DE102017221649A1 - Test method for detecting surface defects on matt and shiny surfaces and associated device and test arrangement between the device and component - Google Patents

Abstract

The invention relates to a method for optical shape detection and / or surface inspection of a component (B _n ), in particular based on the method of shape-from-shading with the following steps: arranging at least one camera (K0), at least one illumination element (101B ) and the component (Bn) in a test arrangement such that at least one region of a component surface corresponding to at least one measurement region (Mn) is illuminated by the at least one illumination element (101B), - capturing a measurement region image sequence by means of the camera (K0 ) in a plurality of measuring areas (M _n ) by a movement of the camera (K0) relative to the component (B _n ) or vice versa, wherein the measuring areas (M _n ) of the component surface (3) imaged in an image plane of the camera (K) and simultaneously the images of the measuring range image sequence are illuminated with the at least one lighting element (101B) in an associated lighting process (L _n ), - Auswe of the recorded images of the measuring range image sequence in at least one of the plurality of measuring regions (M _n ) of the component surface with regard to a changed local surface inclination and / or local optical properties of the component surface.
It is provided that the movement of the camera (K0) and the at least one illumination element, which are arranged together in a test head according to the invention, are carried out continuously with respect to the component (B _n ) or vice versa when recording the measuring range image sequence.

Description

The invention relates to a method for optical shape detection and / or surface inspection of a component, in particular based on the method of shape-from-shading, and an associated device and a test arrangement between the device and the component.

Depending on the various surface testing tasks, special solutions are always developed for the testing of surfaces, which are tailored exactly to the test task. For example, technical solutions are developed at great expense which are suitable for different surface properties, such as, for example, reflective surfaces (painted surface) or matt surfaces.

Known methods include deflectometry, stereometry and the so-called shape-from-shading with static structure. Shape-from-shading techniques determine changes in slope or even flat structures (low valleys, slight elevations with low slopes). In this case, slight changes in the reflected light intensity are evaluated in order to close the known inclination of the reflective areas with a known geometrical arrangement between camera, object and light source.

Due to the process, deflectometry can only be used to test reflective surfaces, such as painted surfaces.

Previously known approaches of the shape-from-shading method are widely known only for matte, not used for reflective surfaces.

The publication WO 2004/051186 A1 ( EP 1 567 827 B1 ) discloses a method for optical shape detection and / or evaluation of optically smooth, shiny or optically rough surfaces. The method is characterized in that a photometric stereo method, a reflectometric method and a diffuser are combined so that the locations on the scatterer surface area code become.

The document is known DE 203 17 095 U1 comprising an apparatus for detecting defects of an object surface of an object, comprising a light source for illuminating the object with an illuminating beam incident on the object at an angle of incidence to the surface; a light detector for detecting a beam reflected from the object surface onto the exposure beam, which is reflected from the object at an angle of reflection to the object surface, the angle of departure being equal to the angle of incidence to obtain image data; and an evaluation device for evaluating the image data in order to detect possible errors. The finding is that a very high-contrast imaging of an object surface and thus a facilitated and / or reliable evaluation of the image data to detect surface defects, is possible if the illumination device and detection device are arranged to the surface to be tested such that the angle of incidence of the illumination beam to the surface at the same angle as the detection beam is inclined to the surface, that is, the gloss angle condition is satisfied, since then a very high-contrast image is obtained, in which faulty of defect-free surface sites differ greatly in their brightness.

The publication DE 10 2004 038 761 A1 relates to a camera-based examination of an object which is illuminated by at least one light source. In this case, an object illuminated by a light source is detected with a camera and the image data is subjected to image processing. The processing uses the method of shape-from-shading, in which the reconstruction of the object surface is done by minimizing a cost function. In order to avoid unwanted reflections on edges and surfaces of the object, not the entire object is illuminated by the light source, but only parts of it. The image areas to be processed are selected in size such that the cost function of the shape-from-shading could be optimally adapted to the desired geometry within these image areas, if the object in this area corresponded to the desired geometry. Alternatively, however, interpolation point values can also be predefined within the image areas in such a way that the cost function of the shape-from-shading is subdivided into discrete sections during guidance through these interpolation points so that they can be optimally adapted to the desired geometry, if that Object in these areas corresponds to the target geometry.

In addition, the publication EP 1 949 673 B1 which describes a method for capturing a number of images of an object in a short time sequence with at least one camera using at least three different phase positions of a structured illumination, namely a fringe pattern or an interference pattern, wherein the phase positions are operated spatially next to each other, wherein the Object is moved relative to the structured illumination, so that a certain feature of the object comes to lie at different times in the different phase angles of the structured illumination, wherein a speed of movement of the Item and / or a time of readout processes is / are chosen so that the test object moves between two readout processes by a pixel pitch or a multiple thereof, and that for each phase position in which the feature comes to lie, the same number of lines of the camera chip is read out, wherein for each phase position in which the feature comes to lie, only a portion of the camera chip is read out, namely as many lines of the camera chip, how to record images with different phase angles or a multiple thereof, and the short temporal sequence short is compared to a temporal sequence that can be achieved by reading all lines of the camera chip.

Also known is a in the document EP 1 864 081 B1 described, also based on a hemisphere illumination system, wherein the hemisphere is designed as a completely opaque scattering body and thus serves exclusively as a reflector, which is used for optical shape measurement and / or optical inspection of objects. The illumination system comprises at least one camera, at least one objective, the opaque scattering body (hemisphere) with at least two light sources arranged inside the scattering body, wherein an inside of the scattering body is illuminated by one or more light sources which can be switched individually or in groups independently of one another such that the at least two light sources are placed outside the center of the scattering body so that the inside of the scattering body along a line extending from a point of the equator of the scatterer toward the north pole and further to an opposite point of the equator with steadily increasing or continuous falling illuminance is illuminated when at least one of the light sources is turned on.

The publication EP 1 949 673 B1 describes a method for capturing a number of images of an object in a short temporal sequence with at least one camera using at least three different phase positions of a structured illumination, namely a stripe pattern or an interference pattern, wherein the phase positions are operated spatially next to each other, wherein the object relative to the structured illumination is moved so that a particular feature of the object comes to lie at different times in the different phase positions of the structured illumination, wherein a speed of movement of the object and / or a time of readout processes is / are selected such that the Test object between two readout processes by a pixel pitch or a multiple thereof moves on, and that for each phase position in which the feature comes to lie, the same number of lines of the camera chip is read, wherein for each phase nlage in which the feature comes to lie, only a portion of the camera chip is read out, namely as many lines of the camera chip, how to record images with different phase angles or a multiple thereof, and wherein the short temporal sequence is short compared to a temporal Sequence that can be reached when reading all the lines of the camera chip.

Also known is the publication WO 2015/000898 A1 US-A-4/613531 discloses a method of optical shape detection and / or inspection of an article and an apparatus for optical shape detection and / or inspection of an article. The method and the device are suitable for form detection and / or testing of objects with an optically rough surface and / or with a glossy surface up to an optically smooth surface. There is a gradual introduction - arranging at least one camera, at least one line-shaped illumination element and an object relative to each other such that an object surface of the at least one illumination element can be illuminated and received by the camera; Causing a relative movement at least between two elements selected from a group consisting of the object, the at least one lighting element and the camera, wherein a direction of movement with the at least one lighting element forms an angle other than 0 °; - capturing an image sequence of the object surface with the camera during the relative movement, wherein the object surface is imaged in an image plane of the camera; Illuminating the object surface during the exposure of the image plane with the at least one illumination element, and evaluating the recorded image sequence with regard to local surface slopes and / or local optical properties of the object surface.

A disadvantage of the known solutions is that the diffusivity of the light emitted by the lighting elements for glossy, for example, painted surfaces, where depending on the type of paint from diffuse scattering (optically rough surface) mostly glossy proportions to specular components occur not is sufficient to suppress reflections of the light sources, in particular light-emitting diodes (LED's) on the component to be tested sufficiently.

In addition, all known solutions for devices and associated methods are very time consuming and complicated and thus hardly suitable for mass production.

The invention is an object of the invention to provide a method and apparatus for optical shape detection and / or surface testing for components with different geometric freeforms, in particular based on the method of shape-from-shading, which are suitable for mass production and Thus, the test times of variably examined components are short, the method and the device should achieve a high-quality test result for both different surface properties, in particular reflective, especially painted surfaces and matte surfaces.

• - Anordnen von mindestens einer Kamera, mindestens einem Beleuchtungselement und dem Bauteil in einer Prüfanordnung derart, dass zumindest ein Bereich einer Bauteiloberfläche, der mindestens einem Messbereich entspricht, von dem wenigstens einen Beleuchtungselement beleuchtet wird,
• - Aufnehmen einer Messbereichs-Bildfolge mittels der Kamera in mehreren Messbereichen durch eine Bewegung der Kamera gegenüber dem Bauteil oder umgekehrt, wobei die Messbereiche der Bauteiloberfläche in einer Bildebene der Kamera abgebildet und gleichzeitig mit der Aufnahme der Bilder der Messbereichs-Bildfolge mit dem mindestens einen Beleuchtungselement in einem zugehörigen Beleuchtungsvorgang beleuchtet werden,
• - Auswerten der aufgenommenen Bilder der Messbereichs-Bildfolge in mindestens einem der mehreren Messbereiche der Bauteiloberfläche in Hinblick auf eine veränderte lokale Oberflächenneigung und/oder lokale optische Eigenschaften der Bauteiloberfläche.

The starting point of the invention is a method for optical shape detection and / or surface inspection of a component, in particular based on the method of shape-from-shading, with the following steps:

• Arranging at least one camera, at least one lighting element and the component in a test arrangement such that at least one area of a component surface that corresponds to at least one measuring area is illuminated by the at least one lighting element,
• - Recording a measuring range image sequence by the camera in several measuring ranges by a movement of the camera relative to the component or vice versa, wherein the measuring ranges of the component surface imaged in an image plane of the camera and simultaneously with the recording of images of the measuring range image sequence with the at least one lighting element illuminated in an associated lighting process,
• Evaluating the recorded images of the measuring range image sequence in at least one of the plurality of measuring regions of the component surface with regard to an altered local surface inclination and / or local optical properties of the component surface.

• - die Bewegung der Kamera gegenüber dem Bauteil oder umgekehrt bei dem Aufnehmen der Messbereichs-Bildfolge kontinuierlich vorgenommen wird.

According to the invention, it is provided that

• - The movement of the camera relative to the component or vice versa in recording the measuring area image sequence is made continuously.

A significant advantage of the method according to the invention is that in a continuous movement of the camera relative to the component or vice versa, the component surface is "scanned" according to the features mentioned.

In the conventional method, a measuring position is approached, the movement is then stopped, the recording of a measuring range image sequence is carried out and then the next measuring position is approached. As a result, only significantly lower measuring speeds can be achieved by the constant stopping and starting to produce the measuring range image sequence.

• - mindestens eine Kamera mit mindestens einem Objektiv zum Aufnehmen von Bilddaten mindestens eines Messbereichs-Bildes einer Messbereichs-Bildfolge einer Bauteiloberfläche des Bauteils,
• - mindestens ein schaltbares Beleuchtungselement als Lichtquelle zur Beleuchtung zumindest eines Bereichs der Bauteiloberfläche des Bauteils während der Aufnahme des mindestens einen Messbereichs-Bildes, wobei
• - das mindestens eine Beleuchtungselement außerhalb des Nordpols eines halbkugelförmigen Streukörpers gegenüber einer Messebene des Messbereichs-Bildes geneigt angeordnet ist, und
• - das mindestens eine Objektiv der Kamera gegenüber dem Streukörper derart angeordnet ist, dass das Objektiv der Kamera durch die Sichtöffnung des Streukörpers an seinem Nordpol den beleuchteten Bereich der Bauteiloberfläche des Bauteils parallel zur Messebene des Messbereichs-Bildes erfasst.

The starting point of the invention is a device comprising a test head with a housing part for optical shape detection and / or surface testing of a component using the method

• at least one camera with at least one objective for capturing image data of at least one measurement area image of a measurement area image sequence of a component surface of the component,
• - At least one switchable lighting element as a light source for illuminating at least a portion of the component surface of the component during recording of the at least one measuring range image, wherein
• - The at least one illumination element is arranged inclined outside the north pole of a hemispherical scattering body with respect to a measuring plane of the measuring range image, and
• - The at least one lens of the camera relative to the scattering body is arranged such that the lens of the camera detected by the viewing aperture of the scatterer body at its north pole the illuminated area of the component surface of the component parallel to the measurement plane of the measuring range image.

• - dem mindestens einen Beleuchtungselement ein Diffussorelement zugeordnet ist, welches das vom dem mindestens einen Beleuchtungselement ausgesendete Licht streut, welches anschließend in einem vorgebbaren Winkel auf eine Innenwand des Gehäuseteils trifft, wobei
• - die Innenwand des Gehäuseteils zur Streuung des Lichts beschichtet ist, so die Innenwand als Lichtreflektor und als Streuelement wirkt, und das gestreute Licht in einem Reflektionswinkel von der Innenwand abstrahlt, welches anschließend auf eine dem Bauteil abgewandte Oberfläche des Streukörpers trifft,
• - wobei der Streukörper das durch ihn hindurchtretende Licht austrittsseitig des Streukörpers verteilt, welches auf den zu beleuchtenden Bereich der Bauteiloberfläche des Bauteils trifft.

According to the invention, it is provided that

• - The at least one lighting element is associated with a Diffussorelement which scatters the emitted light from the at least one illumination element, which then meets at a predetermined angle to an inner wall of the housing part, wherein
• the inner wall of the housing part is coated to scatter the light, so that the inner wall acts as a light reflector and as a scattering element, and the scattered light radiates at a reflection angle from the inner wall, which subsequently impinges on a surface of the scattering body facing away from the component,
• - Wherein the scattering body distributes the light passing through it on the outlet side of the scattering body, which strikes the area to be illuminated of the component surface of the component.

Advantageously, the reflections of the light source (s) of the at least one illumination element only by the reflection on the inner wall, in particular a cylinder inner wall of the test head, and the subsequent transmission by an opaque hemisphere designed as a scattering body suppressed so far that a measurement on shiny surfaces and also on matte surfaces of the respective component to be tested is possible.

Opacity is a measure of the opacity (opacity) of translucent (diffusely translucent) materials and layers. The light (un) permeability of the opaque hemisphere as scattering body is given as the transmission of electromagnetic waves. In other words, part of the light striking the opaque hemisphere with a certain predeterminable wavelength thus passes through the material of the opaque hemisphere.

A test on dull surfaces is also possible with the same test head in the test arrangement and the associated method described below, so that with the test head according to the invention within the test arrangement according to the invention both matte and glossy surfaces of each component to be tested can be detected in an advantageous manner.

The test head has in a preferred embodiment of the invention, the at least one lighting element for tilt adjustment relative to the measuring plane of the component at least one Neigungsverstellelement which is indirectly or directly with the housing part in combination.

The diffuser element is preferably arranged on the lighting element.

In addition, it is preferably provided that a white special color is formed as a coating of the scattering and reflecting inner wall, which has on its inside a rough surface with a predeterminable surface roughness.

In addition, the test head is characterized in that the wall thickness of the opaque hemisphere in the lower part - in the vicinity of the equator - in the direction of the upper part - towards the north pole - towards the upper part decreases significantly. Various materials can be used to make the opaque hemisphere. It is essential that a homogeneous distribution of the opacity is present and that the opacity remains homogeneous when thinning the material, for example by a deep-drawing process.

The test head is in a preferred embodiment of the invention, a hollow cylinder which receives the said components in its interior completely in a compact manner.

The invention additionally comprises a test arrangement, which is characterized in that a robot-guided guided test head is arranged opposite a component arranged for optical shape detection and / or surface testing, wherein the test head for recording a measuring range image sequence by means of the camera in several measuring ranges of the component by a Movement of the camera relative to the component or vice versa is guided by the robot.

Finally, according to the invention, it is provided that the global position of the component for 6D component orientation in space is determined using a position determination system, in particular a stereo camera system, and a 6D reference position is calculated, at least a one-time calibration being performed between a robotic arm of the robot and the system, whereby there is a referencing of the component in three-dimensional space in its nominal position relative to the robot-guided guided test head in a predefinable distance constancy between the test head and the component surface of the component.

The previous solutions can be called static and as not dynamic and considered, since the movement of the camera relative to the component or vice versa when recording the measuring area image sequence is not continuous, so not done in real time.

In a preferred embodiment of the invention, it is provided that the speed of the relative movement between the camera and the component during recording of the plurality of images per measuring range image of the measuring range image sequence is constant.

Furthermore, in a preferred embodiment of the invention, it is provided that the speed of the relative movement between the camera and the component between the recordings of the plurality of images per measurement area image of the measurement area image sequence is constant or variable.

It is preferably provided that the global position of the component in space in a zero position before the recording of the measuring range image sequence by means of the camera is detected three-dimensionally and stored as a desired position.

In addition, it is preferably provided that the distance of the component relative to the camera in dependence on the component size takes place at a predetermined distance from the nominal position of the component, wherein the predetermined distance is maintained during the continuous movement within a predetermined distance accuracy.

In a preferred embodiment of the invention is - as mentioned - provided that for each image of the measuring range image sequence multiple images are subsequently added according to the invention to the measuring range image of the component representing the at least one measuring range.

In this case, the procedure according to the invention proceeds as follows: the recordings of the multiple images of the measuring range image sequence of the several two-dimensional measuring ranges of the detected component surface relative to one another have an overlapping length.

Furthermore, it is preferably provided that each measuring range is assigned a two-dimensional measuring location, in the entire image area of which the image size deviates maximum depth of focus from the component contour of the component as a depth-sharpness condition, the camera being oriented orthogonally to the two-dimensional measuring location, and with respect to FIG Orthogonality a specified tolerance of the inclination towards the measuring level is maintained.

The method is further characterized in that each recording of the multiple images of each image of the measuring range image sequence is carried out within an exposure time on a plateau with a constant luminous flux with a predefined nominal luminous flux.

Preferably, it is further provided that the beginning of each first recording of the multiple images of each image of the measuring range image sequence by a trigger wegtsynchron, in response to the distance traveled relative movement of the camera relative to the component or vice versa, so that the overlap length is constant.

In particular, it is provided that a master trigger signal, as soon as the camera is in dependence on the wegsynchronen control on a first shot of the multiple images of each image of the measuring range image sequence position provided triggers a trigger chain, by means of a slave trigger lighting the at least one illumination element of the at least one illumination device is associated with the associated illumination process and a slave trigger camera of the camera is triggered and started by means of which an image acquisition is undertaken within the plateau, whereafter the next master trigger signal is triggered.

The method is preferably characterized by the following steps:

In a first step a) takes place within an integrated circuit, the recording of the multiple images of each image of the measuring range image sequence.

In a second step b), within the integrated circuit, a displacement correction, the pre-planned superimposed measuring ranges, wherein in addition to the pre-planned overlap additionally unplanned inaccuracies are corrected by the shots of the multiple images each image of the measuring range image sequence and the measuring ranges with each other relative to each other a shift correction is "panned out" after the individual sections of the image acquisition have been transferred to a processor for calculating a displacement correction, the result being sent back as correction data to the integrated circuit for displacement correction, so that the shift is performed in the integrated circuit.

In a third step c), according to the shape-from-shading algorithm, the calculation of the albedo as a measure of the retroreflectivity of the component surface of the component in the at least one of the plurality of measurement ranges is derived.

In a fourth step d), the result of the calculation of the shape-from-shading algorithm is filtered and corrected with corresponding filter and correction algorithms.

In a fifth step e), an analysis of the measuring ranges with respect to areas of particular interest and masking is carried out.

In a sixth step f), the regions of interest are provided with local coordinates which correspond to surface defects relevant to the component surface of the corresponding component, the local coordinates being passed on to the processor for further calculation.

In a preferred embodiment of the invention is further provided that in a seventh step g) a defect detection takes place, in which the potential defects are identified.

In an eighth step h) the potential defects are parameterized according to specific predefinable parameters, in particular the size, and classified into error classes.

In a ninth step h) genuine defects are classified from the potential defects.

In a tenth step i) for these genuine defects from the local coordinates of a measuring range, the global coordinates according to the global position of the component are determined according to claim 2, wherein the local coordinates of the real defects in the respective two-dimensional measuring range be three-dimensionally "mapped" to the multiple measuring ranges of the component, so that the real defects are arranged exactly in the three-dimensional space on the part having a three-dimensional free-form.

The real defects "mapped" in an eleventh step j) are visualized on a monitor after being transmitted to a graphics card.

Finally, in a last twelfth step k) the "mapped" real defects are stored in error tables with appropriate localization with defect type and defect size and provided for further evaluation.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 das erfindungsgemäße Prüfsystem zur Oberflächenprüfung an einem Bauteil, insbesondere an einem beispielhaft dargestellten Stoßfänger;
• 2 eine Außenansicht eines Prüfkopfs des Prüfsystems;
• 3 eine Prinzipskizze zur Darstellung einer Beleuchtungseinrichtung und einer Lichtführung innerhalb des Prüfkopfes des Prüfsystems;
• 4A eine perspektivische Darstellung des Innenaufbaus des aufgeschnitten dargestellten Prüfkopfes;
• 4B eine perspektivische Darstellung der Beleuchtungselemente der Beleuchtungseinrichtung innerhalb des Prüfkopfes;
• 5 eine schematische Darstellung (Draufsicht) einer Anordnung der als Beleuchtungselemente vorzugsweise verwendeten LED's innerhalb der Beleuchtungseinrichtung;
• 6 eine schematische Darstellung (Seitenansicht) der Beleuchtungselemente;
• 7 eine schematische Darstellung (Seitenansicht) der Beleuchtungselemente;
• 8 eine schematische Darstellung einer Anordnung von Kameras innerhalb eines Kamerasystems nach dem Verfahrensprinzip Stereokamera zur Regelung einer Abstandskonstanz;
• 9 eine Darstellung sowie Definition und Nomenklatur von Zeiträumen, die innerhalb der Prüfdauer der dynamischen Oberflächenprüfung von Bauteilen berücksichtigt werden;
• 10 eine Darstellung sowie Definition und Nomenklatur von Bildgrößen, Messbereichen und Überlappungsbereichen innerhalb eines erfindungsgemäßen Bildaufnahmeverfahrens;
• 11 eine prinzipielle Darstellung mehrerer sich überlappender Messfenster;
• 12 eine Definition und Nomenklatur einer zweidimensionale Anordnung von mehreren Messfenstern innerhalb des Bildaufnahmeverfahrens;
• 13 die Anordnung einer Kamera eines Kamerasystems in einer nicht tolerierbaren Neigung gegenüber dem zu prüfenden Bauteil;
• 14 die Anordnung der Kamera in einer orthogonalen Anordnung gegenüber dem zu prüfenden Bauteil;
• 15 eine Darstellung zur Erläuterung der Bedeutung der Positionierung der Kamera unter Berücksichtigung einer Tiefenschärfe innerhalb des Messfeldes;
• 16 eine erfindungsgemäß vorgesehene Taktführung der Bildaufnahmen zwischen zwei aufeinanderfolgenden Messungen innerhalb des Bildaufnahmeverfahrens mittels der Beleuchtungseinrichtung;
• 17 eine Definition und Nomenklatur der Beleuchtungsparameter innerhalb des Bildaufnahmeverfahrens mittels der Beleuchtungseinrichtung;
• 18 eine Darstellung eines Trigger-Konzeptes zur Bildverarbeitung der mittels der Beleuchtungseinrichtung innerhalb des Bildaufnahmenverfahrens aufgenommenen Bilder;
• 19 eine Darstellung der Konfiguration einer Steuervorrichtung des Verfahrens zur dynamischen Prüfung einer Bauteiloberfläche, insbesondere zur Darstellung eines Trigger- und Kommunikationskonzeptes;
• 20 eine schematische Darstellung des zur Auswertung benötigten Softwarekonzeptes;
• 21 eine schematische Darstellung des Softwarekonzeptes, insbesondere der FPGA-Funktionen gemäß den 19 und 20;
• 22 eine schematische Darstellung des Softwarekonzeptes, insbesondere der GPU-Funktionen gemäß den 19 und 20;
• 23 eine schematische Darstellung des Softwarekonzeptes, insbesondere der CPU-Funktionen gemäß den 19 und 20.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

• 1 the test system according to the invention for surface inspection on a component, in particular on a bumper exemplified;
• 2 an external view of a test head of the test system;
• 3 a schematic diagram illustrating a lighting device and a light guide within the test head of the test system;
• 4A a perspective view of the internal structure of the test head shown cut open;
• 4B a perspective view of the lighting elements of the illumination device within the probe;
• 5 a schematic representation (top view) of an arrangement of the preferably used as lighting elements LEDs within the illumination device;
• 6 a schematic representation (side view) of the lighting elements;
• 7 a schematic representation (side view) of the lighting elements;
• 8th a schematic representation of an arrangement of cameras within a camera system according to the method principle stereo camera for controlling a distance constancy;
• 9 a representation and definition and nomenclature of periods taken into account during the dynamic surface inspection of components;
• 10 a representation and definition and nomenclature of image sizes, measuring ranges and overlapping areas within an image recording method according to the invention;
• 11 a schematic representation of several overlapping measuring windows;
• 12 a definition and nomenclature of a two-dimensional array of multiple measurement windows within the image capture process;
• 13 the arrangement of a camera of a camera system in an intolerable inclination relative to the component to be tested;
• 14 the arrangement of the camera in an orthogonal arrangement with respect to the component to be tested;
• 15 a representation for explaining the meaning of the positioning of the camera taking into account a depth of field within the measuring field;
• 16 an inventively provided timing of the image recordings between two successive measurements within the image recording method by means of the illumination device;
• 17 a definition and nomenclature of the illumination parameters within the image acquisition process by means of the illumination device;
• 18 a representation of a trigger concept for image processing of the captured by means of the illumination device within the image recording method images;
• 19 a representation of the configuration of a control device of the method for dynamically testing a component surface, in particular for representing a trigger and communication concept;
• 20 a schematic representation of the software concept required for the evaluation;
• 21 a schematic representation of the software concept, in particular the FPGA functions according to the 19 and 20 ;
• 22 a schematic representation of the software concept, in particular the GPU functions according to the 19 and 20 ;
• 23 a schematic representation of the software concept, in particular the CPU functions according to the 19 and 20 ,

Test system:

1 shows the test system according to the invention 100 for surface inspection on a component B , in particular on a bumper exemplified.

The parallel use of one or more robot-controlled, scanning test systems is envisaged 100 ,

The examination of the component B _n takes place in the embodiment on a component carrier T in other words, the component B _n is in the selected embodiment during the test stationary on / on a component carrier T arranged.

Test head and light guide:

The robot-based test system 100 includes a probe as an essential component 101 , The test head 101 of the test system 100 is by an industrial robot 200 relative to the component B _n guided moves.

The 2 shows an external view of the probe 101 , wherein a hollow cylindrical housing part 101A is shown transparently.

In the upper part of the hollow cylindrical housing part 101A are a camera K0 and at least one lighting element 101B arranged.

In the upper part of an opening is made, which provides ventilation of the housing part 101A , in particular for heat dissipation guaranteed. The camera K0 sits in one in the housing part 101A arranged recording, a position fine adjustment of the camera K0 allows.

In the lower part of the hollow cylindrical housing part 101A is a spherical opaque light distributor 101D arranged on the inside of the hollow cylindrical housing part 101A is attached. The hemisphere points centrically within the hemisphere 101D in extension of the longitudinal extent of the longitudinal axis of the camera K0 a viewing opening 101D - 1 on, above the lens of the camera K0 is arranged.

In 3 the illumination principle or the light guide is shown schematically, which by a special embodiment of the illumination device within the probe 101 of the test system 100 is realized.

The at least one lighting element 101B emits light, which is first on a Diffussorelement 101B - 1 , in particular a diffuser plate, is scattered. The light is at a predeterminable angle to the inner wall of the hollow cylindrical housing part 101A sent out. For tilt adjustment of the at least one lighting element 101B serve tilt adjustment 101E (see 4B) connected to the at least one lighting element 101B connected and in at least one support plate 101F are attached.

The inner wall of the hollow cylindrical housing part 101A is coated with a white special paint - to form a rough surface - so that the inner wall of the hollow cylindrical housing part 101A as a light reflector 101G is formed with a predetermined scattering effect.

The on the cylindrical reflector 101G reflected light thus reaches the surface of the opaque hemisphere at a predefinable angle of reflection 101D that part of the incident light is not through the hemisphere 101D let pass. The passing light (transmission) is also through the opaque hemisphere 101D exit side within the lower portion of the hollow cylindrical housing part 101A distributed.

The illumination device thus comprises the at least one illumination element 101B with the diffuser plate 101B - 1 , the reflector 101G and the opaque hemisphere 101D ,

The opaque hemisphere is designed such that the wall thickness decreases significantly in the lower part in the direction of the upper part towards the upper part.

In conjunction with the partially absorbing properties of the opaque hemisphere, light quantity control is thereby achieved, which is particularly suitable for application of the method according to the invention to components B _n of reflecting surfaces is required.

That of the at least one fastener 101B emitted light is thus by means of the diffuser plate 101B - 1 , by means of the light reflector 101G and the opaque hemisphere 101D scattered, so that's on the component B _n incident light no reflections on the component B _n causes. Consequently, through the diffuser plate 101B - 1 and by the reflection on the as a light reflector 101G formed cylinder inner wall of the test head 101 and the subsequent transmission of light through the opaque hemisphere 101D the reflections of the light source suppressed so far, so that according to the invention a measurement on shiny surfaces of the component to be tested B _n becomes possible.

However, a check on matte surfaces is also done with the same probe setup possible, so that both matte and glossy surfaces of the component to be tested can be detected in an advantageous manner with the test head structure.

The only details representing 4B shows that within the probe assembly two lighting elements 101B are arranged, according to the principle described above, the component to be tested B _n illuminated. The 4B shows in addition the diffuser plates 101B - 1 as details in the assembled state with the lighting elements 101B are connected, in particular in the 6 and 7 is shown.

The 5 shows a lighting element 101B in a top view.

Due to the short exposure times required to minimize the sensitivities to component vibrations that occur, Δt _b = 40-50 μs are high luminous fluxes Φ _ν required in the lighting. Component vibrations are, for example, over the ground on the clamping device in which the component B _n in the carrier T is clamped on the component to be tested B _n transmitted, whereby the vibrations of the component surface when taking the measuring range image sequence by short exposure times of the camera K0 of the test head 101 be taken into account.

Luminous fluxes between Φν _N = 25.000lm and Φν _N = 80.400lm are used. Because of the high luminous flux and the reflective surface to be tested, as explained above, only indirect, diffuse illumination can be used.

The lighting elements 101B preferably comprise a plurality of white white light LEDs with a maximum luminous flux of Φν _N = 80,400 Im (nominal luminous flux of the LEDs at a supply voltage: 39.2 V and a supply current of 13.8 A). Alternatively, especially on very smooth surfaces, blue LEDs (blue light) may be used, taking into account the spectral conversion of the radiant power.

In the embodiment according to 5 Be twelve, in particular white, LED's to a lighting element module of several lighting elements 101B summarized. In the assembled state are like the 6 and 7 in side views, above the lighting elements 101B heatsink 101B - 2 and below the lighting element 101B the already described diffuser plate 101B - 1 arranged. The heat sinks 101B - 2 are also in 4B shown in perspective in a kind of exploded view separated from the LED's.

Testing Technology:

Every test system 100 (see 1 ) checks the existing components B _n in a so-called plant cycle.

As a test technology or as a method for surface inspection of a component B _n comes the adapted shape-from-shading ( SFS ), which according to the invention now works dynamized and is designed accordingly, as will be explained in detail below.

The required accuracy of component positioning of the component B _n opposite the test head 101 in a so-called test arrangement is about +/- 500μm to 2 mm, that is, the position of the probe 101 of the test system 100 opposite the component B _n must correspond to the specified distance accuracy.

The depth of field of the cameras K1 . K2 a stereo camera system 102 (see 8th ) is limited. The entire part of the component to be tested B _n must be within the depth of field, so the distance accuracy about +/- 500μm to 2 mm is of great importance, as will be explained.

A robot path is programmed for all component types during commissioning, with the robot path being the pivoting movement of the robot arm 210 and thus the test head track of the test head 101 opposite the component B _n is determined.

The component B _n is located in a zero position, the position of the component B _n in the room is metrologically recorded and stored.

This metrological detection of the component position is only required if the tolerances of the component storage are so large that the component surface outside the depth of field of the camera K1 . K2 could lie.

In a measuring operation, the three-dimensional position of the component B _n in the room with the stereo camera system 102 ; K1 . K2 , schematic in 8th shown directly after retracting and calming the component B _n metrologically recorded.

Subsequently, a deviation Δs _R the location of the current component B _n determined to a zero position and from this is a correction for the created program for controlling the robot 200 or his robot path determined.

The corrected program for controlling the robot 200 is transmitted to the robot controller. The robot 200 starts the component inspection the corrected course. This correction is only necessary if the tolerances of component storage are so great that the component surface is outside the depth of field of the cameras K1 . K2 of the stereo camera system 102 could lie.

The range of the robot 200 , in particular the robot arm 201 , must be so big that all measuring locations M (i _x . i _y ) can be achieved within a two-dimensional coordinate system.

Care is taken to ensure that the test system is in a so-called measuring position at the measuring location. The robot 200 must have an accuracy that allows the test system 100 with a distance accuracy of Δs _R = ± 500μm to 2 mm component is performed.

It is envisaged that the robot arm 210 the robot track preferably continuously at a constant speed V _R descends, the speed of the robot arm 210 can also vary with this method.

For each measurement to be performed at the respective measuring location M (i _x . i _y ) becomes a robotic track base with the analogous name M (i _x . i _y ) programmed in two dimensions.

The robot control sends when reaching the robot base M (i _x . i _y ) a real-time trigger and location information.

Upon reaching the railway base M (i _x . i _y ) At the measuring location, the real-time trigger is sent, which triggers the execution of the measurement.

Similarly, the location information of the railway base M (i _x ,), ie the position of the railway base M (i _x . i _y ) in the room, sent.

The web programming is carried out in such a way that at each measuring location M (i _x . i _y ) the orientation of the test system is realized so that in the entire image area with the image size .DELTA.S _Bx .DELTA.S _B a measuring plane as depth of field condition deviates at most by the depth of field from the component contour, which will be discussed.

If due to the local curvature of the component B _n In the image area it is not possible to comply with the depth-of-field condition, the size of the image area can be reduced in coordination.

The resulting shifts of the measuring locations M (i _x , for the following measurements are taken into account, as will also be explained.

The robot arm 201 of the robot 200 may be during the recording of all four images including the transmission times of the images or the readout time from the camera K0 and the transmission times of the pictures to the computer of four x Δt _K (compare also 18 )) only move at a constant speed.

Change of direction due to reorientation of the robot arm 201 of the robot 200 are avoided, with a predetermined constant speed must be ensured only until the completion of the recording of the fourth image. Already during the data transmission of the recording of the fourth image, the speed of the camera K0 opposite the component B _n to change. The specifiable speed between the generated measuring range images of the measuring range image sequence can be chosen constant or change, with quite a few speed changes are possible.

Distance Konstanz:

The 8th shows a schematic representation of an arrangement of cameras K1 and K2 within a camera system KS according to the method principle of the stereo camera for controlling a distance constancy between component B _n and test head 101 of the test system 100 within the required distance accuracy of Δs _R = ± 500μm to 2mm.

This metrological detection of the component position is only required if the tolerances of the component storage are so large that the component surface outside the depth of field of the camera K1 . K2 of the stereo camera system 102 could lie.

They become significant identification features on the component B _n for determining the 6D position of the component B _n set in the room.

For position detection by means of stereo measurement, the two cameras K1 . K2 (see 8th ) are used, which have a fixed distance from each other and at a predeterminable slight angle to the component B _n look.

The required distance between the cameras K1 . K2 and the image pickup distance will be determined by the size of the component B _n established.

For a process-reliable 6D component localization in space ( x . y . z . α . β . γ ) at least three corresponding significant test characteristics are determined and recorded in the camera images and evaluated.

Suitable test features represent, for example, openings arranged in different planes or the like.

On the basis of 6D component localization in space ( x . y . z . α . β . γ ) there is an at least one calibration between robot arm 201 and the two cameras K1 . K2 , whereby the referencing of a component B _n present in its three-dimensional space in its desired position.

Before the start of the measurement, the position of the component is thus summarized B _n in the room ( x . y . z . α . β . γ ) with the stereo camera system 102 certainly. The so-called 6D reference position is calculated and used as base displacement to the controller of the robot R transmitted.

The base is the origin coordinate of the robot R , The location of the component B _n was measured. If the location of the component B _n is shifted relative to the target position, it is assumed that the position of the robot R relative to the component B _n has changed. To the positional shift of the component B _n to correct the desired position, that is, the component B _n into the correct (corrected) starting position, the described so-called base shift is performed.

Time control:

9 shows a representation of time periods within the test period of the dynamic surface inspection of components B _n be taken into account.

Definition and nomenclature:

• Δt _H1 = first handling time
• Δt _H2 = second handling time
• Δt _Pges = total test duration for the test of one or more components B _n corresponds to the so-called cycle time.
• Δt _P = test duration per component B _n , During this period becomes a component B _n completely tested. It will be there n _M Measurements performed.
• Δt _M = measurement duration. During this period, a measurement takes place. As part of a measurement, several images (corresponding to the exposure time Δt _B ), in the exemplary embodiment four pictures in time Δt _M added.
• Number of measurements = n _M
• Δt _B = exposure time. During this period, a picture is taken.
• Δt _R = robot (arm) movement time.

During this period, the robot arm moves 201 of the robot 200 from the last measuring position to the component B ₁ to the first measuring position on component B ₂ ,

Δt _K = camera data transmission period. During this period will take a picture of the camera K0 in the test head 101 transferred to the frame grabber FPGA. $$\begin{array}{cc}\mathrm{\Delta }{\text{t}}_{\text{P}}=\frac{\mathrm{\Delta }{\text{t}}_{\text{Pges}}-\mathrm{\Delta }{\text{t}}_{\text{H1}}-\mathrm{\Delta }{\text{t}}_{\text{H2}}-\mathrm{<figure-callout\; id="2"\; label="\Delta \; t\; R"\; filenames="DE102017221649A1\_0008.png,DE102017221649A1\_0009.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}{\text{t}}_{\text{R}}{}_{}}{2}& \mathrm{\Delta }{\text{t}}_{\text{M}}=\frac{\mathrm{\Delta }{\text{t}}_{\text{P}}}{{\text{n}}_{\text{M}}}\end{array}$$

The test duration total is Δt _Pges = cycle time = for example 60s
Test duration per component is Δt _P = 25 s, for example
Δt _H1 + Δt _H2 + _ΔtR = 10s
Δt _B ~ 40-50μs.

In this embodiment, a desired exposure time is in the selected embodiment Δt _B to understand. The exposure time Δt _B may depend on the color of the component to be tested B _n differ from the specified values. For darker components B _n is the exposure time Δt _B tends to be longer, especially about 60-100 μs, with the illumination duration Δt _L adapt accordingly (cf. 17 ).

The exposure time Δt _B is set as short as possible to avoid disturbances due to vibrations and vibrations of the component B hide.

9 shows the basic sequence of a component test as an example on two components B _n ,

1 shows a timeline t , In the embodiment, two components B ₁ and B ₂ tested in one plant cycle (cycle time). The component carrier T (see 1 ) runs in the time span Δt _H1 in a test station.

First, the first component B ₁ checked. The test duration per component B _n is Δt _P , Thereafter, the robot arm moves 201 of the robot 200 in the time span Δt _R for testing the second component B ₂ from the first component B ₁ to the second component B ₂ , The component carrier T (see 1 ) runs in the time span Δt _H2 out of the test station.

Within the test period Δt _P per component B _n becomes a component B _n completely tested. There are several measuring ranges M _n , so-called tiles in the time span Δt _M taken in the embodiment n = 4 shots M _n in several measuring ranges M or tiles, depending on component size) in the time periods Δt _M be performed. This results in a test period Δt _Pges Total for testing one or more components B _n which corresponds to the so-called cycle time.

Image capture design:

10 shows a representation of image sizes in measuring areas and overlapping areas within an image recording method according to the invention.

Definition and nomenclature:

The image size of a tile or of a measuring area / measuring window M ( i _x, i _y ) is defined as ΔS _Bx ; ΔS _By

The measuring range size is defined as ΔS _Mx ; ΔS _My

A recording offset between two measuring ranges / measuring windows is in particular ΔS _A = 120 pixels and is constant, although other recording offsets are possible.

In the exemplary embodiment, the overlap length between two measuring ranges / measuring windows is ΔS _U = 10 pixels and is constant, although other overlap lengths are also possible

The hatched measuring range M _n is the range that is at all n = 4 with the in the test head 101 arranged camera K0 taken pictures 1 to 4 matches.

The in 10 shown frame forms the Überlapplänge ΔS _U between several measuring ranges M _n ( i _x , i _y ) or between two tiles. The overlap length ΔS _U is important to allow the multiple measurement ranges M _n taking into account the overlap length ΔS _U can be arranged together.

The 11 shows a schematic representation of several, with the overlap length ΔS _U overlapping measuring ranges / measuring window M (i _x . i _y ) that is a surface of a component B _n by means of several measuring ranges / measuring windows M ( i _x , i _y ) and two-dimensional capture.

12 shows a definition and nomenclature of a two-dimensional i _x . i _y Arrangement of several measuring windows M (i _x . i _y ) of a component B _n within the image recording method according to the invention.

Positioning the camera K0 in the test head 101 in the Z Direction opposite an imaginary plane of measurement of the surface of the component B _n :

13 shows the arrangement of the camera K0 in the test head 101 in an intolerable inclination to the component to be tested B _n , The through the trapeze in 14 clarified depth of field does not completely cover the measuring range / measuring window M (i _x . i _y ), because the right corner of the trapezoid is the measuring range / measuring window M (i _x . i _y ) not within the depth of field .DELTA.d detected.

The request for the orientation of the camera K0 in the Z Direction is location dependent. Generally speaking, it is ensured that the measuring range / measuring window M (i _x . i _y ), in the depth of field .DELTA.d in the room.

The depth of field .DELTA.d is less than 10 mm. The camera K0 , hence the test head 101 , according to the invention is always orthogonal to the measuring range / measuring window M (i _x , i _y ), whereby a tolerance of the inclination +/- 1.5 ° is maintained.

14 shows the arrangement of the camera K0 in the test head 101 in a correct orthogonal arrangement with respect to the component to be tested B _n , By the orientation of the probe 101 and thus the camera K0 in the z-direction orthogonal to the measuring range / measuring window M (i _x , i _y ) ensures that this is the depth of field .DELTA.d clarifying trapeze in 15 the surface of the component Bn in the measuring range or in the measuring window M (i _x . i _y ) in the depth of field. The right corner of the trapezoid is now compared to 14 in the measuring range / measuring window M (i _x , i _y ) within the depth of field .DELTA.d ,

15 shows a representation for explaining and the importance of the positioning of the camera K0 in the test head 101 taking into account the depth of field .DELTA.d in terms of one within the component B _n lying imaginary measurement level within the measurement window M (i _x , i _y ).

In the exemplary embodiment, the measurement plane is an x / y plane. It can be seen that the shape of the component B _n deviates from a flat measurement plane in the x / y plane.

The camera K0 takes in the measuring range / measuring window M (i _x . i _y ) a rectangular two-dimensional image, as in the two below the component B _n lying rows with multiple rectangles is shown.

In the first line, the rectangles lie aligned next to each other, while the rectangles are arranged twisted in the second line.

It clarifies that the camera K0 for producing a plurality of images relative to the component B _n such over the component B _n led and is aligned so that the recordings are not twisted in the result. Over the lines in the 13 are several camera positions of the camera K0 indicated, whose position relative to the surface of the component B _n according to 14 in the depth of field .DELTA.d (see 14 ), so that finally the entire surface of the component to be tested B _n by mutually untwisted camera shots in the depth of field .DELTA.d which is also included in z Direction orthogonal to the surface are arranged. The test head 101 of the robot 100 provides through a corresponding control algorithm that the recordings orthogonal in z Direction to the surface of the component B _n and each other in a constant recording direction, in the embodiment along the direction of travel of the probe 101 along the x -Axis are aligned.

Clocking Shape-From-Shading:

16 shows an inventively provided timing of the four image recordings between two consecutive measurements or their measuring ranges M ₁ (n = 1) and M ₂ (n = 2) within the image pickup process by means of the illumination device.

Definition and nomenclature:

• S1.1 = erster Messbereich M₁ und erste Bildaufnahme
• S2.3 = zweiter Messbereich M₂ und dritte Bildaufnahme

Eine Strecke/Länge = □S_x
Zeitpunkt Messung x, Bild y = t_x,y
Bsp.:

• t1.1 = Zeitpunkt der ersten Bildaufnahme im ersten Messbereich M₁
• t2.3 = Zeitpunkt der dritten Bildaufnahme im zweiten Messbereich M₃

Zeitdauer = □t_x The location coordinate of a measurement x , Image y ₌ S _{x, y}
Ex .:

• S1.1 = first measuring range M ₁ and first image capture
• S2.3 = second measuring range M ₂ and third image capture

A distance / length = □ S _x
Time measurement x , Image y = t _{x, y}
Ex .:

• t1.1 = time of the first image acquisition in the first measurement range M ₁
• t2.3 = time of the third image acquisition in the second measuring range M ₃

Duration = □ t _x

In 16 are two (compare 10 ) Measuring ranges M ₁ (n = 1) and M ₂ (n = 2) with the overlap length ΔS _U between the two measuring ranges M _n ( i _x . i _y ) or between two so-called tiles. The overlap length ΔS _U is important to allow the multiple measurement ranges M _n taking into account the overlap length ΔS _U can be arranged together.

What is essential is that of a robot-side master trigger R1 and a robot-side master trigger R2 set time of the beginning of the recordings 1 to 4 per measuring range M ₁ ( i _x , i _y ) and M ₂ ( i _x , i _y ) away synchronous, thus depending on the distance traveled s the camera K0 , he follows. The triggers R1 and R2 are not set as usual usually time-controlled, but they are set wegsynchron. That's because the test head 101 of the robot 100 not at constant speed over the component B _n moves. If the probe 101 of the robot 100 for example, in the edge region around the component B _n driving around reduces the driving speed. The path-dependent trigger R1 triggers that the first measurement range M ₁ (i _x . i _y ) is recorded. The path-dependent trigger R2 triggers that second measurement range M ₂ ( i _x , i _y ) is recorded. For timed triggering, the respective overlap lengths would be ΔS _U not constant when the driving speed of the test head 101 of the robot 100 between two with the camera K0 measuring ranges to be recorded M ₁ and M ₂ changes. According to the invention, the overlap lengths are due to the path synchronous triggering ΔS _U constant.

Lighting parameters:

17 shows a definition and nomenclature of the illumination parameters within the image acquisition process by means of the illumination device.
Δt _B = Exposure time

During this period, a picture is taken.
Δt _Lc = Illumination duration with constant luminous flux

Within the illumination period Δt _Lc must be the exposure in an exposure period Δt _B lie. In other words: Δt _B must be in the interval.
Δt _L = Illumination duration.

The period in which the LED Lamp is turned on.
Φν _N = Nominal luminous flux of LED -Lamp
Φν _NLED = Nominal luminous flux one LED modulus

$$\mathrm{\Delta }{\text{t}}_{\text{Lc}}=80\mathrm{\mu }\text{s}$$

$$\mathrm{\Delta }{\text{t}}_{\text{L}}=100\mathrm{\mu }\text{s}$$

$$\mathrm{\Phi }{\mathrm{\nu }}_{\text{N}}=25.000\text{lm}/\text{Lampe}$$

$$\mathrm{\Phi }{\mathrm{\nu }}_{\text{NLED}}\approx 4.000\text{ bis 5000lm}/\text{LED Modul}$$

The following values are preferred. $$\mathrm{\Delta }{\text{t}}_{\text{B}}=50\mathrm{\mu }\text{s}$$

$$\mathrm{\Delta }{\text{t}}_{\text{Lc}}=80\mathrm{\mu }\text{s}$$

$$\mathrm{\Delta }{\text{t}}_{\text{L}}=100\mathrm{\mu }\text{s}$$

$$\mathrm{\Phi }{\mathrm{\nu }}_{\text{N}}=\mathrm{25,000}\text{lm}/\text{lamp}$$

$$\mathrm{\Phi }{\mathrm{\nu }}_{\text{NLED}}\approx 4000\text{up to 5000lm}/\text{LED module}$$

It is proposed to be available in the future LED Use modules with even higher performance, as by further increase in performance of the nominal luminous flux Φν _NLED one LED Modules further improve the process over the LED Modules is achieved with the currently available LED Lamps with maximum nominal luminous flux Φν _N are equipped.

After switching on the module from lighting elements 101B a corresponding time (according to the first ramp) is required until the lighting elements 101B their nominal luminous flux Φν _N = have reached their constant plateau. After that, the nominal luminous flux remains Φν _N constant. After switching off the lighting elements 101B falls the nominal luminous flux Φν _N (according to the second ramp) accordingly back to zero.

A picture is taken within the displayed exposure time Δt _B of the plateau within the illumination period with a constant luminous flux Δt _Lc , resulting in a constant and thus predefined nominal luminous flux Φν _N for all successive shots / images according to the embodiment of the images 1 to 4 is effected.

Trigger concept:

18 shows a representation of a trigger concept for image processing of the captured by the illumination device within the image recording method images.

By means of a graphics card GPU "graphics processing unit".

By means of an integrated circuit FPGA "field programmable gate array".

The robot 200 generates a master trigger signal R _n , in particular R ₁ (see 16 ), as soon as the camera K0 hence the test head 101 steered away at the for taking a picture in the designated position.

The master trigger signal R _n triggers a trigger chain.

First, by means of a slave triggering LED the illumination device according to the first illumination process L _n ; L1 of the measuring range M _n activated and started.

In a short time offset, a slave trigger camera (cf. 17 ) according to the trigger K _n ; K1 the camera K0 controlled and started, the first image acquisition K1 within the plateau of L1 makes.

The picture taken K1 is transmitted from another trigger of a time control block, for example, via a camera link to an FPGA frame grabber, the data transfer the period Δt _K equivalent. During this period Δt _K No further picture taking can take place as the camera K0 the data must first be transferred to the FPGA frame grabber.

The procedure is repeated picture by picture K2 . K3 . K4 according to the previously occurring illumination process L2 . L3 . L4 within a measuring range M _n , Another measuring range M _n follows, which is triggered by a next master trigger signal R _{n + 1} .

Trigger and communication concept:

19 shows a representation of the configuration of a control device for performing the method for dynamic testing of a component surface, in particular for representing the data processing of the trigger and communication concept.

Software concept for evaluation:

20 shows a schematic representation of the software concept required for the evaluation, in particular the components that are of importance for the data processing for testing in the corresponding cycle times (system clock).

The software concept includes the infrastructure functionalities for the software, in particular for the user interface "GUI", a Profibus connection "PROFIBUS", signal processing, especially inputs and outputs "I / O", an error handling block for "error handling", a logger that logs errors "file -Logger "and a diagnostics module" Diagnostics ", which diagnoses and reports errors that still occur in the components.

Another component is the FPGA, which organizes image capture, shape-from-shading algorithms, filter functions, corrections, region of interest ROI, masking, and local coordinate generation.

The GPU finds from the preprocessed images taken by the FPGA coming from the component surface sought errors and classifies the errors. The GPU also determines the global coordinate.

This basic structure is in the 21 to 23 again shown in detail.

Software concept FPGA functionality:

21 shows a schematic representation of the software concept, in particular the FPGA functions according to the 19 and 20 ,

21 shows the FPGA card and graphically prepared again the individual steps.

In a first step a), the image recordings take place by means of the FPGA K _n . K _1, K ₂ . K ₃ . K ₄ ,

In a second step b), a shift correction of the pre-planned superimposed measuring ranges takes place in the FPGA M _n , wherein in addition to the explained pre-planned overlap ΔS _U In addition, still unplanned inaccuracies that result from the robotic arm guide, be corrected by the image recordings K _n . K ₁ . K ₂ . K ₃ . K ₄ and the measuring ranges M _n be "swelled out relative to each other. The offset correction can not be performed directly in the FPGA. For this reason, individual sections of the image recordings K _n . K ₁ . K ₂ . K ₃ . K ₄ created and transmitted to a processor, the CPU, in a loop (compare 23 ) calculates the offset correction, with the result being sent back to the FPGA for correction of offset as correction data (see arrows in FIG 21 and 23 ) so that the actual shift can be performed in the FPGA.

In a third step c), the calculation of the shape-from-shading algorithm is carried out, from which, after the calculation of p and q, the albedo can be derived as a measure of the retroreflectivity of diffusely reflecting, ie not self-luminous surfaces.

In particular, in the different measuring ranges M _n the albedo differences are determined.

In a fourth step d), the result is filtered and corrected with appropriate algorithms.

In a fifth step e) takes place an analysis of the measuring ranges M _n in terms of region of interest ROI and masking, that is, all non-interest areas are cut away so that only the areas of interest are present.

In a sixth step, the regions of interest are provided with local coordinates, as in 21 under point f) is shown. Thus, those local coordinates are now available at which on the component surface of the corresponding component B _n relevant surface defects are present.

This result is used for the calculation to the CPU (cf. 19 ), the further course of action in the 22 and 23 is shown.

Software concept GPU functionality:

22 shows a schematic representation of the software concept, in particular the GPU functions according to the 19 and 20 , The defect detection takes place in the GPU, which is the local coordinates p . q . A received from the FPGA.

In a further step g), a defect is detected. In other words, they become potential defects D _n ; D ₁ . D ₂ . D ₃ identified.

These potential defects D _n ; D ₁ . D ₂ . D ₃ are parameterized in a step h) according to certain specifiable parameters, in particular the size, and classified into error classes. For example, potential defects become D _n ; D ₁ . D ₂ . D ₃ only classified from a size of, for example, 40 pixels as real defects.

Are for example "real" defects D ₁ and D ₃ in step h), in a step i) become these defects D ₁ and D ₃ from the local coordinates of a measuring range M _n the global coordinates on the part B _n determines how in 22 under i).

That is, the local coordinates of the defects D ₁ and D ₃ in the respective two-dimensional measuring range M _n become three-dimensional on the multiple measuring ranges M _n of the component B _n "Mapped", so it's clear where the defects D ₁ and D ₃ exactly in three-dimensional space on the part having a three-dimensional freeform shape B _n lie.

The in 22 under i) shown three-dimensional bumper as a component B _n Thus, for example, has two three-dimensional fixed defects D ₁ and D ₃ which are determined two-dimensionally and locally in the area-by-area analysis using the Shape-from-Shading algorithm.

Software concept CPU functionality:

23 shows a schematic representation of the software concept, in particular the CPU functions according to the 19 and 20 ,

About the CPU of the computer and the GUI of the computer is set according to 23 ensured, that the worker in a step j) the defects D ₁ and D ₃ visualized on a monitor that have been detected in the GPU.

In an additional last step k) the results are stored in error tables with appropriate localization with defect type and defect size and provided for evaluation.

Finally, further advantages of the invention are mentioned.

One advantage is that the test system 100 for various applications, in particular for components B _n with matte and shiny surfaces, is uniform. This does not always require a new development effort for different applications and thus minimized overall.

The test system 100 and the associated computer programs, in particular the software, are standardized and can be used for various applications, which also reduces the costs for the individual application. In addition, an improvement in maintenance, spare parts inventory and support is achieved.

The consistently robot-guided design of the test system opens up the possibility that changes in the component type and thus changes in the three-dimensional free form are understood to mean changes to the computer programs, in particular the evaluation and robot programming. The test system 100 can be used unchanged. This results in a high flexibility of the test system 100 reached.

In addition, the test system 100 through the dynamization, among which the continuous movement of the camera K0 opposite the component B _n or vice versa, when taking the measurement area image sequence at a certain variable speed V _R understood, very fast. In particular, variable adjustable test speeds of 1000 mm / s and faster are achieved. As a result, larger areas to be examined can be checked in short periods of time. When examining the surfaces, in particular painted surfaces of bodies in the plant cycle, these advantages are of great importance. At a typical cycle time of 45 s per component ( B _n ) can with the dynamized test system 100 or the associated test arrangement and the associated method, for example, in a cycle time of 45 s, a component surface of about 7.5 m ² being checked.

In addition, as explained, it is possible to investigate robotically guided three-dimensional contouring of free-form surfaces. In other words, surface inspection of curved surfaces is possible, in particular dynamized possible.

Due to the intended system for 6D position detection of the component B _n can even use components B _n be checked whose position in space is not clearly defined. An exact component positioning is therefore not essential.

The dynamic test system 100 or the associated test arrangement and the associated method is used for the surface inspection of painted or unpainted bumper, in particular the surface inspection of painted bodies in passenger cars and commercial vehicles. In addition, the use of the associated test arrangement and the associated method for the surface inspection in the range of components, in particular of cylinder crankcase sealing surfaces, camshaft associated sealing surfaces, cylinder head sealing surfaces, flywheel, brake discs is provided. Furthermore, surfaces of components in the field of household electrical appliances can be tested, in particular kitchen appliances and / or catering appliances and in the field of telecommunications and the field of consumer electronics.

LIST OF REFERENCE NUMBERS

100

Test System

200

robot

201

robot arm

SFS

Shape from shading

T

component carrier

B

component

B _n

nth component

101

probe

K0

camera

101A

housing part

101B

lighting element

101B-1

Diffussorelement

101B-2

heatsink

101C

electronics

101D

Diffuser, light distributor (opaque hemisphere)

101D-1

view port

101E

Neigungsverstellelement

101F

support plate

101G

light reflector

102

Stereo Camera System

K1

camera

K2

camera

t

Time

L _n

nth lighting process in one measuring range M _n

Δt _b

exposure time

Δt _B

exposure time

Δt _L

lighting time

Δt _Lc

Lighting duration with constant luminous flux

Φ _ν

Luminous flux

Φν _N

Rated luminous flux

LED

led

Φν _NLED

Rated luminous flux one LED modulus

Δs _R

Deviation of the position of the component B _n to a zero position

M (i _x , i _y )

Measuring location, measuring position, measuring window, measuring range (two-dimensional)

V _R

variable speed of the robot arm 201

.DELTA.d

depth of field

ΔS _Bx x ΔS _By

image size

ΔS _Mx ; ΔS _My

Measuring range Size

ΔS _A ; ΔS _A

Capture offset

ΔS _U

overlap length

Δs _R

distance accuracy

x, y, z, α, β, γ

Room parameters for 6D component localization

K _n

nth picture

Δt _H1

Handling time of the first component B ₁

Δt _H2

Handling time of the first component B ₂

Δt _Pges

Test duration of one or more components B _n

Δt _P

Test duration per component B _n

Δt _M

measuring time

M _n

Number of measurements within the test duration per component B _n , n = consecutive nth measurement

Δt _B

exposure time

Δt _R

motion duration robot (arm)

Δt _K

Camera data transfer period

S _{x, y}

Location coordinate of a measurement x , Image y

ΔS _x

Distance / length

t _{x, y}

Time of a measurement x , Image y

Δt _x

time

R ₁

first trigger

R ₂

second trigger

Δt _K

Readout period of a recording and transmission period

R _n

Master trigger robot

D _n

nth potential defects

p, q

albedo

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2004/051186 A1 [0006]
• EP 1567827 B1 [0006]
• DE 20317095 U1 [0007]
• DE 102004038761 A1 [0008]
• EP 1949673 B1 [0009, 0011]
• EP 1864081 B1 [0010]
• WO 2015/000898 A1 [0012]

Claims (21)

Method for optical shape detection and / or surface testing of a component (B _n ), in particular based on the method of shape-from-shading, comprising the following steps: arranging at least one camera (K0), at least one illumination element (101B) and the component (B _n ) in a test arrangement in such a way that at least one area of a component surface which corresponds to at least one measurement area (M _n ) is illuminated by the at least one illumination element (101B), - recording a measurement area image sequence by means of the camera (K0) a plurality of measuring areas (M _n ) by a movement of the camera (K0) relative to the component (B _n ) or vice versa, wherein the measuring areas (M _n ) of the component surface (3) imaged in an image plane of the camera (K) and simultaneously with the recording the images of the measuring range image sequence are illuminated with the at least one lighting element (101B) in an associated lighting process (L _n ), - evaluating the recorded image Images of the measuring range image sequence in at least one of the plurality of measuring regions (M _n ) of the component surface with regard to a changed local surface inclination and / or local optical properties of the component surface, characterized in that - the movement of the camera (K0) relative to the component (B _n ) or, conversely, when recording the measurement area image sequence is made continuously. Method according to Claim 1 , characterized in that the speed of the continuous relative movement between the camera (K0) and the component (B _n ) during the recording of the plurality of images (K _n ) per measuring range image of the measuring range image sequence is constant. Method according to Claim 1 , characterized in that the speed of the relative movement between the camera (K0) and the component (B _n ) between the images of the plurality of images (K _n ) per measuring range image of the measuring range image sequence is constant or variable variable. Method according to Claim 1 , characterized in that the global position of the component (B _n ) in space in a zero position before recording the measuring range image sequence by means of the camera (K0) detected three-dimensionally and stored as a desired position. Method according to Claim 1 , characterized in that the distance of the component (B _n ) relative to the camera (K0) in dependence of the component size at a predetermined distance from the nominal position of the component (B _n ), wherein the predetermined distance during the continuous movement within a predetermined distance accuracy (Δs _R ) is maintained. Method according to Claim 1 , characterized in that for each image of the measuring range image sequence a plurality of images (K _n ) are taken, which are to the at least one measuring range (M _n ) representing measuring range image of the component (B _n ) composed. Method according to Claim 6 , characterized in that the images of the plurality of images (K _n ) of the measuring range image sequence of the plurality of two-dimensional measuring ranges (M _n ) of the detected component surface to one another overlap (ΔS _U ). Method according to Claim 1 , characterized in that each measurement range (M _n ) is associated with a two-dimensional measurement location M (i _x , i _y ), in its entire image area with the image size (ΔS _Bx × ΔS _By ) of the measurement plane as the depth of field maximum by the depth of field of the component contour of the component (B _n ), wherein the camera (K0) orthogonal to the two-dimensional measurement location M (i _x , i _y ) is aligned, and respecting the orthogonality of a predetermined tolerance of the inclination is maintained compared to the measurement plane. Method according to Claim 1 , characterized in that each acquisition of the plurality of images (K _n ) of each image of the measurement area image sequence within an exposure period (Δt _B ) on a constant luminous flux (Δt _Lc ) with a predefined nominal luminous flux (Φν _N ) is made. Method according to Claim 6 and 7 , characterized in that the beginning of each first recording of the plurality of images (K _n ) of each image of the measuring range image sequence by a trigger (R _n ) away synchronous, in dependence on the traveled relative movement of the camera (K0) relative to the component (B _n ) or vice versa, so that the overlap length (ΔS _U ) is constant. Method according to Claim 10 , characterized in that a master trigger signal (R _n ), as soon as the camera (K0) is in accordance with the wegsynchronen control at a first shot of the plurality of images (K _n ) of each image of the measuring range image sequence position provided Triggered trigger chain, wherein by means of a slave trigger lighting the at least one illumination element (101B) of the at least one illumination device, the associated illumination process (L _n ) and in a temporal offset a slave trigger camera of the camera (K0) is controlled and started, by means of an image acquisition (K _n ) within the plateau according to Claim 9 is made after which the next master trigger signal (R _{n + 1} ) is triggered. Method according to Claim 1 and 6 , characterized in that - in a first step a) within an integrated circuit (FPGA) the recording of the multiple images (K _n ) takes place each image of the measuring range image sequence, and - in a second step b) within the integrated circuit (FPGA ) a displacement correction of the pre-planned superposed measuring areas is carried out (M _n), where (in addition to the pre-planned overlap .DELTA.S _U) additionally unplanned inaccuracies are corrected by the recordings of the (plurality of images K _n) of each image of the measurement range image sequence (K _n) and the Measuring ranges (M _n ) are "swelled out" relative to each other by a shift correction after the individual sections of the image acquisition (K _n ) for calculating a displacement correction to a processor (CPU) were transferred, the result as a correction data to the integrated circuit (FPGA) be returned to the offset correction, so that in the integrated circuit (FPGA) the displacement is carried out, and - in a third step c) according to the shape-from-shading algorithm, the calculation of the albedo (A) as a measure of the retroreflectivity of the component surface of the component (B _n ) in the at least one of a plurality of measuring ranges (M _n ) is derived, and - in a fourth step d) the result of the calculation of the shape-from-shading algorithm is filtered and corrected with corresponding filter and correction algorithms, and - in a fifth step e) an analysis of the regions of interest (M _n ) with respect to regions of interest (ROI) and a masking is performed, and - in a sixth step f), provide the regions of interest (ROI) with local coordinates, which correspond to those on the component surface of the corresponding component (B _n ) correspond to relevant surface errors, wherein the local coordinates are passed on to the processor (CPU) for further calculation. Method according to Claim 12 , characterized in that - in a seventh step g) a defect detection takes place, in which the potential defects (D _n ) are identified, and - in an eighth step h) the potential defects (D _n ) according to certain predeterminable parameters, in particular the Size, parameterized and classified into error classes, and - in a ninth step h) real defects (D _n ) are classified from the potential defects (D _n ), and - in a tenth step i) these genuine defects (D _n ) from the local coordinates of a measuring range (M _n ) the global coordinates according to the global position of the component (B _n ) after Claim 2 are determined, wherein the local coordinates of the real defects (D _n ) in the respective two-dimensional measuring range (M _n ) are three-dimensionally "mapped" to the plurality of measuring ranges (M _n ) of the component (B _n ), so that the real defects (D _n ) are arranged exactly in the three-dimensional space on the three-dimensional free-form component (B _n ), wherein - in an eleventh step j) the "mapped" real defects (D _n ) visualized on a monitor after being transmitted to a graphics card (GPU) are displayed, and - in a last twelfth step k) the "mapped" real defects (D _n ) are stored in error tables with appropriate localization with defect type and defect size and provided for further evaluation. Test head (101) with a housing part (101A) for optical shape detection and / or surface testing of a component (B _n ) using the method according to at least one of Claims 1 to 13 comprising at least one camera (K0) with at least one objective for capturing image data of at least one measurement area image of a measurement area image sequence of a component surface of the component (Bn), at least one switchable illumination element (101B) as a light source for illuminating at least one area of the Component surface of the component (Bn) during recording of the at least one measurement area image, wherein - the at least one illumination element (101B) outside the north pole of a hemispherical scattering body (101D) arranged inclined relative to a measuring plane (.DELTA.S _Bx × .DELTA.S _By ) of the measuring range image is, and - that at least one lens of the camera (K0) relative to the scattering body (101D) is arranged such that the lens of the camera (K0) through the viewing aperture (101D-1) of the scatterer (101D) at its north pole the illuminated area the component surface of the component (B _n ) parallel to the measurement plane (ΔS _Bx x ΔS _By ) of the measuring range image characterized in that - the at least one lighting element (101B) is associated with a Diffussorelement (101B-1), which scatters the light emitted by the at least one illumination element (101B), which then at a predetermined angle to an inner wall of the housing part ( 101A), wherein - the inner wall of the housing part (101A) is coated to diffuse the light so that the inner wall acts as a light reflector (101G) and as a diffuser, and the scattered light radiates from the inner wall at a reflection angle, which subsequently a surface of the scattering body (101D) facing away from the component (B _n ) strikes, the scattering body (101D) distributing the light passing through it on the exit side of the scattering body (101D), which projects onto the area of the component surface of the component (B _n ) to be illuminated. meets. Test head (101) after Claim 14 , characterized in that the at least one illumination element (101B) for tilt adjustment relative to the measuring plane (ΔS _Bx × ΔS _B ) of the component (B _n ) at least one Neigungsverstellelement (101E), the indirectly or directly with the housing part (101A) in combination stands. Test head (101) after Claim 14 characterized in that the diffuser element (101B-1) is disposed on the lighting element (101B). Test head (101) after Claim 14 , characterized in that a white special color is formed as a coating of the scattering and reflecting inner wall, which has on its inside a rough surface with a predeterminable surface roughness. Test head (101) after Claim 14 , characterized in that the wall thickness of the hemispherical scattering body (101D) in the lower part - near the equator - in the direction of the upper part - toward the north pole - towards the upper part towards clearly decreases. Test head (101) after Claim 14 , characterized in that the housing part (101A) is a hollow cylinder. Test arrangement, characterized by a robot-guided guided test head (101) after at least one of Claims 14 to 19 opposite to a arranged for optical shape detection and / or surface inspection component (B _n ), wherein the test head (101) for recording a measuring range image sequence by means of the camera (K0) in several measuring ranges (M _n ) of the component (B _n ) by a movement the camera (K0) against the component (B _n ) or vice versa by the robot (200) is guided. Test arrangement according to Claim 20 , characterized in that the global position of the component (B _n ) for 6D-Bauteilillokalisierung in space (x, y, z, α, β, γ) with a system, in particular a stereo camera system (102), determined and a 6D reference position wherein at least one calibration is performed between a robot arm (201) of the robot (200) and the system (102), thereby referencing the component (B _n ) in three-dimensional space in its desired position relative to the robotic guided test head (101) is present in a predefinable distance constancy between the test head (101) and component surface of the component (B _n ).

Images