JPS5871092A - Robot arm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a robot arm in which a wrist portion constituting the arm can be driven and displaced within a three-dimensional space.

2. Description of the Related Art In recent years, the robot arm of industrial robots is required to have a tip that is as flexible as a human wrist, in order to enable, for example, welding and painting of automobile body parts. A robot arm that meets this requirement is 1, for example, 881g352-
It is described in No. 111158. ``These various robot arms include a plurality of links connected in a chain, and adjacent ends of each link are connected by joining two curved surfaces. Therefore, when the links constituting the arm tilt, positional deviations such as slipping and rattling occur at this curved joint. This positional deviation is added together with the tilting of the plurality of links, and is transmitted and reached to the tip of the arm. Therefore, the tip of the arm is moved with an accumulated amount of positional deviation with respect to a predetermined position. Such a positional shift of the arm tip prevents a predetermined task from being executed, which requires maintaining high positional accuracy of the arm tip.

Not desirable.

The present invention has been made based on the above-mentioned matters, and an object of the present invention is to provide a robot arm that does not cause positional deviation when the arm is tilted.

In order to achieve the above-mentioned object, the present invention connects the adjacent ends of a plurality of link members connected in a chain by a means having a single point pair and a bevel pair. It is designed to eliminate misalignment such as slipping and rattling.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the robot arm of the present invention. In FIG. 1, 1 is a holding frame, and 2 is a rotating shaft rotatably supported by the holding frame 1 through a bearing 3. In FIG. This rotating shaft 2 is connected to rotational drive means (not shown). The holding frame 1 is attached to a member (not shown) that moves up and down and rotates. A wrist portion W of a robot arm is mounted on the rotating shaft 2, and a Ube H to which an operating tool such as a painting gun is attached is connected to the tip of the wrist portion W.

The wrist portion W includes a first link member 4 connected in a chain from the holding frame 1 toward the Ube H. It includes a second link member 5, a third link member 6, and a fourth link member 7. One end of the first link member 4 is fixed to the first ring 9 by a pin 8.

The first ring 9 is connected to the rotating shaft 2 by a universal joint 10 . Further, the first ring 9 has a driving member 11 connected thereto so as to allow its rotation, and two actuators 12a connected thereto.

12b and the pin shaft 10a of the universal joint 10.

It can be tilted 10b times. The overlapping portion of the other end of the first link member 4 and one end of the second link member 5 includes the second ring 13 and the universal joint pin shaft 14a,
14b. Second link member 5
The overlapping portion of the other end of the link member 6 and the one end of the third link member 6 is the third ring 15 and the universal joint pin shaft 16a, 1
6b. Similarly, the overlapping portion of the other end of the third link member 6 and one end of the fourth link member 7 is connected by the fourth ring 17 and the universal joint pin shafts 18M and 18b. There is. The other end of the fourth link member 7 is connected to the Ube H. The end of the rotating shaft 2 and the second link member 5 opposite thereto are connected by a first universal joint 19 that functions as a pair and a first universal bearing 20 that functions as a pair. ing. The opposing portions of the first link member 4 and the third link member 6 are connected to the second universal joint 21, the second universal bearing 22, and the K
Therefore, they are connected. Similarly, the second link member 5
The opposing portions of the third link member 7 and the fourth link member 7 are connected by a third universal joint 23 and a third sliding bearing 24 . The aforementioned first, second and third universal joints 19,
21.23+-1 In this example, a type with a cross pin shaft is used, but other types may be used. Also, 1st. In this example, the second and third horizontal bearings 20, 22, 24 are constructed of a rectangular shaft member and a bearing body that guides it so as to enable movement and rotation in the axial direction in order to transmit rotational force. However, Q-joints such as splines and serrations are also possible.

The above-mentioned 1. Second and third universal joints 19°21.
23 and 1st. Second and third plain bearings 20.22.
24 exhibits a mechanism that prevents positional deviations from occurring during angular transmission between the respective link members during the bending motion of the wrist portion W.

Next, the operation of the embodiment of the robot arm of the present invention described above will be explained using FIGS. 1 and 2.

As shown in FIG. 1, in a state where the axis of the ube H is aligned with the axis of the rotating shaft 2, the actuators 12B and 12b shown in FIG. When the first ring 9 and the first link member 4 are fixedly connected, when the first ring 9 and the first link member 4 are fixedly connected, the first link The member 4 tilts at the same angle α1 as the tilt angle α1 of the ring 9 of the electromotive force 1 described above with respect to the axis of the rotating shaft 2. By tilting the first link member 4 at an angle α1, the second link member 5 moves counterclockwise around the first universal joint 9 as a fulcrum. It tilts at an angle β with respect to the link member 4. Therefore, the second link member 5 is tilted by an angle α, +β with respect to the axis of the rotary shaft 2 due to the tilting of the first ring 9 by an angle α. Further, the second link member 5 is connected to the fourth link member 7 via the third link member 6.
, the third link member 6 tilts at an angle α with respect to the second link member 5, and the fourth link member 7 tilts at an angle β with respect to the third link member 6. tilt. As a result, the axis of the flat portion H is finally tilted by an angle α1+β1+α, +β with respect to the axis of the rotating shaft 2. In this example, pin 8. A triangle obtained by the first universal joint 19 and the universal joint pin shaft 14M, the universal joint pin shaft 14a, and the second universal joint 2
2 and the triangle obtained by the universal joint pin axis 16a, and the universal joint pin axis 16a.

Since the triangles obtained by the third universal joint 23 and the universal joint pin shaft 1811 are formed to be geometrically the same, the angle α3. α and α are the same angle, and the angle β8. β and β are the same angle. For this reason 1
Tilt angle α, +β, +α, +β of flat part H with respect to rotation axis 2
, becomes 2(α, +β1), now C11-2QO,
When β=300, the tilt angle of one flat portion H is 1000.

As mentioned above, the base of the triangle obtained by tilting each link member 4 to 7, that is, the distance between the pin 8 and the universal joint pin shaft 11, the distance between the universal joint pin shaft 141 and the universal joint pin shaft 161, and the universal joint The distances between the pin shaft 1651 and the universal joint pin shaft 182 are set to equal constant lengths. When each link member 4 to 7 is positioned in a straight line as shown in FIG.
．． The second and third sliding bearings 20, 22, 24 are similarly located on the same line, but each link member 4-7 is tilted as shown in FIG.

The above-mentioned tilting of each of the link members 4 to 7 is allowed by the universal joints 19, 21.23, which are connection parts between the rotation shaft 2 and each of the link members 4 to 5, but the rotation shaft 2 and the second link The lengths of the member 5 and the third link member 6 in the axial direction become insufficient. This lack of length in the axial direction is the first. This can be supplemented by a second and third flat bearing 20, 22.24. By pivotally connecting each link member 4 to 7 and the rotating shaft 2 with a pair of bearings 20, 22° 24 and a universal joint 19121.23, the tilting angle of each link member 4 to 7 can be shifted. It is possible to reliably transmit the information without causing any distortion, and it is also possible to greatly change the range of the tilt angle between each link member 4 to 7.

The operation of the wrist portion W shown in FIG. 2 is to tilt the flat portion H within a certain plane, and this is achieved by rotating the rotating shaft 2 in the state shown in FIG.

The flat portion H can be rotated around the axis in the state shown in FIG. This allows the Ube mouth to be moved three-dimensionally.

In addition, in the above-mentioned example, the tilting angle α,.

Since β is determined by the geometric distance forming the triangle described above, by changing this geometric distance, the tilting angle of each link member 4 to 7, that is, the bending angle of one wrist portion W can be changed. can be selected as desired. In addition, by further increasing the number of combinations of link members, rings, universal joints, and sliding bearings provided between the flat part H and the rotating shaft 2, the bending angle of the flat part H with respect to the axis of the rotating shaft 2 can be increased. can do.

As described in detail above, according to one aspect of the present invention, the tilting angle input applied from the arm side of the robot arm can be sequentially amplified and transmitted to the flat portion without causing any positional deviation.

As a result, the Ube of the robot arm can be moved with high precision,
and can be positioned.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the wrist portion of the robot arm of the present invention, and FIG. 2 is a plan view showing the tilting motion of the wrist portion of the robot arm of the present invention shown in FIG. . DESCRIPTION OF SYMBOLS 1... Holding frame, 2... Rotating shaft, 4-7... Link member. 9,13115.17-IC//, 1211 12b-
7 Kuchyu-ta% 141614b, 16a. 16b, 18m, 18b--Universal joint pin shaft, 19°21.23--Universal joint, 20.22.24--Sliding bearing, W--Wrist part, H--Flat part.

Claims (1)

[Claims] 16. A robot arm having a large number of bending joints, including a holding frame and a shaft body rotatably supported by the holding frame and connected to rotational drive means. A plurality of link members connected in a chain, a universal joint that pivotally connects the overlapping parts of the link members 6, and a link member and a shaft adjacent to the holding frame side of the link members. a universal joint that pivotally connects the body, a point and a pair of coupling means that connects the opposite ends of the link member and the rotating shaft, and a link that is connected to the universal joint closest to the holding frame side, and A robot arm comprising a tilting drive means for applying a tilting input to a member. 2. A patent characterized in that the point and side coupling means is composed of a universal joint that pivotally connects the ends of adjacent members, and a side joint provided on either one of the adjacent members. A robot arm according to claim 1.