JPS6247503A - Device for recognizing position of circular object three dimensionally by light cutting method - Google Patents

Abstract

PURPOSE:To recognize the position of a circular object three dimensionally under non-contact state and at high speed by causing a light cutting line irradiating a slit light on the object and by obtaining three dimensional shape information. CONSTITUTION:A slit light 2 is emitted from the projector 2 using laser beam, etc., irradiated on the object 4 by being reflected by a movable mirror 3 and a light cutting line 2a is caused on the surface thereof. The image of the part including the light cutting line 2a is picked up by a TV camera 6, then, an image signal thereof is written into an image memory 8 from an image signal uptake part 7 under the control of an arithmetic part 10 and displayed on a display part 9. The movable mirror 3 is displaced by being driven by a slit light sweepage control part 11 under the control of the arithmetic part 10. Thereby the slit light 2 is swept to change the irradiating position of the slit light 2 for the object 4. A hole position calculating part 12 performs the prescribed motion by receiving command signal from the arithmetic part 10, calculates the center position of a circular hole 5 and the inclination of normal and displays on the display part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for three-dimensionally recognizing the position of a circular object using a light cutting method.

[Technical background of the invention and its problems] For example, when automating the work of inserting a bolt into a round hole using a robot, a device that three-dimensionally recognizes the position of the round hole is required. If the object with the round hole is stationary relative to the robot, the configuration of the device for recognizing the position of the hole is not that complicated.

However, when the robot is stationary and the target object is being transported by a conveyor or the like, it is very difficult to three-dimensionally recognize the position of the hole in the object. Moreover, it is necessary to detect the position of a circular hole in a moving object without contact. Conventionally, three-dimensional visual sensors that meet these requirements have not been put to practical use, and it has not been possible to automate the bolt insertion work for moving objects as described above.

[Purpose of the Invention] This invention was made in view of the above-mentioned technical background, and its purpose is to determine the position of a circular object in order to automate bolt insertion into a moving object using a robot. The object of the present invention is to provide a device that can perform three-dimensional recognition in a non-contact manner and at high speed using a photosection method.

[Summary of the Invention] A device for three-dimensionally recognizing the position of a circular object using a light cutting method according to the present invention irradiates the object with a slit light to generate a light cutting line, and a camera detects the light cutting line. Take an image with
An optical system uses a light cutting method to obtain image data that can calculate three-dimensional shape information related to an object, and a slit light is irradiated so that the light cutting line crosses the circular object, and the light cutting line crosses the circular object. and a means for moving the light section line to find a pair of two light section lines having the same chord length (see Fig. 1). reference).

Embodiment of the invention FIG. 2 shows the configuration of an apparatus according to an embodiment of the invention. A slit light 2 is emitted from a projector 1 using a laser or the like, and the slit light 2 is reflected by a movable mirror 3. The slit light 2 produces a bright line (light cutting line) 2a on the surface of the object 4. In this embodiment, the object 4 is a flat object, and a circular hole 5
is opened. This circular hole 5 is the circular object mentioned above.

A television camera 6 installed above the object 4 cuts the light cutting line 2.
The part containing a is ff1(Q).The obtained image signal is
Under the control of the arithmetic unit 10, the image signal is written into the image memory 8 from the image signal acquisition unit 7 and displayed on the display unit 9. The movable mirror 3 is driven and displaced by a hair-pulling control section 11 under the control of the calculation section 9 . The slit light 2 is swept by the displacement of the movable mirror 3, and the irradiation position of the slit light 2 on the object 4 is changed.

The hole position calculation section 12 operates as described below upon receiving a command signal from the calculation section 10, and calculates the position of the center of the circular hole 5 and the slope of the normal line.

Figure 3 (a) (fl) (C) H camera 6
An example of image data to be processed is shown. 2b is an image of the light section line 2a, and this is taken as a light section line image. The output of the camera 6 is an image signal in which the presence or absence of the optical cutting line 2a is converted into black and white binary values.

- A light cut 1!2a occurs on the surface of the object 4, but since light passes through the circular hole 5 of the object 4, no light cut line 2a occurs here. Therefore, if the optical cutting line 2a is created so as to cross the circular hole 5, as shown in FIG.
In the image signal obtained from the camera 6, a light section line image 2 is interrupted at the intersection of the circular hole 5 and the light section line 2a.
b is observed. Two intersections between the outline of the circular hole 5 and the optical section line image 2b are indicated by A and B. In addition, Fig. 3 (a
)(b'> (c) is an example of an image in which the object 4 is tilted at different angles.

The principle and device configuration of three-dimensional measurement using the optical sectioning method are well known, so their explanation will be omitted here.

Based on the image data stored in the image memory 8, the calculation unit 10 determines the intersection point A between the outline of the circular hole 5 on the object 4 and the light section line 2a.

Calculate the three-dimensional coordinates of B, and calculate the length of B to the line segment,
That is, the chord length A of the part where the optical cutting line 2a intersects with the circular hole 5
Calculate B.

The calculation unit 10 also controls the sweep control unit 11 to sweep the slit light 2 as described later, so that a light cutting line intersects the circular hole 5 at points A and B, as shown in FIG. 5(b). and string length A
Find another light F; l'J disconnection that intersects at point 0 and point D, which has a chord length equal to S. And hole position calculation section 12
calculates the center position of the circular hole 5 and the slope of the normal line from the relationship 8B=CD, and displays it on the display section 9.

The coordinates of four points in the relationship AB=CD are respectively A(χt
, V+, Z+), BOl:2. V2. Z2), C(χ3
．． ``i'3. n).

The hole position calculation unit 12 is given the coordinate values of points A, B, C, and D, and calculates the position of the hole center and the unit normal vector using the following formula.

Next, the control and processing for finding two optical cutting lines having the relationship AB=CD will be explained. The flowchart in FIG. 4 shows an example of the control procedure.

As a process before starting the process shown in FIG. 4, while sweeping the slit light 2, a state is created where the light cutting line 2a and the circles 71 and 5 intersect.

First, in step 401, the latest image data is loaded into the memory 8, and in the next step 402, the coordinates of the intersections Δ and B between the optical section line and the outline of the circular hole are detected from the image data, and in the next step 403, the coordinates of the intersection point Δ and B are detected from the image data. The length of AB, that is, the chord length L+
Calculate.

Next, in step 404, the slit light 2 is moved in a fixed direction (here, downward) by a width α. Then, in step 405, new image data is taken into the memory 8, and in step 406, the intersection point C between the moved optical cutting line and the circular hole
The coordinates of and D are detected, and in step 407, the length of the line segment CD, that is, the chord length L2 is calculated.

In the next step 408, the above-mentioned chord lengths L1 and Ll are compared to see if they are equal. If they are not equal, the process proceeds to step 410, where the magnitude relationship between Ll and Ll is compared.

If Ll is longer than Ll, the process proceeds to step 411, in which the slit light 2 is moved upward, contrary to the above, by a width α+Δ greater than the above, and the process returns to the first step 401. The movement of the optical cutting line in this case is shown in FIG. 5(C). The light cutting line moves downward from the AS position corresponding to the movement width α to the CD position, and then moves upward by the movement width α+6. As a result, the third optical cutting line is above the position of AB, and the process from step 4.01 onwards is repeated with the intersection at this time set as a new 8B.

If Ll is longer than Ll, proceed to step 412;
The slit light 2 is directed upward and the width α−Δ is smaller than the above.
The movement of the light section line in this case is shown in FIG. 5(a). The light cutting line of the third grain is AB.
below the position. The intersection between the light cutting line of the third grain and the circular hole becomes new intersections A and B, and the processing from step 401 onwards is repeated.

While the process through step 411 or step 412 is repeated several times, a state where Ll =12 is found. Then, the process advances from step 408 to step 409, where A, B, and C are sent to the hole position extracting section.

Give the coordinates of point D and also give a hole position calculation command.

At the same time, the slit light is moved upward by the same width α as above. Then, the process returns to step 401. The movement of the slit light in this case is shown in FIG. 5(b).

If the circular hole is not moving, once the state Ll = 12 is found, that state will not collapse even if the slit light is moved up and down by the width α. When the circular hole 5 moves together with the object 4, this state collapses and the process of step 411 or step 12 is performed again, and Ll =
We will pursue the state of becoming 12.

[Effect of the invention 1] As explained in detail above, according to the present invention, the position of a circular object can be recognized three-dimensionally and at high speed without contact using the optical cutting method. Even if you are moving, you can continue to track its center position. If this device is applied to a three-dimensional visual sensor for the robot 1, tasks such as inserting bolts into round holes in objects transported by a conveyor can be easily automated.

[Brief explanation of the drawing]

Fig. 1 is a block diagram illustrating the constituent elements described in the claims, Fig. 2 is a block diagram of an embodiment of the device of the present invention, and Fig. 3 is a diagram illustrating an observation screen by a television camera in the same device. , FIG. 4 is a flowchart h of a processing procedure for finding a pair of two optical cutting lines with equal chord lengths in the same apparatus as described above, and FIG. 5 is a diagram showing the operation of the processing of FIG. 4. 1... Floodlight 2... Slit light 2a...
Light cutting line 2b... Light cutting line image 3... Movable mirror 4... Target 5... Circular hole 6... Camera 10... Calculation section 11... Sweep control section 12
... Hole position calculation unit Fig. 1 Fig. 2 Fig. 3

Claims (1)

[Claims] (1) Irradiate the object with slit light to generate a light cutting line, image the light cutting line with a camera, and
An optical system that uses a light section method to obtain image data that can calculate dimensional shape information, and a slit light beam that irradiates a circular object so that the light section line crosses the circular object, and a string where the light section line intersects with the circular object. The position of a circular object is determined three-dimensionally by a light cutting method characterized by having means for calculating the length, and means for moving the light cutting line to find a pair of two light cutting lines having the same chord length. A device that recognizes