JPH1019517A - Method for detecting article position with slit light irradiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method for detecting the reflected light of a sample article even when the sample article is near the background object and many similar images of end point and bending point are generated. SOLUTION: Relating to the detecting method, a slit, light generating device 4 and an imaging device 3 are set at a specified angle against a sample article 1, and the reflection light of slit light irradiated on the article 1 is image- processed. Firstly, second-order differentiation is performed with one component of two-dimensional position coordinate of a slit light image, then, a sum of second-order differentiation values is obtained in a constant range, and the reflection light of straight line part of the article is detected from the least part of the value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating an article with slit light and detecting the position of the article by an image processing apparatus.

[0002]

2. Description of the Related Art When a position of an article is detected by using an image processing apparatus, a captured image is two-dimensional data, so that position information in two directions can be obtained. However, when the image processing apparatus is applied to a teaching playback robot, the operation information of the robot is three-dimensional, so that three-dimensional position information is required. In such a case, triangulation using slit light is used. Set the slit light generator and the imaging device at the required angle,
The slit light is applied to a characteristic portion (edge or the like) of the target article, and the reflected light is imaged by an imaging device.
Since the slit light applied to the characteristic part becomes a line segment having an end point or a line segment having a bending point on the image, the position of the article can be determined by detecting the end point or the bending point using a template matching method or the like. It becomes possible to detect. As described above, when the position of an article is detected using slit light, the position of the article can be measured by detecting an end point or a bending point. However, since the slit light has a certain length, when the distance between the article to be imaged and the background object is short, the reflected light of the slit light applied to the background object or the like is reflected by the imaging device. Since it enters the field of view and occurs as an image similar to an end point or a bending point on an image, it may affect image processing. An example in which such an effect can be considered is Japanese Patent Publication No. 4-4681.
There are four publications. According to this, in the embodiment, an image of the hoop and the wire is taken, the image is binarized by an image processing device, the data on the image is scanned in a certain direction to find the number of black and white intersections, There has been proposed a method of detecting a position having a small number as a hoop position. In this method, since the image processing is performed by the image binarization method, it is conceivable that the image processing is affected by a change in the contrast of the image. In particular, when an environment peculiar to the steel industry to be used is taken into consideration, it is conceivable that conditions such as illumination at the time of detection greatly change, and a change in image contrast is inevitable, making it difficult to detect a stable hoop. Therefore,
Although a method of performing detection using the slit light described above is conceivable, in the embodiment, since the distance between the hoop and the wire is short, even if the slit light is irradiated, the reflected light of the wire enters the field of view. As a result, there are many images of line segments having end points and inflection points, and there is a possibility that the detection method such as template matching cannot distinguish the reflected light from the hoop to be detected. Therefore, in such an example, it is considered that a method of detecting an end point or a bending point by irradiating slit light is very difficult. On the other hand, Japanese Patent Publication No. 5-86003, JP-A-6-235624, JP-A-4-40305, etc.
Although a technique for second-order differentiation of a binarized image is disclosed, it is not applied to recognition of a straight line portion as in the present invention. Therefore, the present invention detects the reflected light of the linear portion of the target article even when the distance between the target article and the background object is short and many similar images of the end points and the bending points are generated. The aim is to provide a method that can do this.

[0003]

In the above prior art, when the distance between a target article and a background object is close, there are many images having end points and bending points.
Since it is difficult to distinguish between the article and the background, it is considered that detection is difficult by a method such as template matching. An object of the present invention is to provide an image processing method capable of detecting reflected light of a target article even when the distance between the target article and the background object is short and many similar images of end points and bending points are generated. Is to provide.

[0004]

An object of the present invention is to provide a slit light generating device and an image pickup device at a required angle with respect to an article to be detected, and perform image processing on reflected light of the slit light applied to the article. In the device for detecting the position of the article, the second derivative is performed on one component of the two-dimensional position coordinates of the slit light image, and the sum of the second derivative is calculated in a certain range, and the reflected light of the article is calculated. Can be achieved by an image processing method for detecting

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for detecting the position of an article according to the present invention will be described below with reference to the illustrated embodiment. FIG. 1 shows an embodiment of an apparatus for carrying out the present invention, and shows an overall configuration. 1 is an object to be detected, 2 is the background of the article, 3 is an imaging device, 4 is a slit light generation device, and 5 is an image processing device. The imaging device and the slit light generator are set at a required angle, and the slit light is applied to the target article. The reflected light of the illuminated slit light is imaged by an imaging device, and the image is taken into an image processing device. Here, it is assumed that the background is close to the object to be detected and the background cannot be separated for detection.

FIG. 2 is an explanatory view of slit light irradiation in the embodiment. The object to be detected is irradiated with slit light, and the reflected light is captured as a two-dimensional image. Since the target article is close to the background, part of the slit light applied to the article is also applied to the background, and the reflected light is captured as an image.

FIG. 3 shows the contents of image processing performed by the visual system. (A) shows an example of a captured image obtained by irradiating a target object with slit light. When the slit light is applied to the target article, the reflected light of the target article is captured as a straight line, and the other reflected light of the background is captured in an arc shape following the shape of the background. (B)
Is obtained by extracting points of a large change in the Y-axis direction (vertical direction on the screen) from the image of (a) and connecting them. (C)
Is obtained by differentiating the line segment (b) in the X-axis direction (left-right direction on the image). As a result of the differentiation, the straight line has a constant value, and the arc-shaped line segment has a shape close to the straight line. (D) is obtained by further differentiating (secondarily differentiating) the line segment of (c). As a result of the differentiation, the line segment having a constant value has a value close to 0, and the straight line has a constant value. (E) shows the result of adding the Y value of the line segment of (d) in a certain range w. By adding, (e) becomes a shape having the minimum value. Here, comparing (a) and (e), the position corresponding to the reflected light of the target article in (a) is:
In (e), it can be seen that it corresponds to the position having the minimum value of the Y value.

As described above, in order to detect the position of a straight line from an image in which the shape of a straight line and an arc are mixed, two lines are required.
By performing the next differentiation and the addition of the differential value and detecting the position of the minimum value, the detection can be easily performed.
Further, even when image noise such as short line segments is mixed, 2
By performing the addition of the next derivative, the added value of the portion corresponding to the image noise becomes a larger value than the straight line portion,
By searching for the minimum value of the added value, it is possible to easily detect a portion close to a straight line. According to the above method, even if the distance between the target article and the background object is short and many similar images of the end points and the bending points are generated, the reflected light of the target article can be detected.

[0009]

As described above, according to the present invention,
The distance between the target object and the background object is close,
Even if many similar images of the end points and the bending points are generated, the reflected light of the target article can be detected, and the position of the article can be detected.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of slit light irradiation in an embodiment.

FIG. 3 is an explanatory diagram of image processing performed by the visual system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Article to be detected 2 ... Background of article 3 ... Imaging device 4 ... Slit light generator 5 ... Image processing device

Claims (1)

[Claims] 1. A position of an article is detected by setting a slit light generation device and an image pickup device at a required angle with respect to an object to be processed, and performing image processing of reflected light of the slit light applied to the article. In the method, a second derivative is performed on one component of the two-dimensional position coordinates of the slit light image, a sum of the second derivative values is obtained in a certain range, and the sum of the second derivative values indicates a minimum value. A position close to a straight line of the slit light by detecting a range of the slit light.