JPH04269194A - Plane measuring method - Google Patents

Abstract

PURPOSE:To correctly detect the position and direction, even in case of a work object face being slipped, with respect to a plane measuring method detecting the work object face of a robot. CONSTITUTION:In the case of a work object face 1 being slipped a marker 2 provided on the work object face 1 is picked up at its image by a visual sensor 3, then the contour 2a and center 2b in the picture image 4 thereof are viewed with their sliding relatively. A picture image processing part 5 detects the sliding thereof from the data of the picture image 4. Namely, the respective gravity coordinate of the contour 2a and center 2b is found, and the slippage between the two gravity coordinates thereof is detected. The slippage between these two gravity coordinates is equivalent to the slippage of the work object face 1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a plane measurement method for detecting the direction (displacement) of a work surface of a robot, and in particular, the present invention relates to a plane measurement method for detecting the direction (shift) of a work surface of a robot. This invention relates to a plane measurement method for detecting the direction of a work surface.

[0002] When a robot performs work, it is necessary to accurately position the robot hand with respect to the work object. For example, when a robot is used to attach parts, the following work steps can be considered: (1) grasping the part to be attached, (2) transporting the part, and (3) fastening or fitting the part. In work processes such as gripping and (3) fastening, it is necessary to directly face (position perpendicularly) the robot hand to the surface to be worked on.

0003

[Prior Art] Conventionally, robots have been used in the above-mentioned (1) and (
When performing work such as 3), it is necessary to teach all the positions and directions of the parts to be worked on in advance using means such as a teaching box. The robot operates the robot hand and performs the work assuming that the part is located at the taught position and direction.

0004

[Problems to be Solved by the Invention] However, the parts to be worked on are not always in the same position or direction, and may shift due to some reason. In such a case, the position and orientation of the component do not match the position and orientation at the time of teaching. As a result, the robot is no longer able to move the robot hand accurately, resulting in a problem that the robot cannot continue its work from then on.

The present invention has been made in view of these points, and provides a plane measurement method that can accurately detect the position and direction of the surface to be worked on even if the work target is shifted. The purpose is to

Another object of the present invention is to provide a marker that is effective for detecting the direction of a surface to be worked on.

[0007]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. A marker 2 is provided on a work surface 1 of the robot. This marker 2 is, for example, two planes 2a and 2 that exist in two planes parallel to the work surface 1 and separated by a certain distance.
It has b. The two surfaces 2a and 2b have their center points on the same straight line perpendicular to the two planes, and one surface (
The contour portion 2a is a larger annular or angular vertically symmetrical surface, and the other surface (center portion) 2b is a smaller solid surface.

The marker 2 is configured to be imaged by a visual sensor 3. The data of the image 4 is sent to the image processing section 5. In the image processing unit 5, from the data of the image 4,
The representative coordinates of the contour portion 2a and the representative coordinates of the center portion 2b are determined. The direction of the work surface 1 is detected from the two representative coordinates.

[0009]

[Operation] The marker 2 provided on the work surface 1 has a contour portion 2a and a center portion 2b. This contour part 2a and the center part 2
If the visual sensor 3 is installed on a straight line connecting the center points of the marker 2 and the marker 2, the center points of the marker 2 will appear to match.

[0010] Here, when the work surface 1 moves and shifts, when the marker 2 is imaged by the visual sensor 3, the image 4
The outline portion 2a and the center portion 2b appear to be relatively shifted from each other. The image processing unit 5 detects the shift from the data of the image 4. That is, in the image 4, representative coordinates of the contour portion 2a and the center portion 2b are determined, and a deviation between the two representative coordinates is detected. The deviation between these two representative coordinates corresponds to the direction of the work surface 1.

Therefore, even if the work surface 1 shifts, its direction can be detected simply by capturing an image of the marker 2. Furthermore, based on the detected data, the position of the robot hand can be corrected, and the robot can be operated accurately. Therefore, even if the work surface 1 shifts, the robot can continue to work.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing the overall configuration for implementing the plane measurement method of the present invention. In the figure, a television camera (visual sensor) 3 is attached to a hand 31 of a robot 30. The robot 30 is the robot control device 4
Controlled by 0. On the work target surface 1 of the part 10,
A marker 2 is provided. The details will be described later. The television camera 3 images the marker 2 and sends the image data to the image processing section 5.

The image processing section 5 includes a processor (CPU) 51
It is mainly composed of. A program for implementing the present invention is stored in the ROM 52, and the processor 51 controls the measurement operation of the work surface 1 according to this program. The RAM 53 is a frame memory, and stores shape data of the marker 2 and the like. In RAM54,
Image data from the television camera 3 is sent to the interface 59
Stored via . The image processing processor 55 is R
Based on each data of AM53 and AM54, the deviation of the representative coordinates of marker 2 is determined. The details will be described later. Data regarding this shift in representative coordinates is stored in the RAM 56.

The robot control device 40 reads the data stored in the RAM 56 from the interface 58 via the communication line 57, recognizes the direction of the work surface 1 based on the data, and controls the robot 30.

FIG. 3 shows examples of markers used in the present invention, in which (A) shows a marker having a conical hole shape, (B) shows a marker having a conical projection shape, and (B) shows a marker having a conical protrusion shape. (
C) shows markers each having a quadrangular pyramidal protrusion shape. The marker 2 shown in FIG. 3(A) has a conical hole machined on the surface 1 to be worked on. The marker 20 shown in FIG. 3(B) has a conical protrusion shape and can be manufactured more easily than the marker 2. Moreover, since it only needs to be installed on the work surface 1, it can be used easily. The marker 21 shown in FIG. 3(C) has a quadrangular pyramidal protrusion shape. The advantage of this marker 21 is that since the image thereof also has a rectangular shape, it is easy to cut out the outline portion 21a using a window, which will be described later. Further, like the marker 20, it is easy to use because it only needs to be installed.

Each marker has two sides, and each marker has two sides.
Surfaces 2a and 2b, 20a and 20b, and 21a and 21b each exist in two planes parallel to work surface 1 and separated by a certain distance, and their center points are on the same straight line perpendicular to the two planes. have The contour portions 2a, 20a, and 21a are each larger annular or angular symmetrical surfaces, and the center portions 2b, 20b, and 21b are smaller solid surfaces. Each contour part and center part are painted black so that they can be easily identified in the image 4 taken by the television camera 3.

FIG. 4 is a diagram for explaining the plane measurement method of the present invention, in which (A) shows the image taken by the television camera, (B) shows the image taken by the television camera from the L1 direction, and ( C) shows images taken by the television camera from the L2 direction. In FIG. 4(A), first, the television camera 3 images the marker 2. This marker 2
As mentioned above, is created by machining a conical hole on the work surface 1, and the contour part 2a and the center part
(Base part) It has two faces 2b. Furthermore, a case will be described in which the center of gravity coordinates are used as the representative coordinates of the marker 2.

When the television camera 3 images the marker 2 from the L1 direction, the obtained image 4 becomes as shown in FIG. It shifts to Based on the data of this image 4, the image processing unit 5 calculates the barycenter coordinates of the contour portion 2a and the center portion 2b.
Find the coordinates of the center of gravity of each. In this case, the barycentric coordinates of the center portion 2b are determined with the contour portion 2a erased (cut out with a window).

[0019] Now, set the coordinate system as shown in the figure,
If the X-direction coordinate of the contour portion 2a is X2, and the X-direction coordinate of the center portion 2b is X1, then X1>X2. The imaging direction of the television camera 3 is changed to match the X-direction coordinates. In other words, the robot hand 31 (TV camera 3) is
Rotate in the positive direction of the axis. Note that the robot hand 31 of the robot 30 is composed of α, β, and γ axes, and each of the axes rotates around the X, Y, and Z axes as shown in FIG. 4(A).

Conversely, when the television camera 3 images the marker 2 from the L2 direction, the obtained image 4 becomes as shown in FIG. 4(C), and the X-direction coordinates X1 and X2 at this time are
It becomes X2. Therefore, the robot hand 31 (television camera 3) is rotated in the negative direction of the β axis.

[0021] If the above operation is also performed in the α-axis direction (Y-axis direction) and the television camera 3 is moved so that finally X1=X2 Y1=Y2, the contour part 2
It is possible to match the barycenter coordinates of a and the center portion 2b. At this time, the work surface 1 is directly facing the television camera 3, that is, the robot hand 31.

FIGS. 5 and 6 are flowcharts for carrying out the plane measurement method of the present invention, and FIG.
1 to S7, and FIG. 6 shows steps S8 to S11. In the figure, the number following S indicates the step number. [S1] Image the marker 2 with the television camera 3. [S2] Find the coordinates of the center of gravity of the contour portion 2a. [S3] Find the coordinates of the center of gravity of the center portion 2b. [S4] It is determined whether the X-direction coordinate X2 of the center of gravity coordinate of the contour portion 2a is equal to the X-direction coordinate X1 of the center of gravity coordinate of the center portion 2b. If they are equal, proceed to S8; if not, proceed to S5. [S5] Determine whether X1 is greater than X2. If it is larger, proceed to S6; if smaller, proceed to S7. [S6] Rotate the robot hand 31 (TV camera 3) around the +β axis. [S7] - Rotate the robot hand 31 (TV camera 3) around the β axis. [S8] It is determined whether the Y-direction coordinate Y2 of the center of gravity coordinate of the contour portion 2a is equal to the Y-direction coordinate Y1 of the center of gravity coordinate of the center portion 2b. If they are equal, the program ends; if they are not equal, the process advances to S9. [S9] Determine whether Y1 is greater than Y2. If it is larger, the process goes to S10, and if it is smaller, the process goes to S11. [S10] Rotate the robot hand 31 (TV camera 3) around the +α axis. [S11] - Rotate the robot hand 31 (TV camera 3) around the α axis.

In this way, the direction of the work surface 1 is detected from the data of the image 4 of the marker 2, and depending on the direction,
The position of the robot hand 31 is corrected. Therefore, the robot hand 31 can be directly opposed to the work surface 1, and even if the work surface 1 is shifted, the robot 30 can be made to perform accurate operations. Therefore, the work by the robot 30 can be continued.

Furthermore, the marker 2 has two surfaces, an outline portion 2a and a center portion 2b, which are located at a certain distance, and the two surfaces 2a, 2a
I decided to take an image. Therefore, in the image 4, the relative displacement between the contour portion 2a and the center portion 2b can be clearly determined. Therefore, when determining the respective barycenter coordinates, it is possible to accurately determine the deviation between the barycenter coordinates.

FIG. 7 is a diagram showing a second embodiment of the present invention. The difference from the first embodiment is that a plurality of markers 2 (for example, 2
). The marker 2A with a large aperture angle θ is effective for imaging from a wider range. On the other hand, the marker 2B with a small aperture angle θ can detect displacement with higher accuracy. Therefore, by first determining the approximate direction based on the marker 2A with a large aperture angle θ and then correcting it with the marker 2B with a small aperture angle θ, it is possible to determine the direction of the work surface 1 with high precision. can.

In this case, by providing three or more markers 2 and decreasing the aperture angle θ of the markers 2 sequentially, the direction of the work surface 1 can be detected from a wider range with higher precision.

In the above explanation, as the representative coordinates of the marker,
Although the center of gravity coordinates were used, it is clear that similar effects can be obtained using the median value.

[0028]

As described above, the present invention is configured to detect the direction of the work surface from the marker image data. The robot moves according to the direction of the work surface.
Correct the position of the robot hand. Therefore, the robot hand can be directly faced to the surface to be worked on, and even if the surface to be worked on is shifted, the robot can be made to perform accurate operations. Therefore, the robot can continue to work.

Furthermore, the marker has two surfaces, an outline portion and a center portion separated by a certain distance, and images of these two surfaces are taken. Therefore, in the image, the relative deviation between the outline and the center can be clearly determined. Therefore, when each representative coordinate is determined, the deviation can be accurately determined.

Furthermore, since a plurality of markers are provided so that the aperture angle becomes smaller in sequence, the direction of the work surface can be detected from a wider range with higher precision.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2 is a diagram showing the overall configuration for implementing the plane measurement method of the present invention.

FIG. 3 is a diagram showing an example of a marker used in the present invention, in which (A) shows a marker having a conical hole shape;
) indicates a marker having a conical protrusion shape, and (C) indicates a marker having a quadrangular pyramidal protrusion shape.

FIG. 4 is a diagram for explaining the plane measurement method of the present invention, in which (A) shows the imaging situation by the television camera, (B) shows the image taken by the television camera from the L1 direction, and (
C) is a diagram showing images taken by the television camera from the L2 direction.

FIG. 5 is a flowchart for executing the plane measurement method of the present invention, showing steps S1 to S7.

FIG. 6 is a flowchart for executing the plane measurement method of the present invention, showing steps S8 to S11.

FIG. 7 is a diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1 Work target surface 2, 20, 21 marker 3 TV camera 4 Image 5 Image processing section 10 Parts 30 Robot 31 Robot hand 40 Robot control device

Claims (3)

[Claims] 1. A planar measurement method for detecting the direction of a work target surface (1) of a robot by imaging a marker (2), wherein a marker (2) is provided on the work target surface (1), and the marker (2) is is imaged by a visual sensor (3), and from the image (4) of the marker (2), the marker (2) is
The representative coordinates of the contour part (2a) and the center part (2b) are determined, and based on the representative coordinates of the contour part (2a) and the center part (2b), the work surface (
1) A plane measurement method characterized by detecting the direction. 2. The marker (2) has two surfaces (2a, 2b) each existing in two planes parallel to the work surface (1) and separated by a certain distance;
2a, 2b) have their center points on the same straight line perpendicular to the two planes, and the two planes (2a, 2b)
Claim 1, wherein one of the surfaces (2a) is a larger annular or angular symmetrical surface vertically and horizontally, and the other surface (2b) is a smaller solid surface. Plane measurement method described. 3. In the work target surface (1), the 2
The plane measuring method according to claim 2, characterized in that a plurality of the markers (2) are provided with different distances between two planes.