WO2012069664A1

WO2012069664A1 - Glare-free lighting device for the inspection of objects by means of machine vision

Info

Publication number: WO2012069664A1
Application number: PCT/ES2010/070755
Authority: WO
Inventors: José Angel GUTIÉRREZ OLABARRIA; Alfredo Bilbao Martxueta
Original assignee: Fundación Robotiker
Priority date: 2010-11-22
Filing date: 2010-11-22
Publication date: 2012-05-31

Abstract

The invention relates to a glare-free lighting device for the inspection of parts which comprises a torus-shaped light diffusing surface (2d, 3d) corresponding to the inner surface of the casing (1); a casing (3) with a front central opening (4) and a rear central opening (5), concentric with the diffusing surface (2d, 3d); front light sources (19, 20) adjacent to the front central opening (4) and rear light sources (21, 22) adjacent to the rear central opening (5), the front light sources (19,20) being spaced apart from the rear light sources (20, 21) by a lighting segment (B-B) in which an object to be inspected (6) is illuminated, the light sources (19, 20, 21, 22) being arranged concentrically with the diffusing surface (2d, 3d) of the diffusing surface (2d, 3d) and oriented to illuminate the diffusing surface (2d, 2d).

Description

GLOSS-FREE LIGHTING DEVICE FOR INSPECTION OF OBJECTS THROUGH ARTIFICIAL VISION

TECHNICAL FIELD OF THE INVENTION

The present invention falls within the technical field of object inspection systems and, particularly, in the field of lighting systems for the inspection of objects by artificial vision.

BACKGROUND OF THE INVENTION

In the systems of inspection of objects by means of artificial vision, the illumination is of paramount importance since the possible brightness and shadows that can take place based on the geometry and the characteristics of the surface of the object to inspect can distort the quality and accuracy of the images captured by inspection cameras.

One of the most effective lighting systems without glare is called "Cloudy Day lllumination (CDI)", also called dome lighting systems, such as those marketed, for example, by the CDI® system from MICROSCAN (see: http: //www.microscan.eom/en/Products/NERLITE-lluminaci0n-de-Visi0n- Artificial / CDI.aspx) and the DOM2414 system from DCM SYSTEMES (see: http: //www.dcmsistemes.com/dom2414i.html). In the DCI system, uniform diffused light from the same axis of the camera is used to illuminate the object from all directions with diffused light and with high intensity light incident on the object at a very small angle, so that shadows are eliminated and glitters.

To illuminate more or less flat and continuous profiles, lighting and image acquisition systems are known that need to be oriented perpendicular to the surface of the object to be inspected, so that, when the profile moves longitudinally, different sections are obtained with diffuse lighting with the same characteristics due to the impact of light in all directions. In this regard, it is worth mentioning, for example, the article "Wilson, A." Novel lllumination - Innovative LED lighting producís are putting machine vision in a new light "; Vision Systems, vol. 15: edition 1, January 2010 (OptolQ)" , accessible at http: // www. optoiq .com / i ndex / mach i ne- vision-imaqinq-processinq / displav / vsd-article-displav / 4263394089 / articles / vision- svstems-desiqn / volume-15 / issue-1 / feature / novel-illumination.html.

When the surface of the object to be analyzed is not flat but has geometric characteristics that present surfaces in several planes, conventional lighting systems lose effectiveness. Thus, in the case of metal profiles or "bars" of varied shapes and geometries (in terms of cross section), such as circular, square, hexagonal sections, etc., with conventional lighting systems only illuminates correctly one of the surfaces, while the rest of the surfaces, that is, the surfaces that are not arranged perpendicularly to the lighting, are worse illuminated, since the dispersion of the light rays causes reflections and / or areas of shadow.

To avoid these negative effects, it is necessary to either rotate the profile and capture the images in each rotated position, or to arrange in series various lighting systems and image acquisition oriented each so that it is arranged perpendicularly to one of the surfaces of the profile. Both solutions are not satisfactory, since the first requires that the profile to be inspected has to go through the system several times, which requires excessive time, and the second requires the presence of several lighting systems and adjustable image acquisition, which is expensive.

It was, therefore, desirable to obtain a lighting system that would avoid the inconvenience of the state of the art and that would allow a single lighting system to produce uniform diffuse lighting regardless of the geometry of the object to be analyzed, that is to say independently of the geometry of the cross section of the object, such as, for example, a bar or a metal profile, which is inspected.

DESCRIPTION OF THE INVENTION

The object of the present invention is to overcome the drawbacks of the state of the art detailed above, by means of a brightness-free lighting device for the inspection of objects by artificial vision, which comprises a dome lighting system with a plurality of light sources, a diffusing surface of light that reflects light emitted by the light sources to illuminate with diffuse uniform light an object to be inspected, the light sources and the diffusing surface being located in the housing with a front opening and rear opening; That characterized because

the light diffusing surface has a substantially toroidal shape with a geometric axis of revolution;

the front opening is a front central opening, and the rear opening is a rear central opening, said central openings being substantially concentric with the diffusing surface;

the light sources comprise front light sources adjacent to the front central opening and rear light sources adjacent to the rear central opening, the front light sources being distanced from the rear light sources by a lighting section in which the object to be inspected is illuminated;

the light sources are arranged concentrically with the diffusing surface and oriented to illuminate the diffusing surface;

it comprises means for arranging at least one vision camera, and preferably several vision cameras that focus on the object to be inspected from equidistant angular positions, being able, for example, to have four vision cameras arranged by couples that focus on the object to be inspected from diagonal positions opposite.

The means for arranging the vision cameras may comprise, for example, side tubes that flow into respective side holes in the diffuser surface. The side holes can be sealed respectively by a transparent material and / or by a semi-mirror

According to the invention, the diffuser surface may have, in its outer part, a vertical semicircle cross section! or parabolic, and a semi-circular horizontal cross section! or parabolic In turn, the light sources, which can be light emitting diodes (LEDs), can comprise at least one row of front light sources and at least one row of rear light sources. In a preferred embodiment, the light sources comprise at least two rows of front light sources and a! minus two rows of back light sources. These rows of light sources can be arranged annularly around the geometric axis of revolution of the diffuser surface.

Preferably, the housing has a hollow toroid shape whose geometric axis of revolution coincides with the geometric axis of revolution of the diffuser surface. In one embodiment of the invention, the front light sources may be arranged in a front portal light element comprising a clamping part coupled to the housing around the front central opening and a light part part on whose external face the front light sources are arranged. On the other hand, the rear light sources can be arranged in a rear portauminary element comprising a clamping part coupled to the housing around the rear central opening and a portal part on whose external face the rear light sources are arranged. In this embodiment, the housing may comprise a front annular section surrounding the front central opening, and a rear annular section surrounding the rear central opening. These annular sections are flat at least on their side directed inside the housing. The clamping part of the front carrier element is coupled to the front annular section, while the clamping part of the rear carrier element is coupled to the rear annular segment.

According to a particular embodiment of the invention, the housing may comprise a first half with an internal dome-shaped surface, and a second half with a second internal dome-shaped surface, the halves being joined by their respective bases. In this embodiment, the front central opening is composed of two complementary front recesses provided in the respective front edges of the bases the halves of the housing. In turn, the rear central opening consists of two complementary rear entrances provided on the respective rear edges of the bases, the halves of the housing, while the diffusing surface is formed by the domes formed by said internal surfaces.

According to this particular embodiment, the front portauminary element may comprise a first front carrier element coupled to the first half of the housing bordering the front recess of said first half, and a second front carrier element coupled to the second half of the housing bordering the recess front of said second half of the housing. In turn, the rear portauminary element in this case comprises a first rear carrier element coupled to the first half of the housing bordering the rear inlet of said first half, and a second rear carrier element coupled to the second half of the housing bordering the rear recess of said second half.

Also, in this particular embodiment, the front annular portion may be composed of a first front arcuate section that borders the front recess in said first half of the housing and a second front arcuate section that borders on the front recess in said second half of the housing, while the rear annular section is composed of a first section rear arc that borders the rear recess in said first half of the housing and a second rear arcuate section that borders in rear recess in said second half of the housing. In this way, the fastening part of the first front bearer element can be coupled to said first front arcuate section, the fastening part of the second front bearer element to said second frontal arcuate section, the fastening part of the first rear bearer element to said first rear arcuate section, and the securing part of the second front carrier element to said second rear arcuate section.

As it can be seen, the present invention achieves its object by means of a device of simple structure and of easy use, which allows to effectively illuminate objects to be inspected, such as for example bars or profiles, of different cross sections.

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Aspects and embodiments of the invention are described below on the basis of schematic drawings, in which

Figure 1 is a partially sectioned front elevational view of an embodiment of an image capture device incorporating an embodiment of the lighting system according to the present invention;

Figure 2 is a partially sectioned side elevation view of the device shown in Figure 1;

Figure 3 is a partially sectioned side-side perspective view of the device shown in Figure 1;

Figure 4 is an antero-lateral perspective view of the device shown in Figure 1 partially disassembled;

Figure 5 is an antero-lateral perspective view of the components that make up the upper half of the device shown in Figure 1.

In these figures numerical references appear that identify the following elements: 1 C3. C3.SH

2 first half of the housing

2nd flange of the first half

2b flat arched section of the first half of the housing

2c flat arched rear section of the first half of the housing

2d internal surface of the first half of the

3 second half of the housing

3rd flange of the second half of the housing

3b flat arched front section of the second half of the housing

3c flat arched rear section of the second half of the housing

3d internal surface of the second half of the

Case

4 front center opening

4a, 4b front entrances

5 rear center opening

5a, 5b rear incoming

6 profile to inspect

7, 8, 9, 10 side tube

1 1, 12, 13, 14 vision camera

15th 16th, 17th, 18th part is clamped

15b, 16b, 17b, 18b luminaire part

19, 20, 21, 22 light sources

MODES OF CARRYING OUT THE INVENTION

In the embodiment shown in the figures, the lighting system comprises a -1-hollow housing composed of two halves -2, 3- symmetrical. The two halves -2, 3- of the housing -1 - are joined by flanges -2a, 3a- that emerge from their respective free edges facing each other. On its front side and on its rear side, the housing -1 - respectively comprises a front central opening -4- and an axially aligned rear central opening -5-, through which a profile to be inspected can move axially -6- passing through the inside of the housing -1 -. On the other hand, on the lateral periphery of the housing -1 - there are four lateral tubes -7, 8, 9, 10- arranged in pairs in diagonally opposite locations, and leading into the interior of the housing -1 - through of two side holes. On the side tubes -7, 8, 9, 10- are installed two vision cameras -1 1, 12, 13, 14- that focus inside the housing -1 - to capture images of the profile to be inspected -6-.

In the embodiment shown in the figures, the two halves -2, 3- of which the housing -1 is composed, form a set of two symmetrical domes, with an annular frontal plane section -2b, 3b- surrounding the opening front center -4-, and a flat rear annular section -2c, 3c- that surrounds the rear central opening -5-. The central front opening -4- is composed of two front recesses -4a, 4b- semicircular respectfully provided for the respective front edges of the first half -2- and the second half -3- of the housing -1 -, while opening rear center -5- is composed of two front recesses -5a, 5b- semicircular provided respectfully at the rear edges of the first half -2- and the second half -3- of the housing -1 -. In turn, each flat annular section -2b, 3b; 2c, 3c- consists of an arcuate flat section -2b, 2c- of the first half -2- and an arcuate flat section -3b, 3c- of the second half of the housing 1.

On each arched flat section -2b, 3b, 2c, 3c- a carrier element -15a, 15b, 16a, 16b, 17a, 17b, 18a, 18b- of light sources -19, 20, 21, 22- is mounted. Each carrier element - comprises a part that is held -15a, 16a, 17a, 18a- attached and attached to one of the respective arcuate flat sections -2b, 2c, 3b. 3c- by screws (not shown in the figures) that pass through respective through holes aligned in the holding part -15a, 16a, 17a, 18a- and in the arched flat section -2b, 3b; 2c, 3c- to which it is attached, and a luminaire holder part -15b, 16b, 17b, 18b- that extends perpendicularly horizontally from the outer edge of the clamping part -15a, 16a, 17a, 18a-. On the outer face of each luminaire -15b, 16b, 17b, 18b- the light sources -19, 20, 21, 22- are arranged uniformly in the form of light emitting diodes (LEDs).

Each of the respective internal surfaces -2d, 3d- of halves -2, 3- of the housing -1 - has a domed interior contour substantially in the form of dome, and is internally coated with a conventional light diffuser coating, such as paint or other matt white material. The respective domes are faced so that their internal surfaces -2d, 3d- form a light diffusing surface so that it has a substantially toroidal shape, which envelops the profile to be inspected -6-, and that has a geometric axis of revolution

A-A The curvatures of the light diffusing surface and the positions of the light sources -19, 20, 21, 22- are designed so that the light emitted by the light sources -19, 20, 21, 22- is reflected and blurred such that it illuminates the profile to be inspected -6- on all its sides without glare and shadow areas that could negatively interfere with the image capture of the profile -6- by the vision cameras -1 1, 12, 13-14- . For this, the light sources are arranged concentrically with the diffuser surface -2d, 3d- with respect to the geometric axis of revolution A-A of the diffuser surface -2d, 3d-.

Claims

1. Glitter-free lighting device for the inspection of objects by artificial vision, comprising a dome lighting system with a plurality of light sources, a light diffusing surface that reflects light emitted by the light sources to illuminate with uniform diffused light an object to be inspected, the light sources and the diffusing surface being located in the housing with a front opening and rear opening; characterized because

the diffusing surface (2d, 3d) of light has a substantially toroidal shape with a geometric axis of revolution (A-A);

the front opening is a front central opening (4), and the rear opening is a rear central opening (5), said central openings (4, 5) being substantially concentric with the diffusing surface (2d, 3d);

the light sources comprise front light sources (19, 20) adjacent to the front central opening (4) and rear light sources (21, 22) adjacent to the rear central opening (5), the front light sources being distanced (19, 20 ) of the rear light sources (20, 21) by a lighting section (BB) in which the object to be inspected is illuminated (6);

the light sources (19, 20, 21, 22) are arranged concentrically with the diffusing surface (2d, 3d) and oriented to illuminate the diffusing surface (2d, 2d); it comprises means (7, 8, 9, 10) for arranging at least one vision camera (1 1, 12, 13, 14).

2. Lighting device according to claim 1, characterized in that the housing (1) has a hollow toroid shape whose geometric axis of revolution coincides with the geometric axis of revolution (A-A) of the diffuser surface (2d, 3d).

3. Lighting device according to claim 1 or 2, characterized in that the light sources (19, 20, 21, 22) comprise at least one row of front light sources (19, 20) and at least one row of rear light sources (20, 21), said rows of light sources (19, 20, 21, 22) being arranged annularly around the geometric axis of revolution (AA) of the diffusing surface (2d, 3d).

4. Lighting device according to claim 1, 2 or 3, characterized in that the light sources (19, 20, 21, 22) are light emitting diodes.

5. Lighting device according to one of the preceding claims, characterized in that the diffuser surface (2d, 3d) has a semi-circular vertical cross-section! on the outside

6. Lighting device according to one of claims 1 to 4, characterized in that the diffuser surface has a parabolic vertical cross-section in its outer part.

7. Lighting device according to one of the preceding claims, characterized in that the diffusing surface (2d, 3d) has a semi-circular horizontal cross-section! on the outside

8. Lighting device according to one of claims 1 to 6, characterized in that the diffusing surface (2d, 3d) has a parabolic horizontal cross-section in its outer part.

9. Lighting device according to one of the preceding claims, characterized in that the front light sources (19, 20) are arranged in a front portal light element (15a, 15b, 16a, 16b) comprising a clamping part (15a, 16a ) coupled to the housing (1) around the central front opening (4) and a portal part (15b, 16b) on whose outer face the front light sources (19, 20), and the rear light sources (21, 22) are arranged in a rear portauminary element (17a, 17b. 18a. 18b) comprising a clamping part (17a, 18a) coupled to the housing (1) around the central rear opening (5) and a portauminary part ( 17b, 18b) on whose outer face the rear light sources (20, 21) are arranged.

10. Lighting device according to claim 9, characterized in that

the housing (1) comprises a front annular section (2b, 3b) that surrounds the front central opening (4), and a rear annular section (2c, 3c) that surrounds the rear central opening (5);

said annular sections (2b, 3b, 2c, 3c) are flat a! less on its directed side inside the housing (1);

the clamping part (15a, 16a) of the front carrier element (15a, 15b, 16a, 16b) is coupled to the front annular section (2b, 3b), and the clamping part (17a, 18a) of the rear carrier element (17a , 17b, 18a, 18b) is coupled to the rear annular section (2c, 3c).

eleven . Lighting device according to one of claims 1 to 8, characterized in that

the housing (1) comprises a first half (2) with an internal surface (2d) in the form of a dome, and a second half (3) with a second internal surface (3d) in the form of a dome, the halves (2, 3) united by their respective bases; the central front opening (4) consists of two complementary front recesses (4a, 4b) provided on the respective front edges of the bases, the halves (2, 3) of the housing (1);

the central rear opening (4) consists of two rear entrances (5a,

5b) complementary to the halves (2, 3) of the housing (1) provided on the respective rear edges of the bases;

the diffuser surface (2d, 3d) is formed by the domes formed by said internal surfaces.

12. Lighting device according to claim 1, characterized in that

the front light sources (19, 20) are arranged in a front portal light element (15a, 15b, 16a, 16b) comprising a clamping part (15a, 16a) coupled to the housing (1) around the central front opening ( 4) and a portaluminary part (15b, 16b) in which the front light sources (19, 20) are arranged, and the rear light sources (21, 22) are arranged in a rear portauminary element (17a, 17b, 18a, 18b) comprising a clamping part (17a, 18a) coupled to the housing (1) around the rear central opening (5) and a portal-part part (17b, 18b) in which the rear light sources (20, twenty-one );

the front portauminary element comprises a first front carrier element (15a, 15b) coupled to the first half (2) of the housing (1) bordering the front recess (4a) of said first half (2), and a second front carrier element (16a, 16b) coupled to the second half (3) of the housing (1) bordering the front inlet (4b) of said second half (3)

The rear mining portal element comprises a first rear carrier element (17a, 17b) fitted to the first half (2) of the housing (1) bordering the rear recess (5a) of said first half (2), and a second carrier element rear (18a, 18b) coupled to the second half (3) of the housing (1) bordering the rear inlet (5b) of said second half (3).

13. Lighting device according to claim 12, characterized in that

said annular sections (2b, 3b, 2c, 3c) are flat at least on their side directed to the inside of the housing (1);

the front annular section (2b, 3b) is composed of a first arched front section (2b) that borders the front recess (4a) in said first half (2) of the housing

(1) and a second front arcuate section (3b) that borders on the front recess (4b) in said second half (3) of the housing (1);

the rear annular section (2c, 3c) is composed of a first rear arcuate section (2c) that borders the rear recess (5a) in said first half (2) of the housing (1) and a second rear arcuate section (3c) bordering on back incoming

(5b) in said second half (3) of the housing (1);

the holding part (15a) of the first front carrier element (15a, 15b) is coupled to said first front arcuate section (2b);

the holding part (16a) of the second front carrier element (16a, 16b) is coupled to said second front arcuate section (3b);

the holding part (17a) of the first rear carrier element (17a, 17b) is coupled to said first rear arcuate section (3b);

the holding part (18a) of the second front carrier element (18a, 18b) is coupled to said second rear arcuate section (3c).

14. Lighting device according to one of the preceding claims, characterized in that it comprises means (7, 8, 9, 10) for arranging four vision cameras (1 1, 12, 13, 14) arranged in pairs that focus on the object to inspect (6) from diagonally opposite positions.

15. Lighting device according to one of the preceding claims, characterized in that the means (7, 8, 9, 10) for arranging the vision cameras (1 1, 12. 13, 14) comprise side tubes (7, 8, 9, 10) that flow into respective side holes in the diffuser surface (2d, 3d).

16. Lighting device according to claim 15, characterized in that the side holes are respectively sealed by a transparent material and / or by a semi-mirror.

17. Lighting device according to one of the preceding claims, characterized in that it comprises means (7, 8, 9, 10) for arranging a plurality of vision cameras (1 1, 12, 13, 14) that focus on the object to be inspected (6) from equidistant angular positions.