JPH11277472A - Coating robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent twist and rubbing of a tube without being influenced by the degree of a skill of a teaching person, and in turn keep coating quality at a uniform state. SOLUTION: A coating robot comprises an articulated manipulator 1 ; an articulated wrist unit 9 attached to the tip part of a second arm 8; a coating gun 12 to inject paint, supplied through a tube 15, against a work; and a controller 16 to control operation of the manipulator 1. The tube 15 is connected to the coating gun 12 through the internal part of the wrist unit 9 and the controller 16 drives and controls the manipulator 1 so that the joint angle θ4 of a fourth joint and the joint angles θ6 of a sixth joint on both sides of the wrist unit 9 are equalized with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a painting robot used for painting a work.

[0002]

2. Description of the Related Art A conventional painting robot has a manipulator composed of a plurality of joints. In addition, a wrist unit having a plurality of joints is provided at a distal end portion of the manipulator, and a coating gun for spraying paint supplied through a tube onto a workpiece is provided at a distal end portion of the wrist unit. Is attached. In the painting robot, the tube may be externally attached along the outer peripheral surface of the wrist unit, or may be built in the wrist unit.

[0003]

In the conventional painting robot, when the tube is externally attached, the joint angles of the joints on both sides of the wrist unit are used in order to prevent the tube from being twisted or rubbed. The teaching by the operator is performed in consideration of the allowable value. However, in this case, there is a problem that the teaching operation requires skill because the instructor must confirm whether or not each joint angle on both sides of the wrist unit exceeds an allowable value at the time of teaching. Furthermore, in the conventional painting robot, even when the tube is built in the wrist unit, if the teacher is immature, the tube may be twisted or rubbed beyond the allowable angle. there were. Furthermore, in the conventional painting robot, if the painting work is actually performed with the tube twisted, it is not possible to obtain the proper paint flow rate and air flow rate, so that the coating quality cannot be kept uniform. There was a problem. The present invention has been made under such a background, and it is possible to prevent the tube from being twisted, rubbed, and the like without depending on the skill of the teacher, and to keep the coating quality uniform. The purpose is to provide a painting robot.

[0004]

According to a first aspect of the present invention, there is provided a wrist unit rotatably attached to a distal end of an arm and having a plurality of joints composed of two members, and a rotatable distal end of the wrist unit. A coating tool that is attached to the workpiece and sprays a coating agent onto a workpiece, a tube that is disposed along the wrist unit and supplies the coating agent to the coating tool, and a joint angle of the wrist unit. A joint angle calculation unit to be obtained; and control means for driving and controlling the manipulator and the wrist unit such that the joint angles of the two members are equal based on the joint angles obtained by the joint angle calculation unit. It is characterized by the following. According to the first aspect of the present invention, since the joint angles of the two members of the wrist unit are automatically controlled to be equal, the tube is twisted or rubbed without being affected by the skill. Can be prevented, and the coating quality can be kept uniform. According to a second aspect of the present invention, there is provided a wrist unit rotatably attached to a distal end portion of an arm and having a plurality of joints formed of two members, and a wrist unit rotatably attached to a distal end portion of the wrist unit to coat a workpiece. A coating tool for injecting an agent, a tube arranged along the wrist unit, for supplying the coating agent to the coating tool, a joint angle calculation unit for determining each joint angle of each joint, Based on the respective joint angles obtained by the joint angle calculator,
And a control means for driving and controlling the manipulator and the wrist unit such that a difference between joint angles of the members becomes a minimum value. According to the second aspect of the present invention, since the difference between the joint angles of the wrist unit is automatically controlled so as to be a minimum value, the tube is twisted and rubbed without being affected by the skill. Etc. can be effectively prevented, and the coating quality can be kept uniform.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an external configuration of the painting robot according to the first embodiment of the present invention. In this figure, 1 is an articulated manipulator, and 3 is a base installed on a factory floor (not shown). Reference numeral 4 denotes a rotating member rotatably attached to the base 3, which is driven by a drive unit (not shown) around the first joint axis in the direction of arrow H1 shown in FIG. Here, the joint composed of the base 3 and the rotating member 4 is referred to as a first joint, and the angle of the first joint is referred to as a joint angle θ1.

Reference numeral 5 denotes a drive unit provided between the rotating member 4 and the first arm 6, which drives the first arm 6 around the second joint axis in the direction of arrow H2 shown in FIG. .
Here, the joint formed by the rotating member 4 and the first arm 6 is referred to as a second joint, and the angle of the second joint is referred to as a joint angle θ2.

Reference numeral 7 denotes a joint drive unit mounted between the first arm 6 and the second arm 8, and moves the second arm 8 around the third joint axis in the direction of arrow H3 shown in FIG. Drive. Here, the first arm 6 and the second arm 8
Is referred to as a third joint, and the angle of the third joint is referred to as a joint angle θ3. 9 is the second arm 8
A wrist unit attached to the tip 8a of the
It is driven with a degree of freedom. The wrist unit 9 includes a first wrist member 10 and a second wrist member 11. The first wrist member 10 is driven to rotate around the fourth joint axis in the direction of arrow H4 shown in FIG. Here, the distal end portion 8a of the second arm 8 and the first wrist member 10
Is referred to as a fourth joint, and the angle of the fourth joint is referred to as a joint angle θ4.

The second wrist member 11 is driven to rotate around the fifth joint axis in the direction of arrow H5 shown in FIG. here,
The joint formed by the first wrist member 10 and the second wrist member 11 is called a fifth joint, and the angle of the fifth joint is called a joint angle θ5. The detailed configuration of the wrist unit 9 will be described later. 12 is the flange 10
0 is a coating gun attached to the second wrist member 11 of the wrist unit 9 through a tube 13, and tubes 13, 13,.
The mist-like paint is discharged from the paint supply device (not shown) to the workpiece through the paint flow control device 14 and the plurality of tubes 15. The coating gun 12 is arranged around an axis H6 shown in FIG.
It is driven to rotate in the direction. Here, the second wrist member 11
The joint formed by the (flange 100) and the paint gun 12 is referred to as a sixth joint, and the angle of the sixth joint is referred to as a joint angle θ6. The coating gun 12 is attached to the second wrist member 11 via a flange 100 at an angle of 0 degree with respect to the sixth joint.

The paint flow control device 14 includes a tube 13,
, And a plurality of tubes 15, and adjusts the flow rate of the paint to be supplied to the coating gun 12, in other words, the discharge flow rate of the paint from the coating gun 12.
The plurality of tubes 15 are connected to the first wrist member 10 and the second wrist member 10.
Is provided inside each of the wrist members 11 of the
2 to supply paint.

Reference numeral 16 denotes a controller connected to the manipulator 1 via a cable 17, which controls the operation of the manipulator 1 and controls the flow rate of paint discharged from the coating gun 12. The configuration and operation of the controller 16 will be described in detail. Reference numeral 18 denotes a teaching pendant used to input various data when operating the manipulator 1, and has a plurality of keys.

FIG. 2 is a diagram modeling the manipulator 1 shown in FIG. In this figure, parts corresponding to respective parts in FIG. 1 are denoted by the same reference numerals. The base coordinate system ΣB shown in this figure is a coordinate system fixed to the base 3,
xb is a unit vector in the x-axis direction, yb is a unit vector in the y-axis direction, and zb is a unit vector in the z-axis direction. The wrist coordinate system Δh is a coordinate system fixed to the tip of the coating gun 12, and the posture of the wrist coordinate system Δh changes following the posture of the coating gun 12. That is, the posture of the wrist coordinate system Σh changes relatively to the fixed base coordinate system ΣB.

In the wrist coordinate system Δh, xh is a unit vector in the x-axis direction, and the direction of the unit vector xh is the same as the direction in which the paint is discharged from the paint gun 12.
That is, the unit vector xh represents the paint discharge direction. yh is a unit vector in the y-axis direction, and zh is a unit vector in the z-axis direction.

FIG. 3 is a partially cut-away sectional view showing a configuration near the wrist unit 9 shown in FIG. In this figure,
Parts corresponding to the respective parts in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 3, reference numeral 10a denotes a rotation shaft provided inside the second arm 8 corresponding to the first wrist member 10, and is rotated by a motor (not shown). 10b is a spur gear attached to the end of the rotating shaft 10a. 10c is the second through a ball bearing
Is a cylindrical member rotatably disposed at the distal end portion 8a of the arm 8. 10d is a gear attached to one end surface of the cylindrical member 10c, which meshes with the spur gear 10b.
Also, the first wrist member 1 is provided on the other end surface of the cylindrical member 10c.
0 is attached. That is, the rotational force by the rotating shaft 10a is transmitted through the gear 10d and the spur gear 10b.
The power is transmitted to the first wrist member 10.

Reference numeral 11a denotes a rotation shaft provided inside the second arm 8 corresponding to the second wrist member 11,
It is rotationally driven by a motor (not shown). 11b is a spur gear attached to the end of the rotating shaft 11a. 11
c is a cylindrical member, which is rotatably mounted on the distal end portion 8a of the second arm 8 via a ball bearing and the cylindrical member 10c, and is coaxially arranged with the cylindrical member 10c. Reference numeral 11d denotes a gear attached to one end surface of the cylindrical member 11c, which meshes with the spur gear 11b. 11e
Is a bevel gear attached to the other end surface of the cylindrical member 11c.

Reference numeral 11f denotes a cylindrical member rotatably disposed at the distal end of the first wrist member 10 via a ball bearing. Reference numeral 11g denotes a bevel gear attached to one end surface of the cylindrical member 11f, which meshes with the bevel gear 11e. A second wrist member 11 is attached to the other end surface of the cylindrical member 11f. That is, the rotating shaft 11
The rotational force a is transmitted to the second wrist member 11 via the spur gear 11b, the gear 11d, the cylindrical member 11c, the bevel gear 11e, the bevel gear 11g, and the cylindrical member 11f.

Reference numeral 12a denotes a second gun corresponding to the coating gun 12.
And a rotation shaft provided inside the arm 8, which is rotatably driven by a motor (not shown). 12b is the rotating shaft 12
5A is a spur gear attached to the end of FIG. Reference numeral 12c denotes a cylindrical member, which includes a ball bearing and a cylindrical member 10c.
The second arm 8 is rotatably mounted on the distal end portion 8a of the second arm 8 via a shaft and coaxially with the cylindrical member 10c. 12d
Is a gear attached to one end surface of the cylindrical member 12c, and meshes with the spur gear 12b. 12e is a bevel gear attached to the other end surface of the cylindrical member 12c.

Reference numeral 12f denotes a cylindrical member rotatably disposed at the distal end of the first wrist member 10 via a ball bearing. 12g is a bevel gear attached to one end surface of the cylindrical member 12f, which meshes with the bevel gear 12e. 12h is a bevel gear attached to the other end surface of the cylindrical member 12f. Reference numeral 12i denotes a cylindrical member rotatably disposed at the distal end of the second wrist member 11 via a ball bearing. Reference numeral 12j denotes a bevel gear attached to one end surface of the cylindrical member 12i, which meshes with the bevel gear 12h. The coating gun 12 is attached to the other end surface of the cylindrical member 12i via a flange 100.

Further, a plurality of tubes 15, 15,...
Is the wrist unit 9 so as to conform to the shape of the wrist unit 9.
Are arranged so as to form a bundle in the internal space, and each end extends to the coating gun 12. These tubes 1
Are fixed by a fixed support member 200. In the following description, tube 1
.. Are collectively referred to as a tube group 19.
The fixed support member 200 serves to prevent the tube group 19 from being twisted.

FIG. 4 is a block diagram showing an electrical configuration of the painting robot according to the first embodiment of the present invention. In this figure, parts corresponding to respective parts in FIG. 1 are denoted by the same reference numerals. In the controller 16 shown in FIG.
Denotes a CPU (Central Processing Unit), which controls various operations such as creation of teaching data of the robot and each device. Note that CP
Details of the processing performed by U20 will be described later.

Reference numeral 21 denotes a ROM (Read Only Memory), which stores a program used in the CPU 20. Reference numeral 22 denotes a RAM (random access memory), which stores the taught position data, parameters associated with painting, and the like. Reference numeral 23 denotes a motor driver.
Motor 2 based on the motor drive signal Sm supplied from the
4 is driven. The motor 24 is connected to the manipulator 1
The first to sixth joints (see FIG. 1) are driven. Further, the motor 24 outputs a position signal Sp representing each current position of the first to sixth joints to the CPU 20 via the motor driver 23. The CPU 20 calculates the position of the coating gun 12 from the input position signal Sp of each joint.

Next, the operation of the painting robot according to the first embodiment will be described. In FIG. 4, when data relating to the position and orientation of the coating gun 12 is input from the teaching pendant 18, the CPU 20
Data on the target trajectory of the coating gun 12 is generated from the attitude data. Here, the target trajectory is a position vector ph
And the attitude vector Rh. The position vector ph is a vector representing an offset value indicating the origin position of the wrist coordinate system Σh as viewed from the base coordinate system ΣB shown in FIG. 2, and is represented by the following equation (1). ph = [phx phy phz] ^T (1) In the above equation (1), the subscript T represents transposition. The posture vector Rh is a vector representing the posture of the wrist coordinate system Σh viewed from the base coordinate system ΣB shown in FIG. 2, and is represented by a rotation matrix shown in the following equation (2). Rh = [xhyhzh] (2)

Next, the CPU 20 determines the joint angles θ1 to θ6 of the first to sixth joints as the joint angle vector θ shown in the following equation (3) from the obtained position vector ph and posture vector Rh. θ = [θ1 θ2 θ3 θ4 θ5 θ6] ^T (3) In this case, the atomization pattern of the paint discharged from the coating gun 12 is a circular pattern.
2 is not a posture vector Rh but a position vector xh
Is determined by From this, the CPU 20 actually obtains the joint angle vector θ shown in Expression (3) from the unit vectors ph and xh. However, the CPU 20 determines the joint angle vector θ such that the joint angle θ6 and the joint angle θ4 in the joint angle vector θ are equal.

Next, the CPU 20 outputs a motor drive signal Sm corresponding to the joint angle vector θ to the motor 24. Thus, the joint angles θ1 to θ6 of the first to sixth joints in the manipulator 1 shown in FIG.
The manipulator 1 is driven so as to have the value of. As a result, the driving force of the motor 24 is
a, is transmitted to the first wrist member 10 via the spur gear 10b, the gear 10d, and the cylindrical member 10c, and the first wrist member 10 is rotationally driven with the joint angle θ4.

The driving force of the motor 24 is
a, the second through the spur gear 11b, the gear 11d, the cylindrical member 11c, the bevel gear 11e, the gear 11g, and the cylindrical member 11f.
And the second wrist member 11 is rotationally driven with the joint angle θ5. Further, the motor 24
Are driven by a rotating shaft 12a, a spur gear 12b, and a bevel gear 1.
2d, cylindrical member 12c, gear 12e, gear 12g, cylindrical member 12f, bevel gear 12h, gear 12j, cylindrical member 1
It is transmitted to the coating gun 12 via 2i and the flange 100, and the coating gun 12 is rotationally driven with the joint angle θ6.

At this time, since the joint angle θ6 shown in FIG. 3 follows the joint angle θ4, the tube group 19 is not twisted or rubbed. Therefore, according to the coating robot according to the first embodiment described above, since the paint flow rate and the air flow rate do not change due to the twisting and rubbing, coating quality can be maintained uniformly. Further, according to the coating robot according to the first embodiment described above, the tube group 19 is twisted,
Since rubbing and the like do not occur, there is no possibility that the tube group 19 will come off or be damaged.

<Second Embodiment> Next, a painting robot according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a perspective view showing an external configuration near the wrist unit 9 in the painting robot according to the second embodiment.
In this figure, parts corresponding to the respective parts in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 5, a third wrist member 25 is newly provided, and the second wrist member 11 and the third wrist member 25 are provided.
A sixth joint is constituted by the wrist member 25 of FIG. The third wrist member 25 includes the second wrist member 11 and the coating gun 1.
2 and serves to set the angle between the second wrist member 11 and the coating gun 12 to t. Here, FIG. 6 shows a diagram modeling the manipulator 1 in the coating robot according to the second embodiment. In this figure, parts corresponding to the respective parts in FIGS. 2 and 5 are denoted by the same reference numerals.

Next, the operation of the painting robot according to the second embodiment will be described with reference to the flowchart shown in FIG. In FIG. 4, when data relating to the position / posture of the coating gun 12 is input from the teaching pendant 18, the process proceeds to step S1 shown in FIG. 7, where the position vector ph (see equation (1)) and the posture vector Rh are described.
After obtaining the unit vector xh (see FIG. 6) in (see equation (2)), the process proceeds to step S2.

In step S2, the CPU 20 determines the attitude vector Rh on the assumption that the rotation angle α of the coating gun 12 around the unit vector xh shown in FIG. 6 is zero, and then proceeds to step S3. In step S3, the CPU 20
After setting 2π as the joint angle threshold value Δθ46, the process proceeds to step S4. The joint angle threshold value Δθ46 is the joint angle θ
This is a threshold value used for comparing the difference between 4 and the joint angle θ6.

In step S4, the CPU 20 determines the joint angles θ1 to θ6 of the first to sixth joints from the unit vector xh in the position vector ph and the posture vector Rh by using the joint angle vector θ (= [Θ1 θ2 θ3
θ4 θ5 θ6] ^T ), and then proceeds to step S5. In step S5, the CPU 20 determines in step S4
The absolute value of the difference between the joint angle θ4 and the joint angle θ6 in the joint angle vector θ obtained in the above is determined by the joint angle threshold Δθ46 (= 2
π) is determined. Specifically, CP
U20 determines that the absolute value is the minimum when the absolute value of the difference is smaller than the joint angle threshold value Δθ46. In this case, assuming that the absolute value of the difference is equal to or larger than the joint angle threshold value Δθ46, the CPU 20 sets the determination result of step S5 to “NO” and proceeds to step S6.

In step S6, the CPU 20 adds a fixed value Δα to the assumed rotation angle α, and then proceeds to step S7.
Proceed to. In step S7, the CPU 20 determines in step S7
It is determined whether or not the addition result (α = α + Δα) in Step 6 is smaller than 2π. If the determination result is “YES”, the difference between the joint angles θ4 and θ6 cannot be reduced further. Therefore, the process proceeds to step S9. In this case, assuming that the addition result is 2π or more, the CPU 20
Assuming that the determination result of step S7 is "NO",
Proceed to 8. In step S8, the CPU 20 substitutes the absolute value of the difference between the current joint angle θ4 and the joint angle θ6 into the joint angle threshold Δθ46, and returns to step S4 to repeat the above-described operation.

Then, in step S5, the absolute value of the difference between the joint angle θ4 and the joint angle θ6 is equal to the joint angle threshold value Δ
If it becomes smaller than θ46, the CPU 20 sets the determination result to “YES” and proceeds to step S9. Step S
9, the CPU 20 determines that the current joint angle vector θ (=
[Θ1 θ2 θ3 θ4 θ5 θ6] ^T ) is set as a vector corresponding to the target joint angles θ1 to θ6, and the motor drive signal Sm corresponding to the joint angle vector θ is output to the motor 24. Thereby, the manipulator 1 is driven such that the joint angles θ1 to θ6 of the first to sixth joints in the manipulator 1 shown in FIG. 1 become the value of the joint angle vector θ. At this time, since the difference between the joint angle θ6 and the joint angle θ4 shown in FIG. 6 is minimized, the tube group 19 is less likely to be twisted or rubbed. Therefore, according to the painting robot according to the second embodiment described above, the twist,
Since the paint flow rate and the air flow rate do not change so much due to the rubbing, the coating quality can be kept uniform. Further, according to the coating robot according to the above-described second embodiment, the tube group 19 is less likely to be twisted or rubbed, so that the tube group 19 is less likely to come off or be damaged.

Although the painting robot according to the first and second embodiments of the present invention has been described in detail above, the specific configuration is not limited to the first and second embodiments, and the gist of the present invention is described. Even a design change or the like within a range not departing from the present invention is included in the present invention. For example, in the painting robot according to the first and second embodiments described above, the painting gun 1
2 has been described as an example, but the type of gun does not matter. Therefore, in the coating robots according to the first and second embodiments described above, a sealing gun may be used instead of the coating gun 12, and a sealing material may be used instead of the paint.

[0034]

As described above, according to the present invention,
The tube can be prevented from being twisted or rubbed without being influenced by the skill of the instructor, and the effect that the coating quality can be kept uniform can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external configuration of a painting robot according to a first embodiment of the present invention.

FIG. 2 is a diagram modeling the manipulator 1 shown in FIG.

FIG. 3 is a partially cut-away sectional view showing a configuration near the wrist unit 9 shown in FIG.

FIG. 4 is a block diagram illustrating an electrical configuration of the painting robot according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing an external configuration near a wrist unit 9 in the painting robot according to the second embodiment.

FIG. 6 is a diagram modeling the manipulator 1 in the painting robot according to the second embodiment.

FIG. 7 is a flowchart illustrating an operation of the painting robot according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manipulator 3 Base 4 Rotary member 5 Drive unit 6 First arm 7 Drive unit 8 Second arm 9 Wrist unit 10 First wrist member 11 Second wrist member 12 Painting gun 16 Controller 15 Tube

Claims (2)

[Claims] 1. A wrist unit rotatably attached to a distal end of an arm and having a plurality of joints composed of two members, and a coating agent is rotatably attached to a distal end of the wrist unit to spray a coating agent onto a workpiece. A coating tool, a tube arranged along the wrist unit and for supplying the coating agent to the coating tool, a joint angle calculation unit for calculating each joint angle of the wrist unit, and the joint angle calculation unit A coating robot, comprising: control means for driving and controlling the manipulator and the wrist unit such that the joint angles of the two members are equal based on the determined joint angles. 2. A wrist unit rotatably attached to a distal end portion of an arm and having a plurality of joints composed of two members, and a coating agent is rotatably attached to a distal end portion of the wrist unit to spray a coating agent onto a workpiece. A coating tool, a tube arranged along the wrist unit, for supplying the coating agent to the coating tool, a joint angle calculation unit for obtaining each joint angle of each joint, and the joint angle calculation unit A control means for controlling the driving of the manipulator and the wrist unit such that the difference between the joint angles of the two members becomes a minimum value based on the joint angles obtained by (1).