JPH0829512B2 - Articulated industrial robot - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint type industrial robot to which a four-bar parallel link mechanism is applied.

[0002]

2. Description of the Related Art As a joint type industrial robot of this type, for example, a structure shown in FIGS. 5 and 6 is known.

As shown in FIGS. 5 and 6, the lower arm 2 supported by the bracket 1a on the swivel base 1 has an axis P.
It is rotatable about ₁ in the direction of arrow A, and the upper arm 3 is supported by the axis P ₂ with respect to the lower arm 2 and rotatable in the direction of arrow B. A wrist portion 8 is provided at the tip of the upper arm 3.

At the lower end of the lower arm 2, the lower arm 2
And a link 4 having the same axis P ₁ on the other hand, and on the other hand, a link 5 is also connected to the end portion of the upper arm 3 via the axis P ₄ . By connecting these links 4 and 5 to each other via the axis P ₃ , the lower arm 2 and the upper arm 3 are connected.
A four-bar parallel link mechanism is included.

Then, the lower arm 2 is rotated in the direction of arrow A by the action of the drive motor 6 through a speed reduction mechanism (not shown). At this time, since the upper arm 3 and the link 4 are always parallel as a characteristic of the parallel link mechanism, the upper arm 3 maintains the parallel state before and after driving the lower arm.

With respect to the upper arm 3, the link 4 is centered on the axis P ₁ by the action of the drive motor 7.
Is rotated, the rotational displacement of the link 4 is transmitted to the upper arm 3 via the link 5. As a result, the upper arm 3 is moved around the axis P ₂ by the arrow B.
It will rotate in the direction.

Since the drive motor 6 has a parallel link mechanism, it does not directly bear the rotational moment of the upper arm 3, and therefore the torque that the drive motor 6 bears generally does not have a parallel link mechanism. It is said to be smaller than an industrial robot.

[0008]

In the conventional articulated industrial robot as described above, when the angle θ formed by the lower arm 2 and the upper arm 3 approaches 180 degrees or 0 degrees, respectively, the top dead center or It reaches the limit as the bottom dead center, and further rotation is impossible. Therefore, the practical operating range is limited to the range of about 30 to 120 degrees in θ value.

That is, FIG. 7 shows an operating region of a conventional industrial robot, and a hatched region Q in FIG. 7 is an operating region of the center P ₀ of the wrist section 8.

Assuming that a vertical line passing through the axis P ₁ is Y, the angle α ₁ formed by the vertical line Y and the lower arm 2 is limited by the interference between the swivel base 1 and the lower arm 2, and in FIG. The range is about 60 degrees in the clockwise direction (minus direction) and about 45 degrees in the clockwise direction (plus direction).

The angle θ formed by the lower arm 2 and the upper arm 3 is limited by the interference between the arms 2 and 3 and the interference between the lower arm 2 and the link 5. In FIG. 7, it is theoretically in the range of about 45 to 135 degrees.

Similarly, the angle α ₂ formed by the vertical line Y and the link 4 is limited by the interference between the link 4 and the turning base 1 and the interference between the link 4 and the lower arm 2,
In FIG. 7, a counterclockwise direction (minus direction) from the vertical line Y
At about 15 degrees, the range is about 120 degrees in the clockwise direction (plus direction).

Due to the above-mentioned restrictions, in FIG. 7, unless the swivel base 1 is swung, the working area Q is limited to the left half of the vertical line Y. That is, in the structure of the conventional industrial robot, it is impossible to pass the upper arm 3 shown by the solid line in FIG. 7 right above the turning base 1 and rotate it to the rear side. When attempting to handle a workpiece in the operating area Q and then sandwich the vertical line Y to handle the workpiece in a rear area opposite to the operating area Q, the robot as a whole is swung together with the swivel base 1 after gripping the workpiece. Need to work. As a result, in order to prevent interference between the robot and its peripheral equipment, it is necessary to secure a sufficient space for turning around the robot, especially in a robot work line where multiple robots are installed side by side in terms of space efficiency. Significantly disadvantageous.

The present invention is an articulated industrial robot capable of increasing the transportable weight while making the structure compact and taking advantage of the advantages of the conventional four-bar parallel link mechanism type robot. Is to provide.

[0015]

The articulated industrial robot of the present invention comprises a fixed link provided on a base, a lower arm rotatably connected to one end of the fixed link, and an upper end portion of the lower arm. A four-bar parallel link mechanism is constituted by an upper link whose one end is rotatably connected to each other, and a lower link which connects the other end of the fixed link and the other end of the upper link to each other. The upper arm is rotatably connected to the upper link through a single shaft common to the shaft connecting the upper link and the upper link or the shaft connecting the upper link and the lower link, and the lower arm. It is characterized in that lower side driving means for rotating the upper arm and upper side driving means for rotating the upper arm are individually provided.

[0016]

According to the present invention, since the upper arm can freely rotate without being restricted by the four-bar parallel link mechanism and has a high degree of freedom of rotation, as apparent from FIG. 4 of the embodiment. An extremely large value of about 45 to 315 degrees can be secured for the angle formed by the lower arm and the upper arm, and there is no limitation due to α ₂ shown in FIG. 7. Therefore, it is possible to secure an extremely large operating area as shown by the diagonal lines in FIG.

Further, by aligning one of the shafts at both ends of the upper link with the center of rotation of the upper arm, the upper arm is driven on the same axis as either of the shafts at both ends of the upper link. Since a drive motor can be provided, there is no increase in the number of parts or complication of the structure as in the case where the center of rotation of the upper arm is separately set in a portion other than the shaft of the upper link, and the drive motor is not generated. As a result, a large-capacity motor can be adopted, and the transportable weight can be increased while making the structure compact.

In other words, for example, if the rotation center of the upper arm is separately set in a portion other than one of the axes of the upper link, the drive motor is arranged on the same axis as the rotation center, which is necessary. As the number of shafts and bearings to be used increases, it is necessary to increase the length of the upper link to secure the installation space for the drive motor (especially in the case of a large capacity motor with a large diameter).
However, in the case of the present invention, such a problem can be avoided.

In addition, by aligning one of the shafts at both ends of the upper link with the center of rotation of the upper arm as described above, the maximum arm when both the lower arm and the upper arm are fully extended. It is possible to secure a large length and to further expand the operating area.

[0020]

1 and 2 are views showing a more specific embodiment of the present invention, and FIG. 3 shows details of a joint portion corresponding to a section taken along the line III-III of FIG.

As shown in FIGS. 1 and 2, the lower arm 12 is connected through a shaft P ₁₁ with respect to the bracket 11a of the fixed link is fixed on the swivel base 11, and over this axial P ₁₁ Drive motor 1 provided on the same axis
By the function of 6, the lower arm 12 rotates in the direction of arrow A via a speed reduction mechanism (not shown). These drive motors 16
And the deceleration mechanism constitute the lower side drive means for rotating the lower arm 12. The swivel base 11 has another axis P ₁₃ that is parallel to the axis P ₁₁ and located on the same horizontal plane, and the lower link 14 is rotatably connected to the bracket 11 a via this axis P ₁₃ .

A shaft P ₁₂ is provided at the upper end of the lower arm 12 as shown in FIG. 3, and the upper arm 13 and the upper link 15 are rotatable with respect to the lower arm 12 via the shaft P _12. Connected and further axis P ₁₂
A drive motor 17 for rotating the upper arm 13 is provided on the same axis.

The lower link 14 and the upper link 15 are connected to each other via a shaft P ₁₄ , and the bracket 1 is attached to the lower link 14 and the upper link 15.
4a parallel link mechanism 1 by adding 1a and lower arm 12
9 is composed. In this case, the bracket 11a having the two axes P ₁₁ and P _{13 serving} as the fulcrum functions as a fixed link.

The upper arm 13 and the lower arm 12 constituting the four-bar parallel link mechanism 19 are shown in FIG.
Is offset in the axial direction of the axis P ₁₂ as shown in
Rotation plane of upper arm 13 and four-bar parallel link mechanism 1
By making the rotation plane of 9 different from each other, the rotation of the upper arm 13 does not interfere with the four-bar parallel link mechanism 19, and the so-called cantilever type wrist portion 18 at the tip of the upper arm 13 is provided. The tip 18a on the hand side and the axis of the lower arm 12 are located on the same plane as the turning center O of the turning base 11.

The drive motor 17 is fixed to the upper arm 13 via a housing 20 as shown in FIG. 3, and its output shaft 21 is connected to the input portion of the speed reduction mechanism 22. The drive motor 17 and the speed reduction mechanism 22 constitute an upper drive means for rotating the upper arm 13.

The deceleration mechanism 22 (commercial product name: harmonic drive) comprises a generator 23 as an input section in which a ball bearing is arranged on the outer circumference of an elliptical cam, and an elastically deformable cup-shaped ring gear in which a spline is formed on the outer circumference. 24 and a ring gear 25 with a spline formed on the inner circumference
Composed of and. In this embodiment, the ring gear 24 is the shaft P.
The ring gear 25 is fixed to ₁₂ , and the other ring gear 25 is fixed to the housing 20, and the number of teeth of the ring gear 25 is set to be two more than that of the ring gear 24. Therefore, when the generator 23 makes one rotation, the ring gear 25, that is, the upper arm 13 rotates by the difference in the number of teeth of two.

The housing 20 has an upper arm 13
Further, the shaft P ₁₂ is fixed to the upper link 15, and the bearings 26 and 27 are provided between the housing 20 and the shaft P ₁₂ and between the lower arm 12 and the shaft P ₁₂ , respectively.
Is interposed. The structure of the speed reduction mechanism 22 is as follows.
The same applies to the speed reduction mechanism on the side of the drive motor 16 described above.

In the industrial robot configured as described above, the lower arm 12 rotates in the direction of arrow A in FIG. 1 by the action of the drive motor 16. At this time, the upper link 15 always maintains the state parallel to the line connecting the axes P ₁₁ and P ₁₃ , that is, the horizontal state.

The upper arm 13 is a drive motor 1
By the function of 7, it rotates in the direction of arrow B. For more information,
In FIG. 3, when the drive motor 17 is activated, the reduction mechanism 2
The ring gear 24 is connected to the shaft P ₁₂ via the second generator 23.
Try to rotate with. However, the ring gear 24
Since the shaft P ₁₂ to which is fixed is also fixed to the upper link 15, it cannot be rotated due to the restraint of the four-bar parallel link mechanism 19.

Therefore, on the contrary, the upper arm 13 including the drive motor 17 and the housing 20 receives the rotational reaction force and rotates in either direction of arrow B in FIG. That is, the upper arm 13 rotates independently without the movement of the four-bar parallel link mechanism 19.

In this embodiment, as shown in FIG. 4, the angle α ₁ formed by the vertical line Y and the lower arm 12 is 60 degrees in the counterclockwise direction (minus direction) and the clockwise direction (plus direction) 45. The angle θ between the lower arm 12 and the upper arm 13 is set in the range of 45 to 315 degrees. As a result, the center point P of the list section 18
The operating region at ₀ is a shaded region Q. Therefore, as compared with FIG. 7, the operation area Q is remarkably expanded particularly on the rear side of the robot.

In addition, it is possible to secure a large maximum arm length when the lower arm 12 and the upper arm 13 are fully extended, and to enlarge the working area in plan view when the turning function of the turning base 11 is used together. It can also be achieved.

In the operating area Q shown in FIG. 4, the upper arm 13 passes directly above the turning base 11 and from the front (to the left of the vertical line Y in the operating area Q shown in FIG. 4) to the rear. (A vertical line Y in the operating area Q shown in FIG. 4)
Since it can rotate more to the right) than when rotating a work gripped by a hand (not shown) from the front to the rear, it is not necessary to rotate the entire robot together with the rotation base 11, unlike the conventional case. By passing the arm 13 directly above the swivel base 11, the hand can take a trajectory that is least likely to interfere with peripheral devices, and extra space is required to avoid interference between the robot and peripheral devices. Not.

Next, when the conventional structure and the structure of this embodiment are compared, it will be examined whether or not the moment to be carried by the lower arm drive motor changes depending on the weight of the upper arm.

FIG. 8 schematically shows the conventional structure. The moment the drive motor 6 should bear due to the weight of the upper arm 3 (see FIG. 5) is M _A, and M _A = F _M ×
S. Depending on the balance of moments, F
_Ask for _M.

· To stop the rotation due to the weight W, F ₁
The power of is needed.

When W × S ₁ = F ₁ × S ₂ F ₁ = W × S ₁ / S ₂ · F ₁ is decomposed into F _1a and F _1b .

F _1a = F ₁ cos θ ₁ + F ₁ sin θ ₁ tan (θ ₁ −θ ₂ ) F _1b = F ₁ sin θ · {1 / cos (θ ₁ −θ ₂ )} ・ W and F at the fulcrum P _{2 In} order to support ₁ and _1, a force of F ₂ = W + F ₁ is required. This is decomposed into F _2a and F _2b .

F _2a = F ₂ cos θ ₁ F _2b = F ₂ sin θ ₁ · F _1b is further decomposed into F _1ba and F _1bb .

F _1ba = F _1b sin (θ ₁ −θ ₂ ) F
_1bb = F _1b cos (θ ₁ −θ ₂ ). Here, since F _2b and F _1bb are forces in opposite directions, the difference is obtained as F _M.

F _M = F _2b −F _1bb = F ₂ sin θ ₁ −F _1b cos (θ ₁ −θ ₂ ) = (W × S ₁ / S ₂ + W) sin θ ₁ − (W × S ₁ / S ₂ ). _{· cos (θ 1 -θ 2)} sinθ 1 · {1 / cos (θ 1 -θ 2)} = W · sinθ 1 Likewise some embodiment structure seek F _M on the basis of FIG.

F ₁ to stop the rotation due to the weight W
The power of is needed.

W × S ₁ cos θ ₂ = F ₁ · S ₂ F ₁ =
W × (S ₁ / S ₂ ) cos θ ₂ · F ₁ is decomposed into F _1a and F _1b .

F _1a = F ₁ · (1 / cos θ ₁ ) F _1b
= F ₁ tan θ ₁・ F ₂ = W + F ₁ to support W and F _{1 at the} fulcrum P _12.
Force is required to decompose this into F _2a and F _2b .

F _2a = F ₂ cos θ ₁ F _2b = F ₂ sin θ ₁ · F _1b is further decomposed into F _1ba and F _1bb .

The difference between F _1ba = F _1b sin θ ₁ F _1bb = F _1b cos θ ₁ · F _2b and F _1bb is obtained as F _M.

F _M = F _2b −F _1bb = {W + W × (S ₁ / S ₂ ) · cos θ ₂ } sin θ ₁ −W × (S ₁ / S ₂ ) cos θ ₂ · tan θ ₁ · cos θ ₁ = W · sin θ _{1 + (W × S 1 /} S 2) · cosθ 2 (sinθ 1 -sinθ 1) = W · sinθ 1 above, the moment generated fulcrum P _1, P ₁₁ by the weight of the upper arm, W, If the conditions such as S ₁ and S ₂ are the same, both are the same.

Therefore, also in the case of the above embodiment, the advantage of the conventional parallel link mechanism type robot that the torque that the drive motor 16 bears is small can be utilized as it is.

Further, according to this embodiment, as is apparent from FIG. 2, the two motors 16 and 17 can be arranged so as to be aligned on one side, so that the overall width becomes small. Further, as shown in the figure, a so-called cantilever type wrist portion 18 is adopted, but the offset amount from the swing center O of the swing base 11 to the hand side tip 18a of the wrist portion 18 is zero.

Here, in this embodiment, the axis P which is common to the axis connecting the lower arm 12 and the upper link 15
_The upper arm 13 is rotatably connected to the upper link 15 via ₁₂ . As a result, the turning base 11
When the upper arm 13 is twisted and rotated by a turning moment, a torsion moment acts on the lower arm 12.
2 is a four-bar parallel link mechanism 19 for driving the drive motor 16.
Since it is manufactured with high rigidity in order to transmit to, the structure is suitable for withstanding the above-mentioned torsion moment without special reinforcement. However, instead of this, the upper arm 13 may be connected to the upper link 15 via a shaft P ₁₄ that is common to the shaft that connects the upper link 15 and the lower link 14.

As described above, either one of the shafts P ₁₂ and P ₁₄ at both ends of the upper link 15 and the upper arm 1 are connected.
By making the rotation centers of 3 coincide with each other, a drive motor 17 for driving the upper arm 13 can be provided on the same axis as the axis P ₁₂ or the axis P ₁₄ , so that, for example, the axis P _{12 of the} upper link 15 can be provided. , P ₁₄ does not lead to an increase in the number of parts and a complicated structure as in the case where the rotation center of the upper arm 13 is separately set, and a large-capacity motor can be adopted as the drive motor 17. As a result, the load capacity can be increased while the structure is made compact.

In other words, for example, the upper link 15
If the rotation center of the upper arm 13 is separately set in a part other than the shafts P ₁₂ and P _{14 of the} above, the drive motor 17 is arranged on the same axis as the rotation center, and the required shaft and bearing As the number increases, it is necessary to increase the length of the upper link 15 to secure the installation space for the drive motor 17, but in the case of the above-described embodiment, such a problem does not occur. .

Moreover, according to the present embodiment, the list unit 1
No. 8 hand side tip 18a and the turning center O of the turning base 11
Are located on the same plane parallel to the plane of rotation of the upper arm 13 and the offset amount is set to zero, so that the coordinate conversion formula of the robot is simplified, The route accuracy is improved during control,
This has the effect that the robot can perform extremely accurate work as intended. Hereinafter, that point will be described in detail.

That is, the route control is a control performed to move the robot from a certain point to a certain point so that the route becomes a target. The smaller the difference between the target route and the actual route is, the more the route accuracy becomes. Will be high.

"Mechatronics" series edited by the Japan Society of Mechanical Engineers, IV, Basic edition (3) Industrial robots and their applications: 1984 1
February 5, As described in P.89, P.90, 4.5.3 Coordinate transformations issued by Gihodo Publishing Co., Ltd., generally, when determining the position and angle when controlling the robot, the robot specific Calculation by coordinate conversion formula is used,
Based on the equation derived from this coordinate conversion formula, there is a method of calculating the position of the wrist unit from the angle of each motion axis (arm) of the robot, or conversely a method of calculating the angle of each motion axis from the position of the wrist unit. Has been taken.

In the former method, the angle x of each motion axis in the equation is given, so that the position x,
y and z are calculated, and in the latter method, the angle θ of each operation axis is calculated by giving the positions x, y and z of the list part in the equation.

These equations are composed of arithmetic elements such as addition, subtraction, multiplication and division, various trigonometric functions, square roots, etc., and the robot controller sequentially performs arithmetic operations on these individual arithmetic elements to perform the above calculation. Therefore, the smaller the number of calculation elements in the equation, the shorter the calculation time required for the calculation. In other words, the smaller the number of constants in the coordinate conversion formula that affects the number of calculations in the equation, the smaller the calculation time. short.

Here, in this embodiment, the hand side tip 18a of the wrist portion 18 and the turning center O of the turning base 11 are located on the same plane parallel to the plane of rotation of the upper arm 13 and the offset amount thereof. Is set to zero, the number of constants in the coordinate conversion formula is small, resulting in a short calculation time.

[Mechatronics] edited by Japan Society of Mechanical Engineers
Series IV Basics (3) Industrial robots and their applications: 8
December 5, 4 P85-P published by Gihodo Publishing Co., Ltd.
As described in 4.5 Playback Robot in 91, it is known that interpolation control is performed for the purpose of generating a predetermined path between two points when controlling the path of the robot. . This interpolation calculation is a method in which a route between two points is connected by a straight line (straight line interpolation) or a circular arc (circular interpolation) that is divided into several parts, and is generated to approximate the target route. The greater the number, the smaller the difference between the target route and the actual route, and the higher the route accuracy.

The above-mentioned coordinate conversion equation peculiar to the robot is used for this interpolation calculation, and the calculation of the dividing position is performed by the equation derived from this coordinate conversion formula.

Here, the relationship between the path accuracy and the operating speed of the robot will be described.

First, the movement time when the robot is moved from a certain point to a certain point is determined by the operation speed. what if,
The lower the operating speed, the longer the moving time, and the higher the operating speed, the shorter the moving time. In the former case, the number of times the equation can be calculated within the traveling time is large, and conversely, in the latter case, the number of times the equation can be calculated within the traveling time is small.

By the way, it has been explained that the greater the number of divisions, the higher the route accuracy. However, if the operation speed is lowered as described above, the equation can be calculated many times, and the number of divisions increases, resulting in a route. Higher accuracy.

However, since the operation speed is set to the optimum value according to the work content, the path accuracy is uniquely determined by the operation speed.

However, first, the tip of the wrist portion 18 on the hand side and the turning center O of the turning base 11 are located at the upper arm 1.
If it is located on the same plane parallel to the rotation plane of 3 and the offset amount is set to zero, the number of constants in the coordinate conversion formula is small and the calculation time is shortened. As described above, if the calculation time can be shortened, the number of times the equation can be calculated within the same movement time can be increased, the number of divisions can be increased, and the route accuracy can be improved.

According to the robot of this embodiment having such a structure, since the calculation time is shortened, the number of divisions in the route control can be increased under the condition of the same operation speed, and the route accuracy can be improved.

Therefore, according to the robot of the present embodiment, it is possible to perform a work on a route extremely close to the target route under the condition of the same operation speed, and the robot can perform a very accurate work as intended. Is something that can be done.

[0068]

According to the present invention, the fixed link provided on the base, the lower arm rotatably connected to one end of the fixed link, and the one end of the lower arm rotatably connected to the upper end of the lower arm. A four-bar parallel link mechanism is formed by the connected upper link and the lower link that connects the other end of the fixed link and the other end of the upper link to each other, and connects the lower arm and the upper link. Drive means on the lower side for rotatably connecting the upper arm to the upper link and rotating the lower arm via a single shaft common to the connecting shaft or the shaft connecting the upper link and the lower link. And a drive means on the upper side for rotating the upper arm, respectively.

Therefore, the four-bar parallel link mechanism and the upper arm have different planes of rotation, and even if the upper arm rotates, the four-bar parallel link mechanism interferes with the lower arm, the lower link, etc. that form the four-bar parallel link mechanism. Therefore, the advantage of the conventional four-bar parallel link type robot that can reduce the load torque and shape of the lower arm drive motor can be utilized as it is. Since there are very few restrictions on the rotational degree of freedom, the rotational degree of freedom of the upper arm dramatically increases, and the operating area of the entire robot is significantly enlarged by expanding the operating area especially to the rear side of the robot compared to the conventional one. Can be secured.

Further, since the upper arm can rotate largely from the front side to the upper side and the rear side while passing right above the swivel base, for example, when the work gripped by the hand is conveyed from the front side to the rear side, it is conventionally required. It is no longer necessary to rotate the entire robot with the swivel base as in the above example. By passing the upper arm directly above the swivel base, it becomes possible to take a trajectory that is the least likely to interfere with peripheral equipment. No extra space is needed to avoid interference with the, and space efficiency is significantly improved. Therefore, particularly when a plurality of robots are arranged side by side to form a robot work line, the space constraint on the line formation is greatly alleviated.

Further, an actuator or the like for driving the wrist portion (wrist) is provided, for example, at the end portion of the upper arm on the side opposite to the wrist portion, and then the wrist portion is connected via a transmission member arranged in the upper arm. Since it can also be moved, the weight of the wrist drive actuator, etc., occupies a small part of the load capacity, and a large net load capacity can be secured, which contributes to the expansion of the above operating range. Therefore, there is an effect that it can greatly contribute to the improvement of the basic performance of the robot.

The upper arm is connected to the upper link via a shaft common to the shaft connecting the lower arm and the upper link, or a single shaft common to the shaft connecting the upper link and the lower link. Since it is rotatably connected to one of the shafts at both ends of the upper link and the center of rotation of the upper arm, the upper arm is driven on the same axis as the single shaft. Since driving means on the upper side can be provided, the number of parts increases and the structure becomes complicated, for example, when the center of rotation of the upper arm is separately set in a portion other than the shafts at both ends of the upper link. It is possible to use a large-capacity motor as the driving means on the upper side without increasing the weight, while achieving a compact structure and a large load capacity. Can Kusuru.

Further, by aligning one of the shafts at both ends of the upper link with the center of rotation of the upper arm, the upper arm is driven on the same axis as either of the shafts at both ends of the upper link. Since a drive motor can be provided, there is no increase in the number of parts or complication of the structure as in the case where the center of rotation of the upper arm is separately set in a portion other than the shaft of the upper link, and the drive motor is not generated. As a result, a large-capacity motor can be adopted, and the transportable weight can be increased while making the structure compact.

In other words, for example, if the center of rotation of the upper arm is set separately in a portion of the upper link other than one of the axes, the drive motor is arranged on the same axis as the center of rotation, which is necessary. It is necessary to increase the length of the upper link and secure the installation space for the drive motor as the number of shafts and bearings to be increased increases. However, in the case of the above-mentioned embodiment, such a problem does not occur. It will be.

In addition, by aligning one of the shafts at both ends of the upper link with the center of rotation of the upper arm as described above, the maximum arm when both the lower arm and the upper arm are fully extended. Has a merit that it is possible to secure a large length and to further expand the operating region.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is an explanatory view showing an operation area of the robot shown in FIG.

FIG. 5 is a front view of a conventional articulated industrial robot.

FIG. 6 is a right side view of FIG. 11.

FIG. 7 is an explanatory view showing an operation area of the robot shown in FIG. 11.

8 is an explanatory diagram of arm moment of the robot shown in FIG.

9 is an explanatory diagram of arm moment of the robot shown in FIG. 1. FIG.

[Explanation of symbols]

11 ... Revolving base 11a ... Bracket as fixed link 12 ... Lower arm 13 ... Upper arm 14 ... Lower link 15 ... Upper link 16, 17 ... Drive motor 18 ... Wrist part 19 ... Four-section parallel link mechanism 22 ... Reduction mechanism O ... Revolving Centers P ₁₁ , P ₁₂ , P ₁₃ , P ₁₄ ... Axis.

Claims (2)

[Claims] 1. A fixed link (11a) provided on a base (11), a lower arm (12) rotatably connected to one end side of the fixed link (11a), and an upper end of the lower arm (12). An upper link (15) whose one end is rotatably connected to the part, and the fixed link (1).
1a) and the lower link (14) connecting the other end of the upper link (15) to each other constitute a four-bar parallel link mechanism (19), and the lower arm (12) and the upper link (14). 15) via a single shaft (P ₁₂ or P ₁₄ ) which is common to the shaft connecting the upper arm (15) and the lower link (14). 13) is rotatably connected to the upper link (15), and lower side driving means (16) for rotating the lower arm (12) and upper side driving means (17) for rotating the upper arm (13). ) And an articulated industrial robot characterized by being respectively provided. 2. A single shaft (P) common to the shaft connecting the lower arm (12) and the upper link (15).
The articulated industrial robot according to claim 1, characterized in that the upper arm (13) is rotatably connected to the upper link (15) via the ( ₁₂ ).