JPS598086A - Form detector - Google Patents

Abstract

PURPOSE:To obtain stably the secondary form corresponding to the information on unevenness of a subject, by extracting a light cut-off line out of a detected picture to obtain a binary picture through a process of threshold value and then detecting the secondary form of the subject. CONSTITUTION:The area which can be viewed from an image detector 5 is observed among the slit bright lines projected to a subject 2 as well as to a table 1, and no bright line is seen at the area of a dead angle. Thus a light cut-off line extracting circuit 9 extracts a light cut-off line. For instance, a video signal is obtained at a part shown by a one-dot chain line as a middle point between Z1 and Z2 in the form of the value Z of the light cut-off line. This value is obtained for every coordinates to obtain a light cut-off line. Then a threshold value process is given to the light cut-off line to obtain a binary signal. Thus an overall binary picture is obtained. In such a way, it is possible to detect the secondary form of the subject 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the positioning and shape recognition of machines and parts, and particularly to an automatic shape detection method suitable for detecting stable planar shapes.

The most common conventional shape detection method is to illuminate the object with a lamp or the like and detect its image with a TV camera. Although it is effective for detecting the shape of objects with clear brightness and darkness, it is also effective for many scenes that exist in manufacturing sites and are subject to automation, such as scenes consisting of uniform colors and metal objects with machined surfaces. isn't it. For example, in a mechanical part having a cut surface, even if the direction of illumination and detection is kept constant, one surface may be detected as bright or dark depending on the orientation of the cutter mark. For such objects, the conventional methods described above are completely ineffective.

An object of the present invention is to eliminate the drawbacks of the conventional methods described above and to provide a shape detection device capable of detecting the two-dimensional shape of an object without being affected by nine colors and brightness of the object's surface condition. It is.

In order to achieve the above object, a shape detection device according to the present invention includes a light cutting optical system that projects a slit bright line onto an object whose shape is to be detected, and an image detector that detects an image of the slit bright line. , a light-cutting line extraction circuit for extracting a light-cutting line from the thus detected image; a binarization circuit for binarizing the light-cutting line into two values corresponding to different heights; It includes a binary image processing device that sequentially stores the binary signals obtained by the binarization circuit and processes the detected binary image, and a feeding mechanism that relatively moves the object and the light cutting optical system. The gist is that.

That is, the shape detection device according to the present invention uses a light cutting method as an optical detection method. A light section line is extracted from the detected image, and a binary signal is obtained by subjecting it to dark value processing. The above-mentioned binary signal is obtained repeatedly while relatively moving the detector and the object, and the two-dimensional shape of the object is detected as a binary image as a whole.

The present invention will be described in more detail below using examples with reference to the accompanying drawings, but these are merely illustrative, and various modifications and improvements may be made without going beyond the scope of the present invention. Of course.

FIG. 1 and FIG. 2 are block diagrams showing an example of the configuration of the shape detection device according to the present invention when the object whose shape is to be detected is placed on a fixed table and a conveyor, respectively. This detects the shape of an object 2 on a table 1 or a conveyor driven by a motor.

The shape detection device includes a slit projector 4 that projects a slit bright line 3 onto the object 2 from vertically above, an image detector 5 that detects the slit bright line from diagonally from the side, and a table 1 and the object. A feed mechanism 6 that moves the object 2 relative to the object 2 (in Fig. 1, a feed screw 6 is used as the feed mechanism)
was displayed.

Although the sliding mechanism is necessary, it is not shown because it is obvious. In FIG. 2, the feed mechanism 6' of the conveyor is shown. ), feed motor 7
or 7', motor control circuit 8. and a light cutting line extraction circuit 9 for extracting a light cutting line from the slit bright line signal detected from the image detector 5. A binarization circuit 10 that binarizes the detected optical cutting line signal. A control circuit 11 that controls the speed 1 position of the feed motor and the timing of extracting the optical cutting line. and 2
It is comprised of a binary image processing device i12 which temporarily stores the binary signals obtained from the digitizing circuit 10 and recognizes the shape and two positions of the object from the obtained binary image. The area surrounded by broken lines in the diagram is an automatic assembly machine and a shape inspection and sorting machine.

It is incorporated as a visual subsystem in a robot system, etc. The control circuit 11 receives a start signal from the device main body 13, and based on the command, it identifies the shape, detects the position and orientation of the object, and performs binary image processing. The detection results are transmitted from the device 12 to the device main body 13.

The operation will be explained below. FIG. 3 shows the state of projection and detection of the slit bright line in this embodiment. In this case, the image detector 5 detects a light section image shown in FIG. That is, in the slit bright line projected onto the object 2 and the table 1 or the conveyor 1', a portion visible from the image detector 5, that is, a portion that does not become a blind spot, is observed.
The bright line cannot be seen in the blind spot. Optical cutting line extraction circuit 9
Extracts the optical cutting line from the detected image in FIG. That is, it is sufficient to find the center point of the portion of the detected image shown in FIG. 4 in the vertical and two-direction directions, where the value is equal to or higher than the preset threshold value 71. - For example, when the video signal in the portion indicated by the dashed line in FIG. 4 is as shown in FIG. 5, the value 2 of the optical cutting line at the X coordinate can be determined as the midpoint between Zl and z2. By finding this for the entire screen, that is, for all the X coordinates, the light cutting line Z (x) can be found. Note that when one vertical video signal is always smaller than 1, the output value of its X coordinate is zero, that is, 2(g)=0. As a result, the value of the light section line will be zero in the blind spot.

FIG. 6 illustrates the optical cutting line obtained from FIG. 4.

In addition to the method described above, the method for extracting the optical cutting line may be the method described in the invention related to the earlier application filed by the present applicant. The binarization circuit 10 binarizes the optical section line obtained by the optical section line extraction circuit 9 by comparing it with a threshold value Zl.

In FIG. 6, the threshold value z1 is shown by a broken line. Figure 7 shows the obtained binary signal. Here, the threshold value z1 may be a constant value set in advance, or may be a frequency distribution for the binary values of the detected 13u cutting line, the average Z value of the conveyor or the table, or the average Z value of the top surface of the object. The value may be determined and 21 may be determined as the intermediate value. As described above, one binary signal is obtained from one slit bright line.

This is transmitted over the entire detection range on a conveyor or table, that is, when the object 2 is on a fixed table, the transmitter 4 and image detector 5 are moved in the y direction by the feeding mechanisms 6 and 7, and the binary signal is detected. By repeating the detection, a binary image of the object can be obtained on the memory of the binary image processing device 12. FIG. 8 shows an example of a binary image obtained.

In FIG. 8, the portion corresponding to the value 1 is shown with diagonal lines, and the portion corresponding to 0 is shown in solid color. Here, the feed υ motor 7 is a step motor, and by making the )' coordinate correspond to the step position, it can be made to correspond to the coordinate in the y direction. It is also possible to use an fcDC motor and obtain the y-direction coordinate with an encoder.

Note that the obtained binary signal is processed as a binary image in the binary image processing device 12, and its shape and posture are identified.

It is possible to obtain position detection.

In the above embodiments, the slit projector is a projector that emits a slit-shaped light band, but this may be of a type that scans a spot light at high speed. Furthermore, a TV camera can be used as the image detector, and the TV camera can be rotated 90 degrees and installed so that the Z-axis direction coincides with the horizontal scanning direction of the TV camera. As the image detector, in addition to the TV camera, various types of two-dimensional scanning power imaging methods such as a combination of a -dimensional image sensor and a galvanometer mirror can be used.

Furthermore, as an optical system configuration for the light sectioning method, we have illustrated an example in which υ slit light is projected from above and detected from an angle, but as shown in Figure 9, a slit light is projected from an angle and detected from above. Alternatively, as shown in FIG. 10, a slit light is emitted diagonally and detected from the opposite diagonal direction. Furthermore, as shown in FIG. 11, a method may be adopted in which slit light is projected from above and detected from both diagonal directions. In the method shown in FIG. 11, a portion that is a blind spot in one image detector may not be a blind spot in the other image detector, and more accurate shape detection is possible. In this case, the image detector 5° optical cutting line extraction circuit 9. And two sets of binarization circuit 1o are required,
The two obtained binary signals may be logically summed, and this may be stored in the binary image processing device 12 as a final binary signal.

According to the present invention as described above, the shape of the object can be detected as a binary image according to the unevenness information of the target scene, so the color, brightness, direction of cutting marks, etc. of the object in the scene can be detected. The advantage is that a two-dimensional shape can be stably detected without being affected by the surface condition of the object.

[Brief explanation of drawings]

Fig. 2 is a block diagram showing the configuration of a shape detection device according to the present invention when an object whose shape is to be detected is placed on a fixed table, and Fig. 2 shows a conveyor in which the object is driven by a motor. FIG. 3 is a block diagram showing the configuration of the shape detection device according to the present invention when the shape detection device is placed on top of the device;
Fig. 4 is a diagram showing an example of a detected optical section image, Fig. 5U
A diagram explaining how to obtain the value of one video signal and the optical section line,
FIG. 6 is a diagram showing an example of an extracted optical section line, FIG. 7 is a diagram showing an example of the obtained binary signal, and FIG. 8 is a diagram showing an example of a shape detected as a binary image. 9 to 11 are configuration diagrams of optical systems of different embodiments used in the shape detection device according to the present invention. 1...Table, 1'...Conveyor, 2...Object, 3...Slit bright line, 4...Slit floodlight,
5... Image detector, 6.6'... Feeding mechanism, 7.7'
...Transmission υ motor, 8...Motor control circuit, 9 optical cutting line extraction circuit, 1()...Binarization circuit, 11...Control circuit, 12...Binary image processing device , 13... Apparatus body agent Patent attorney Masami Akimoto Fi51 Figure 2 Figure 3 Figure 4 484- 5th cause Figure 6 7th cause o - "]- Figure 8 Figure 9 101 11th ratio

Claims (1)

[Claims] A light cutting optical system that projects a slit bright line onto an object whose shape is to be detected, an image detector that detects an image of the slit bright line, and an image detector that extracts the light cutting line from the thus detected image. A light cutting line extraction circuit, a binarization circuit that binarizes the light cutting line into two values corresponding to different heights, and sequentially storing and detecting the binary signals obtained by the binarization circuit. a binary image processing device that processes a binary image;
A shape detection device characterized in that it includes a conveyance mechanism that relatively moves the object and the light cutting optical system.