JPS629880A - Parallel link type 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] [Field of Application of the Invention] The present invention relates to a parallel link type robot arm, and in particular,
The present invention relates to a parallel link type robot arm suitable for increasing the rigidity of multi-joint joints of industrial robots and improving control accuracy.

[Background of the invention]

There are various types of articulated industrial robots depending on the drive method, such as parallel link type and direct joint drive type.
Parallel link type robots are often used. (US Pat. No. 4,076,131) Therefore, a conventional parallel link type robot arm will be explained with reference to FIGS. 4 to 8.

First, FIG. 4 is a schematic configuration diagram of a conventional parallel link type robot.

As shown in FIG. 4, the parallel link type robot includes a rotating body 1, an upper arm 2' associated with a first arm member provided on the rotating body 1, and a rotating body that swings through a pivot on this upper arm 2'. The forearm 3' related to the second arm member and the link member 4' related to the auxiliary member, which can be coupled together, form a parallel link, and the arm 3' has a wrist portion 5 at its distal end. There is.

The degrees of freedom of movement in this case generally consist of three degrees of freedom for rotation, upper arm, and forearm function, and two to three degrees of freedom for the wrist.

Among these, the drive for the degree of freedom of the wrist portion 5 located at the tip of the forearm 3' also poses a problem.

Since articulated industrial robots require high speed and high precision, they require lightweight, vibration-free and highly rigid mechanisms and drive systems. The driving force is important.

There are many methods for driving the wrist portion 5, such as direct drive, chain drive, torque tube drive, and belt drive, but chain drive and torque tube drive are often used. in this case.

A driving mechanical element or mechanism (hereinafter referred to as a driving element system) such as a chain or a torque tube is generally arranged within the structure of the forearm 3', in other words, above the forearm axis 3o.

Figures 5 and 6 show a conventional chain-based wrist-driven robot arm near the joint between the forearm and upper arm, with Figure 5 being a side sectional view and Figure 6 being a front sectional view. It is.

As shown in FIG. 5, a required number of chains 6 are arranged within the box-shaped structure of the forearm 3A, for example, two chains in the example shown in FIG.

The upper arm 2A and the forearm 3A are connected, for example, as shown in FIG. 6, by providing support bosses 9 on opposing brackets 2a on the upper part of the upper arm 2A, which is configured in a box shape. It is supported via a bearing 8 mounted on the boss 7, and is rotatably coupled by a coupling pin 10 related to a pivot.

In the case of chain drive as shown in FIGS. 5 and 6, since the chain 6 runs, the connection center, which is the center of the connection pin 10, is located approximately in the middle of the chain.

Further, since the forearm 3A swings around this connection center, interference with the upper end wall 2c of the upper arm 2A becomes a problem. Therefore, the effective height H of the bracket 2a of the upper arm 2A needs to be quite large.

The bracket 2a needs to support not only the load in the plane of the parallel link that is applied to the joint, but also the out-of-plane lateral load and torsional torque. On the other hand, since the brakerato 2a has an open cross section, the greater the height H, the lower the rigidity with respect to these.
This becomes a problem from the perspective of vibration 1 intensity. In order to prevent this, it may be possible to increase the thickness of the bracket 2a, but this would be unreasonable as it would increase the weight. Also, although it is effective to bring the coupling rotation center closer to the bottom in Figure 5,
is running, so it is difficult beyond a certain point.

On the other hand, as shown in FIG.
Normally, a, 3-b, and 3-c are arranged in a straight line.

In FIG. 4, 3-a is the wrist bending axis fulcrum related to the fulcrum of the connection between the forearm 3' and the wrist part 5 at the tip of the forearm 3', and 3-b is the connection fulcrum between the upper arm 2' and the forearm 3'. Fulcrum, 3-
C is a connecting fulcrum between the link member 4' and the forearm 3', which are provided parallel to the upper arm 2'. The joint fulcrums 3-b and 3-c serve as surface joint fulcrums of parallel links, and this surface joint fulcrum 3-b.

The line 3P connecting 3-c is called the parallel link axis. Also,
30 is the longitudinal centerline of the forearm 3' and is referred to as the forearm axis.

The parallel link axis 3P and the forearm axis 30 are on the same straight line in the case of FIG.
The wrist bending axis fulcrum 3-a is located on the extension line of c.

This is because the advantage of simplifying the control software for robot control is great. Therefore, if the surface joint supports 3-b and 3-c of the parallel links are shifted from the forearm axis 30 (so-called offset), this advantage in terms of control software will be lost.

Next, FIG. 7 is a front cross-sectional view of a conventional torque tube-based wrist-driven robot arm, showing the joint between the forearm and the upper arm, and the joint fulcrum 3-b between the upper arm 2B and the forearm 3B. It shows a cross section.

The forearm 3B, which forms the complete circle WJW through which the torque tube 12 penetrates, is rotatable via a bearing 8 by a coupling pin 11 related to a pivot attached to an opposing bracket 2d on the upper part of the upper arm 2B configured in a box shape. Supported.

In this case, the wrist bending axis fulcrum 3-a is on an extension of the parallel link axis 3P, similar to that shown in FIG. As a result, the presence of the torque tube 11 increases the effective height H of the bracket 2d, which is not reasonable, as in the case of chain drive.

On the other hand, Fig. 8 is a diagram showing the main parts of the same conventional torque tube-driven parallel link type robot, and the same numbers as in Figs. 4 and 7 are the same parts as in the previous example. Therefore, the explanation will be omitted.

A plurality of drive motors 13 for operating the wrist portion 5 in multiple degrees of freedom are installed on the side opposite to the wrist of the forearm 3B.
A torque tube 12 for transmitting the power of each drive motor 13 to the wrist portion 5 passes through the inside.

14 is a forearm drive means connected to the forearm 2B and the link member 4B, and this forearm drive means 14 is connected to the drive motor 14.
A ball screw 14B operated by A is provided.

In the robot arm of FIG. 8, the connecting fulcrum 3-b of the upper arm 2B and forearm 3B and the connecting fulcrum 3-c of the link member 4B and forearm 3B are connected via brackets 15 and 16, respectively. The parallel link axis 3P connecting the fulcrums 3-b and 3-c is deviated by an amount D (so-called offset amount) from the forearm axis 30 through which the first wrist bending axis fulcrum 3-a passes, forming a parallel link.

As a result, interference between the forearm 3B and the upper arm 2B during rocking is reduced, the effective height H of the bracket 2d of the upper arm 2B is reduced, and the rigidity of the bracket 2d is reduced.

Strength increases. However, since the joint fulcrums 3-b, 3-C and the wrist bending axis fulcrum 3-a are misaligned, there is a problem in that the robot control software becomes complicated and unreasonable.

[Purpose of the invention]

The present invention has been made to solve the problems of the prior art described above, and includes a first arm member and a second arm member constituting a parallel link.
The purpose of this invention is to provide a parallel link type robot arm that can have high rigidity and light weight at the joints of arm members, and can improve accuracy and reliability by taking advantage of the advantages of robot control software.

[Summary of the invention]

The configuration of the parallel link type robot arm according to the present invention is such that a parallel link is configured by a first arm member, a second arm member swingably coupled to the first arm member, and an auxiliary member. A parallel link type robot arm in which a wrist part is connected to the distal end of a second arm member, and a driving element system for the wrist part is disposed on the axis of the second arm member. The joint intersection of the second arm member and the first arm member, and the second
The connecting fulcrum of the wrist portion is positioned on an extension of the parallel link axis connecting the surface connecting fulcrum of the connecting fulcrum of the arm member and the auxiliary member, and the connecting fulcrum of the wrist portion is used as a fulcrum to connect the parallel link axis. , the axis of the wrist drive element system in the second arm member maintains a required angle to maintain a gap that prevents interference between the wrist drive element system and the first arm member. .

Additionally, the idea behind developing the present invention is as follows.

In a conventional parallel link type robot arm, the wrist bending axis fulcrum is located at the tip of the forearm on the forearm axis of the second arm member that constitutes a part of the parallel link, and furthermore, In many cases, the axis was aligned.

In addition, even in a configuration in which the axes do not coincide with each other, the eighth
As shown in the figure, since the parallel link axis 3P and forearm axis 3Q are parallel to each other and have a deviation amount (offset) D, the wrist bending axis fulcrum 3-a is misaligned with the parallel link axis 3P. became.

In order to improve this point, the wrist bending axis fulcrum located on the extension line of the parallel link axis is used as a fulcrum, and the axis of the wrist drive element system in the forearm is tilted at a required angle with respect to the parallel link axis. The idea was to secure space for the arrangement of the drive element system.

As a result, in terms of control, a parallel link structure with no deviation is obtained, and the engagement fulcrum of the upper arm related to the first arm member and the forearm related to the second arm member is set to the forearm axis (i.e., the axis of the wrist drive element system). The idea was to create a lightweight and highly rigid robot arm structure by shortening the bracket arm at the joint.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

First, FIG. 1 is a configuration diagram of a parallel link type robot according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 4 are the same parts or equivalent parts, so the explanation thereof will be omitted. do.

In FIG. 1, 1 is a rotating body, 2 is an upper arm related to a first arm member provided on the rotating body 1, and 3 is a second arm slidably coupled to this upper arm 2 via a pivot shaft. forearm related to the member;
4 is a link member related to an auxiliary member, and 5 is a wrist portion coupled to the distal end portion of the forearm 3. The upper arm 2 and the forearm 3 form a parallel link via an auxiliary member such as a link member 4.

The connecting fulcrum 3-b of the upper arm 2 and forearm 3 and the connecting fulcrum 3-c of the forearm 3 and link member 4 constitute the reconnecting fulcrum of the parallel link, and these reconnecting fulcrums 3-s and 3-c are A wrist bending axis fulcrum 3-a, which is a fulcrum for connecting the forearm 3 and wrist portion 5, is located on an extension of the connecting parallel link axis 3P.

6 is a chain for driving the rotation and bending operations of the wrist portion 5; 14 is a sprocket wheel for driving the chain; these are disposed within the box-shaped structure of the forearm 3 as a driving element system of the wrist portion 5; ing.

3S indicates the chain drive system axis related to the wrist drive element system axis.

This chain drive system axis 3S is the wrist bending axis fulcrum 3-
The chain 6, sprocket 14, etc. are arranged so as to maintain an angle θ with the parallel link axis 3P using a as a fulcrum.

This angle θ is determined by the angle θ required to maintain a gap where the chain 6, sprocket 14, etc. do not interfere with the upper end wall 2c of the box-shaped structure of the upper arm 2. It's an angle.

According to this embodiment, the connecting fulcrum 3-b between the upper arm 2 and the forearm 3
can be provided as close to the end of the forearm 3 as possible, and the problem of interference with the upper arm 2 caused by the swinging of the forearm 3 can be greatly improved. That is, the bracket height H of the upper arm 2 can be reduced, and the rigidity and strength of the joint can be improved. In addition, by making it small and compact, it is possible to reduce the weight, which brings about excellent results for the drive system of the upper arm, turning, etc. Furthermore, it becomes possible to expand the range of motion of the forearm, making it possible to provide a highly accurate robot arm with better workability.

Moreover, the wrist bending axis fulcrum 3-a is the centroid link axis 3P.
Since it is an extension of the above, the robot control software can also be simplified.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a configuration diagram of a parallel link type robot according to another embodiment of the present invention. In the figure, parts with the same symbols as in FIG. 1 are equivalent to those in the embodiment of FIG. The explanation will be omitted.

The embodiment shown in FIG. 2 is basically the same as the embodiment shown in FIG. -b and 3-c are shifted via brackets 3d and 3e related to supporting structural members.

Wrist bending axis fulcrum 3-a and parallel link reconnection fulcrum 3-
b and 3-c are on the same line, and the chain drive system axis 3S
As in the embodiment shown in FIG. 1, the parallel link axis 3P is inclined at a required angle θ with respect to the parallel link axis 3P.

According to the embodiment shown in FIG. 2, the same effects as those of the embodiment shown in FIG. 1 can be expected, and the forearm 3C can be made lighter.

Next, still another embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a block diagram of the main parts of a parallel link type robot according to yet another embodiment of the present invention. In FIG. 1, parts with the same reference numerals as those in FIG. Omitted.

The embodiment shown in FIG. 3 uses a torque tube 12 as the wrist driving element system, and is different from the conventional example shown in FIG. Parallel link axis 3 connecting surface joint fulcrums 3-b and 3-C of
Position it on the extension of P.

With this wrist bending axis fulcrum 3-a as a fulcrum, the axial center 3T of the torque tube 12, which is provided through the structure of the forearm 3B, is inclined by a required angle θ with respect to the parallel link axial center 3P. It is that you are.

This angle θ is the forearm 3B that the torque tube 12 penetrates.
is the required angle to maintain a gap so as not to interfere with the constituent members of the upper arm 2B.

According to the embodiment shown in FIG. 3, the amount of deviation between the parallel link axis 3P and the forearm axis 30 in the conventional example shown in FIG. Effects similar to those described in the embodiment shown in the figure are expected.

In each of the above-described embodiments, the wrist portion is driven by a chain drive and a torque tube drive. However, the present invention is not limited to this, and other drive element systems may also be used. The same applies if the system is placed in the forearm.

Further, the shapes and structures of the first arm member, the second arm member, etc., the structure of each coupling fulcrum, etc. are not limited to the above-mentioned embodiments.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to increase the rigidity and reduce the weight of the joint between the first arm member and the second arm member that constitute the parallel link, and also to take advantage of the advantages of the robot control software. A parallel link robot arm can be provided that can improve accuracy and reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a parallel link type robot according to an embodiment of the present invention, FIG. 2 is a block diagram of a parallel link type robot according to another embodiment of the present invention, and FIG. 3 is a block diagram of a parallel link type robot according to another embodiment of the present invention. A main part configuration diagram of a parallel link type robot according to still another embodiment of
FIG. 4 is a schematic configuration diagram of a conventional parallel link type robot;
Figures 5 and 6 show a conventional chain-based wrist-driven robot arm near the joint between the forearm and upper arm, with Figure 5 being a side sectional view, Figure 6 being a front sectional view, and Figure 6 being a front sectional view. 7
The figure shows a front sectional view of a conventional wrist-driven robot arm using a torque tube, showing the joint between the forearm and upper arm. This is a composition diagram. 2.2B...upper arm, 2a...bracket, 2c...
・Upper end wall, 3.3B, 3G...Forearm, 3-a...Wrist bending axis fulcrum, 3-b, 3-c-joint fulcrum, 3d, 3e
-Bracket, 3P...parallel link axis, 3S...
Chain drive system axis, 3T...torque tube axis,
5... Wrist part, 6... Chain, 12... Torque tube, 14... Sprocket wheel, 1.5.
16...Bracket. VJl Atlas 2 Diagram

Claims (1)

[Claims] 1. A parallel link is formed by a first arm member, a second arm member swingably connected to the first arm member, and an auxiliary member,
In a parallel link type robot arm, a wrist part is coupled to a distal end of the second arm member, and a driving element system for the wrist part is disposed on the axis of the second arm member, the parallel link comprising: The joint fulcrum of the wrist portion is located on the extension of the parallel link axis connecting the joint intersection of the second arm member and the first arm member, and the joint fulcrum of the second arm member and the auxiliary member. At the same time, the parallel link axis and the axis of the wrist drive element system in the second arm member interfere with each other, and the wrist drive element system and the first arm member interfere with each other, using the coupling fulcrum of the wrist part as a fulcrum. A parallel link type robot arm characterized in that it is configured to maintain a required angle to maintain a gap. 2. In the item described in claim 1, both coupling fulcrums of the parallel link are support structure members protruding from the constituent body of the second arm member around the axis of the wrist drive element system in the second arm member. Parallel link type robot arm installed on top.