DE102018209032A1 - Apparatus and method for automatically determining the position of the bar code of a tire or green tire and a corresponding computer program, computer program product and a computer-readable data carrier - Google Patents

Abstract

The invention relates to a method for automatically determining the position of the barcode of a tire or green tire, comprising at least the following steps: a) providing or producing a tire or green tire against a background, b) recording a first image of the one provided or produced in step a) Tire or green tire using a recording device comprising a lens element with a predetermined exposure time, c) determining at least one edge of the tire or green tire on the first image as a function of the mean value of the intensity of the entire first image or the intensity of a section of the first image, d) determining the position of the barcode by means of one edge determined in step c) or by means of the more than one edge of the tire or green tire determined in step c). The invention also relates to a device for automatically determining the center of a tire or green tire, for carrying out the method, and a corresponding computer program with program code means and a corresponding computer program product.

Description

The invention relates to a method for automatically determining the position of the barcode of a tire or green tire. The invention also relates to a device for automatically determining the center of a tire or green tire, for carrying out the method and a corresponding computer program with program code means, a corresponding computer program product and a computer-readable data carrier.

An important topic for today's companies is the topic of "Industry 4.0", in which the manufacturing processes should be automated as much as possible and which should enable the production conditions of every production step of a product to be recorded comprehensibly. This not only allows an individualized production of different products but also an even better control over the quality management. Among other things, this is ensured in the tire industry by providing each manufactured tire with its own barcode.

Tires are provided on the sidewalls and tread with specific markings during the production process, e.g. describe the individual position of the center of gravity of a manufactured tire. Since the center of gravity and other individual tire parameters, and thus the location of their markings, may vary with each tire, even within a manufacturing line, due to small differences in manufacturing conditions, their positions must be applied relative to a reference point. Knowing the location of this reference point, it can be seen from the relative position to the reference point, the location of the tire parameters on each individual tire. The reference point for such specific markings today is the center of the barcode of a tire. The barcode must therefore first be found on the tire to be marked before a person or computer can determine the location of the remaining tire-specific markings. In the methods known in the art, the entire tire surface, and possibly beyond it, is scanned by appropriate means to find the bar code. Such an approach not only takes a correspondingly long time, but also requires a relatively large computing capacity.

An object of the invention is to provide an improved method for determining the position of the tire center and / or the barcode of a tire or green tire.

1. a) Bereitstellen oder Herstellen eines Reifens oder Reifenrohlings vor einem Hintergrund,
2. b) Aufnehmen eines ersten Bildes des in Schritt a) bereitgestellten oder hergestellten Reifens oder Reifenrohlings mittels eines ein Linsenelement umfassenden Aufnahmegeräts,
3. c) Ermitteln des Mittelwertes der Intensität des gesamten ersten Bildes oder der Intensität eines Ausschnitts des ersten Bildes und Ermitteln mindestens einer Kante des Reifens oder Reifenrohlings auf dem ersten Bild in Abhängigkeit des Mittelwerts der Intensität des gesamten ersten Bildes oder der Intensität des Ausschnitts des ersten Bildes,
4. d) Ermitteln der Position des Barcodes im ersten Bild mittels der in Schritt c) ermittelten einen Kante oder mittels der in Schritt c) ermittelten mindestens einen Kante des Reifens oder Reifenrohlings.

This object is achieved according to the invention by a method for automatically determining the position of the barcode of a tire or green tire, comprising at least the following steps:

1. a) providing or producing a tire or green tire against a background,
2. b) taking a first image of the tire or green tire provided or produced in step a) by means of a recording device comprising a lens element,
3. c) determining the mean value of the intensity of the entire first image or the intensity of a section of the first image and determining at least one edge of the tire or green tire on the first image as a function of the average of the intensity of the entire first image or the intensity of the section of the first image .
4. d) determining the position of the barcode in the first image by means of the one edge determined in step c) or by means of the at least one edge of the tire or green tire determined in step c).

• - entweder einer Kante eines Reifen(-rohling)s, insbesondere der Kante des unteren Reifendurchmessers eines Reifen(-rohling)s im ersten Bild, oder
• - einem anderen Übergang

zuordnen kann. Es ist daher erfindungsgemäß sinnvoll den für jeden Pixel aufgenommenen Intensitätswert mithilfe des vorstehend beschriebenen Mittelwertes der relativen Intensität zu normieren und hierdurch den Erwartungsbereich, in welchem ein bestimmte Intensitätsunterschied mit großer Wahrscheinlichkeit einer Kante eines Reifens oder eines Reifenrohlings entspricht, zu verkleinern. Dies hat den technischen Vorteil, dass sowohl Rechenzeit als auch Rechenkapazität gespart wird.Since there are usually a large number of intensity differences in the recorded first image for various reasons, in an automated process, the edges of the tire or green tire must be detected as reliably as possible. Due to frequently changing conditions, such as the ambient light or surface changes of the equipment used or in particular due to the different-looking tires or green tires, the intensity differences in the first image, which belong to a green tire or to a tire, usually different degrees. It is therefore an outstanding achievement of the present invention that the edges of any underlying tire or tire tire can be detected in a shorter time or with less computing capacity within a computerized process, if the relative intensity of the ambient exposure or exposure of the exposure equipment is previously determined has been. The determination of this relative intensity results in a computer or computing unit reading the intensity differences in the first image in a shorter time or with less computing capacity

• either an edge of a tire, in particular the edge of the lower tire diameter of a tire in the first image, or
• - another transition

can assign. It is therefore useful according to the invention to normalize the intensity value recorded for each pixel by means of the above-described mean value of the relative intensity and thereby to reduce the expected range in which a certain intensity difference corresponds with high probability to an edge of a tire or a green tire. This has the technical advantage that both computing time and computing capacity is saved.

Preferred is a method as described above, wherein the intensity values of all pixels of the first image are normalized or divided by the determined mean value of the intensity.

The method according to the invention is also intended to reliably detect the position of an edge of a tire or of a green tire when the first image is taken with only a short exposure time, in particular with the exposure times described below. Although a short exposure time has the disadvantage that the intensity differences of the edges to be determined are smaller and thus more difficult to determine. In the worst case, the barcodes of the particular tire or tire blank can not be distinguished from the sidewall. Therefore, it has been a long-felt need in the automation industry of the tire industry to expose the tire or green tire so as to simultaneously identify the edges of the tire or green tire and thus the corresponding tire type as well as the position of the bar code on the tire , This is possible by means of a method according to the invention. This enormously speeds up an automated manufacturing process, as the position of the barcode can be detected more quickly.

Preferably, a method as described above or as described above as preferred, wherein the steps of the inventive method are performed several times to determine the position of the bar codes of different tires or different green tires.

Also preferred is a method as described above or as described above as preferred, wherein the one edge determined in step c) is the edge of the lower rim diameter of the tire or green tire in the first image. The advantage of this aspect of the present invention is that, in particular, the edge of the lower rim diameter can be recognized particularly well on the first image since it differs well from a background described above or below and thus detected quickly and without error by a computer or a computing unit can be.

Also preferred is a method as described above or as described above as preferred, wherein the recording of the first image in step b) takes place with a predetermined exposure time.

• - eine weiße Fläche ist, bevorzugt die Oberfläche eines Förderbandes, und/oder
• - eine Fläche oder die Oberfläche eines Förderbandes ist, welche elektromagnetische Strahlung mit einer Wellenlänge im Bereich von 800 nm bis 2000 nm mindestens zu 10 % reflektiert, bezogen auf die Gesamtintensität der Strahlung. Bevorzugt reflektiert die Oberfläche sogar 30% der elektromagnetischen Strahlung mit einer Wellenlänge im Bereich von 800 nm bis 2000 nm.

Also preferred is a method as described above or as described above as preferred, wherein the background

• a white surface is, preferably the surface of a conveyor belt, and / or
• - Is a surface or the surface of a conveyor belt, which reflects at least 10% electromagnetic radiation having a wavelength in the range of 800 nm to 2000 nm, based on the total intensity of the radiation. Preferably, the surface even reflects 30% of the electromagnetic radiation having a wavelength in the range of 800 nm to 2000 nm.

Such a surface or surface which reflects at least 10% of electromagnetic radiation having a wavelength in the range of 800 nm to 2000 nm consists, for example, of rubber or a material selected from the group consisting of aluminum, polypropylene, polyethylene and polyethylene terephthalate.

An advantage of the above-described aspect of the present invention is that electromagnetic radiation in the range described above is particularly good at the edges of tires or green tires and less so as to reflect soils or other defects in production.

Also preferred is a method as described above or as described above as preferred, wherein in step c) determining the average value and / or determining the one or at least one edge of the tire or the green tire by means of a computing unit or by means of a computer comprising a Arithmetic unit is done.

Also preferred is a method as described above or as described above as preferred wherein the first image taken in step b) has an aspect ratio, i. a side format, in the range of 16: 3 to 3:16, preferably from 4: 3 to 3: 4, more preferably 1: 1, and most preferably the entire tire or the entire green tire shows the position of the barcode in Step d) is determined.

• - die Auflösung der Fotokamera mindestens 1200 Pixel mal 1200 Pixel ist und/oder
• - die Lichtstärke des verwendeten Objektives der Fotokamera im Bereich von 1 bis 22 liegt, bevorzugt 5, 6 ist,

und besonders bevorzugt das Verhältnis von Signal zum Rauschen der Fotokamera mindestens 3 ist, bevorzugt mindestens 6.Also preferred is a method as described above or as above described, wherein the recording device with the lens element is a photo camera with a lens and preferred

• - The resolution of the camera is at least 1200 pixels by 1200 pixels and / or
• the light intensity of the camera lens used is in the range from 1 to 22, preferably 5, 6,

and particularly preferably the ratio of signal to noise of the camera is at least 3, preferably at least 6.

An advantage of the preferred method according to the invention as described above is that due to the nomination by the mean of the relative intensity as described above, the signal to noise ratio is not changed and thus the edges are also changed at a signal to noise ratio of 3 and 6, respectively can still be reliably determined. This differs from methods in which the normalization does not occur as in a method according to the invention by a division of the individual intensity value of a pixel by the determined mean value, but a mathematical subtraction takes place.

Also preferred is a method as described above or as described above as preferred, wherein the color temperature of the light source for the exposure time described above is particularly preferably in the range of 400 nm to 2000 nm, most preferably 800 to 1050 nm, particularly particularly preferably 850 nm is.

The advantage of the light source described above is that by means of this light, edges of a tire or a green tire have particularly large intensity differences in a captured image.

Also preferred is a method as described above or as described above as preferred, wherein taking a second image of the tire or green tire picked up in step b) by means of a recording device comprising a lens element, wherein preferably the optical axis of the lens element when recording the second image so aligned as in step b), and wherein particularly preferably the exposure time is the same as in step b), and most preferably the exposure intensity when taking the second image has been adjusted so that a maximum contrast of the edges of the one provided or produced in step a) Tire or green tire in the second image, which lie on the second image within the visible tire surface.

The advantage of taking a second image is that the exposure time can once again be adjusted to achieve a greater intensity difference of the various edges in the first image and thus be able to reliably determine which edges belong to the tire or green tire and which do not.

• - die Oberfläche eines Förderbandes ist, auf dem der Reifen oder der Reifenrohling liegt, oder
• - parallel zu und innerhalb der Oberfläche des Förderbandes ist, auf dem der Reifen oder der Reifenrohling liegt.

Preferred is a method as described above or as described above as preferred, wherein once before the method, the distance between the lens element and the tire or the green tire facing surface of the background of a computing unit is provided. In this case, it is preferable for the surface of the background facing the tire or the green tire

• - is the surface of a conveyor belt on which the tire or green tire lies, or
• - is parallel to and within the surface of the conveyor belt on which the tire or green tire lies.

An advantage of the above-described aspect of the present invention is that the focus of the imaging device with the lens element can be adjusted substantially to the level of the background or the surface of the conveyor belt prior to the process, such that the edges of the tire captured in the first image or green tires can be seen sharper in the first picture. This increases the reliability of the inventive method described above, since the intensity differences between two pixels thus become generally larger. When injecting in particular the opening angle of the recording device Zinses lens element is chosen so that the entire tire appears on the first image and you reach a minimum resolution of 2 mm per pixel at the level of the background or on the surface of the conveyor belt.

Preferably, a method as described above or as described above as preferred, wherein before each step a) the specific data of the tire or green tire are provided to a computing unit and the determination of the position of the barcode in step d) additionally by means of these specific data of the Tire or tire blanks and the arithmetic unit takes place.

As already explained above, it is now possible to closely follow the manufacturing conditions of each tire in a factory, especially because each green tire has an individual barcode. By capturing the Specific data of a tire or green tire may limit the region on the first image where the bar code may be on the tire or green tire. This region is also called the critical region in the context of the present invention and should be as small as possible in order to save the time and / or computing capacity of said arithmetic unit. This is preferably done by determining the rim diameter of the respective tire or green tire located closer to the background in the first image and determining therefrom the rim diameter in the first image which is farther from the background. The determination of the critical region is given below by way of example in the description of the figures 3 described.

The limitation of the region to be searched in the first image to a critical region makes sense in accordance with the invention since otherwise a computer must examine the transitions of all pixels of the first image. This takes a very long time, since each pixel has four transitions to adjacent pixels. Due to the restriction of the area to be searched, therefore, the required computing time and capacity are reduced by a multiple. This is another technical advantage of the above aspect of the present invention.

• - die optische Achse des Linsenelements beim Aufnehmen des ersten Bildes entlang der Achse des Reifens oder Reifenrohlings verläuft und senkrecht zur radialen Richtung des Reifens oder Reifenrohlings ausgerichtet ist, und/oder
• - die Belichtungszeit zum Aufnehmen des ersten Bildes im Bereich von 10 µs bis 300 ms liegt und/oder die Beleuchtungsstärke zum Aufnehmen des ersten Bildes im Bereich von 0,1 Lux bis 10000 Lux liegt.

Preferred is a method as described above or as described above as being preferred, wherein in step b)

• - The optical axis of the lens element during recording of the first image along the axis of the tire or green tire extends and is aligned perpendicular to the radial direction of the tire or green tire, and / or
• the exposure time for taking the first image is in the range of 10 μs to 300 ms and / or the illuminance for taking the first image is in the range of 0.1 lux to 10,000 lux.

An advantage of the above-described aspect of the present invention is that the method according to the invention becomes even more reliable since the respective edges in the first image are highlighted by even greater differences in intensity compared to inventive or non-inventive methods with different exposure times or a different orientation of the optical Axis of the lens element.

Preferably, a method as described above or as described above as preferred, wherein in step c) the average of the intensity of a section of the first image is determined, wherein the cutout in the first image within the reflection of the background for the tire or green tire is arranged wherein the section preferably comprises 1% to 10% of the pixels of the total number of pixels of the first image and / or is arranged in the center or image center of the first image. The cutout is preferably square-shaped.

An advantage of the above-described aspect of the present invention is that by using a background described above for determining the mean value of the intensity, changes in the exposure can still be accurately determined.

Preferably, a method as described above or as described above as preferred, wherein in step d) both the center of the tire or green tire and the center of the barcode of the tire or green tire is determined.

An advantage of the above-described aspect of the present invention is that the determination of the center of the tire or green tire makes it possible to determine a critical region as above or as described below and thus to limit the range in which the barcode could be located.

Particularly preferably, a method as described above or as described above as preferred, wherein the center of the tire or green tire is determined in step d) by determining a rim diameter of the tire or green tire, wherein the rim diameter by means of the intensity differences two or more than two adjacent Pixels along a straight line and optionally along other straight lines in the first image is determined, wherein a rectilinear line in the first image preferably along the background, wherein a straight line is particularly preferably parallel to the conveying direction of a conveyor belt and through the center of the image of the first Picture runs. Preferably, this determination is made with the one straight line as described above and a certain number of further straight lines. This particular number is preferably in the range of 4 to 16, more preferably in the range of 8 to 12, most preferably 10.

An advantage of the above-described aspect of the present invention is that the lower rim diameter can be determined efficiently and quickly by means of a straight line starting from the center of the first image, in particular if there is a background described above or below behind the tire, and thus the first larger one Intensity difference of adjacent pixels equal to the edge of the lower rim diameter corresponds. However, it is particularly advantageous if further straight lines are used as described above to detect a plurality of points on the edge of the lower rim diameter in the first image. This particularly advantageous method is more reliable, since any soiling, which cover a corresponding edge in the first image, can be detected as so-called outliers in the process. When determining an outlier, the arithmetic unit can then only consider the points of the rectilinear line in the corresponding evaluation, which do not represent an outlier and in the first image can be approximated as exactly as possible to a circle by means of statistical regression. The circle approximated in the first image will thus run in a very accurate manner along the lower rim diameter in the first image. Subsequently, the center of the tire can be recognized by means of the circle drawn in the first image.

In the context of the present invention, the lower rim diameter corresponds to the rim diameter closer to the background. In the context of the present invention, the upper rim diameter corresponds to the rim diameter farther from the background.

• - ein Schwellwert zur Kantenzuordnung berechnet wird und dieser Schwellwert zur Kantenzuordnung durch den in Schritt c) ermittelten Mittelwert der Intensität normiert wird und/oder
• - bei Überschreiten eines in Schritt d) ermittelten Intensitätsunterschiedes über den Schwellwert zur Kantenzuordnung der überschreitende Intensitätsunterschied einer Kante zugeordnet wird.

Particularly preferred is a method as described above or as described above as preferred, wherein

• a threshold value for the edge allocation is calculated and this threshold value for the edge assignment is normalized by the mean value of the intensity determined in step c) and / or
• - When exceeding an intensity difference determined in step d) above the threshold value for the edge assignment, the exceeding intensity difference of an edge is assigned.

An advantage of the above-described aspect of the present invention is that only the height of the threshold, which is an indicator of the edge to be found, needs to be changed and not every pixel in the image. This saves an enormous amount of computation time compared to standardizing the entire image as described above.

wobei

=

in Schritt c) ermittelte Mittelwert der Intensität,

N =

Standardintensität bei Standardbedingungen,

S =

Schwellwert zur Kantenfindung.

The default value (ie "default value") for the threshold value is set, for example, to 20 intensity units under self-defined standard conditions, whereby a standard intensity N is present under these standard conditions. The mean value of the intensity determined in step c) is then multiplied by the value 20 in the example and divided by the standard intensity N. The following formula follows in this example: $$S^{ScHwellwert}=20\cdot \frac{I_{ScHrittc)}^{\phi }}{N}.$$

in which

=

in step c) determined mean intensity,

N =

Standard intensity at standard conditions,

S =

Threshold for edge detection.

Particularly preferred is a method as described above or as described above as preferred, wherein prior to step a) a standard intensity of the entire first image or the intensity of a section of the first image is determined under standard conditions.

Particularly preferred is a method as described above or as described above as preferred, wherein the further rectilinear lines are parallel to the one straight line described above, wherein each further rectilinear line preferably has the same distance to the respective adjacent line. Very particular preference is given to a method according to the invention as described above or as described above as preferred, where the straight line and the further straight lines in the first image are arranged so that the distance to the respective adjacent line in the first image is 1/80 of the width of the first Image or 20 pixels in the first image with a resolution of the image width of 1600 pixels. It is preferred in this case if the background described above or a background described above is perpendicular to the optical axis of the lens element. It is particularly preferred if the background is also square and has such a width and a height in the first image that it extends further than the lower rim diameter in the first image.

Very particular preference is also given to a process as described above or as described above as being preferred, in particular as described above as being particularly preferred, where two, three, four, five, six, seven, eight, nine, ten, twenty, thirty, forty, fifty, one hundred, two hundred, three hundred, or five hundred intensity differences in the first image are determined to determine two, three, four, five, six, seven, eight, nine, or ten edges of the tire or green tire provided or manufactured in step a). More preferably, 22 intensity differences are determined in the first image to determine four edges of the tire or green tire.

Preferably, a method as described above or as described above as preferred, wherein in step d) a critical region in the first image on the surface of the tire or green tire is determined, wherein the critical region in the first image preferably a maximum of 20%, more preferably maximum 10%, most preferably at most 5% of the pixels of the first image, in each case based on the total number of pixels of the first image, wherein the critical region in the first image is preferably annular and the outer and inner diameter of the annular critical region as described above is determined on the basis of or a rim diameter of the tire or green tire. Thus, the critical region is the region between two circles formed in the first image and concentric circles, the centers of these two circles in the first image being at the midpoint of the center of the tire as described above. The diameters of the two circles depend on the respective tire type and are determined by the arithmetic unit based on the tire data previously provided on the arithmetic unit.
In addition, to the critical region, the above and below described various preferred embodiments apply. The advantages of the above-described aspect of the present invention are described above or below. The determination of a critical region is given in detail and according to a possible embodiment below in the context of the description of the figures 3 again explained in addition.

1. a) Bereitstellen oder Herstellen eines Reifens oder Reifenrohlings vor einem Hintergrund,
2. b) Aufnehmen eines ersten Bildes des in Schritt a) bereitgestellten oder hergestellten Reifens oder Reifenrohlings mittels eines ein Linsenelement umfassenden Aufnahmegeräts mit einer vorbestimmten Belichtungszeit,
3. c) Ermitteln des Mittelwertes der Intensität des gesamten ersten Bildes oder der Intensität eines Ausschnitts des ersten Bildes und Ermitteln mindestens einer Kante des Reifens oder Reifenrohlings auf dem ersten Bild in Abhängigkeit des Mittelwerts der Intensität des gesamten ersten Bildes oder der Intensität des Ausschnitts des ersten Bildes,
4. d) Ermitteln der Position des Barcodes mittels der in Schritt c) ermittelten einen Kante oder mittels der in Schritt c) ermittelten mehr als einen Kante des Reifens oder Reifenrohlings,

wobei

• - vor jedem Schritt a) die spezifischen Daten des Reifens oder Reifenrohlings einer Recheneinheit zur Verfügung gestellt werden und die Ermittlung der Position des Barcodes in Schritt d) zusätzlich mittels dieser spezifischen Daten des Reifens oder Reifenrohlings und der Recheneinheit erfolgt,
• - einmalig vor dem Verfahren der Abstand zwischen dem Linsenelement und der dem Reifen oder dem Reifenrohling zugewandten Oberfläche des Hintergrunds einer Recheneinheit zur Verfügung gestellt wird,
• - die Belichtungszeit zum Aufnehmen des ersten Bildes im Bereich von 10 µs bis 300 ms liegt und die Beleuchtungsstärke zum Aufnehmen des ersten Bildes im Bereich von 0,1 Lux bis 10000 Lux liegt,
• - in Schritt c) der Mittelwert der Intensität eines Ausschnitts des ersten Bildes ermittelt wird, wobei der Ausschnitt im ersten Bild innerhalb der Reflektion des Hintergrundes für den Reifen oder Reifenrohling angeordnet ist, wobei der Ausschnitt 1 % bis 10 % der Pixel der Gesamtpixelanzahl des ersten Bildes umfasst und im Zentrum des ersten Bildes angeordnet ist,
• - wobei in Schritt d) sowohl der Mittelpunkt des Reifens oder Reifenrohlings als auch der Mittelpunkt des Barcodes des Reifens oder Reifenrohlings ermittelt wird,
• - der Mittelpunkt des Reifens oder Reifenrohlings in Schritt d) mittels der Bestimmung des näher am Hintergrund befindlichen Felgendurchmessers des Reifens oder Reifenrohlings ermittelt wird, wobei der Felgendurchmesser mittels der Intensitätsunterschiede entlang einer geradlinigen Linie und entlang zehn weiterer geradlinigen Linien im ersten Bild ermittelt wird, wobei die eine geradlinige Linie im ersten Bild entlang des Hintergrundes verläuft, wobei die eine geradlinige Linie durch den Bildmittelpunkt des ersten Bildes verläuft, wobei jede Linie einen Abstand von 20 Pixeln zur benachbarten Linie aufweist und
• - in Schritt d) eine kritische Region im ersten Bild auf der Oberfläche des Reifens oder Reifenrohlings bestimmt wird, wobei die kritische Region im ersten Bild bevorzugt maximal 20 % der Pixel des ersten Bildes ausmacht, jeweils bezogen auf die Gesamtzahl der Pixel des ersten Bildes, wobei die kritische Region im ersten Bild ringförmig ist und der Außen- und Innendurchmesser der ringförmigen kritischen Region auf Basis des Felgendurchmessers und der spezifischen Daten des Reifens oder Reifenrohlings ermittelt wird

Particularly preferred is a method as described above comprising the following steps:

1. a) providing or producing a tire or green tire against a background,
2. b) taking a first image of the tire or green tire provided or produced in step a) by means of a recording device comprising a lens element with a predetermined exposure time,
3. c) determining the mean value of the intensity of the entire first image or the intensity of a section of the first image and determining at least one edge of the tire or green tire on the first image as a function of the average of the intensity of the entire first image or the intensity of the section of the first image .
4. d) determining the position of the barcode by means of the one edge determined in step c) or by means of the more than one edge of the tire or green tire determined in step c),

in which

• before each step a) the specific data of the tire or green tire is made available to a computing unit and the determination of the position of the barcode in step d) additionally takes place by means of this specific data of the tire or green tire and the computing unit,
• once, before the method, the distance between the lens element and the surface of the background of the processing unit facing the tire or the green tire is made available to a processor,
• the exposure time for taking the first image is in the range of 10 μs to 300 ms, and the illuminance for taking the first image is in the range of 0.1 lux to 10,000 lux,
• in step c) the average of the intensity of a section of the first image is determined, the section in the first image being located within the reflection of the background for the tire or green tire, the section comprising 1% to 10% of the pixels of the total number of pixels of the first Image and is located in the center of the first image,
• wherein in step d) both the center of the tire or green tire and the center of the barcode of the tire or green tire are determined,
• the center of the tire or green tire is determined in step d) by determining the rim diameter of the tire or green tire closer to the background, the rim diameter being determined by means of the intensity differences along a straight line and along ten further straight lines in the first image which is a straight line in the first image along the background, wherein the one straight line through the center of the image of the first image, each line having a distance of 20 pixels to the adjacent line, and
• a critical region in the first image on the surface of the tire or green tire is determined in step d), the critical region in the first image preferably representing at most 20% of the pixels of the first image, in each case based on the total number of pixels of the first image, wherein the critical region in the first image is annular and the outer and inner diameters of the annular critical region are determined based on the rim diameter and the specific data of the tire or green tire

The above-described advantageous aspects of inventive methods for automatically determining the position of the barcode of a tire or green tire also apply to all aspects of a device described below and the advantageous aspects of inventive devices discussed below apply correspondingly to all aspects of inventive methods for automatically determining the position of the barcode Tire or tire blanks.

• - mindestens ein Aufnahmegerät umfassend ein Linsenelement,
• - einen Hintergrund, wobei die optische Achse des Linsenelements bevorzugt senkrecht zum Hintergrund verläuft,
• - einer Ablagefläche zum Ablegen eines Reifens oder eines Reifenrohlings, wobei die Ablagefläche bevorzugt ein Förderband ist,
• - eine mit dem Aufnahmegerät verbundene Recheneinheit, welche dazu eingerichtet ist, den Mittelpunkt eines Reifens oder Reifenrohlings mittels des Aufnehmens eines, zweier oder mehr als zwei Bilder des Reifens oder Reifenrohlings zu ermitteln.

The invention also relates to a device for automatically determining the center of a tire or green tire, for carrying out a method as described above or as described above as being preferred, the device preferably having one, two, three or all of the following units:

• at least one recording device comprising a lens element,
• a background, wherein the optical axis of the lens element is preferably perpendicular to the background,
• a storage surface for depositing a tire or a green tire, wherein the storage surface is preferably a conveyor belt,
• a calculating unit connected to the recording device, which is set up to determine the center of a tire or green tire by taking one, two or more than two images of the tire or green tire.

The above-described advantageous aspects of methods according to the invention for automatically determining the position of the barcode of a tire or green tire or devices according to the invention also apply to all aspects of computer programs or computer program products described below and to the data carriers described below and the advantageous aspects of computer programs or computer program products according to the invention described below Data carriers accordingly apply to all aspects of inventive methods for the automated determination of the position of the barcode of a tire or green tire or devices according to the invention.

The invention also relates to a computer program with program code means for performing one or all of the steps of a method as described above or as described above as preferred when the computer program is on a computer operatively connected to the recording device, in particular with a computing unit as described above or as above as described preferred, is executed.

The invention also relates to a computer program product having program code means which are stored on a computer-readable medium to perform one or all of the steps of a method as described above or as described above as preferred when the computer program is on a computer operatively connected to the recording device, in particular with an arithmetic unit as described above or as described above as being preferred.

The invention also relates to a computer-readable data medium on which the computer program described above or the computer program product described above is stored.

list of figures

• 1: Ansicht auf ein schematisch dargestelltes erstes Bild mit einem Quadrat im Zentrum und einem Reifen oder Reifenrohling in einer erfindungsgemäßen Vorrichtung, wobei innerhalb des Quadrats der Mittelwert der Intensität bestimmt werden soll;
• 2: Ansicht auf ein schematisch dargestelltes erstes Bild mit geradlinigen Linien, wobei auf dem ersten Bild ein Reifen oder Reifenrohling mit einem Barcode in einer erfindungsgemäßen Vorrichtung während des Schrittes c) eines erfindungsgemäßen Verfahrens zu sehen ist;
• 3: Seitenansicht auf eine erfindungsgemäße Vorrichtung mit einem Reifen oder Reifenrohling

It shows:

• 1 : View of a schematically represented first image with a square in the center and a tire or green tire in a device according to the invention, wherein within the square the mean value of the intensity is to be determined;
• 2 : View of a schematically represented first image with straight lines, the first image showing a tire or green tire with a barcode in a device according to the invention during step c) of a method according to the invention;
• 3 : Side view of an inventive device with a tire or green tire

• In einem ersten Schritt wird der Reifen 1 mittels eines geeigneten Förderbandes 25 unter die Kamera 5 und in den Aufnahmebereich der Kamera 5 gefahren. Der Aufnahmebereich der Kamera 5 ist dabei der Bereich, welcher vom ersten Bild 4 erfasst wird und in 1 und 2 durch die durchgezogene Umrandung dargestellt ist. Senkrecht unterhalb der Linse 6 der Kamera 5 sollte sich der Hintergrund 3 mit der dem Reifen 1 zugewandten Oberfläche 11 befinden. Die Oberfläche 11 des Hintergrundes 3 sollte dabei ausreichend groß gewählt werden, so dass das Quadrat 9 zur Bestimmung des Mittelwertes der Intensität innerhalb des Quadrate 9 des ersten Bildes 4 vollständig über der Oberfläche 11 im ersten Bild 4 liegt, wie dies in 1 dargestellt ist.
• In einem zweiten Schritt wird dann das erste Bild 4 mit einer kurzen Belichtungszeit aufgenommen, so dass ein Überblenden des Barcodes 2 und der Reflexionen auf der restlichen Reifenoberfläche 26 reduziert werden. Anschließend wird ein Quadrat 9 wie vorstehend beschrieben über das erste Bild 4 gelegt. Hierdurch entsteht ein erstes Bild 4 wie in 1 schematisch dargestellt. Mithilfe des nun aufgenommen ersten Bildes 4 kann nun der Mittelwelt der Intensität innerhalb des Quadrates 9 bestimmt werden, um geeignete Schwellenwerte zur Bestimmung der Positionen der verschiedenen Kanten 7, 8, 8a, 8b auf der Reifenoberfläche 26 zu finden. Die Bestimmung dieser Schwellenwerte auf Basis eines Ausschnittes 9 des ersten Bildes 4 stellt einen großen Vorteil der vorliegenden Erfindung dar, da somit die verschiedenen Kanten eines Reifens schneller und zuverlässiger gefunden werden können.
• In einem dritten Schritt wird wieder das erste Bild 4, wie es ohne das Quadrat 9 aufgenommen wurde, so bearbeitet, dass mehrere zu einander parallel verlaufende geradlinige Linien 18, 19 entlang der Förderrichtung 31 über das erste Bild 4 gelegt werden, wobei die mittlere Linie 18 der geradlinigen Linien 18, 19 durch den Bildmittelpunkt 20 des ersten Bildes 4 verläuft. Es können hierzu beispielsweise 11 geradlinige Linien oder wie in 2 dargestellt 3 geradlinige Linien verwendet werden. Anschließend werden von der Linienmitte nach außen gehend die einzelnen Pixel einer geradlinigen Linien 18, 19 nacheinander auf ihre Helligkeit bestimmt, um ausreichend große Intensitätsunterschiede zwischen aufeinander folgenden Pixeln entlang der geradlinigen Linien 18, 19 zu identifizieren, welche zu den Kanten 7, 8, 8a, 8b eines Reifens 1 gehören. Diese ausreichend großen Intensitätsunterschiede werden dabei wie vorstehend beschrieben mittels eines Schwellwerts definiert, welcher wie vorstehend beschrieben in einem erfindungsgemäßen Verfahren mithilfe des Mittelwerts der Intensität in dem Quadrat 9 des ersten Bildes 4 bestimmt wird.

The inventive method should again with reference to the 1 to 3 to be introduced:

• In a first step, the tire becomes 1 by means of a suitable conveyor belt 25 under the camera 5 and in the shooting range of the camera 5 hazards. The shooting range of the camera 5 is the area, which from the first picture 4 is recorded and in 1 and 2 is shown by the solid outline. Vertically below the lens 6 the camera 5 should be the background 3 with the tire 1 facing surface 11 are located. The surface 11 of the background 3 should be chosen large enough so that the square 9 for determining the mean of the intensity within the squares 9 of the first picture 4 completely over the surface 11 in the first picture 4 lies, as in 1 is shown.
• In a second step, the first picture is taken 4 recorded with a short shutter speed, allowing a fading of the barcode 2 and the reflections on the rest of the tire surface 26 be reduced. Subsequently, a square becomes 9 as described above on the first image 4 placed. This creates a first picture 4 as in 1 shown schematically. Using the now captured first image 4 can now the middle world of intensity within the square 9 be determined to provide suitable thresholds for determining the positions of the various edges 7 . 8th . 8a . 8b on the tire surface 26 to find. The determination of these thresholds based on a section 9 of the first picture 4 represents a great advantage of the present invention, since thus the different edges of a tire can be found faster and more reliably.
• In a third step, the first picture becomes again 4 as it is without the square 9 was recorded, edited so that several parallel to each other rectilinear lines 18 . 19 along the conveying direction 31 about the first picture 4 be placed, the middle line 18 the straight lines 18 . 19 through the center of the picture 20 of the first picture 4 runs. For example, 11 straight lines or as in 2 shown 3 straight lines are used. Then, going from the middle of the line to the outside, the individual pixels of a straight line 18 . 19 in turn determined for their brightness to sufficiently large intensity differences between successive pixels along the rectilinear lines 18 . 19 to identify which to the edges 7 . 8th . 8a . 8b a tire 1 belong. As described above, these sufficiently large intensity differences are defined by means of a threshold value which, as described above, is determined in a method according to the invention by means of the mean value of the intensity in the square 9 of the first picture 4 is determined.

Is between the center of the line to the top of the first image 4 a sufficiently large intensity difference on the one and optionally the other straight lines found, ie, for example, the threshold is exceeded, and is between the line center to the lower edge of the first image 4 also found a sufficiently large intensity difference on the same same straight line, so is a first circle along the lower rim diameter 8a adjusted by the differences in intensity found. This means that, at best, on the one straight line 18 and on each of the other straight lines 19 exactly two intensity differences are assigned to edges. From the first circle and the specific tire data, two further circles are then defined to define the annular critical region 21 calculated, which is the outside diameter 22 and the inside diameter 23 represent the annular critical region. Outliers are sorted out. Using the critical region 21 can thus change the position of the barcode 2 and then the center 16 of the tire 1 be determined. This critical region 21 thus helps finding the barcode 2 thereby speeding up that not the entire surface 26 of the tire 1 must be searched, but only the critical region 21 ,

In 3 is a cross-sectional view along the section AA as in 1 shown schematically. You can see it in 3 like a computer 10 over a connection 30 with the recording device 5 connected is. The recording device 5 includes a lens element 6 , wherein the lens element 6 an optical axis 13 having. In the 3 shown optical axis 13 overlaps with the axis in this embodiment 14 of the tire 1 and passes through the center 16 of the tire 1 , Is shown in 3 also the distance 12 between the lens element 6 and the surface 11 of the background 3 as well as the tire height 27 with the tire specific heights h1 28 and tire specific heights h2 29. In addition, in 3 the surface 26 of the tire 1 , The conveyor belt 25 and the radial direction 15 of the tire 1 shown.

After a computer 10 or a computing unit 10 By means of the above-described rectilinear lines in the first image has detected the edge of the lower rim diameter, the arithmetic unit 10 Find the center of these edges and then adjust a circle to that edge using regression. From this he can determine the diameter of the fitted circle in pixels and thus in centimeters, since he knows the resolution at the conveyor belt height or at the height h1 28. Similarly, the arithmetic unit 10 or computer now the tire width 33 of the tire 1 and the height h2 29 of the upper rim diameter 8b determine. In addition, with the height h2 29 and the opening angle β of the recording device 5 the resolution at the height h2 29 and thus the upper rim diameter 8b be determined. Since there is a fixed distance between the upper rim diameter and the bar code in most tires, a critical region on the surface of the tire in the first image can now be determined in order to limit the scanning of the area for searching the bar code. Since the critical region comprises a much smaller number of pixels than the entire first image, recognition of the barcode is accelerated many times over.

Determining the position of the bar code, including the binarization, is as follows: Within the critical region 21 leads the arithmetic unit 10 binarizing the existing pixels by which pixels below a certain threshold value 0 and all other pixels on the value 1 be set. The limit value becomes dependent on the mean value of the intensity in the square 9 of the first picture 4 certainly. As a result, the arithmetic unit performs 10 an erosion of the areas through which the value 1 own to remove outliers and small areas. The remaining areas with the value 1 are potential candidates for the position of the barcode 2 , Using the previously determined resolution at the height of the upper rim and knowing the dimensions of the barcode 2 ie the size and aspect ratio of the barcode 2 or the size and aspect ratio of the barcode 2 , the arithmetic unit can 10 check these candidates for their geometry and so the barcode 2 different from other types of interference.

LIST OF REFERENCE NUMBERS

1

Tire or green tire

2

barcode

3

background

4

first picture

5

Recording device; camera

6

Lens element, lens

7

Edge of the tire or green tire

8th

Rim diameter of the tire or green tire

8a

rim diameter closer to the background; lower rim diameter

8b

further away from the background rim diameter; upper rim diameter

9

Clipping of the first picture, square

10

computer unit

11

the surface of the background facing the tire or green tire

12

Distance between the lens element and the surface of the background

13

optical axis of the lens element

14

Axle of tire or green tire

15

radial direction of the tire or green tire

16

Center of the tire or tire blank

17

Center of the barcode of the tire or green tire

18

a straight line through the center of the image of the first image

19

more straight lines

20

Image center of the first image; Center of the first picture

21

critical region, ring-shaped

22

Outer diameter of the annular critical region

23

Inner diameter of the annular critical region

24

inventive device

25

Conveyor belt; Storage area for storing the tire or green tire

26

Surface of the tire or green tire

27

tire height

28

Height h1

29

Height h2

30

Connection of computer and recorder

31

Conveying direction of the conveyor, the conveyor belt

32

outer circumference of the tire

33

tire width

ß

opening angle

Claims (12)

Method for automatically determining the position of the barcode (2) of a tire or green tire (1), comprising at least the following steps: a) providing or producing a tire or green tire (1) against a background (3), b) picking up a first image (4) of the tire or green tire (1) provided or produced in step a) by means of a recording device (5) comprising a lens element (6), c) determining the mean value of the intensity of the entire first image (4) or the intensity of a section (9) of the first image (4) and determining at least one edge (7) of the tire or green tire (1) on the first image (4) depending on the mean value of the intensity of the entire first image (4) or the intensity of the detail (9) of the first image (4), d) determining the position of the barcode (2) in the first image (4) by means of the one edge (7) determined in step c) or by means of the at least one edge (7) of the tire or green tire (1) determined in step c). Method according to Claim 1 in which - before each step a), the specific data of the tire or green tire (1) is made available to a computing unit (10) and the determination of the position of the barcode (2) in step d) additionally by means of this specific data of the tire or green tire (1) and the arithmetic unit (10), and / or - once before the process, the distance (12) between the lens element (6) and the surface (11) of the background (3) facing the tire or green tire (1) ) is provided to a computing unit (10). Method according to one of the preceding claims, wherein in step b) - The optical axis (13) of the lens element (6) during recording of the first image (4) along the axis (14) of the tire or green tire (1) and perpendicular to the radial direction (15) of the tire or green tire (1) aligned is, and / or - The exposure time for taking the first image (4) in the range of 10 microseconds to 300 ms and / or the illuminance for recording the first image (4) is in the range of 0.1 lux to 10,000 lux. Method according to one of the preceding claims, wherein in step c) the mean value of the intensity of a section (9) of the first image (4) is determined, the section (9) in the first image (4) within the reflection of the background (3). wherein the cutout (9) preferably comprises 1% to 10% of the pixels of the total number of pixels of the first image (4) and / or in the image center (20) of the first image (4) is arranged. Method according to one of the preceding claims, wherein in step d) both the center (16) of the tire or green tire (1) and the center (17) of the barcode (2) of the tire or green tire (1) is determined. Method according to one of the preceding claims, wherein the center point (16) of the tire or green tire (1) is determined in step d) by determining a rim diameter (8a, 8b) of the tire or green tire (1), the rim diameter (8a, 8b) is determined by means of the intensity differences along a rectilinear line (18) and optionally along further rectilinear lines (19) in the first image (4), the one rectilinear line (18) in the first image (4) preferably along the background (3 ), wherein the one rectilinear line (18) particularly preferably runs parallel to the conveying direction (31) of a conveyor belt (25) and extends through the image center (20) of the first image (4). Method according to Claim 6 , wherein - a threshold value for edge assignment is calculated and this threshold value for edge assignment is normalized by the mean value of the intensity determined in step c) and / or - when exceeding an intensity difference determined in step d) above the threshold value for edge assignment, the exceeding intensity difference of an edge ( 7) is assigned. Method according to one of the preceding claims, wherein in step d) a critical region (21) in the first image (4) on the surface (26) of the tire or green tire (1) is determined, the critical region (21) in the first image (4) preferably at most 20%, particularly preferably at most 10%, very particularly preferably at most 5% of the pixels of the first image (4), in each case based on the total number of pixels of the first image (4), the critical region (21 ) in the first image (4) is preferably annular and the outer and inner diameters (22, 23) of the annular critical region (21) are determined on the basis of or a rim diameter (8a, 8b) of the tire or green tire (1) Device for the automated determination of the center of a tire or green tire (1), for carrying out a method according to one of the preceding claims, wherein the device preferably has one, two, three or all of the following units: at least one recording device (5) comprising a lens element (6), a background (3), wherein the optical axis (13) of the lens element (6) is preferably perpendicular to the background (3), - a storage surface (25) for depositing a tire or a green tire (1), wherein the storage surface (25) is preferably a conveyor belt (25), - A computing unit (10) connected to the recording device (5), which is adapted to the center (16) of a tire or green tire (1) by taking one, two or more than two images of the tire or green tire (1) determine. Computer program comprising program code means for carrying out one or all of the steps of a method according to one of the Claims 1 to 7 when the computer program is running on a recorder (5) computer operatively connected, wherein the computer preferably a computing unit (10) according to one of Claims 1 to 7 includes. A computer program product comprising program code means stored on a computer readable medium for carrying out any or all of the steps of a method according to any one of Claims 1 to 7 when the computer program is executed on a computer operatively connected to the recording device (5), wherein the computer preferably has a computing unit (10) according to one of the Claims 1 to 7 includes. Computer-readable disk on which the computer program is based Claim 9 or the computer program product Claim 10 is stored.

Images