DE102019202798A1 - Method and device for determining the relative speed between an object and a detector - Google Patents

Abstract

With regard to a particularly simple and reliable determination of the relative speed between an object and a detector (1) with structurally simple means, a method for determining the relative speed between an object and a detector (1) is specified, with a relative movement between the object and the detector (1) can take place in one direction of movement, the object having at least one detection element (2) divided into at least two sub-elements (3, 4), the sub-elements (3, 4) each at a predeterminable spatial distance (ds) from one another are arranged at predeterminable positions on, on or in the object, with a first sub-element (3) at a first predeterminable point in time for a predeterminable first illumination duration (t) with a first during the possible relative movement and for image recording by the detector (1) Light with a first wavelength (6) and after a time interval (dt) a second sub-element (4) at a later, second prescribable point in time for a prescribable second illumination duration (t) with a second light with a second wavelength (7). A corresponding device for determining the relative speed between an object and a detector (1) is also specified.

Description

The invention relates to a method for determining the relative speed between an object and a detector, wherein a relative movement between the object and the detector can take place in one direction of movement. The present invention also relates to a corresponding device for carrying out such a method.

Methods and devices of the type mentioned are known from practice and exist in different embodiments. Such methods and devices are used, in particular, in industrial areas in which objects moving relative to a detector must be monitored, preferably in an automated manner.

For example, from the EP 0 532 169 A1 a method is known in which the relative speed between an object on a surface and a detector can be determined with a CCD array. The relative speed is determined on the basis of the sequence of individual image recordings.

Furthermore, from the EP 1 729 086 A1 a method for image processing is known, wherein relative speeds between an object and a detector are determined.

The known methods for determining the relative speed are well suited for the applications described in the above prior art. However, in many applications today it is necessary to achieve a particularly high level of reliability when determining the relative speed. The methods known from the prior art are only suitable to a limited extent for this purpose, since, in particular if one of the individual measuring components in the image processing chain fails, it cannot immediately be determined that a speed measurement is faulty. The aim here is to increase the reliability of the determination of the relative speed.

The present invention is therefore based on the object of specifying a method and a device for determining the relative speed between an object and a detector, according to which a particularly reliable determination of the relative speed between an object and a detector is made possible with structurally simple means.

According to the invention, the above object is achieved by a method having the features of claim 1 and by a device having the features of claim 17.

Thereafter, the method according to the invention forms a method for determining the relative speed between an object and a detector, wherein a relative movement between the object and the detector can take place in one direction of movement,
wherein the object has at least one detection element divided into at least two sub-elements, the sub-elements being arranged at a predeterminable spatial distance from one another at predeterminable positions on, on or in the object,
during the possible relative movement and for an image recording by the detector first sub-element is illuminated at a first predeterminable time for a predeterminable first illumination duration with a first light with a first wavelength and after a time interval (dt) a second sub-element is illuminated with a second light with a second wavelength at a later second predeterminable time for a predeterminable second illumination duration become,
where the wavelengths are chosen so
that with an illumination with the first wavelength the first partial element is dark and with an illumination with the second wavelength the second partial element is also detected dark with a correspondingly low brightness relative to a background by the detector, or
that with an illumination with the first wavelength the first partial element is detected brightly and with an illumination with the second wavelength the second partial element is also detected brightly with a correspondingly high brightness relative to a background by the detector,
wherein an image of the sub-elements is generated in an image recording by the detector, and
wherein - to determine the relative speed on the basis of forming a quotient from the spatial distance and the time interval between the first and the second point in time - an evaluation device checks whether the sub-elements in the image are mapped in a predeterminable relative positioning to one another.

Furthermore, according to claim 17, a device for performing a method for determining the relative speed between an object and a detector is specified, wherein a relative movement between the object and the detector can take place in one direction of movement,
wherein the object has at least one detection element divided into at least two sub-elements, the sub-elements being arranged at a predeterminable spatial distance from one another at predeterminable positions on, on or in the object,
wherein during the possible relative movement and for an image recording by the detector, a first sub-element at a first predeterminable point in time for a predefinable first illumination duration with a first light with a first wavelength and after a time interval (dt) a second sub-element at a later second predeterminable time for a specifiable second illumination duration can be illuminated with a second light with a second wavelength,
where the wavelengths are chosen so
that in the case of an illumination with the first wavelength the first partial element is dark and in the case of an illumination with the second wavelength the second partial element can also be detected dark by the detector with a correspondingly low brightness relative to a background, or
that with an illumination with the first wavelength the first partial element is brightly and with an illumination with the second wavelength the second partial element can also be detected brightly with a correspondingly high brightness relative to a background by the detector,
wherein an image of the sub-elements can be generated in an image recording by the detector, and
where - to determine the relative speed on the basis of forming a quotient from the spatial distance and the time interval between the first and the second point in time - it can be checked by means of an evaluation device whether the partial elements in the image are mapped in a predeterminable relative positioning to one another.

In the manner according to the invention, it was first recognized that a particularly reliable determination of the relative speed between an object and a detector with the aid of predeterminable illumination during the possible relative movement and suitable image recording by the detector is possible with structurally simple means. The expression "possible relative movement" and "possible direction of movement" means that the determination of the relative speed between an object and a detector also covers the case in which the relative speed is zero, i.e. there is no relative speed in any direction of movement. If there is a relative movement, this then takes place in the "possible direction of movement". The term “relative speed” in this document therefore also includes the case in which the relative speed is equal to zero.

Specifically, for this purpose the object has at least one detection element divided into at least two sub-elements, the sub-elements being arranged at a predeterminable spatial distance from one another at predeterminable positions on or in the object. During the relative movement, on the one hand, a first sub-element is illuminated at a first prescribable point in time for a prescribable first illumination duration with a first light with a first wavelength. After a time interval, at a later, second predeterminable point in time, a second partial element is illuminated for a predeterminable second illumination duration with a second light with a second wavelength.

In a first alternative, the wavelengths are chosen such that when illuminated with the first wavelength the first sub-element is dark according to its reflectance spectrum and when illuminated with the second wavelength the second sub-element is also dark according to its reflectance spectrum with a correspondingly low brightness relative to a background of the detector is detected. In a second alternative, the wavelengths are chosen such that when illuminated with the first wavelength the first partial element is bright according to its remission spectrum and when illuminated with the second wavelength the second partial element is also bright according to its remission spectrum with a correspondingly high brightness relative to a background of the detector is detected. In this context, “light” or “dark” mean intensities of the brightness that can be differentiated by the particular detector used due to its sensitivity, so that a contrast between the illuminated sub-elements and the background can be perceived by the detector with suitable lighting.

In an image recording by the detector, an image of the sub-elements is generated by means of the method. The brightnesses detected by the detector are integrated during the duration of the image recording.

To determine the relative speed, an evaluation device is used to check whether the sub-elements in the image are mapped in a predeterminable relative positioning to one another. For example, the predeterminable relative positioning can mean the positioning of the sub-elements in the undivided state of the detection element. In this case, the successive imaging of the sub-elements during the image recording brings about a combination of the sub-elements to form the undivided detection element. The undivided detection element can be seen in the figure. As an alternative to this complete composition of the detection element in the image, any predeterminable relative positioning can be selected as part of the evaluation by means of the evaluation device. The relative speed is determined on the basis of the formation of a quotient from the predeterminable spatial distance between the sub-elements and the time interval between the first and the second point in time. Is the predeterminable relative positioning, for example, the assembled position of the sub-elements for Formation of the undivided detection element, the speed results directly from the quotient of the spatial distance between the arrangement of the partial elements and the time interval between the first and the second point in time. In the case of a differently selected, predeterminable relative positioning in the image, the spatial distance between the divided detection elements is no longer to be selected in the formation of the quotient, but a distance corresponding to the currently selected predeterminable relative positioning, for example a smaller distance if the selected predeterminable relative positioning means a not yet assembled situation of the sub-elements to form the detection element in the undivided state.

A device according to the invention has at least one detector, a lighting device for generating the first light and the second light, and an evaluation device for checking the predeterminable relative positioning for performing the method according to the invention.

With the method according to the invention and the corresponding device according to the invention, a particularly reliable determination of the relative speed is possible with structurally simple means, merely by suitable arrangement and illumination of sub-elements of at least one detection element.

In an advantageous manner, a monochrome camera can be used as a detector, it being possible to use a camera with a pixel sensor. Such a camera can ensure reliable image recording of light and dark sub-elements. In a further advantageous manner, the pixel sensor can be designed as a CMOS sensor or CCD sensor or as a line sensor.

In principle, it is desirable to select the illumination duration, preferably short as a flash, in order not to interfere, for example, with a process of position detection between the object and the detector, which is also based on a specifiable illumination. Advantageously, the first illumination duration can be between approximately 10 and approximately 200 microseconds and / or the second illumination duration between approx. 10 and approx. 200 microseconds. When choosing the illumination duration, on the one hand the mentioned avoidance of disturbances, for example of other detection methods, and on the other hand a reliable image recording through sufficiently long first and / or second illumination durations must be ensured.

The time interval or a pause between the first lighting duration and the second lighting duration can be approximately 0.5 to 20 ms depending on the application.

Furthermore, with a view to particularly reliable image recording, the background can have a lower reflectivity than the sub-elements. It should be noted here that part of the background is usually located in a viewing window of the detector during image acquisition. The background can be designed in a corresponding manner to ensure reliable image recording. For example, in a simple case, the background can be white and the detection elements black or dark. Alternatively, the background can be black or dark and the sub-elements light or white. As a further alternative, the background can be designed in such a way that it reflects less than the partial elements when illuminated with the first and / or the second wavelength. For example, the background can be designed in such a way that it has only 50% of the reflectivity or the reflectivity of the sub-elements.

In a particularly simple embodiment of the method, the first wavelength and the second wavelength can be the same. For example, the sub-elements can be designed as black or same-colored sub-elements which are illuminated in a suitable manner with the first and second wavelengths, which are the same, in order to ensure reliable image recording by the detector. With this particularly simple embodiment, the relative speed can be reliably determined.

At this point it should be noted that throughout the document, the terms “wavelength” and “illumination wavelength” can refer to not only an isolated wavelength but also a wavelength range or a combination of different individual wavelengths and / or wavelength ranges in the entire electromagnetic spectrum. In this respect, the term “wavelength” or “illumination wavelength” is synonymous with one or more individual wavelengths and / or one or more wavelength ranges. There is no restriction to the visible wavelength range when using the term “color”. The entire electromagnetic spectrum is also included here. When using the term “color”, this can be understood as a mere exemplary designation of a section of the electromagnetic spectrum that relates to the visible wavelength range.

In a further advantageous embodiment of the method according to the invention, the sub-elements can be designed in different colors or have different reflectance spectra. In this case, too, a reliable determination of the relative speed is possible if the Wavelengths are chosen such that the illuminated sub-elements are suitably dark or light - and thus in contrast - detected. In this case too, the wavelengths can basically be the same, provided that the color design or the reflectance spectra of the sub-elements is or are selected in such a way that suitable dark or light detection is possible.

With the exemplary embodiments described above, it is possible to determine the relative speed, but it is not possible to determine the associated direction of movement. However, if the sub-elements are designed with different colors in a suitable manner, the direction of movement can also be detected with a suitable choice and sequence of the wavelengths, in which case the wavelengths are to be selected differently. Specifically, the wavelengths can be selected such that when illuminated with the first wavelength, the first partial element is dark and the second partial element is light, and when illuminated with the second wavelength, the first partial element is light and the second partial element is dark with correspondingly low or relatively high brightness to the background is detected by the detector, or that with an illumination with the first wavelength the first partial element light and the second partial element dark and with an illumination with the second wavelength the second partial element light and the first partial element dark with correspondingly high or low brightness relative to the background is detected by the detector.

By knowing and taking into account the sequence of the first and the second illumination duration with the corresponding first and second wavelength and knowing the color design of the sub-elements, it can be determined, with appropriate evaluation, whether the mapping of the sub-elements is a mapping that correlates with a known speed and direction of movement has led.

Furthermore, with a view to a particularly reliable determination of the relative speed and possibly the direction of movement, the sub-elements can be arranged along the direction of movement. To determine speeds in directions deviating from the direction of movement, the sub-elements can additionally be arranged along a corresponding, predeterminable further direction running at an angle to the direction of movement.

In the case of an arrangement of at least two sub-elements as described above, basically only a speed can be determined which correlates with the spatial distance between the sub-elements and the time interval between the first and the second point in time of the illuminations. To determine a plurality of different speeds, the sub-elements can be arranged in a particularly advantageous manner in a plurality of arrangements with different predeterminable spatial distances from one another at predeterminable positions on, on or in the object. When implementing these multiple arrangements, a number of speeds corresponding to the number of multiple arrangements can be determined if the spatial spacings of the partial elements in the arrangements are all different.

In a specific embodiment, the sub-elements can be picture elements of an overall image or of the detection element. Such picture elements can be printed in a simple manner on a suitable object in order to ensure the desired arrangement of the sub-elements.

In a particularly advantageous embodiment, the at least one detection element can be a code, in particular a data matrix code or a barcode with a plurality of bars. Such codes can be recorded and evaluated in a particularly simple manner by suitable detectors.

In the case of using a barcode as the at least one detection element, the bars of the barcode can alternately be designed with different colors to form sub-elements, whereby preferably several barcodes can be arranged one above the other in a prescribable manner in an image plane and / or the different colored sub-elements can be spatially shifted from one another. With a suitable choice of wavelengths and with a suitably selected time interval between the illuminations, different colored partial elements shifted in this way can be brought back into a readable barcode in the image generated by the image recording, as it was before the partial elements were shifted relative to one another.

To avoid interference with other lighting-related provisions or evaluations, preferably on or with the same object, the color design of the sub-elements and the first wavelength and / or the second wavelength can be selected to be coordinated so that additional lighting of a code arranged on or on the object, in particular a data matrix code or a barcode, with which the first light and / or the second light does not cause any interference or falsification of reflections and / or absorptions generated during, for example, a position determination with the code.

Furthermore, with regard to a particularly reliable determination of the relative speed, the time interval and / or the Sequence of lighting with the first light and the second light can be specified. This specification can preferably take place by means of a control device and more preferably randomly or pseudo-randomly. By specifying the time interval and / or the sequence of lighting with the first light and the second light, a very specific - expected - detection can be generated by the detector, it being assumed that the level of the relative speed is within an expected range . The image recording and image of the sub-elements generated by the detector in such a case can be compared by means of an evaluation device with an image expected on the basis of the selected parameters in the form of the time interval and / or the sequence of lighting with the first light and the second light, with a detected deviation of the generated image from the expected image above a predeterminable threshold value, suitable measures can be taken to influence or even prevent a further relative movement between the object and the detector or the deviation can be displayed. Such a deviation can indicate a malfunction in the image processing, for example in the detector. If no deviation occurs, a very reliable speed measurement can be assumed.

With regard to a particularly reliable determination of the relative speed, the time interval can be specified in such a way that the object or the partial elements do not move or move out of a viewing window of the detector during the time interval. This ensures, for example, that all sub-elements are mapped in the required manner during the image acquisition and thus no information is lost when determining the relative speed.

With regard to the reduction of an undesired external light influence during the image acquisition, the image acquisition by the detector can only take place during the first illumination duration and the second illumination duration and / or not take place between the first illumination duration and the second illumination duration. This ensures the image recording with regard to the sub-elements, while at the same time preventing undesired extraneous light from reducing the quality of the image recording or a signal-to-noise ratio between the illumination periods. For this purpose, a shutter can advantageously be used for the detector or the camera, which, for example, is only open during the first illumination period and the second illumination period and is otherwise closed. This enables a particularly reliable reduction in extraneous light to be carried out.

• 1 in einer schematischen Darstellung ein bei einem Ausführungsbeispiel des erfindungsgemäßen Verfahrens verwendbares Detektionselement in Form eines Data Matrix Codes, der in zwei verschiedenfarbige Teilelemente aufgeteilt wird, wobei eine Abbildung der Teilelemente bei entsprechender Beleuchtung und mit ansteigender Relativgeschwindigkeit zwischen dem Objekt und dem Detektor gezeigt ist,
• 2 in einer schematischen Darstellung in einem weiteren Ausführungsbeispiel ebenfalls ein als Data Matrix Code ausgebildetes Detektionselement, das in zwei verschiedenfarbige Teilelemente aufgeteilt ist, wobei der Hintergrund bei diesem Ausführungsbeispiel dunkel ist,
• 3 in einem weiteren Ausführungsbeispiel die Verwendung von fünf als Barcode ausgebildeten Detektionselementen mit entsprechender Aufteilung in jeweils zwei verschiedenfarbige Teilelemente,
• 4 in einer schematischen Darstellung ein Szenario wie in 3, jedoch mit der doppelten zurückgelegten Strecke während der Relativbewegung,
• 5 in einer schematischen Darstellung ein gleiches Szenario wie in 3, jedoch mit einer Vertauschung der Wellenlängen und damit der Beleuchtung mit dem ersten Licht und dem zweiten Licht, und
• 6 in einer schematischen Darstellung eine typische Abfolge von Beleuchtungsdauern für eine Bildaufnahme durch einen Detektor.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, reference is made on the one hand to the subordinate claims and on the other hand to the following explanation of preferred exemplary embodiments of the method according to the invention and the device according to the invention with reference to the drawing. In connection with the explanation of the preferred exemplary embodiments with reference to the drawing, generally preferred configurations and developments of the teaching are also explained. Show in the drawing

• 1 a schematic representation of a detection element in the form of a data matrix code which can be used in an embodiment of the method according to the invention and which is divided into two differently colored sub-elements, with an image of the sub-elements being shown with appropriate lighting and with increasing relative speed between the object and the detector,
• 2 in a schematic representation in a further exemplary embodiment also a detection element designed as a data matrix code, which is divided into two differently colored sub-elements, the background in this exemplary embodiment being dark,
• 3 In a further exemplary embodiment, the use of five detection elements designed as barcodes with a corresponding division into two differently colored sub-elements,
• 4th in a schematic representation a scenario as in 3 , but with twice the distance covered during the relative movement,
• 5 a schematic representation of the same scenario as in 3 , but with an exchange of the wavelengths and thus the illumination with the first light and the second light, and
• 6th a schematic representation of a typical sequence of illumination periods for an image recording by a detector.

Based on 1 is an embodiment of the method according to the invention for determining the relative speed between an object and a detector 1 explained, the detector 1 is designed as a camera. The object has a detection element designed as a data matrix code 2 on that into two sub-elements 3 and 4th on a background 5 that is split into one spatial distance ds from one another are arranged at predeterminable positions on the object. The sub-elements 3 and 4th have different colors, with the in 1 right sub-element 3 exemplary red and that in 1 Sub-element shown on the left 4th is exemplarily designed in blue. This color difference is based on the different hatching in the sub-elements 3 and 4th clarified.

At a) is the detection element 2 shown in unchanged form. In b) a corresponding coloration is made in blue and red. At c) is the division of the detection element 2 into the sub-elements 3 and 4th at a distance ds shown.

The sequence changing from c1) to c5) shows images of the sub-elements 3 and 4th with the detector 1 in a corresponding image recording, the sequence correlating with an increasing relative speed. In case c1), a standstill situation without relative speed and relative movement is also shown.

The image recording is generated in that the red first sub-element 3 at a first specifiable point in time for a specifiable first illumination duration with a first blue light with a first wavelength 6th and the blue second sub-element 4th at a later second predeterminable point in time for a predeterminable second illumination duration with a second red light with a second wavelength 7th be illuminated. The sub-elements 3 and 4th in the still immobile situation c1) the same distance ds as with the original division of the detection element 2 into the sub-elements 3 and 4th according to the partial representation c).

In areas c2) and c3), a relative speed is now the basis, which increases from c2) to c3). The sub-elements lie accordingly 3 and 4th in the respective in 1 The figure shown is increasingly closer together. In the situation according to c4) are the sub-elements 3 and 4th now mapped in a relative positioning to one another that of the original design of the detection element 2 in its form as a data matrix code. This predeterminable relative positioning of the sub-elements 3 and 4th each other can now be recognized by means of an evaluation device, namely by the fact that the data matrix code can only be read again in the first place. In the situations according to c1), c2) and c3), such readability of the data matrix code is not possible.

Therefore, in situation c4), the speed can be determined by forming the quotient from the spatial distance ds and the time interval dt between the first illumination duration and the second illumination duration. As soon as the data matrix code can be read again, this clear determination of the speed can take place through the quotient formation mentioned.

If the speed continues to increase, a situation like in c5) in 1 result in the sub-elements 3 and 4th are again shown at a distance from one another.

In the embodiment according to 1 it is possible both the first sub-element 3 as well as the second sub-element 4th to illuminate each together with the first light and the second light. A selective lighting only on one sub-element 3 or the other sub-element 4th is not necessary because the color design of the sub-elements 3 and 4th and the appropriate choice of wavelengths 6th and 7th to the desired mapping of the sub-elements 3 and 4th according to situations c1) to c5). If no color design of the sub-elements and no color difference between the first light and the second light is selected, it is preferred to selectively illuminate the sub-elements 3 and 4th to make only one image of the illuminated sub-element 3 or 4th to obtain. However, this selective lighting and evaluation is not absolutely necessary and the method also works with a non-colored design of the sub-elements 3 and 4th and a not different choice of wavelengths 6th and 7th . The check of whether the respective specified relative positioning of the sub-elements 3 and 4th is present in the image, for example by determining the legibility of a data matrix code, is also the case with a non-colored design of the sub-elements 3 and 4th and at the same wavelengths 6th and 7th possible. In this respect, a reliable determination of the relative speed results in each case.

In the scenarios according to 1 and the color design of the sub-elements 3 and 4th there is therefore a situation in which the scenario with the partial elements is completely illuminated in red 3 and 4th and the background 5 only the blue sub-element 4th is detected dark. If everything is illuminated in blue, only the red sub-element becomes 3 detectable. In this case, it is desirable to select only a very short, lightning-like illumination duration with the blue and red light in order not to interfere with possible other detection processes relating to lighting, for example a position determination. Due to the spatial separation of the sub-elements 3 and 4th of the data matrix code in the distance ds decoding of the data matrix code is no longer possible. If now the detector 1 moved relative to the object, the two sub-elements move 3 and 4th in the figure relative to each other, depending on the speed, the spatial distance ds and the time interval German between the first and the second time of illumination. With a very specific combination of these three parameters - speed, distance ds and time interval German - According to c4) there is a data matrix code in the figure that can be decoded. In this situation, based on the checksum CRC, it can be assumed that the speed is in a certain range. In the case according to the situation 1 the detector moves 1 relative to the sub-elements 3 and 4th to the left, so that the detector is initially in the blue exposure 1 above the red sub-element 3 which is then detected dark. According to the time interval German the detector is located above the blue sub-element 4th and exposes it to red, so that this also appears dark and corresponds to the previous exposure of the first partial element 3 superimposed. In order to obtain a readable code in the other direction of movement, exposure must be carried out in the reverse order, ie first red and then blue. The speed results in both cases as v = ds / dt, regardless of the direction of movement. Taking into account, ie knowing the lighting sequence - first blue and then red or first red and then blue - it is also possible to infer the direction of movement. This detection of the direction of movement is only possible in the case of a correspondingly colored configuration according to the scenario in FIG 1 and not if the sub-elements are designed in the same color 3 and 4th and equal illumination wavelengths 6th and 7th possible.

To determine a suitable time interval in advance German For example, an acceleration sensor can be used which determines the time interval German may specify if necessary.

Several arrangements of sub-elements can be used to determine different speeds 3 and 4th be provided on the object, the sub-elements 3 and 4th at different spatial distances ds are to be arranged from each other. The respective underlying codes can have different content in order to enable reliable conclusions to be drawn about the relative speed when a code is recognized. Depending on the speed, for example, only a code that can be read will fit.

The method can also be used to detect a standstill. For this purpose, both sub-elements 3 and 4th be arranged undisplaced on, on or in the object. These can only be decoded if there is no relative speed. In another case the different colored sub-elements would 3 and 4th are mapped spaced apart.

In an advantageous embodiment of the method, the detection elements used to determine the relative speed can be implemented several times on an object. The detection elements can in each case be provided separately for determining the speed. To that extent, they can be implemented independently of codes used, for example, for determining a position.

In the case of implementing different arrangements of sub-elements 3 and 4th To determine different speeds, a suitable control device can determine the time interval and the sequence of the exposure colors or wavelengths 6th and 7th preferably vary randomly or pseudo-randomly. This then results in speeds that are determined in different ways, ie with different parameters. This enables the parameters specified by the control device to be compared with the images generated by the image recording. In other words, the images generated by the image recording must correspond to the selected parameters with regard to the time interval German and sequence of exposure colors "match". In this way, in the event of discrepancies, a conclusion can be drawn about incorrect functioning of the processing chain between the lighting control and the determined speed. This allows a through the detector 1 and the evaluation device formed “black channel” can be verified for correctness by means of the variation of the parameters by the control device.

2 shows a schematic representation of a further embodiment of the present invention, the in 2 scenarios a) to c5) shown in the corresponding scenarios in 1 basically correspond. However, there is a dark background here 5 elected. Otherwise, to avoid repetition, refer to the explanations for 1 to get expelled.

3 shows in a schematic representation according to a further embodiment detection elements 2 generated on the basis of a barcode. According to Part I. in 3 five codes selected, which are converted into five barcodes and arranged one above the other in an image plane according to II. Thus II. Shows five detection elements 2 in the form of "short" barcodes arranged one above the other. The transition from I. to II. Is in the right part of the 3 shown schematically, with the code "-01" selected as an example, which is shown as the second code from above. According to II., The five different barcodes are only positioned one above the other or one above the other in the image plane. This is not a "stacked barcode" or something similar.

According to III. become all bars 8th the codes are colored alternately blue and red. The blue and red bars created by this, by the respective colored bars 8th modules formed from all blue and red bars 8th of a respective barcode, which as sub-elements 3 (blue) and 4 (red) are spatially shifted from one another according to IV. The degree of shift is explained in the table in Part IV. The two modules of the first detection element are here 2 shifted by 2 mm to the left (blue) or to the right (red). This displacement distance of 2 mm is selected merely as an example, so that other displacement distances are also possible. The modules of the second detection element 2 are only shifted by 1 mm to the left (blue) or right (red). The modules of the third detection element 2 are not shifted and the modules of the fourth and fifth detection element 2 are compared to the situation in Part III. opposite to the first two detection elements 2 shifted so that the shift situation shown in Part IV. results overall.

In part V. an image is now shown that is available after a corresponding exposure. For this purpose, it was first briefly exposed to blue lighting, so that the red modules are shown in the position they are in after they have been moved relative to one another in accordance with Part IV. In this respect, the situation with regard to the red modules is unchanged compared to Part IV.

After waiting for the time interval dt, the exposure was briefly red, so that an image of the blue modules results to an extent corresponding to the shift that has taken place in the meantime. The shift is ds = -2 mm.

In Part VI. an image is shown by a monochrome area sensor chip, it being possible to recognize according to a line-by-line decoding that only the second code from above can be decoded. The corresponding code content is "-01" as described above. The speed can then be set as on the right in Part VI. are calculated. It should be emphasized that this is an exemplary implementation of the method. The determined speed is -0.5 m / s.

4th shows in a schematic representation essentially the same scenario as in 3 with first red and then blue lighting and the same direction of movement, whereby here during the time interval dt has been shifted by twice the distance. This double distance results from the doubling of the time interval dt.

Since both the time interval dt and the interval ds have been doubled, the result is the same speed of -0.5 m / s as in 3 . It can be seen from this that the pure decoding process takes place independently of the time interval dt. The speed is still reliably determined.

5 shows a scenario in accordance with FIG 3 , whereby the sequence of exposure has been swapped so that exposure was first red and then blue. The corresponding illustration by the detector is in Part IX. evident. The blue modules - sub-element 3 - are off compared to the illustration in Part IV 3 positioned unchanged. However, the red modules - sub-element 4 - have been moved to the right by the distance ds.

Here too, according to part X., it can be seen that the pure decoding system determines the time interval German ultimately does not know or need to know that, however, with the method according to the invention, overall a reliable speed determination is possible, since in this exemplary embodiment the correct speed of -0.5 m / s as well as in the scenarios according to FIGS 3 and 4th results.

6th shows in a schematic representation a typical sequence of illumination periods t ₁ and t ₂ with a break or a time interval t _delta between the lighting periods t ₁ and t ₂ . The time course is along a time t applied against the lighting. With such short periods of illumination t ₁ and t ₂ can be prevented between these illumination periods t ₁ and t ₂ unwanted extraneous light from the detector 1 is recorded. This could be realized by shutting a sensor chip of the detector 1 only during the lighting period t ₁ and t ₂ remains open and otherwise closed.

This increases the image quality and reduces a signal-to-noise ratio. The shutter of the sensor chip remains between the lighting periods t ₁ and t ₂ closed, the extraneous light is largely blocked. For example, during the lighting period t ₁ be exposed in red. The shutter is then closed. After the time has passed t _delta the shutter is opened again. During the subsequent lighting period t ₂ is exposed in blue, for example.

This extraneous light reduction can be implemented using different sensor chips. In one execution, during a lighting period t ₁ or t ₂ normally exposed and in between the target voltage reduced to a minimum, so that the Sensor is not very sensitive to light in this intermediate area.

Another sensor technology can use two different inputs, which are used as shutters t ₁ and shutter t ₂ can be used. Binning can be used for reading out or the two inputs can be combined via an external circuit.

There are also sensor chips in which multiple exposure is possible before the data is read out. All such sensor chips can be used within the scope of the method according to the invention.

With regard to further advantageous embodiments of the teaching according to the invention, to avoid repetition, reference is made to the general part of the description and to the appended claims.

Finally, it should be expressly pointed out that the exemplary embodiments described above only serve to explain the teaching claimed, but do not restrict them to these exemplary embodiments.

List of reference symbols

1

detector

2

Detection element

3

Sub-element

4th

Sub-element

5

background

6th

first wavelength

7th

second wavelength

8th

bar

ds

spatial distance

German

Time interval

t

time

t ₁

Lighting duration

t ₂

Lighting duration

t _delta

Duration

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• EP 0532169 A1 [0003]
• EP 1729086 A1 [0004]

Claims (17)

Method for determining the relative speed between an object and a detector (1), wherein a relative movement between the object and the detector (1) can take place in one direction of movement, the object being at least one detection element (3, 4) divided into at least two sub-elements (3, 4). 2), the sub-elements (3, 4) being arranged at a predeterminable spatial distance (ds) from one another at predeterminable positions on, on or in the object, with during the possible relative movement and for an image recording by the detector (1) a first sub-element (3) at a first predeterminable point in time for a predeterminable first illumination duration (t ₁ ) with a first light with a first wavelength (6) and after a time interval (dt) a second sub-element (4) at a later second predeterminable time for a predeterminable second illumination duration (t ₂ ) are illuminated with a second light with a second wavelength (7), the Wavelengths (6, 7) are chosen such that when illuminated with the first wavelength (6) the first partial element (3) is dark and when illuminated with the second wavelength (7) the second partial element (4) is also dark with correspondingly less Brightness relative to a background (5) is detected by the detector (1), or that with an illumination with the first wavelength (6) the first partial element (3) is bright and with an illumination with the second wavelength (7) the second partial element (4) is also detected brightly with a correspondingly high brightness relative to a background (5) by the detector (1), an image of the sub-elements (3, 4) being generated in an image recording by the detector (1), and where - to determine the relative speed based on the formation of a quotient from the spatial distance (ds) and the time interval (dt) between the first and the second point in time - it is checked by means of an evaluation device whether the part elements duck (3, 4) are shown in the figure in a predeterminable relative positioning to each other. Procedure according to Claim 1 , characterized in that a monochrome camera, preferably a camera with a pixel sensor, is used as the detector (1), the pixel sensor further preferably being designed as a CMOS sensor or CCD sensor or as a line sensor. Procedure according to Claim 1 or 2 , characterized in that the first illumination duration (t ₁ ) between about 10 and about 200 microseconds and / or the second illumination duration (t ₂ ) between about 10 and about 200 microseconds and / or that the time interval (dt) or a pause between the first illumination duration (t ₁ ) and the second illumination duration (t ₂ ) is approximately 0.5 to 20 ms. Method according to one of the Claims 1 to 3 , characterized in that the background (5) has a lower reflectivity than the sub-elements (3, 4). Method according to one of the Claims 1 to 4th , characterized in that the first and the second wavelengths (6, 7) are the same. Method according to one of the Claims 1 to 4th , characterized in that the sub-elements (3, 4) are designed in different colors or have different reflectance spectra. Procedure according to Claim 6 , characterized in that the wavelengths (6, 7) are chosen such that when illuminated with the first wavelength (6) the first sub-element (3) dark and the second sub-element (4) light and when illuminated with the second wavelength (7) the first sub-element (3) light and the second sub-element (4) dark with correspondingly low or high brightness relative to the background is detected by the detector (1), or that when illuminated with the first wavelength (6) the first sub-element (3) light and the second sub-element (4) dark and with an illumination with the second wavelength (7) the second sub-element (4) light and the first sub-element (3) dark with correspondingly high or low brightness relative to the background is detected by the detector (1). Method according to one of the Claims 1 to 7th , characterized in that the sub-elements (3, 4) are arranged along the direction of movement and preferably additionally along a predeterminable further direction running at an angle to the direction of movement. Method according to one of the Claims 1 to 8th , characterized in that the sub-elements (3, 4) are arranged in several arrangements with different predeterminable spatial distances (ds) from one another at predeterminable positions on, on or in the object. Method according to one of the Claims 1 to 9 , characterized in that the sub-elements (3, 4) are picture elements of an overall image or of the detection element (2). Method according to one of the Claims 1 to 10 , characterized in that the at least one detection element (2) has a code, in particular a Data Matrix Code or a barcode with multiple bars. Procedure according to Claim 11 , characterized in that the bars (8) of the barcode to form sub-elements (3, 4) are alternately designed in different colors , preferably several barcodes in a predeterminable manner in an image plane one above the other and / or the different-colored sub-elements (3, 4) spatially are arranged shifted to each other. Method according to one of the Claims 1 to 12 , characterized in that the color design of the sub-elements (3, 4) and the first wavelength (6) and / or the second wavelength (7) are selected to be coordinated with one another in such a way that additional illumination of a code arranged on or on the object, in particular a data matrix code or a bar code with which the first light and / or the second light does not cause any interference or falsification of reflections and / or absorptions generated when determining the position with the code. Method according to one of the Claims 1 to 13 , characterized in that the time interval (dt) and / or the sequence of lighting with the first light and the second light - preferably by means of a control device and more preferably randomly or pseudo-randomly - are or will be specified. Method according to one of the Claims 1 to 14th , characterized in that the time interval (dt) is specified in such a way that the object or the partial elements (3, 4) do not move or move out of a viewing window of the detector (1) during the time interval (dt). Method according to one of the Claims 1 to 15th , characterized in that the image is recorded by the detector (1) only during the first illumination duration (t ₁ ) and the second illumination duration (t ₂ ) and / or between the first illumination duration (t ₁ ) and the second illumination duration (t ₂ ) not happened. Device for carrying out a method for determining the relative speed between an object and a detector (1), preferably for carrying out a method according to one of the Claims 1 to 16 , wherein a relative movement between the object and the detector (1) can take place in one direction of movement, the object having at least one detection element (2) divided into at least two sub-elements (3, 4), the sub-elements (3, 4) in one predeterminable spatial distance (ds) from one another are arranged at predeterminable positions on, on or in the object, with a first sub-element (3) at a first predeterminable point in time for a predeterminable during the possible relative movement and for an image recording by the detector (1) first illumination duration (t ₁ ) with a first light with a first wavelength (6) and after a time interval (dt) a second sub-element (4) at a later second predeterminable time for a predeterminable second illumination duration (t ₂ ) with a second light of a second wavelength (7) can be illuminated, the wavelengths (6, 7) being selected in such a way that when illuminated with the first wavelength (6 ) the first sub-element (3) is dark and, when illuminated with the second wavelength (7), the second sub-element (4) is also dark with a correspondingly low brightness relative to a background (5) can be detected by the detector (1), an illumination with the first wavelength (6) the first partial element (3) brightly and with an illumination with the second wavelength (7) the second partial element (4) also bright with a correspondingly high brightness relative to a background (5) from the detector ( 1) is detectable, whereby an image of the partial elements (3, 4) can be generated in an image recording by the detector (1), and wherein - to determine the relative speed on the basis of forming a quotient from the spatial distance (ds) and the time interval (dt) between the first and the second point in time - it can be checked by means of an evaluation device whether the partial elements (3, 4) in the image are mapped in a predeterminable relative positioning to one another det are.

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