driving the movable arm members.

Description

SPECIFICATION A flexible arm for a robot The present invention relates to a flexible arm for use in an industrial robot or other programme controlled manipulator.

There has already been proposed a teachingplayback type robot, in which a support post is mounted on a turntable, and an arm is swingably attached to one end of the support post with a painting spray gun, for example, carried on the leading end of the arm to be brought automatically to desired positions by rotation of the support post and by swinging motion of the arm thus allowing painting operations to be performed.

However, since the arm in such a robot is not generally flexible or bendable, the positioning of the gun to the desired position is relatively difficult.

Thus, a robot having such arm can only be used on workpieces having simple shapes.

In recent years, on the other hand, there have also been proposed a variety of elephant nose type arms.

These all have complex constructions and in addition, if the arm is made relatively long, it flexes under its own weight thereby making it difficult to set the gun at the desired position. If this difficulty is to be overcome, arm members having a remarkable rigidity have to be used which is not practical.

In the conventional flexible arms, moreover, it is difficult to ensure sufficient deformation for the actuation which is caused by an actuator, thus failing to make the most use of the advantage resulting from the bendability.

According to the present invention there is provided a flexible arm including a base member, an actuating rod movably mounted on said base member, a first arm member fixed to said base member, a second arm member rotatably connected to said first arm member and swingably connected at one end to said actuating rod, a third arm member connected rotatably to said second arm member, and a link member swingably connected at one end to one end of said first arm member and swingably connected at the other end to one of said third arm member.

The invention provides a flexible arm which has desirable bendability and allows a robot to have such wide applications that it can work workpieces having complex shapes without difficulty. Good rigidity is obtained with a simple construction but without using the exceptionally rigid particular members. This ieads to precise positioning and moreover only slight actuation of the actuator is needed to cause the arm to bend.

The invention will be more clearly understood from the following description which is given by way of example only with reference to the accompanying drawings in which: Figure 1 is a side view showing a robot with a flexible arm according to a preferred embodiment of the present invention; Figure 2 is also a side view but shows only the flexible arm shown in Figure 1; Figure 3 is a bottom view of the flexible arm shown in Figure 2; Figure 4 is a section taken along line IV-IV of Figure 3; and Figures 5and 6 are explanatory views explaining the operations of the flexible arm shown in Figure 2.

In the embodiment to be described with reference to the accompanying drawings, a flexible arm is constructed such that alternate arm members are swingably connected by link members so that the angular displacement of the second arm members relative to the first arm members by an actuating rod is transmitted as that of the subsequent arm members.

A manipulator 1 is constructed of a platform 2, a support post 3 and an elongated non-flexible arm 4, and the post 3 is mounted on a turntable 5, which is disposed above the platform 2, so that it is rotated about a center line 6 in the direction of arrow D as the turntable 5 turns. In the platform 2, there is disposed a hydraulic actuator which is made operative to turn the turntable 5 in the direction D. The post 3, which is connected to the bracket of the turntable 5 through a shaft 7, is made so swingable in the direction of arrow E in a vertical plane that it is swung in the direction E by the actuation of a hydraulic cylinder 8 which is so interposed between the post 3 and the turntable 5 as to act as an actuator.The arm 4 is so connected to the post 3 through a shaft 9 that it can be freely swung in the direction of arrow F in a vertical plane, whereby it is swung in the direction F by a hydraulic cylinder 10 which is so interposed between the arm 4 and the post 3 as to act as a hydraulic actuator. To the leading end of the arm 4, there is attached a flexible i.e., bendable arm 12 which is covered with an extendible and flexible cover 11. To the arm 12, there is attached a handle 13, which is gripped by an operator to teach the programme controlled manipulator 1. A painting spray gun 16 is carried through a supporting member 15 on a rod 14 which protrudes from the arm 12.

The arm 12 is equipped with a cylindrical base member 18 which is mounted on the arm 4 rotatably, i.e., in a manner to freely rotate in the direction of arrow G about a center line 17 and to which a pair of first arm members 19 facing to wide plane each other are fixed at their one ends. The first plankshaped paired arm members 19 are bridged by a plank member 19a. An actuating rod 20, which extends through the base member 18 movably in a direction parallel to the extending direction of the center line 17, is connected through a shaft 21 at their leading ends to a pair of link members 22 which faces each other. The shaft 21 has a center portion 23 formed into a ball shape, to which the rod 20 is connected at its annular end 24 so that it can be swung generally in any desired direction relative to the shaft 21.Thus, a ball joint is constructed of the center portion 23 and the annular end 24. To both the ends of a shaft 25 which extends rotatably through the link members 22, there are rotatably connected a pair of plank-shaped second arm members 26, respectively, which are rotatably connected at their one ends at the side of the member 18 to the rod 20 through the shafts 21 and 25 and the link members 22.

The second arm members 26 are rotatably con nected at their substantially center portions to the first arm members 19 through shafts 27. A pair of third arm members 28 facing to wide plane each other at rotatably connected at their substantially center portions to the second arm members 26 through shafts 29 and further rotatably connected at their one ends at the side of the member 18 to the one ends of a pair of link members 31 through shafts 30. The other ends of the facing paired link members 31 are rotatably connected to the other ends of the first arm members 19 through shafts 32. The paired third arms 28 are bridged by a pair of plank members 33.The other ends of the second arm members 26 are rotatably connected through shafts 34 to the one ends of link members 35, respectively, the other ends of which are rotatably connected through shafts 36 to the one ends of a pair of plank-shaped fourth arm members 37 at the side of the member 18. The paired fourth wide arm members 37 are rotatably connected at their substantially center portions to the third arm members 28 through shafts 38. A pair of fifth arm members 39, which are made wide similarly to the aforementioned arm members and which face each other, are connected at their one ends at the side of the member 18 through shafts 41 to the one ends of link members 40, the other ends of which are connected through shafts 42 to the other ends of the third arm members 28. The plank-shaped paired fifth arm members 39 are bridged by a pair of plank members 42a.The fifth arm members 39 are rotatably connected at their substantially center portions to the other ends of the fourth arm members 37 through shafts 43.

A gun rotating mechanism 44, which extends substantially on the center line 17 of the arm 12, is constructed of a link rod 46, which is connected to an actuator 45, and link rods 47 to 50. The link rod 46, which is interposed between the paired arm members 19, is so supported by the member 18 that it can rotate through a bearing 51 in the direction G on the center line 17. The link rod 46 and the link rod 47 interposed between the paired arm members 26, the link rod 47 and the link rod 48 interposed between the paired arm members 28, the link rod 48 and the link rod 49 interposed between the paired arm members 37, and the link rod 49 and the link rod 50 interposed between the paired arm members 39 are connected by universal joints 52 to 55, respectively, so that, when the arm 12 is bent, the gun rotating mechanism 44 is accordingly bent.The universal joints 52 to 55 per se are weli known in the art. The link rod 48 is rotatably supported through a bearing 57 on a supporting member 56 which is fixed to the plank members 33. Likewise, the link rod 50 is rotatably supported through a bearing 59 on a supporting member 58 which is fixed to the plank members 42a. The rod 14 is attached to the link rod 50 so that it is rotated in the direction G when the gun rotating mechanism 44 is rotated in the direction G.

To the rod 20, there is connected a hydraulic 3ctuator 60, by which the rod 20 is moved back and forth in the direction of arrow A or B, i.e., in the direction along the center line 17. A hydraulic actuator 61 is so connected to the member 18 that it can rotate the latter in the direction G on the center line 17. Thus, the rotations of the member 18 and the rod 46 can be performed independently of each other.

The manipulator 1 having the elephant nose type arm 12 thus constructed has the following operations. The post 3 is rotated about the center line 6 by the actuation of the hydraulic actuator disposed in the platform 2 and is swung in the vertical plane about the shaft 7 by the actuation of the hydraulic cylinder 8, and the arm 4 is swung in the vertical plane about the shaft 9 by the actuation of the hydraulic cylinder 10.

When the member 18 is rotated on the center line 17 bythe actuation of the actuator61,the arm 12 is likewise rotated on the center line 17, and, when the rod 46 is rotated on the center line 17 by the actuation of the actuator 45, the rod 14 is rotated, whereby the gun 16 is rotated. When the rod 20 is moved in the direction B, for example, by the actuator 60, the second arm members 26 are swung in the direction of arrow C about the shafts 27. When the arm members 26 are swung in the direction C, the link members 31 are swung in the direction C about the shafts 32, and the third arm members 28 are swung in the direction C about the shafts 29.

When the third arm members 28 are swung in the direction C, the link members 35 are swung in the direction C about the shafts 34, and the fourth arm members 37 are also swung in the direction C about the shafts 38. When the fourth arm members 37 are swung in the direction C, the link members 40 are swung in the direction C about the shafts 42, and the fifth arm members 39 are also swung in the direction C about the shafts 43. As a result, the arm 12 is bent in such a manner as is shown in Figure 5.

When the arm 12 is thus bent, the gun rotating mechanism 44 is also bent in a manner to correspond to the bending operation of the arm 12. Even at this state, the rod 14 can be rotated by rotating the rod 46 by the actuation of the actuator 45. Moreover, the arm 12 itself can also be rotated by the actuator 61. On the contrary, if the rod 20 is moved in the direction A by the actuator 60, the arm 12 is bent in the opposite direction to that of Figure 5, i.e., as is shown in Figure 6. Even at the bent state shown in Figure 6, the rod 14 and the arm 12 per se can be rotated independently of each other.

Incidentally, although the link members and the arm members are constructed in pairs in the embo dimentthus far described, the present invention should not be limited thereto but can be constructed such that the link members and the arm members are made of single components, respectively, if necessary. Moreover, the rod 14 may be made to protrude from the third arm members, for example.

In addition, the flexible arm may be constructed by connecting more arm members and link members such as sixth arm members. Furthermore, although the arm 12 is attached to the arm 4 in the embodimenu thus far described, the arm may be made as a whole into a flexible arm and attached to the post 3 or platform 2. Furthermore, the present invention can be applied not only to the painting manipulator and a welding manipulators controlled by data processing machine but also to such a manipulator as can grip workpieces.

Claims

1. Aflexible arm including a base member, an actuating rod movably mounted on said base member, a first arm member fixed to said base member, a second arm member rotatably connected to said first arm member and swingably connected at one end to said actuating rod, a third arm member connected rotatably to said second arm member, and a link member swingably connected at one end to one end of said first arm member and swingably connected at the other end to one end of said third arm member.

2. A flexible arm according to Claim 1, including first, second and third link rods respectively juxtaposed with said arm members and connected to each other through universal joints, said first link rod being rotatably supported by said base member and said third link rod being connected through said second link rod to said first link rod and being rotatably supported by said third arm member.

3. Aflexible arm according to Claim 2, including a first actuator for moving said actuating rod in the direction of the center line of said arm relative to said base member, a second actuator for rotating said base member, which is rotatable, and a third actuator for rotating said first link rod relative to said base member.

4. Aflexible arm according to any of the preceding Claims, wherein each of said first to third arm members is a pair of members facing each other.

5. A flexible arm according to any of Claims 1 to 3, wherein each of said first to third arm members is made of a pair of plank-like members which have wide sides facing each other.

6. Aflexible arm according to Claim 2 or 3, wherein each of said first to third arm members is made of a pair of plank-like members which have wide sides facing each other, the corresponding ones of said link rods being interposed between said plank members.

7. A flexible arm according to any one of the preceding Claims, wherein said actuating rod and said second arm member are connected through another link member, said actuating rod and said another link member being swingably connected to each other, said another link member and said second arm member being swingably connected to each other.

8. A flexible arm constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A robot including a flexible arm according to any preceding Claim.

10. A robot constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.