JPH0665902U - Robot controller - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the robot control device, which controls the robot body including the external axis, is to measure the apparent change of the work by image processing and correct the coordinates. [Arrangement] Changes X and Y in the position of one of the marks before and after the movement of the robot body, and a positional difference ΔX in the X direction between the two marks after the movement of the robot body.
And the movement angle θ defined by the ratio of the position difference ΔY in the Y direction.
(= Arctan (ΔY / ΔX)) is obtained by the image processing apparatus, and the position of the robot coordinate system of the robot body is corrected by these X, Y and θ.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a robot control device that controls a robot body including an external axis.

[0002]

[Prior art]

 As a conventional robot control device, for example, there is known one in which a robot body having a plurality of joint axes is hung on a moving axis and moved, and then a predetermined work is performed by the robot body on a stationary work. The work coordinate system, which is an arbitrary orthogonal coordinate axis, is set on the work, and the position and orientation of the hand of the robot body is taught as the position and orientation in the work coordinate system.

When reproducing, the teaching position in the work coordinate system is coordinate-converted to the robot coordinate system set on the robot body, and then the position / orientation in the coordinate-converted robot coordinate system is calculated. The joint angles of each joint axis are converted to control the joint axes of the robot body.

[0004]

[Problems to be solved by the device]

 When the work is large compared to the movement range of the robot body, the robot control device moves the robot body along the movement axis while controlling many joint axes of the robot body at the same time. Need to work. In robot control, an axis other than the joint axis of the robot, such as the running axis, is called an external axis.

However, the robot coordinate system moves as the robot body moves along the movement axis, while the work coordinate system remains stationary. Therefore, when viewed from the moving robot coordinate system, the position of the work coordinate system apparently shifts. In such a case, in order to perform more accurate work on the work than the robot body, the apparent position is apparent. It is necessary to correct the work position.

Therefore, it is considered to measure the relative three-dimensional position of the robot with respect to the work by using the image processing technology. As a means therefor, for example, a stereo vision method using two cameras for three-dimensional measurement is known, but the stereo vision method has a problem that it is difficult to associate points on the left and right images. . In addition, the monocular moving vision method, which moves one camera in the horizontal direction, and the light section method are known.

However, even if the three-dimensional position of the work can be measured by these methods, since the robot coordinate system moves along with the external axis, the work coordinate system is defined for a stationary work, and the robot main body and the external When working with coordinated movements of axes, even if the work coordinate system shifts or rotates, the teaching position does not shift or rotate with respect to a work that is stationary.Therefore, work position misalignment correction can be performed by correcting the work coordinate system. It was not possible to do this, and it was necessary to perform coordinate correction calculation for each teaching position in the program that describes the robot operation, but this work was extremely complicated.

As described above, since the robot coordinate system that moves along the moving axis is a relative coordinate system, when working on a stationary work while moving the robot body along the traveling axis, There is a problem that complicated correction calculation is required. The present invention has been made in view of the above prior art, and provides a robot control device capable of performing accurate work without complicated correction calculation when the robot body and the external axis are simultaneously controlled in cooperation. The purpose is.

[0009]

[Means for Solving the Problems]

 In order to achieve such an object, the structure of the present invention is a robot control device for performing work by the robot main body while moving the robot main body relative to the work along an external axis. Is photographed by a camera attached to the robot body, and the change in the position of any one of the marks before and after the movement of the robot body is X, Y according to the robot coordinate system set on the robot body. A moving angle θ (= arctan (ΔY / ΔX)) defined by the ratio of the positional difference ΔX in the X direction of the two marks and the positional difference ΔY in the Y direction is obtained by an image processing device, and these X, Y And θ are used to correct the position of the robot coordinate system of the robot body, and then another mark provided on the workpiece is photographed by the camera to obtain another mark. Characterized Rukoto determined by the X-direction position and the position in the Z direction image processing apparatus.

[0010]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. FIG. 1 shows an embodiment of the present invention. As shown in the figure, the robot control device of this embodiment comprises a robot controller 1, an image processing device 2, a robot body 3, a camera 4, a monitor 5 and a personal computer 6.

The robot control device moves the robot main body 3 along a movement axis (not shown), and at the same time, performs work on a work. For example, as shown in FIG. 2, the robot body 4 is moved with respect to a rectangular parallelepiped table which is the work 6, and the pin 7 gripped by the robot body 4 is inserted into the hole 8 of the work 6. It is something.

As shown in FIG. 2, the work 6 is provided with the first and second marks 9 and 10 on the upper surface thereof, and the hole 8 provided on the front surface thereof can be used as the third mark 11. It is like this. Generally, as shown in FIG. 3, the third mark 11 is the same as the first and second marks 9 and 10 except that the mounting position is different.

A camera 4 is attached to the tip of the robot body 3. As shown in FIG. 3, the camera 4 can photograph the first, second, and third marks 9, 10, 11 by moving the robot body 3. The visual field of the camera 4 is composed of vertical 479 pixels × horizontal 511 pixels, and if the upper left corner is the origin (0,0) on the screen, the coordinates of the center of the screen are (255,239).

The images of the first, second, and third marks 9, 10, and 11 taken by the camera 4 are displayed by the image processing device 2 as shown in FIGS. 4 (a) (b) (c). The barycentric position is image-processed as a measurement point, and the result can be confirmed by the monitor 5. The image processing apparatus 2 can be operated through the personal computer 6, and the result of the image processing by the image processing apparatus 2 is input to the robot controller 1 and the robot coordinate system (X, Y, Z) of the robot body 1 is input. It is used for coordinate correction of.

A robot coordinate system (X, Y, Z) as shown in FIG. 3 is set in the robot body 3. The robot coordinate system (X, Y, Z) is a relative coordinate system that changes as the robot body 3 moves along the movement axis. Therefore, before the robot body 3 is moved, according to the robot coordinate system (X, Y, Z), the work observed at the position shown by the solid line in FIG. The position apparently changes to the position indicated by the broken line.

Here, as shown in FIG. 5, before the movement of the robot body 3, the work 6 is at the position indicated by the solid line, and by moving the camera 4 in the Y direction by the movement distance L, the camera 6 is moved. It is assumed that the centers of the first and second marks 9 and 10 are located at the centers (255, 239) of the visual field of No. 4. That is, the first and second marks 9 and 10 are based on the time when they are separated by the distance L in the Y direction by the robot coordinate system (X, Y, Z).

After the robot body 3 is moved, the work 6 is moved to the position shown by the broken line in FIG. 5, and the camera 4 is moved in the Y direction by the movement distance L to move the respective positions. Then, the coordinates of the measurement points of the first and second marks 9 and 10 in the field of view of the camera are observed at (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ), respectively.

That is, the procedure is shown in the flowchart of FIG. First, the robot controller 1 moves the robot body 3 to the position of the second mark 10, and then transmits a measurement command for the second mark 10 to the image processing apparatus 2. After the initial setting, the image processing device 2 receives the measurement command from the robot body 3, captures the image of the _second mark 10 via the camera 4, and measures the center of gravity (X ₂ , Y ₂ ) is calculated.

Next, the robot controller 1 moves the robot body 3 to the first mark 9, and then transmits a measurement command for the first mark 9 to the image processing apparatus 2. The image processing device receives the measurement command from the robot body 3, captures the image of the first mark 9 via the camera 4, and calculates the measurement point (X ₁ , Y ₁ ) by measuring the center of gravity. . When the measurement is impossible, a measurement impossible flag is set.

Here, considering the second mark 10 as a reference point, the change (X, Y) in the position of the second mark 10 before and after the movement of the robot body 3 is calculated by the following equation. X = (255−X ₂ ) k Y = (Y ₂ −239) k where k is the resolution of the camera 4.

Further, the positional difference ΔX in the X direction and the positional difference ΔY in the Y direction between the first and second marks 9 and 10 after the movement of the robot body 3 are calculated by the following equations. ΔX = (255−X ₂ ) k − ((255−X ₁ ) k + L) = (X ₁ −X ₂ ) k−L ΔY = (Y ₂ −239) k − ((Y ₁ −239) k + L) = (Y ₂ -Y ₁₎ k

Then, as shown in FIG. 5, the movement angle θ around the second mark 10 before and after the movement of the robot body 3 is defined by the following equation. θ is the apparent inclination of the work in the robot coordinate system. θ = arctan (ΔY / ΔX) The robot coordinate system is corrected by X, Y and θ obtained in this way, and then the third mark 11 is photographed by the camera 4 to obtain the third mark in the robot coordinate system. The coordinates (X ₃ , Z ₃ ) of 11 in the X and Z directions are obtained by image processing.

The procedure is shown in the flowchart of FIG. First, the robot controller 1 transmits (X, Y, θ) obtained by the image processing device 2 to the robot body 3, and the robot body 3 receives it. After that, the robot main body 3 performs coordinate correction with (X, Y, θ) and moves to the third mark 11.

Then, the robot controller 1 transmits a measurement command for the third mark to the image processing device 2, and after the image processing device 2 receives this command, the third mark is sent via the camera 4. The image is captured and the center of gravity is measured to obtain the coordinates (X ₃ , Z ₃ ) in the X and Z directions. The third mark 11 was photographed by setting the camera 4 sideways because of the posture of the robot body 3. When the measurement is impossible, a measurement impossible flag is set.

After that, the robot controller 1 transmits (X ₃ , Z ₃ ) obtained by the image processing device 2 to the robot body 3, and the robot body 3 receives it. Thereafter, the robot body 3 moves to the position corrected by (X ₃ , Z ₃ ) and inserts the pin into the hole which is the third mark 11 to complete the work.

As described above, in the present embodiment, in the control of the robot including the external axis, by observing the two marks, once corrected with (X, Y, θ), (X ₃ , Z ₃ ) is measured. Therefore, it is possible to perform highly accurate work. That is, when the robot body 3 is moved along the movement axis, the apparent position of the work 6 changes in the robot coordinate system, but such an apparent change occurs because the work 6 is corrected by (X, Y, θ). The pin can be accurately inserted into the hole of the work 6 without being adversely affected.

[0027]

[Effect of device]

 As described above in detail based on the examples, in robot control that simultaneously controls the robot body together with the external axis, two marks are observed by using image processing technology, and the apparent change of the workpiece is observed. (X, Y, θ) is calculated, the coordinates are corrected, and then other marks are measured. Therefore, accurate work can be performed without being adversely affected by the apparent change of the work. Is.

[Brief description of drawings]

FIG. 1 is a block diagram of a robot controller according to an embodiment of the present invention.

FIG. 2 is a perspective view showing how a work is performed.

FIG. 3 is a perspective view showing a position of a camera for observing a work.

FIG. 4 is an explanatory diagram showing a field of view of a camera for observing each mark.

FIG. 5 is an explanatory diagram showing changes in the apparent position of the work before and after the movement of the robot body along the movement axis.

FIG. 6 is a flowchart showing a procedure for observing first and second marks.

FIG. 7 is a flowchart showing a procedure for observing a third mark.

[Explanation of symbols]

 1 Robot Controller 2 Image Processing Device 3 Robot Main Body 4 Camera 5 Monitor 6 Personal Computer

Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number for FI Technical location G05D 3/12 T 9179-3H (72) Creator Kiyohide Abe 2-1-1 Osaki, Shinagawa-ku, Tokyo Stockholders Association Inside the Shameidensha (72) Inventor Satoru Nomura 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Stock Company Inside the Shameidensha (72) Inventor Katsuhiro Hayashi 2-1-117 Osaki, Shinagawa-ku, Tokyo Inside the Shameidensha

Claims (1)

[Scope of utility model registration request] 1. A robot control device for performing work by the robot body while moving the robot body relative to a workpiece along an external axis, wherein two marks provided on the workpiece are attached to the robot body. And a change in the position of one of the marks before and after the movement of the robot body, X and Y, and the movement after the movement of the robot body by the robot coordinate system set on the robot body. A movement angle θ (= arctan (ΔY / ΔX)) defined by the ratio of the positional difference ΔX between the two marks in the X direction and the positional difference ΔY in the Y direction.
Is obtained by the image processing device, and the position of the robot coordinate system of the robot body is corrected by these X, Y and θ, and then another mark provided on the work is photographed by the camera to obtain the other mark. Position of mark in X direction and Z
A robot controller characterized in that a position in a direction is obtained by an image processing device.