JP3539537B2 - Articulated robot - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an articulated robot. More specifically, the present invention relates to an improvement of an articulated robot that transports a work such as a semiconductor wafer between a cassette and a process device.
[0002]
[Prior art]
An articulated robot is used to transfer a work such as a semiconductor wafer from a cassette to a process device or vice versa. As the articulated robot, there is an articulated robot, such as an articulated robot 101 formed of two arms 102 and 103 and a hand 105 shown in FIG. . In this case, the articulated robot 101 or the articulated robot 101 having three arms 102, 103, and 104 as shown in FIG. 9 moves the hand 105 holding the work 110 linearly in the axial direction. Thus, the workpiece 110 is transported without being rotated.
[0003]
As a mechanism for linearly moving the hand unit 105 in this manner, there is a transmission mechanism such as a belt or a pulley provided so that the arm units 102 and 103 are linked. With such a mechanism, the articulated robot 101 limits the movement of the arm units 102, 103 (104), etc., to a certain extent, and, for example, allows each workpiece placed at a different position such as each cassette in a multiple cassette. , 110 are held by the hand unit 105 and provided so as to be able to be conveyed in parallel from that position.
[0004]
[Problems to be solved by the invention]
However, when the hand unit 105 moves in parallel with the axis of the hand unit 105 passing near the rotation center 106 of the first arm unit 102, that is, the center locus of the conveyed work 110 is When passing through the vicinity, the center of rotation 106 of the first arm unit 102 becomes a so-called singular point, and there is a possibility that a load is generated in the movement of each of the arm units 102 and 103 mechanically. That is, as shown in FIGS. 10A to 10C, when the support point 107 of the hand unit 105 passes near the rotation center (singular point) 106 of the first arm unit 102, each of the arm units 102, The arm 103 has to move around the rotation center (singular point) 106 by about 180 degrees, and if the work 110 is to be moved at a constant speed, the arms 102 and 103 need to move quickly. Therefore, there is a possibility that the movement may be unreasonable. The same applies to the articulated robot 101 including three arms 102 to 104 and a hand 105 as shown in FIG.
[0005]
On the other hand, as shown in FIG. 12, an articulated robot 101 having a linear motion mechanism 109 that enables parallel movement of each base 108 has also been proposed. The workpiece 110 can be translated in a state where the workpiece 110 is separated from the rotation center 106. Therefore, it is possible to prevent the hand unit 105 from passing near the center of rotation 106, and it is possible to solve the above-described problem that a singular point is generated. However, in order to provide the articulated robot 101 with the base 108 so as to be able to move in parallel, a space for installation is required, and the linear motion mechanism 109 is liable to generate dust during the parallel movement, so that it can be used in a clean room or the like. It has the problem that it may not be suitable for use.
[0006]
Therefore, an object of the present invention is to provide an articulated robot that can move a work in a straight line without excessively moving an arm portion, and that hardly generates dust during the operation of moving the work. .
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to an articulated robot in which four links each including an arm portion or a hand portion have a driving source and perform a rotational motion independent of other links. A first rotation axis is formed at a position eccentric with respect to the center to constitute a first arm portion, and the position of the first rotation axis is sufficient for a work transfer center trajectory according to a position of a work to be transferred. distance by moving the holding one position such, the first rotational shaft position, the tip of the link from the first arm portion is prevented from becoming singular point requiring going around quickly around the first rotary shaft A rotary table, a second arm portion rotatably held on the first rotation shaft, a third arm portion rotatably held on the tip of the second arm portion, and a rotation on the tip end of the third arm portion. Held possible Wherein by rotating the control first arm portion and a command portion at a position capable of preventing the occurrence of singularities in a state of stopping the second arm and the third arm portion and the hand portion independently Hand The part is moved linearly while pointing in a certain direction .
[0008]
Therefore, the work can be held and transported by combining the rotational movements of the second arm, the third arm, and the hand. Moreover, in this case, before holding and transporting the work, the position of the first rotating shaft can be appropriately moved by first rotating the first arm portion appropriately. Therefore, even if the work is placed at various positions, the rotation axis of the second arm is arranged so that the distance from the locus through which the center of the work passes is sufficiently maintained, and the singular point is set during the transfer of the work. It can be prevented from occurring.
Further, in the articulated robot according to the first aspect, the hand portion is linearly moved by the second arm portion and the third arm portion, and the hand portion is oriented in a fixed direction, and the rotation control of the first arm portion is performed. By doing so, the occurrence of a singular point is prevented, so that the work is moved in parallel and linearly while being held by the hand unit.
[0009]
In the articulated robot according to the second aspect, the first arm or the second arm is configured to be vertically movable. Therefore, the degree of freedom of movement of the articulated robot is increased, and the work can be transported more freely.
[0011]
In the articulated robot according to the fourth aspect, when the distance between the axes of the first arm part is L1, the distance between the axes of the second arm part is L2, and the distance between the axes of the third arm part is L3, (L2- L3) ≦ L1 is set. Therefore, by appropriately setting the position of the first arm, the workpiece can be transferred so that the distance from the rotation center of the first arm moves linearly from 0 to the maximum (L1 + L2-L3).
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0013]
1 to 6 show an embodiment of the articulated robot according to the present invention. In the articulated robot 10, the first rotary shaft 2a is formed at a position eccentric with respect to the rotation center 1a of the rotary table, and the rotary table is used as the first arm 1, and is rotatably held by the first rotary shaft 2a. The second arm 2 is a second arm 2, and the third arm 3 is held at the tip of the second arm 2, and the hand 4 is held at the tip of the third arm 3 so as to be rotatable. By controlling the rotation of the first arm 1, the second arm 2, the third arm 3, and the hand 4, the occurrence of a singular point can be prevented. Hereinafter, a configuration for preventing occurrence of a singular point will be described.
[0014]
In the present embodiment, the first arm unit 1 is formed of a rotary table rotatably provided at the rotation center 1a, but is not particularly limited to this. For example, the first arm unit 1 may be formed of an arm provided on a fixed base. is there. Since the first arm unit 1 is rotatable, the second arm unit 2, the third arm unit 3, and the hand unit 4 on the distal end side are moved circumferentially from the first rotation shaft 2a and stopped at an arbitrary position. Can be done.
[0015]
The four links of the first arm unit 1, the second arm unit 2, the third arm unit 3, and the hand unit 4 constituting the articulated robot 10 of the present embodiment have independent drive sources, respectively, and have other links. Are provided so as to be able to perform rotational movements independent of each other. Therefore, only one link can move independently, or a movement combining a plurality of links can be performed. The drive source is not particularly limited, but is, for example, a stepping motor or a servomotor, and the rotation of each of the arms 1, 2, 3 and the hand 4 is controlled by control means such as a computer.
[0016]
Similarly to the case where the second arm 2 is rotatably held on the first rotating shaft 2a by an articulated structure, the third arm 3 and the hand unit 4 are the second rotating shaft 3a and the third rotating shaft 4a, respectively. It is held rotatably. Regarding the length of each link, as shown in FIG. 2, the distance between the axes of the first arm 1 is L1, the distance between the axes of the second arm 2 is L2, and the distance between the axes of the third arm 3 is L2. L3. At the tip of the hand unit 4, a transfer unit for transferring the work 20, for example, a unit for sucking and holding the semiconductor wafer from the lower surface when transferring a semiconductor wafer is provided. The length from the third rotation shaft 4a to the center of the suction means is L4.
[0017]
Further, in the articulated robot 10 of the present embodiment, as shown in FIG. 3, the arms 2, 3 and the hand 4 are configured to be integrally movable up and down. Therefore, the articulated robot 10 has a total of five degrees of freedom, and is provided so that it can freely move in the vertical direction. The same effect can be obtained even if the first arm 1 is configured to be vertically movable instead of the second arm 2. 2 and 3, reference numeral 11 denotes an aligner for rotating the work 20, and reference numeral 12 denotes a detection means for detecting a notch (not shown) provided at an end of the work 20.
[0018]
Next, a case where the workpieces 20,..., 20 placed on the multiple cassettes 21,. Here, as shown in the figure, a center line C parallel to the work transfer direction passing through the rotation center 1a is imagined, and a distance from the work center 20a to the center line C is hereinafter referred to as an offset length D.
[0019]
When removing the work 20, first, the rotation of the first arm 1 is controlled, and the second arm 2, the third arm 3, and the hand 4 are moved to positions suitable for the position of the work 20. . The preferred position in this case is a position where occurrence of a singular point can be prevented, and specifically refers to each position as shown in FIGS. 5 (A) to 5 (C). That is, in each of the embodiments of FIG. 5, the first rotation shaft 2a, which is the rotation shaft of the second arm 2, is moved to a position that maintains a sufficient distance from the center locus of the work 20 to be conveyed. For example, a work 20 located away from the first arm unit 1 as shown in FIG. 5A is moved toward the work 20 while the first arm unit 1 as shown in FIG. The approaching work 20 is moved to a position on the lower side in the figure to keep a sufficient distance from the center locus of the work 20. Similarly, in the case shown in FIG. 4, the first rotating shaft 2a is moved to a suitable position for each of the works 20,..., 20 by the rotation of the first arm unit 1. When the work 20 is taken out from the lower cassette 21 in the figure, it is needless to say that the arms 2, 3 and the hand 4 may be positioned so as to be symmetric with respect to the center line C in FIG. Nor. Reference numeral 22 in the drawing indicates a process device.
[0020]
After the first rotating shaft 2a is moved to a suitable position in this manner, the first arm 1 is stopped at the position, and the workpiece 20 is moved by the second arm 2, the third arm 3, and the hand 4. Take out from the cassette 21. At this time, the hand unit 4 is linearly moved by the second arm unit 2 and the third arm unit 3, and the hand 20 is taken out while the hand unit 4 is oriented in a certain direction. That is, when the workpiece 20 is transported by using the articulated robot 10, the workpiece 20 is moved linearly by combining the rotational motions of the links, and the inclination of the longitudinal axis of the hand unit 4 with respect to the workpiece transport direction is set to 0. , And the work 20 is moved in a parallel and linear manner.
[0021]
In the embodiment shown in FIGS. 4 and 5, the second arm 3 and the third arm 3 do not intersect during the operation of transporting the work 20 from the cassette 21. Another embodiment in which the work 20 is conveyed while moving is also possible. As shown in FIGS. 6A and 6B, the third arm 3 is superimposed on the second arm 2 while the work 20 is being conveyed, and the work 20 is continuously conveyed by being further rotated. Is what you do. In this case, the lengths of the center distances L1, L2, and L3 of the respective arm portions are not particularly limited. However, as shown in FIG. When conveying 20, it is necessary to set so that (L2−L3) ≦ L1. In this case, by appropriately setting the position of the first rotating shaft 2a, it is possible to convey the work 20 so that the offset length D linearly moves from 0 to the maximum (L1 + L2-L3).
[0022]
According to the articulated robot 10 configured as described above, first, the first rotation axis 2a is moved to a suitable position where the distance from the center locus of the work 20 is sufficiently maintained. It can be moved linearly at a position away from the first rotation shaft 2a. Therefore, a singular point hardly occurs when the work 20 is moved linearly, and even when the work 20 is conveyed at a constant speed, it is possible to prevent an unreasonable movement of each link. Further, according to the above-described another embodiment, the work 20 can be transported on the center trajectory in which the offset distance D is a maximum (L1 + L2−L3) away from 0. According to the first embodiment, the work 20 can be further moved. It is possible to convey on a distant center locus.
[0023]
In addition, since the first arm 1 in the present embodiment is formed by a rotary table, dust is less likely to be generated when the second arm 2 and the like are rotationally moved, and the installation space can be reduced.
[0024]
The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, when the hand unit 4 is moved linearly, the longitudinal axis of the hand unit 4 is made to coincide with the work transfer direction. However, as shown in FIG. By moving the axis 4c while tilting the axis 4c, it is possible to take out and transport the work 20 at a position further distant from the above-described embodiment. However, in this case, not only must the hand unit 4 and the cassette 21 not interfere with each other, but in order to transport the work 20 without rotating it, it is necessary to move the work while keeping the inclination of the axis 4c constant. Needless to say.
[0025]
【The invention's effect】
As apparent from the above description, in the articulated robot according to the first aspect of the present invention , the first rotary shaft is formed at a position eccentric to the rotation center of the rotary table constituting the first arm. The first rotation axis is moved to a position where a singular point does not occur while maintaining a sufficient distance with respect to the transfer center trajectory of the work in accordance with the position of the work to be transferred. Each work placed at a plurality of positions can be moved linearly without making any unnecessary movement, and the movement speed of the work can be kept constant.
[0026]
Moreover, the articulated robot of the present invention is suitable for use in a clean room or the like, since the first arm portion is formed by a rotary table, so that dust is unlikely to occur during operation and space can be saved.
Further, in the articulated robot according to the first aspect of the present invention, since the hand section is linearly moved by the second arm section and the third arm section, and the hand section is oriented in a fixed direction, the workpiece is not rotated. And can be conveyed in a straight line in parallel. Moreover, since the occurrence of a singular point is prevented by controlling the rotation of the first arm, each work placed at a plurality of positions can be moved without forcibly moving the arm or the like. .
[0027]
In the articulated robot according to the second aspect of the present invention, since the first arm or the second arm is configured to be vertically movable, the degree of freedom of movement of the articulated robot is increased, and the workpiece can be transported more freely. can do.
[0029]
Further, in the articulated robot according to the fourth aspect of the present invention, since the distance between the axes of the respective arm portions is set so as to satisfy (L2−L3) ≦ L1, the position of the first arm portion is appropriately set. Thus, the work can be transported so as to move linearly from a distance 0 from the rotation center of the first arm portion to the maximum (L1 + L2-L3).
[Brief description of the drawings]
FIG. 1 is a plan view illustrating an embodiment of an articulated robot according to the present invention.
FIG. 2 is a plan view showing one form of each arm unit and hand unit of the articulated robot.
FIG. 3 is a side view showing an articulated robot in which an arm and the like are provided to be vertically movable.
FIG. 4 is a plan view showing a state in which a work placed on a cassette is taken out by an articulated robot.
FIGS. 5A to 5C are plan views showing modes in which a workpiece is carried by an articulated robot, and FIGS. 5A to 5C show differences in offset length D. FIGS.
FIGS. 6A and 6B are plan views showing another embodiment when a workpiece is transferred by an articulated robot, wherein FIG. 6A shows a case where an offset length D is present, and FIG. 6B shows a case where the offset length D is zero.
FIG. 7 is a plan view showing another embodiment when a work placed on a cassette is taken out by an articulated robot.
FIG. 8 is a plan view showing a conventional articulated robot.
FIG. 9 is a plan view showing a conventional three-arm articulated robot.
FIG. 10 is a plan view showing how the articulated robot shown in FIG. 8 conveys a work in the vicinity of a singular point, and shows the progress of conveyance from (A) to (C).
11 is a plan view showing how the articulated robot shown in FIG. 9 conveys a work near a singular point, and shows the progress of conveyance from (A) to (C) in order.
FIG. 12 is a plan view showing a conventional articulated robot having a linear motion mechanism.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 rotary table 1a rotation center 2 second arm 2a first rotation axis 3 third arm 4 hand 10 articulated robot L1 distance L2 between first arm L2 distance L3 between second arm L3 third arm Distance between shafts

Claims (3)

An articulated robot in which four links each composed of an arm portion or a hand portion has a driving source and performs a rotating motion independent of other links, wherein a first rotating shaft is formed at a position eccentric with respect to a center of rotation. the first constitutes the arm portion Te, by moving a sufficient distance to maintain its one position with respect to the transport center locus of the workpiece according to the position of the workpiece to be transported to the position of the first rotary shaft, the A rotary table for preventing a position of a first rotation axis from becoming a singular point that requires a link ahead of the first arm to quickly wrap around the first rotation axis; and a rotatable rotation about the first rotation axis. A second arm portion held, a third arm portion rotatably held at a tip of the second arm portion, and the hand portion rotatably held at a tip of the third arm portion, Source of the singularity By controlling the rotation of the second arm, the third arm, and the hand independently of each other in a state where the first arm is stopped at a position where the hand can be prevented, the hand is moved in a certain direction. An articulated robot that moves linearly while facing . The articulated robot according to claim 1, wherein the first arm or the second arm is configured to be vertically movable. When the center distance of the first arm is L1, the center distance of the second arm is L2, and the center distance of the third arm is L3, (L2−L3) ≦ L1. The articulated robot according to claim 1 or 2, wherein:

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