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WO2021176386A1 - Procédé et systèmes de détection et de classification de défauts sur des surfaces - Google Patents

Procédé et systèmes de détection et de classification de défauts sur des surfaces Download PDF

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Publication number
WO2021176386A1
WO2021176386A1 PCT/IB2021/051798 IB2021051798W WO2021176386A1 WO 2021176386 A1 WO2021176386 A1 WO 2021176386A1 IB 2021051798 W IB2021051798 W IB 2021051798W WO 2021176386 A1 WO2021176386 A1 WO 2021176386A1
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WO
WIPO (PCT)
Prior art keywords
head
defects
resolution
heads
scanning
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2021/051798
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English (en)
Inventor
Daniel RASPONE
Marco Piloni
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Geico SpA
Original Assignee
Geico SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Geico SpA filed Critical Geico SpA
Publication of WO2021176386A1 publication Critical patent/WO2021176386A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8806—Specially adapted optical and illumination features

Definitions

  • the present invention relates to a method and to systems for the detection and classification (or cataloguing) of defects on complex surfaces, such as motor vehicle bodies.
  • the defects to be detected may be for example appearance defects on painted surfaces.
  • the defects present on the painted surfaces often have a three-dimensional character, i.e. are not simply local variations in colour, but are bumps, missing material or in any case irregularities on the surface.
  • the spatial surfaces to be scanned are defined as being "complex” since they may be a combination of concave surfaces and convex surfaces, both also with variable radii of curvature and with the presence of cusps and curvilinear lines connecting lines the different parts which form the said surface.
  • a motor vehicle body may be regarded as being a complex surface since it has the aforementioned characteristics.
  • the localization of the defects on a complex surface is a fundamental step of the industrial process since it allows the tracing and any correction of the appearance defects of the product which may be noticed by the end user and which often are regarded as being an indication of the quality of the entire product.
  • the scanning head which produces the images to be processed by the detection programs, to have a relatively high spatial resolution.
  • the spatial resolution required the area recorded by the head must be however necessarily very small and the head is moved along the surface in order to examine it completely.
  • the image processing speed (and generally the speed of displacement of the head on the surface) is relatively low.
  • the object of the present invention is to provide a method and systems for detection and classification of defects on surfaces, including large-area surfaces, such as motor vehicle bodies, which are fast and reliable.
  • the idea which has occurred is to provide, according to the invention, a method for the automatic detection and classification of defects on the surface of an object, comprising: a first defect detection step during which a first scanning head for taking images at a first resolution is moved along scanning paths on the surface of the object, defects on the surfaces are located in the images taken by the first scanning head and the position of the defects is detected; and a second defect classification step during which a second scanning head for taking images at a second resolution, higher than the first resolution, is moved to the positions of the defects detected in the first step and the defects are classified on the basis of the images taken by the second scanning head.
  • the idea which has occurred is to provide a system for the automatic detection and classification of defects on the surface of an object according to the above method, comprising the first scanning head for taking images at the first resolution; the second scanning head for taking images at the second resolution; at least one motorized positioner for moving and positioning the heads on the surfaces; at least one electronic control and processing unit connected to the heads and to the positioner for receiving the images taken by the heads and moving the heads on the surfaces of the object.
  • FIG. 1 shows a schematic view of a first defect detection system according to the invention
  • FIG. 2 shows a schematic side elevation view of a possible embodiment of two scanning heads in a system according to the invention
  • Figure 3 shows a schematic plan view of the scanning heads according to Figure 2;
  • FIG. 4 shows a schematic perspective view of a second embodiment of a defect detection system according to the invention
  • FIG. 5 shows a schematic perspective view of a third embodiment of a defect detection system according to the invention.
  • Figure 1 shows a system, denoted overall by 10, provided in accordance with the invention for detecting surface defects on an object 11 , for example the painted body of a motor vehicle.
  • the surface defects may for example comprise bubbles, dimples, scratches, possible missing paint, inclusions in the paint of foreign bodies (threads, powder, etc.), and so on.
  • the system 10 may also comprise a known transportation system 12 which conveys in sequence the objects 11 to be analysed.
  • the transportation system may be a conveyor for example.
  • the transportation system 12 may be a known conveyor of the skid type where the bodies are mounted on known skids.
  • the system 10 comprises a first scanning head 13a and a second scanning head 13b which are moved so as to follow suitable paths 14 (one of which is shown by way of example in Figure 1) and suitably travel along the surfaces 15 of the object 11 on which the possible defects are to be detected.
  • the two heads 13a and 13b are both moved by a suitable motorized positioner 16 which may be advantageously a robot suitably programmed to move automatically the head along the said paths above the surfaces of the object 11.
  • the robot 16 may be advantageously a known anthropomorphic robot arm, for example with six axes controllable in an interpolated manner, with both heads 13a and 13b mounted on the wrist 17 of the robot.
  • the head 13a is an image recording head which has a first resolution
  • the head 13b is an image recording head which has a second resolution greater than the first head.
  • the first resolution may be chosen so as to allow detection of the presence of a defect in a certain position on the surface, although not with a high degree of precision, and without precise classification of the defect.
  • the second resolution instead will be chosen relatively high so as allow classification of the defects.
  • the resolution may be divided into optical resolution due also to the lenses of the camera and resolution of the sensor (allowing the definition also of that which is actually acquired).
  • the first optical resolution may be between 5 mm/pixel and 0.1 micron/pixel and preferably around 0.1 mm/pixel.
  • the first resolution of the sensor may be advantageously between 0.25 and 70 megapixels and, preferably, around 5 megapixels.
  • the second optical resolution may be between 2 mm/pixel and 0.01 mm/pixel and, preferably, around 15 micron/pixel.
  • the second resolution of the sensor may be preferably between 512 and 16,384 pixels/line and, preferably, around 7142 pixels/line.
  • the first head 13a may be chosen, also depending on its smaller resolution, so as to have a recording area greater than the recording area of the second head.
  • the recording area of the first head may be between 5 and 100,000 times, advantageously around 1800 times (preferably around 1850 times), the recording area of the second head.
  • each head will comprise a suitable known acquisition unit (for example a camera).
  • the heads may also comprise known illumination systems for suitably illuminating the recorded area.
  • At least the second head may advantageously comprise a known stereoscopic camera so as to supply three-dimensional images to the system for processing and cataloguing the defects. This allows easier classification of the defects which result in variations in height of the surface, with a greater distinction for example between projecting bubbles and dimples in the painted surface.
  • a suitable electronic control unit 41 controls the movement of the heads along the scanning paths, by means of the positioner 16, in a manner synchronized with the acquisition of the images by the heads, such that the images which in each case are recorded by the head may be added together to form broader images of the surfaces.
  • the heads 13a and 13b may be designed so as to form linear image acquisition units, namely acquisition units formed by light sensors located substantially along a single line, so as to obtain along their optical axis, or the viewing direction of the head, an image which is formed essentially by a recording segment 18a, 18b (namely an image with a very limited amplitude in the direction of movement of the head along the path). Scanning of the surfaces 15 of the object 11 will therefore be performed in this case by recording segments 18 which are parallel to each other and transverse to the movement path of the head.
  • the parallel recording segments 18a or 18b which in each case are acquired by the scanning head 13a or 13b owing to a relative movement of head and surface to be scanned, transverse to the recording segments, thus compose the images of the surface as the sum of the single recording segments.
  • Suitable linear cameras to be inserted in heads are for example known per se.
  • Figures 2 and 3 shows by way of example two heads 13a and 13b mounted on a single support 19 so as to be moved simultaneously by the positioner 16.
  • the heads may be mounted on the support 19 with divergent viewing directions 29a and 29b. During use, the heads may therefore be directed alternately with their viewing direction towards and perpendicular to the surface 15 so as to follow the desired paths 14 and be used alternately to scan these surfaces and obtain the desired images thereof.
  • FIG. 3 also shows the possible different recording segments 18a and 18b of the two heads 13a and 13b realized by means of linear image acquisition units.
  • the control unit 41 may also perform processing of the images using methods (known per se and therefore not shown or described in detail here since they may be easily imagined by the person skilled in the art) which will allow automatic identification of the defects on the surfaces 15 in the recorded images and if necessary classification thereof, with the degree of precision permitted by the resolution of the images produced by the heads.
  • the system 41 will cause the movement of the positioner 16 so as to perform a first scan of the surfaces 15 by means of the first head 13a.
  • the unit 41 will thus identify (using the image processing process known per se) the existence of any defects on the visible surfaces in the images produced by the head 13a. For each defect identified, the unit 41 will detect the spatial coordinates of the defect on the surface so as to be able to find it again.
  • the unit 41 will carry out a second scanning step for classification of the defects. During this second scanning step, the unit 41 will use the second scanning head 13b, operating it so that it directly scans the surfaces at the coordinates of the defects detected during the first scanning step.
  • the first step involving the scanning of the entire surfaces 15 will be faster than if it were carried out with a head having the resolution characteristics - and where applicable recording range - of the second head.
  • the second head must carry out the scanning only of the zones of the surfaces with the defects already detected during the first step.
  • the second head which is slower owing to the higher resolution and where applicable the smaller recording range, must examine only small zones of the surfaces where a defect has already been detected so as to be to classify it (using the classification methods known per se) owing to its higher resolution.
  • the second head owing to its higher resolution, may also refine the detection of the position of the defect based on the defect coordinates obtained by means of the first head.
  • the system according to the invention therefore rapidly provides both the precise position of the defects and their classification. This information may then be passed to known manual, automatic or semi-automatic defect processing systems, as known in the sector.
  • Figure 4 shows a first variation of embodiment of a system for the detection and classification of defects according to the invention.
  • this variant denoted overall by 110, there are again the two heads 13a and 13b as described above, but these heads are each supported by associated positioners, respectively indicated by 16a and 16b (which may be essentially of the same type as the positioner 16 of the preceding embodiment).
  • control unit 41 may move in a substantially simultaneous and independent manner the two heads over the surface 15. If required, the two scanning steps, for detecting the defects and classifying the defects, respectively, may thus be carried in a parallel or semi-parallel manner.
  • the control unit 41 detects defects by means of the first head
  • the second head may be operated so as to classify the defects, while the first head detects further defects, and so on. This speeds up even more the overall defect detection and classification operations.
  • Figure 5 shows a second variation of embodiment of a system for the detection and classification of defects according to the invention.
  • this variant denoted overall by 210, there are again the two heads 13a and 13b as described above, but these heads are each supported by associated positioners, respectively indicated by 16a and 16b, and located in different scanning stations 50 and 51 into which the objects 11 are conveyed in sequence.
  • the first station 50 therefore constitutes a station for automatic detection of the defects
  • the second station 51 constitutes a station for automatic classification of the defects detected in the first station.
  • control unit 41 may move in a substantially simultaneous and independent manner the two heads over the surfaces 15 also on different objects in the two stations.
  • the defect detection step performed in the station 50 on a following object may thus be carried out in parallel with the defect classification step performed in the station 51 on a preceding object which has already passed through the station 50 for identification of the position of the defects.
  • the total time of the detection and classification cycle carried out on a continuous sequence of objects (such as motor vehicle bodies in a processing and painting plant) will therefore be substantially shorter.
  • the heads may have a form and/or proportions different from those shown, depending for example on the nature of the cameras and the illumination devices used to form them and/or the configuration and area of the surfaces to be scanned.
  • the head may have a square form in plan view, instead of a rectangular one, and may also have dimensions smaller than those shown in the drawings, so as to inspect for example surfaces which are smaller, with a greater concavity or within confined spaces.
  • the recording segment of the camera (and therefore of the head) may also be more or less long depending on the extension of the surfaces and the desired scanning speed.
  • the two heads may also be mounted inside the same housing.
  • heads with several cameras and/or several illumination devices so as to obtain recording areas or segments which are bigger or smaller depending on the specific requirements.
  • a positioner for the head different from that shown and described by way of example may be used.
  • a Cartesian positioner or a gantry could be used, depending also on the geometrical form of the object to be scanned.
  • the control unit 41 may also be divided up or comprise a defect detection unit and a defect classification unit, with the former which passes on the defect coordinates to the latter, as may be now easily imagined by the person skilled in the art on the basis of the description provided above.
  • each station may comprise an associated control unit with the processing of the images provided by the corresponding head and the movement of this head.
  • the control unit of the defect detection station may thus simply pass on the defect coordinates to the control unit of the classification station.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

L'invention concerne un procédé de détection et de classification automatiques de défauts sur la surface (15) d'un objet (11) comprenant une première étape et une seconde étape. La première étape consiste à détecter les défauts et au cours de cette étape, une première tête de balayage (13a) permettant de capturer des images à une première résolution est déplacée le long de trajectoires de balayage sur la surface de l'objet, des défauts sur les surfaces sont situés dans les images capturées par la première tête de balayage (13a) et la position des défauts est identifiée. La seconde étape consiste à classifier les défauts et au cours de cette étape, une seconde tête de balayage (13a) permettant de capturer des images à une seconde résolution, supérieure à la première résolution, est déplacée vers les positions des défauts détectés au cours de la première étape et les défauts sont classifiés en fonction des images capturées par la seconde tête de balayage (13b).
PCT/IB2021/051798 2020-03-06 2021-03-04 Procédé et systèmes de détection et de classification de défauts sur des surfaces Ceased WO2021176386A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102020000004783A IT202000004783A1 (it) 2020-03-06 2020-03-06 Metodo e sistemi per la rilevazione e classificazione di difetti su superfici
IT102020000004783 2020-03-06

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WO2021176386A1 true WO2021176386A1 (fr) 2021-09-10

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IT (1) IT202000004783A1 (fr)
WO (1) WO2021176386A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114118266A (zh) * 2021-11-24 2022-03-01 华侨大学 一种表面含砂浆的再生骨料的视觉检测分类方法和系统

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000002037A1 (fr) * 1998-07-07 2000-01-13 Applied Materials, Inc. Procede et dispositif permettant de detecter au niveau du pixel les defauts des plaquettes gravees
US6271916B1 (en) * 1994-03-24 2001-08-07 Kla-Tencor Corporation Process and assembly for non-destructive surface inspections
US6710868B2 (en) * 2002-05-22 2004-03-23 Applied Materials, Inc. Optical inspection system with dual detection heads
US20050219519A1 (en) * 2004-03-30 2005-10-06 Harding Kevin G Multi-resolution inspection system and method of operating same
US20190272630A1 (en) * 2018-03-05 2019-09-05 Omron Corporation Image inspecting apparatus, image inspecting method and image inspecting program
WO2019239307A1 (fr) * 2018-06-12 2019-12-19 Geico Spa Procédé et installation de localisation de points sur une surface complexe dans l'espace

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6271916B1 (en) * 1994-03-24 2001-08-07 Kla-Tencor Corporation Process and assembly for non-destructive surface inspections
WO2000002037A1 (fr) * 1998-07-07 2000-01-13 Applied Materials, Inc. Procede et dispositif permettant de detecter au niveau du pixel les defauts des plaquettes gravees
US6710868B2 (en) * 2002-05-22 2004-03-23 Applied Materials, Inc. Optical inspection system with dual detection heads
US20050219519A1 (en) * 2004-03-30 2005-10-06 Harding Kevin G Multi-resolution inspection system and method of operating same
US20190272630A1 (en) * 2018-03-05 2019-09-05 Omron Corporation Image inspecting apparatus, image inspecting method and image inspecting program
WO2019239307A1 (fr) * 2018-06-12 2019-12-19 Geico Spa Procédé et installation de localisation de points sur une surface complexe dans l'espace

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114118266A (zh) * 2021-11-24 2022-03-01 华侨大学 一种表面含砂浆的再生骨料的视觉检测分类方法和系统

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