JP2008137143A - Teaching method of painting robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a teaching method of a painting robot capable of preventing a singular point while maintaining painting quality. <P>SOLUTION: In the teaching method of the painting robot, a posture of the painting robot interpolated linearly is calculated in advance when interpolating between teaching points (Step 30), when the posture takes the singular point (YES at Step S40), a painting gun is rotated centering around a central axis of the painting gun (Step S50), and the posture of the painting robot is changed to a posture which prevents the singular point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a painting robot teaching method (hereinafter also referred to as teaching) applied to the painting of automobile bodies and automobile parts.

  Interpolation methods such as axis interpolation and linear interpolation are conventionally known as interpolation methods between robot teaching points. However, in the painting process of automobile bodies and parts, the painting distance between the painting gun and the workpiece, Linear interpolation is used to ensure the coating quality by keeping the coating angle of the coating gun with respect to the coating.

  In this linear interpolation, since the parameters of each axis of the robot are calculated from the coordinate points of the teaching points, a singular point where the posture of the robot is not uniquely determined is physically generated (see, for example, Patent Document 1).

  Such singular points can be avoided by changing the teaching points. However, such an avoidance technique changes the teaching point set as the optimum posture position for painting, and is not necessarily preferable in terms of painting quality.

  Also, with a painting robot that supports the tracking operation in which the painting robot follows the coating material flowing through the continuous line and performs the painting operation, the posture of the painting robot changes during teaching and during reproduction (during actual painting work). Therefore, singular points that did not occur during teaching may occur during reproduction, and it is difficult to completely remove singular points by temporarily changing the teaching points as described above.

  Furthermore, the pose of the painting robot may change and a new singularity may be generated by temporarily stopping the conveyor that occurs at random timing in the actual production site or by correcting the program when a problem occurs.

JP-A-8-241108

  An object of the present invention is to provide a method for teaching a painting robot capable of avoiding singularities while maintaining the painting quality.

  In order to achieve the above object, according to the present invention, there is provided a teaching method for a painting robot equipped with a painting gun, wherein a linearly interpolated posture of the painting robot is calculated in advance when interpolating between teaching points. When the posture takes a singular point, the coating gun is rotated about the central axis of the coating gun, and the posture of the painting robot is changed to a posture that avoids the singular point. A robot teaching method is provided.

  In the present invention, the posture of the painting robot that is linearly interpolated between the teaching points is calculated in advance, and when the posture becomes a singular point, the posture of the painting robot is changed by rotating the painting gun. By rotating the painting gun, the value of each axis of the painting robot is corrected, so that singular points can be avoided. Also, since the posture of the painting robot is changed by rotating the painting gun, the painting quality is maintained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a painting line provided with a painting robot in an embodiment of the present invention, FIG. 2 is a schematic side view showing the painting robot in an embodiment of the present invention, and FIG. 3 is attached to the painting robot shown in FIG. It is a top view which shows the coating pattern by the made coating gun.

  The painting robot 10 in this embodiment is installed in a painting booth S of a painting line L for painting a body B of an automobile. A coating gun 20 is attached to the tip of the painting robot 10 as an end effector. The coating gun 20 is connected to a paint supply device 30 via a paint hose 31, and the vehicle body B can be electrostatically coated by applying the paint supplied from the paint supply device 30 from the paint gun 20. It is possible. A control device 40 is connected to the painting robot 10 and the paint supply device 30 in a controllable manner.

  The car body B, which is the object to be coated, can be moved in the paint booth S by the moving carriage D, and the painting robot 10 can perform the painting work (tracking operation) while following the moving car body B. It is possible.

  The painting robot 10 according to the present embodiment is an articulated robot having six joints including a first axis 11 to a sixth axis 16 as shown in FIG. 2, and a painting gun 20 attached to the tip is placed in a three-dimensional space. It is possible to arbitrarily move and control the posture.

In addition, when linear interpolation is performed between teaching points taught to the painting robot 10 having such a skeleton system, the coordinates TP _m (X _m , Y _m , Z _m , α _{m of the} teaching points are used by using an inverse transformation equation. , Β _m , γ _m ), the angles (S1, S2, S3, S4, S5, S6) of the first to sixth axes 11 to 16 of the painting robot 10 are calculated. At this time, if the angle S5 of the fifth axis 15 is close to 0 degrees (specifically, for example, −5 degrees ≦ S5 ≦ + 5 degrees), the solution of the posture of the painting robot 10 becomes infinite, and the painting robot In some cases, the 10 postures may be singular points that are not uniquely determined.

  Although not particularly illustrated, the coating gun 20 is a rotary atomizing coating gun (bell type coating gun) including a bell cup (atomizing head) rotatably supported for atomizing and spraying the coating material. The bell cup of the painting gun 20 has a cup shape having a substantially circular opening. When painting, the bell cup sprays paint while rotating around its axis, and paints while shaping the spray pattern with shaping air sprayed from the surroundings.

  As shown in FIG. 3, the paint sprayed from the coating gun 10 forms a substantially circular coating pattern on the surface of the automobile body B, which is an object to be coated. Since the coating pattern is a perfect circle, even if the value of γ of the coating gun 20 is arbitrary, there is no particular influence on the coating quality, and it is not necessary to control the γ rotation of the coating gun 20 for the coating quality. In the present invention, the form of the coating gun is not particularly limited to the rotary atomizing type coating gun, and if the coating pattern when applied to the object is substantially circular, for example, air atomization A paint gun may be used.

  FIG. 4 is a flowchart showing a method for teaching a painting robot according to an embodiment of the present invention, FIG. 5 is a front view of an automobile body for explaining teaching points to the painting robot in the embodiment of the present invention, and FIG. FIG. 6B is a conceptual diagram showing the posture of the paint gun after change.

  Below, the teaching method of the painting robot in embodiment of this invention is demonstrated.

First, as shown in FIG. 5, teaching points TP _m (TP ₁ to TP _{8 in the} example shown in FIG. 5) necessary for painting the automobile body B are taught to the painting robot 10. In order to ensure the coating quality, each teaching point TP _m has a constant distance from the surface of the automobile body B to the painting gun 20, and the attitude of the painting gun 20 with respect to the surface of the automobile body B is also constant. It has become.

Next, as shown in step S10 of FIG. 4, on a straight line connecting a certain teaching point TP _m (for example, TP _{1 in} FIG. 5) and the next teaching point TP _{m + 1} (for example, TP _{2 in} FIG. 5). Then, N virtual teaching points TQ _i are created, and the posture of the painting robot 10 on the straight line is calculated.

Then, first, i = 1 for when (step S20), from the coordinate and the next teaching point _{TP m + 1} of the coordinates of the taught point TP _m, each axis of the painting robot 10 at the time of the linear interpolation of the virtual teaching point TQ _1. 11 to The value of 16 angles (S1, S2, S3, S4, S5, S6) is calculated (step S30).

  Next, it is determined whether or not the angle S5 of the fifth shaft 15 is near 0 degrees in the posture of the painting robot 10 calculated in step S30 (step S40).

In the determination of step S40, in a case where the angle S5 in the fifth shaft 15 is determined to be 0 degrees near (YES at step S40), the posture of the spray gun 20 in the virtual teaching point TQ ₁ shown in FIG. 6A By rotating in the γ direction, the virtual teaching point TQ ₁ ′ shown in FIG. 6B is changed (step S50). Here, in FIG. 6A, the γ value of the virtual teaching point TQ ₁ before the change is γ _i , whereas in FIG. 6B, the γ value of the virtual teaching point TQ ₁ ′ after the change is γ _i ′. has been edited. By rotating the posture of the painting gun 20 in the γ direction, the angle S5 of the fifth axis 15 of the painting robot 10 is moved away from the vicinity of 0 degrees, so that the posture of the painting robot 10 can be prevented from becoming a singular point. .

Next, the value of the posture (S1, S2, S3, S4, S5, S6) of the painting robot 10 at the virtual teaching point TQ ₁ ′ after the change is calculated (step S30), and the fifth axis 15 in the posture of the painting robot 10 is calculated. Whether or not the angle S5 is near 0 degrees is determined again (step S40).

  If the angle S5 of the fifth axis 15 is still near 0 degrees (YES in step S40), the virtual teaching point is changed again (step S50).

On the other hand, in the determination of step S40, the angle S5 in the fifth axis 15, for example, if not 0 degrees near as 10 degrees (NO in step S40), the singularity painting robot 10 in the virtual teaching point TQ ₁ it is determined that not taking, storing the virtual teaching point TQ ₁ as a new teaching point (step S60). When the virtual teaching point TQ ₁ is changed to TQ ₁ ′ in step S50, the changed virtual teaching point TQ ₁ ′ is stored as a new teaching point in step S60.

For TQ ₂ to TQ _N created between the teaching points TP ₁ and TP ₂ in step S 10 (steps S 70 and S 80), the above processing (steps S 30 to S 60) is repeated to avoid a singular point. Is stored as a new teaching point. Next, in step S90, normal linear interpolation is performed on the new teaching points TQ _{1 to} TQ _N (TQ _i ′ when the virtual teaching point is changed), and the teaching points TP _m and TP _{m + 1 are} between. Complete teaching.

Taking the motion trajectory shown in FIG. 5 as an example, the above processing is performed between TP ₁ and TP ₂ , between TP ₃ and TP ₄ , between TP ₅ and TP ₆ , and between TP ₇ and TP _8. To avoid singular points between each teaching point.

  Further, the singular point may be removed by performing the above processing when the tracking operation is replayed or when the posture of the painting robot 10 is changed due to the temporary stop of the conveyor, program correction, or the like.

  As described above, in this embodiment, by rotating the painting gun 20, the values (S1, S2, S3, S4, S5, S6) of the axes 11 to 16 of the painting robot 10 are corrected. Can be avoided. Moreover, since the coating pattern is substantially a perfect circle, the coating quality is maintained even when the coating gun 20 is rotated.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above-described embodiment, the case where the posture of the painting robot between the teaching points takes a singular point has been described. However, the present invention is not particularly limited to this, and the teaching point TP _m (TP ₁ to TP ₁ in FIG. when the posture of the painting robot is a singular point in the TP _8), it may be changed the attitude of the spray gun 20 at the teaching point TP _m to rotate with the teaching point TP m _'in the γ direction and the changed The teaching point TP _m ′ may be taught as a new teaching point.

FIG. 1 is a schematic view showing a painting line provided with a painting robot in an embodiment of the present invention. FIG. 2 is a schematic side view showing the painting robot in the embodiment of the present invention. FIG. 3 is a front view showing a painting pattern by a painting gun attached to the painting robot shown in FIG. FIG. 4 is a flowchart showing a method for teaching a painting robot according to an embodiment of the present invention. FIG. 5 is a plan view showing teaching points to the painting robot in the embodiment of the present invention. FIG. 6A is a conceptual diagram showing the posture of the paint gun before the change. FIG. 6B is a conceptual diagram showing the posture of the paint gun after the change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Paint robot 11 ... The 1st-6th joint 20 ... Paint gun 30 ... Paint supply apparatus 31 ... Paint piping 40 ... Control apparatus B ... Automobile body D ... Mobile trolley L ... Paint line S ... Paint booth

Claims (5)

A method for teaching a painting robot equipped with a painting gun,
When interpolating between teaching points, calculate the posture of the painting robot that has been linearly interpolated in advance, and when the posture takes a singular point, rotate the painting gun around the central axis of the painting gun, A method for teaching a painting robot, wherein the posture of the painting robot is changed to a posture that avoids the singular point.   When the posture of the painting robot at the teaching point takes a singular point, the posture of the painting robot is changed to a posture that avoids the singular point by rotating the painting gun around the central axis of the painting gun. The method for teaching a painting robot according to claim 1.   The teaching method of the painting robot according to claim 1 or 2, wherein the posture of the painting robot after being changed so as to avoid the singular point is taught to the painting robot as a new teaching point.   The method for teaching a painting robot according to any one of claims 1 to 3, wherein the coating pattern applied to the object to be coated by the coating gun has a substantially circular shape.   5. The method for teaching a painting robot according to claim 4, wherein the painting gun is a rotary atomizing painting gun.

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