Devices and methods for reliably determining the position of an object

Abstract

With a view to reliably determining the position of an object (1) with high resolution and simple means, a device for reliably determining the position of an object (1) with respect to a relative movement between the object (1) and a path (2) is specified, comprising: a detector (3) attached to or integrated into the object (1), at least one marker (4) arranged along the path (2), wherein the at least one marker (4) is detected by the detector (3) within its spatial detection range (5) to determine the position of the object (1) relative to the at least one marker (4), generating means for providing a definable graphic representation (7, 8) or graphic representation sequence, wherein the graphic representation (7, 8) or graphic representation sequence is detected by the detector (3) within its spatial detection range (5), and evaluation means forVerifying a match or relationship between the provided graphic representation (7, 8) or graphic representation sequence and corresponding data detected by the detector (3) to verify whether software within the detector (3) is still functioning correctly or is possibly frozen, hanged, or has a time shift or delay, wherein the generating means comprise a first light source (9) and a second light source (10), wherein the first light source (9) emits a definable first light color or a definable first light color spectrum, and the second light source (10) emits a definable second light color or a definable second light color spectrum different from the first light color for illuminating a correspondingly colored graphic representation (7, 8) or graphic representation sequence provided by the generating means, such that, depending on theThe graphic representation (7, 8) or a part of the graphic representation is visible or not by means of the detector (3) with or in a predefinable intensity and / or color, and wherein the colored graphic representation (7, 8) and the at least one marker (4) are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker (4), wherein the generating means have at least one additional light source (11) for illuminating at least one sub-area (12) of the at least one marker (4), and wherein the at least one additional light source (11) emits the first or second light color or the first or second light color spectrum or a third light color different from the first or second light color or a third light color spectrum different from the first or second light color spectrum onto the at least one sub-area (12) suchis designed such that, in the case of a marker (4) illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker (4) produced by the first light color or the second light color spectrum or the third light color or the third light color spectrum, with respect to intensity and / or color, in the at least one partial area (12) illuminated by the at least one additional light source (11) is modifiable by illumination by the at least one additional light source (11) with the second light color or the first light color spectrum or the third light color or the third light color spectrum, and / or that, in the case of a marker (4) illuminated by the second light source with the second light color or the second light color spectrum, the visibility of the marker (4) produced by the second light color or the second light color spectrum, with respect to intensity and / or color, is modifiable by illumination by the at least one additional light source (11) with the second light color or the first light color spectrum or the third light color or the third light color spectrum, with respect to intensity and / or color, in the partial area (12) illuminated by the second light source (11) ... second additional light source (11) with the second light color or the first light color spectrum or the third light color or the third light color spectrum.The illumination of at least one sub-area (12) is modifiable by at least one additional light source (11). Furthermore, a corresponding procedure is specified.

Description

[0001] The invention relates to a device for reliably determining the position of an object with respect to a relative movement between the object and a path, comprising: a detector attached to or integrated into the object, at least one marker arranged along the path, wherein the at least one marker is detected by the detector within its spatial detection range to determine the position of the object relative to the at least one marker, generation means for providing a definable graphic representation or graphic representation sequence, wherein the graphic representation or graphic representation sequence is detected by the detector within its spatial detection range, and evaluation means for verifying a correspondence or relationship between the provided graphic representation or graphic representation sequence and corresponding data.which are detected by the detector to verify whether software within the detector is still functioning correctly or is possibly frozen, has crashed, or has a time shift or delay, wherein the generating means have a first light source and a second light source, wherein the first light source emits a definable first light color or a definable first light color spectrum, and the second light source emits a definable second light color or a definable second light color spectrum different from the first light color for illuminating a correspondingly colored graphic representation or graphic representation sequence provided by the generating means.such that, depending on the illuminating first or second light color or the illuminating first or second light color spectrum, the graphic representation or a part of the graphic representation is visible or not by means of the detector with or in a predefinable intensity and / or color, and wherein the colored graphic representation and the at least one marker are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker.

[0002] Furthermore, the present invention relates to a device for reliably determining the position of an object with respect to a relative movement between the object and a path, comprising: a detector attached to or integrated into the object, at least one marker arranged along the path, wherein the at least one marker is detected by the detector within its spatial detection range to determine the position of the object relative to the at least one marker, generation means for providing a definable graphic representation or graphic representation sequence, wherein the graphic representation or graphic representation sequence is detected by the detector within its spatial detection range, and evaluation means for verifying a correspondence or relationship between the provided graphic representation or graphic representation sequence and corresponding data.which are detected by the detector to verify whether software within the detector is still functioning correctly or is possibly frozen, has crashed, or has a time shift or delay, wherein the generating means have a first light source, wherein the first light source emits a definable first light color or a definable first light color spectrum for illuminating a correspondingly colored graphic representation or graphic representation sequence provided by the generating means, such that, depending on the illuminating first light color or the illuminating first light color spectrum, the graphic representation or a part of the graphic representation is visible by means of the detector with or in a predefinable intensity and / or color, or not.and wherein the colored graphic representation and the at least one marker are identical, or the colored graphic representation sequence is formed by a sequence of representations of the marker,

[0003] Furthermore, the present invention relates to methods corresponding to the devices mentioned above for reliably determining the position of an object with respect to a relative movement between the object and a path, which are described in the preambles of claims 14 and 15.

[0004] From EP 3 167 252 B1 with the associated WO 2017 / 045704 A1, a device and a method for reliably determining the position of an object of the type mentioned above are known, wherein a position determination is described in particular on the basis of dual illumination of a marker.

[0005] Further devices and methods for determining the position of an object are known from WO 2017 / 045705 A1, WO 2017 / 045706A1 and DE 10 2020 202 914 A1.

[0006] The problem with known devices and methods is that a reliable position determination can only be performed within half the reading window. This means that a resolution can only be provided down to approximately the size of a marker, such as a code.

[0007] In this document, "certain" means that there is conformity with the Functional Safety Directive for Products (EN61508). "Uncertain," on the other hand, means that a position was identified which is correct, but does not comply with the Functional Safety Directive.

[0008] The present invention is therefore based on the objective of providing devices and methods of the type mentioned at the outset, according to which a reliable determination of the position of an object is made possible with high resolution and structurally simple means.

[0009] According to the invention, the foregoing problem is solved by devices having the features of claims 1 and 2 and by methods having the features of claims 14 and 15.

[0010] A device of the type mentioned at the outset according to claim 1 is then designed and further developed such that the generating means have at least one additional light source for illuminating at least one partial area of ​​the at least one marker and that the at least one additional light source for emitting the first or second light color or the first or second light color spectrum or a third light color different from the first or second light color or a third light color spectrum different from the first or second light color spectrum onto the at least one partial area is designed such that that, in the case of a marker illuminated by the first light source with the first light color or light color spectrum, the visibility of the marker, as produced by the first light color or light color spectrum, in at least one sub-area illuminated by the at least one additional light source, can be changed by illumination by at least one additional light source with the second light color or light color spectrum or the third light color or light color spectrum, and / or that, in the case of a marker illuminated by means of the 2nd light source with the 2nd light color or the 2nd light color spectrum, the visibility of the marker, generated by the 2nd light color or the 2nd light color spectrum with regard to intensity and / or color, in the at least one partial area illuminated by means of the at least one additional light source, can be changed by illumination by means of at least one additional light source with the 1st light color or the 1st light color spectrum or the 3rd light color spectrum.

[0011] Furthermore, a device of the type mentioned at the outset according to claim 2 is designed and further developed such that the generating means have at least one additional light source for illuminating at least one partial area of ​​the at least one marker and that the at least one additional light source is designed to emit a second light color or a second light color spectrum different from the first light color or a second light color spectrum onto the at least one partial area such that that, in the case of a marker illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker, generated by the first light color or the first light color spectrum with regard to intensity and / or color, in the at least one partial area illuminated by the at least one additional light source, can be changed by illumination by the at least one additional light source.

[0012] Furthermore, a method of the type mentioned at the outset according to claim 14 is designed and further developed such that the generating means have at least one additional light source for illuminating at least one partial area of ​​the at least one marker and that the at least one additional light source is designed to emit the first or second light color or the first or second light color spectrum or a third light color different from the first or second light color or a third light color spectrum different from the first or second light color spectrum onto the at least one partial area and is used in such a way that that, in the case of a marker illuminated by the first light source with the first light color or light color spectrum, the visibility of the marker, as produced by the first light color or light color spectrum, in at least one partial area illuminated by the at least one additional light source, is altered by illumination by at least one additional light source with the second light color or light color spectrum or the third light color or light color spectrum, with regard to intensity and / or color. that, in the case of a marker illuminated by the second light source with the second light color or the second light color spectrum, the visibility of the marker, as produced by the second light color or the second light color spectrum, is altered in terms of intensity and / or color in the at least one partial area illuminated by the at least one additional light source by means of illumination by means of at least one additional light source with the first light color or the first light color spectrum or the third light color or the third light color spectrum.

[0013] Finally, a method of the type mentioned at the outset according to claim 15 is designed and further developed such that the generating means have at least one additional light source for illuminating at least one partial area of ​​the at least one marker and that the at least one additional light source is used to emit a second light color or a second light color spectrum different from the first light color or a second light color spectrum onto the at least one partial area in such a way that that when a marker is illuminated by the first light source with the first light color or light color spectrum, the visibility of the marker, as produced by the first light color or light color spectrum with regard to intensity and / or color, is changed in at least one partial area illuminated by the at least one additional light source by illumination by at least one additional light source.

[0014] In accordance with the invention, it has first been recognized that the aforementioned problem is solved in a surprisingly simple manner by cleverly implementing an illumination or illumination sequence. For this purpose, in a further simple manner according to the invention, the generating means comprise at least one additional light source with which at least one partial area, i.e., one or more partial areas, of the at least one marker can be illuminated. The at least one additional light source can emit a light color or a light color spectrum with which the visibility of the marker in the illuminated partial areas of the marker can be altered. This alteration of visibility is a change that was previously generated by illumination with a first and / or a second light source.Thus, at least one additional light source is used to selectively modify the visibility of at least one definable sub-area of ​​the marker for the detector. For example, a sub-area illuminated by an additional light source that appears dark under illumination from a first and / or second light source may now appear bright. Alternatively, a sub-area illuminated by an additional light source that appears bright under illumination from a first and / or second light source may now appear dark. Through suitable decoding and evaluation, a position determination for the object can be made based on this change, the resolution of which ultimately corresponds to the size of the sub-area illuminated by the additional light source. This applies to the case with a first light source, a second light source, and / or a second light source.light source and at least one additional light source according to claims 1 and 14, as well as in the case with a first light source and at least one additional light source according to claims 2 and 15. In the first case, in addition to the first light source, the second light source and the at least one additional light source, further light sources can be implemented and used, for example a third light source, etc., which do not only illuminate at least a partial area of ​​the marker.

[0015] Consequently, the devices and methods according to the invention provide devices and methods which enable a reliable determination of the position of an object with high resolution and structurally simple means.

[0016] It should be explicitly noted here that the expression "at least one sub-area" refers to one or more sub-areas of the at least one marker. This means that the expression "at least one sub-area" does not imply that the expression refers to either a sub-area or the entire marker.

[0017] In a specific embodiment, the marker(s) can be implemented by means of one or more codes or Data Matrix codes, whereby several codes or Data Matrix codes can be implemented in the form of a code strip.

[0018] In another embodiment, the at least one sub-area can be formed by at least one strip-shaped area or by at least one element or module of the marker. This could, for example, be an element or module of a Data Matrix code. Both with a strip-shaped area and with an element or module, a particularly high resolution for position determination can be reliably achieved. Alternatively, the at least one sub-area can be formed by a surrounding area of ​​at least one strip-shaped area, element, or module of the marker. In this alternative, the functionality is essentially reversed compared to the previously mentioned alternative; that is, by illuminating the sub-area, another area is excluded from the illumination.For example, a dark striped area or a dark element or module, or a light striped area or a light element or module, can be created.

[0019] More specifically, the at least one additional light source can be designed to provide illumination corresponding to the shape of the at least one sub-area, for example, strip-shaped or point-shaped illumination, or illumination illuminating the surrounding area of ​​at least one strip-shaped area, element, or module of the marker. This allows for particularly precise illumination of the at least one sub-area.

[0020] Advantageously, the generating means can include a control unit for defining the illumination or illumination sequence of the first and / or second light source to provide a change in the visibility of the at least one marker or part of the at least one marker by means of the detector. With appropriately selected illumination or illumination sequence, reliable position determination can be ensured by means of the evaluation means, which can include an evaluation unit. The control unit can specify the type of illumination pseudo-randomly.

[0021] For reliable control of the illumination with the at least one additional light source, the generating means can include a control unit for defining a time and / or duration of illumination of the at least one sub-area of ​​the at least one marker to be illuminated and / or a lighting sequence for the at least one sub-area of ​​the at least one marker to be illuminated with the at least one additional light source. The additional light source can act as a source of interference, disrupting illumination generated by the first light source and / or the second light source with the emission of a corresponding light color or light color spectrum.

[0022] In a further embodiment, the generating means can include a control unit for defining the first and / or second light color and / or third light color or the first and / or second light color spectrum and / or third light color spectrum of the first light source, the second light source, and / or the at least one additional light source. This control unit allows for simple central control and thus specification of the light color or light color spectrum emitted by the first light source, the second light source, and / or the at least one additional light source.

[0023] In a further advantageous way, the evaluation tools can be used – for example, with an evaluation unit designated as evaluation unit 2 in Fig. Figure 11 shows that the device is designed to a) check the at least one marker for correctness using an algorithm, b) correct any change in the visibility of the marker detected by illumination with the at least one additional light source in the at least one sub-area, which is recognized as an error by the algorithm, and c) determine a corrected sub-area, a corrected strip-shaped area or a corrected element or module of the marker, for example a changed bit or several changed bits, by comparison with data read by the detector, so that the position, an angular position and / or a distance of the object relative to the at least one marker or to the path can be calculated or determined.Illumination generated by at least one additional light source creates a change or disturbance in at least one sub-area, which is recognized and corrected by the algorithm as an error. The location of this change or disturbance can be determined based on the marker's layout, for example, Data Matrix codes. As a result, the object's position relative to the path can then be determined.

[0024] In another embodiment, with a view to simple calculation or determination of the position, the at least one additional light source for illuminating the at least one partial area can be designed at a definable distance from an optical axis of the detector.

[0025] In a specific embodiment, the illumination direction of the at least one additional light source can be parallel to an optical axis of the detector. Particularly with regard to determining the angular position of the object relative to the marker, illumination with the at least one additional light source can be at an angle to the at least one marker.

[0026] In another specific embodiment, the detector can be a camera and / or the object a vehicle.

[0027] In exemplary embodiments of the devices and methods according to the invention, the position of an object relative to a path can be reliably determined down to the module size of a code. A change in the visibility of a single module or a few modules within the code, generated by the at least one additional light source, can be sufficient to reliably detect the change and provide high resolution for accurate position determination.

[0028] It is important that even when using at least one additional light source, all markers or codes within the area of ​​a reading window or detection area of ​​the detector remain decodable and usable. This is often not guaranteed with devices and methods known from the aforementioned prior art.

[0029] There are now various ways to advantageously develop and further refine the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the dependent claims and, on the other hand, to the following explanation of preferred embodiments of the devices and methods according to the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows Fig. 1 in a diagram an embodiment of the device according to the invention, Fig. 2a-f schematically represent steps of an embodiment of the method according to the invention, as well as a further representation of an associated code and codeword array. Fig. 3 in another diagram the exemplary embodiment from Fig. 1, Fig. 4 in a schematic representation a further embodiment of the device according to the invention with a deflection mirror, Fig. 5 in a schematic representation a further embodiment of the device according to the invention with light sources arranged behind an optic, Fig. 6 in a schematic representation a further embodiment of the device according to the invention, Fig. 7a-d in schematic representations steps of a further embodiment of the method according to the invention, Fig. 8a-d in schematic representations steps of a further embodiment of the method according to the invention, Fig. 9 in a schematic representation a code with oblique illumination by an additional light source, Fig. 10 in a schematic representation a code corresponding to the code from Fig. 9 with modules for which error correction is necessary under blue lighting, and Fig. 11 in a further diagram a further embodiment of the device according to the invention.

[0030] Fig. Figure 1 shows a diagram illustrating an embodiment of the device according to the invention for reliably determining the position of an object 1 with respect to a relative movement between the object 1 and a path 2, wherein in this diagram the object 1 has a camera 3 which may be integrated into the object 1. In a specific embodiment, the object 1 may, for example, be a self-driving vehicle in an industrial application.

[0031] The device further comprises several markers 4 in the form of Data Matrix codes 4 arranged along the path 2, wherein several markers 4 are detected by means of the detector 3 within its spatial detection area 5 or reading window 5 to determine the position of the object 1 relative to the markers 4.

[0032] Furthermore, the device comprises generating means for providing a definable graphic representation 7, 8 or graphic representation sequence, wherein the graphic representation 7, 8 or graphic representation sequence is formed on the basis of illuminated markers 4 and is detected by means of the detector 3 within its spatial detection range 5.

[0033] The device further includes evaluation means for verifying a match or relationship between the provided graphic representation 7, 8 or graphic representation sequence with corresponding data detected by the detector 3, in order to verify whether software within the detector 3 is still functioning correctly or may be frozen or hanged or have a time shift or delay.

[0034] The generating means comprise a first light source 9 and a second light source 10, wherein the first light source 9 emits a definable first light color or a definable first light color spectrum, and the second light source 10 emits a definable second light color or a definable second light color spectrum different from the first light color for illuminating a correspondingly colored graphic representation 7, 8 or graphic representation sequence provided by the generating means through illumination with the first light source 9 and the second light source 10, such that, depending on the illuminating first or second light color or the illuminating first or second light color spectrum, the graphic representation 7, 8 or a part of the graphic representation is visible or not by means of the detector 3 with or in a predefinable intensity and / or color.The colored graphic representation 7, 8 and at least one marker 4 are identical, or the colored graphic representation sequence is formed by a sequence of representations of marker 4.

[0035] To provide a particularly high resolution for determining the position of the object 1 relative to the path 2, the generating means have an additional light source 11 for illuminating a sub-area 12 of a marker 4, wherein the additional light source 11 is designed to emit the 1st or 2nd light color or the 1st or 2nd light color spectrum onto the sub-area 12 such that that, in the case of a marker 4 illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker 4, as produced by the first light color or the first light color spectrum, in the sub-area 12 illuminated by the additional light source 11, is changeable with regard to intensity and / or color by illumination by the second light source 11 and / or that, in the case of a marker 4 illuminated by means of the 2nd light source with the 2nd light color or the 2nd light color spectrum, the visibility of the marker 4 produced by the 2nd light color or the 2nd light color spectrum in the sub-area 12 illuminated by means of the additional light source 11 with regard to intensity and / or color can be changed by illumination by means of the additional light source 11.

[0036] In contrast to methods known from the prior art, in this method according to an embodiment of the present invention, only a partial area 12 of one or more codes 4 is changed by the additional light source 11, which can be recognized and verified by a safe control unit 13 or superimposed control 13.

[0037] The safe control unit 13 or the superimposed control unit 13 can also detect errors in an evaluation unit 6 of the evaluation equipment. Errors that are relevant for a SIL level can also occur in the evaluation unit 6.

[0038] In the embodiment shown here, the first light source 9 is designed to emit blue light, the second light source 10 is designed to emit red light, and the additional light source 11 is designed to emit blue light.

[0039] A key concept of the invention is based on the chain superimposed control 13 -> interference illumination -> interference illumination area by additional light source 11 -> camera 3 -> evaluation unit 6 -> superimposed control 13.

[0040] For example, the aforementioned WO 2017 / 045704 A1 specifies a principle based on reliable positioning using dual illumination and a multicolored code band. This method allows for the reliable detection of a code 4 within the reading window 5. However, it cannot reliably determine the precise location of the code 4 within the reading window 5 itself.

[0041] The in Fig. The embodiment shown adds an additional light source 11 to an existing dual lighting system with the first light source 9 and the second light source 10. This additional light source illuminates only a relatively small part or area 12. The sequence or timing of the lighting with the first light source, the second light source, and / or the additional light source is usually determined by the evaluation unit 6 and transmitted to the higher-level control unit 13. Alternatively, this sequence or timing can be determined by the higher-level control unit 13. The higher-level control unit 13 selects which of the lighting sources are active and which are not. The evaluation unit 6 does not have this information.

[0042] In the embodiment shown here, a section 12 in the form of a strip is projected at an axial distance d from an optical axis of the camera 3. The color of the strip is chosen to be the color of the illumination that is currently inactive. In this case, the second light source 10 is active with red illumination, so the additional light source 11 emits blue illumination – the currently inactive light color. As a result, modules 14 of the code 4, which appear dark under the current illumination and are not black, now appear bright. This, in turn, leads to the detection of errors during decoding, which can typically be corrected. The corrected error locations are passed on to the higher-level control unit 13, which can then verify that the error locations correspond to the uncertain position values.The distance d between the optical axis of the camera 4 and the optical axis of the additional light source 11 is known.

[0043] Fig. Figures 2a-f show schematic representations of steps of an embodiment of the method according to the invention as well as a further representation of an associated code and codeword array.

[0044] In Fig. 2a shows part of a colored code 4, which is illuminated in red by the second light source 10. A further section 12, illuminated in blue by the additional light source 11 (not shown here), is also shown. The modules 14 of the code 4 are colored black, cyan, yellow, and white, and the red and blue illumination is indicated here but not yet switched on.

[0045] In Fig. In step 2b, the red lighting with the second light source 10 is now switched on. As a result of the red lighting, code 4 appears with light and dark modules 14. The blue interference strip lighting with the additional light source 11 is not yet switched on here, but only indicated.

[0046] In Fig. Figure 2c now shows the situation in which the blue lighting with the additional light source 11 is also switched on. As a result, the cyan colored modules 14 in the area of ​​the interference strip or sub-area 12 then change from dark to light, which is particularly noticeable in module 14 in the penultimate line of code 4.

[0047] In Fig. Figure 2d shows modules 14, which undergo a change in brightness. The corresponding symbols indicate the individual changes: ^ Module 14 becomes brighter. Module 14 changes its state from dark to light. Module 14 could change its state from dark to light, but it doesn't have to.

[0048] In Fig. Modules 2e are marked as those that could change their state from dark to light. Module 5.6, designated here with the reference number 14, will definitely do so; the others will change depending on the magnitude of the brightness change.

[0049] In Fig. 2f are the bits in the codeword array that could be changed.

[0050] Without loss of generality, Code 4 is a Data Matrix code (ECC200) with a size of 16x16 modules 14 and 14x14 modules 14 data content. According to the standard, Code 4 contains 12 bytes of user data and 12 bytes of correction data. This totals 192 modules 14, or bits.

[0051] The codeword array is typically checked for correctness after evaluation, for example using a Reed-Solomon correction algorithm. The goal of the algorithm is to detect and correct errors in the data / bits. The result is the corrected codeword array. By comparing it with the read codeword, the changed bits can be identified.

[0052] The changed bits can be reassigned to the layout of the Data Matrix code 4 in reverse direction, and thus it is clear that the interference lighting generated by the additional light source 11 must have been in the area of ​​column 5.6.

[0053] Since the size of code 4 is known and the distance d between the background light and the camera axis is known, the camera axis must be located at the position of codeword 5.6 + / - distance d. This ambiguity can be eliminated by using additional background light, for example by means of another auxiliary light source 11, at a different location.

[0054] The position determined in this way is independent of the calculation of the unsafe position. The unsafe position is typically determined via the position of code 4 in the image. The safe position can be output directly or compared with the unsafe position to verify its plausibility. To comply with the functional safety standard, it is advisable to implement a second interference strip illumination with the other complementary color.

[0055] By design, the location of the interference is independent of any frozen images or image read-in errors. Even tilting of the lens or interference from external sources can be detected using this method.

[0056] Fig. Figure 3 shows the exemplary embodiment in another diagram. Fig. 1. Here, a sensor with components arranged within it, such as the lighting 9, 10, the additional light source 11, the camera 3, the evaluation unit 6, and the superimposed control unit 13, is represented as a quasi-integrated component. The superimposed control unit 13 specifies the type of lighting to the lighting 9, 10 in a pseudo-random manner. Image acquisition and switching on of the lighting are carried out conventionally via the evaluation unit 6; however, the type of lighting specified by the control unit 13—the emitted colors—remains unknown to it.

[0057] As described above, the code tape with the codes 4 reacts to the lighting situation and the camera 3 records the situation.

[0058] The evaluation unit 6 evaluates the codes 4 recorded in the image and, based on the content and position in the image, determines the position of the camera 3 of the object 1 relative to the code tape corresponding to path 2. However, the position is uncertain. In parallel, the code content(s) and the corrected bits are passed on to the higher-level control unit 13.

[0059] In another embodiment, the evaluation unit 6 and the superimposed control unit 13 can be implemented as a single component, with the evaluation unit 6 potentially encompassing the control unit 13. However, the independent functions of the evaluation unit 6 and the control unit 13, as described here, are retained.

[0060] Faults in code 4 are corrected by evaluation unit 6, but the cause of the faults remains unknown to the evaluation unit. It can therefore be considered a black channel in terms of functional safety. The faults themselves do not affect the calculation of the unsafe position, so this chain is also independent of the lighting type.

[0061] Thus, the following channels, which are completely independent of each other but still pass through the same black channel, are implemented: 1: Unsafe position 1, as already present in existing products known from the prior art. Modified or faulty modules 14 are detected and corrected, but the cause remains unknown. 2: Uncertain position 2 based on the detected corrected modules 14 and the known lighting arrangement.

[0062] Both position values ​​are independent of each other, and the superimposed control 13 can validate the values ​​against each other and thus establish a secure position.

[0063] In general, the evaluation tools perform the following functions: • Decoding the graphical representation 7, 8 -> Data • Calculating a position from the data • Output of the error correction data of the respective graphical representation 7, 8

[0064] These evaluation tools essentially act as a so-called black channel; that is, it is assumed that this part in particular exhibits errors (frozen, time delay, miscalculation, etc.) that initially go unnoticed. These can then be detected by the higher-level control system 13. Calculation of disturbance level:

[0065] An example code 4 (16x16 modules, 14x14 module data area) used in the implementation examples described here has 192 modules for information encoding (12 bytes of data + 12 bytes of Reed-Solomon correction). If a single line is to be examined, the following scenarios arise: Betroffene Zeilen / Spalten Alle Modulebetroffen 25% der Modulebetroffen 1 7,3% 1,8% 2 14,6% 3,6% 3 21,9% 5,5%

[0066] Depending on the width of the illuminated strip (section 12) on the code tape, either 1, 2, or 3 lines are affected. This depends on the spacing, the strip width, and the exact position. If all modules 14 in a row undergo a color change, the changes are shown in the middle column. Typically, however, only every fourth module 14 is in this color, so only 25% of the modules 14 are affected. These values ​​are given in the right-hand column. In all cases, the decoder should be able to make a correction. Normally, this will be around the aforementioned 3.6%.

[0067] The following errors can be identified in exemplary implementations carried out in this way: 1) Dirty code tape: Even without interference from the lighting, a dirty code tape will indicate an error on a module. The area affected by the dirt usually doesn't correspond to the uncertainly determined position. It is therefore detectable. 2) Permanent ambient light: It is detected like a dirty code tape. 3) Temporary ambient light: It is recognized as a dirty code tape for only a short time, then returns to normal. 4) Disturbance caused by spotlights: It might be detected in an image. Typically also in a complementary image or an image without interfering lighting. It should be treated like a dirty code tape. 5) Misaligned optics (any type: camera or stray light): The uncertainly calculated position does not match the position determined via the ambient light. 6) Incorrect image feed: This has the same effect as a misalignment of the optics, since the calculated uncertain position does not match the expected disturbance. 7) Frozen image or shifted image captures: The position of the interference lighting generated by the additional light source 11 does not change as expected. The code content does not change with the lighting as expected.

[0068] Examples of light sources that can serve as lighting include: • LED • VCSEL, including arrays thereof • Laser (-diode) • Xenon flash lamps, rather unusual these days

[0069] In further embodiments, a combination of several generation methods can be used, for example, area illumination with LEDs and a line using a laser.

[0070] As sub-area 12, a strip can be positioned at a defined distance d from the camera axis.

[0071] To deflect illumination with an additional light source 11, a MEMS mirror can be used, for example, which can direct a light beam in different directions. This is shown in Figure 1. Fig. Figure 4 shows a schematic representation of another embodiment of the device according to the invention with a deflecting mirror 15. It should be noted, however, that due to a typical offset, the illuminated areas change with variations in distance. This must be measured and known beforehand. Typically, this type of illumination can be used for point illumination.

[0072] Fig. Figure 5 shows a schematic representation of a further embodiment of the device according to the invention with light sources 16 of the auxiliary light source 11 arranged behind an optic. Light sources 16 arranged behind an optic 17 – such as a point, strip, LED, VCSEL, etc. – can be selectively controlled and then project a light beam in the corresponding direction depending on their spatial relationship to the optic 17. A disadvantage of this is that the position of the light sources 16 relative to the optic 17 is usually fixed, and therefore not every desired position of a sub-area 12 can be achieved. The individual codes 4 are designated here as P1, P2, P3, P4, and P5.

[0073] Alternatively, a projector can be used as a light source. It is important to ensure constant illumination during image capture. Typical DLP projectors with a color wheel are rather unsuitable for this purpose. Three-color-source DLP projectors, however, are suitable.

[0074] Instead of one stripe, several stripes can also be projected, since with a fixed stripe, it can also fall between two Data Matrix codes 4 and thus have no effect.

[0075] Alternatively, only a single module 14 of a code 4 can be illuminated. This reduces the interference, which is based on only a single "point". In this case, either a projector or a deflection mirror 15 is preferably used. The advantage here is that a relatively high degree of positioning accuracy can be achieved, as the area of ​​interference illumination can be thoroughly tested by slightly varying the position from image to image.

[0076] Determining the precise location of the light source can, for example, be done using the results of an uncertain position analysis. However, the challenge lies in the fact that, especially when dealing with movement, it is necessary to estimate in advance the exact location to which the light point should be directed. In this context, "point" refers to an area on the order of a module of 14.

[0077] This shows Fig. Figure 6 shows a further embodiment of the device according to the invention in a schematic representation, in which a module 14 is illuminated by an additional light source 11.

[0078] The safe or superimposed control 13 can decide for itself how the lighting should be applied. This allows the interference lighting generated by the additional light source 11 to be completely eliminated in an image capture, ensuring that the interference was caused solely by the interference lighting and is not generally present on the code tape.

[0079] Alternatively, instead of a complementary illumination color, activatable ink can be used. For example, a section 12 in the form of a strip can be illuminated with a UV light source. Some or all of the black modules 14 can be printed with UV-activatable ink. This will selectively make them glow. This is also possible with the standard modules 14.

[0080] Similarly, with the colored modules 14, it is possible to overlay them with UV-activated ink.

[0081] Alternatively, individual black modules 14, e.g., in the case of red / blue illumination, can be printed in green. Green appears dark under red and blue illumination. If the interference stripe is now printed in green, only these modules 14 will appear light. Preferably, the light modules 14 can also be printed in magenta. Green illumination has no effect on these. Thus, only the green-printed modules 14 will show a difference in brightness under suitable illumination.

[0082] This scenario is described in the following Fig. 7a-d shown, where Fig. 7a the basic situation as Fig. Figure 2a shows, however, with the difference that the black modules 14 are colored green and the white modules 14 are magenta. The illumination is provided by the second light source 10 in red, and the interference strip illumination by the additional light source 11 (not shown here) in green, whereby in this illustration neither the second light source 10 nor the additional light source 11 are yet switched on.

[0083] In Fig. 7b now shows the second light source 10, illuminated in red. The additional light source 11 is still not switched on. As a result of the red illumination, code 4 appears, displaying both light and dark modules. yellow + magenta: light blue + green: dark

[0084] In Fig. In 7c, the additional light source 11 is now also switched on. The green modules 14 then change from dark to light in the area of ​​the interference strip created by the additional light source 11.

[0085] In Fig. In 7d, modules 14 are shown, which undergo a change in brightness: x The module changes its state from dark to light. The module could change its state from dark to light, but it doesn't have to.

[0086] In further embodiments, it is also possible to implement the device with only two illumination colors. This allows for savings in lighting requirements. Furthermore, coexistence operation with known – non-safety-related – sensors is possible, which, for example, only have pure red illumination. The need for dual illumination to achieve a SIL level is also eliminated, since dual-channel capability exists and a standstill in signal processing can be detected by switching the interference strip illumination off / on / toggling. Such a standstill could indicate that software within detector 3 is malfunctioning, frozen, hangs, or exhibits a time shift or delay.

[0087] The following points are particularly advantageous here: 1) Only two colors are needed for illumination, so, for example, a line laser with only one wavelength is sufficient. 2) Increased insensitivity to ambient light can be achieved through the choice of color.

[0088] Fig. Figures 8a-d show schematic representations of the steps of such an embodiment of the method according to the invention, in which only two colors are required for illumination.

[0089] Similarly, the number of colors required for printing can be reduced. Specifically, if all black modules are replaced by green modules, only two colors are needed, although this variant is not shown here.

[0090] Fig. Figure 8a shows the basic situation as Fig. 2a, however, with the difference that all modules that were yellow there are now magenta, and all black or cyan modules are now either green or black. This would correspond to red lighting, but is not important here. The lighting with light source 10 is now red again, and the interference strip lighting with the additional light source 11 (not shown here) is green, whereby in this illustration neither light source 10 nor the additional light source 11 is yet switched on.

[0091] In Fig. In step 8b, light source 10 is now switched on with the red color. The auxiliary light source 11 is still not switched on. As a result of the red illumination, code 4 appears with light and dark modules. The interference strip illumination is not yet taken into account here. White + magenta: light Black + green: dark

[0092] In Fig. In module 8c, the additional light source 11 is now switched on. The green modules 14 then change from dark to light in the area of ​​the interference strip created by the additional light source 11. All others remain unchanged.

[0093] In Fig. Modules 14, which undergo a change in brightness, are shown in 8d: Module 14 changes its state from dark to light. Module 14 could change its state from dark to light, but it doesn't have to.

[0094] In the example above, not all modules 14 that appear dark were colored green, but only a few. This doesn't have to be implemented this way, but it has significant advantages: 1) The number of modules 14 can be significantly reduced, so that fewer corrections need to be made. 2) The modules 14 can be specifically positioned so that they are located as close to the edge as possible, thus allowing for the best possible determination of angles and positions. Distance determination:

[0095] If the direction of illumination with the additional light source 11 is not parallel to the optical axis of the camera 3, but at an angle, the position of the disturbance on the code tape shifts with the distance. Given a known angle, the distance between two disturbances can thus be determined reliably and / or plausibly compared to the angle determined in the classical way. Angle determination:

[0096] Using exemplary implementations, the angle of object 1 relative to code 4 or path 2 can also be determined, although not with very high accuracy, but sufficiently high for many cases.

[0097] Fig. Figure 9 shows a schematic representation of a code 4 designed as above, with oblique illumination from an additional light source 11. This ambient light is obliquely positioned within the code 4. In this case, the illumination with the 1st and / or 2nd light source should be perpendicular to the image field – the drawing plane. Fig. 9 - lying and the code 4 to it or to detector 3 or to camera 3 should be turned.

[0098] Fig. Figure 10 shows a schematic representation of a code 4 corresponding to code 4 from Fig. 9 with modules 14, for which error correction is necessary under blue illumination. It is clearly evident that this arrangement is only possible within a certain angular range. Thus, the angle can also be reliably determined and / or verified against the angle determined in the classical way.

[0099] Fig.Figure 11 shows a further embodiment of the device according to the invention. Here, the evaluation means comprises an evaluation unit 6, which is divided into a first evaluation unit and a second evaluation unit.

[0100] In principle, at least one marker can also be checked for correctness using an algorithm, and any change in the marker's visibility detected by illumination with at least one additional light source 11 in at least one sub-area, which is recognized by the algorithm as an error, can be corrected. By comparing this with data read by detector 3, a corrected sub-area, a corrected strip-shaped area, or a corrected element or module of the marker, for example, a changed bit or several changed bits, can be determined. From this, the position, angular position, and / or distance of the object relative to the at least one marker or to the path can be calculated or determined.Illumination or ambient light generated by at least one additional light source 11 creates a change or disturbance in at least one sub-area, which is recognized and corrected by the algorithm as an error. The location of this change or disturbance can be determined based on the layout of the marker, for example, Data Matrix codes. As a result, the position of the object relative to the path can then be determined.

[0101] The superimposed control 13 compares the determined position values ​​from a normal image processing - uncertain position 1 - and the determined position values ​​from the disturbed modules - uncertain position 2 - with each other and detects deviations according to a SIL approach.

[0102] Corrected object data is used for position determination. The modified object data or properties are used to verify the position determination. A second position determination – an uncertain position 2 – is performed using this error correction data. These two resulting "uncertain" positions 1 and 2 can then be compared and validated by the higher-level control system 13.

[0103] Other embodiments may have the following features and / or advantages: ◯ Illuminations can each be performed with a defined spectrum. ◯ One or more markers or one or more codes can consist of several areas with different remission properties. ◯ At least one light source illuminates only part of the image or the marker(s) or code(s). ◯ At least one lighting system is controlled by a superimposed safe control system. ◯ Changes in the marker or code properties are detected, corrected, and reported via error correction. ◯ The corrected data of the marker or code is used for position determination. ◯ Two procedures can be carried out: ▪ The data or properties changed by the error correction are used to verify the position determination. ▪ A second position is determined using the error correction data. ◯ The superimposed control 13 determines a safe position from the data, which extends into the area of ​​the individual areas of the individual remission spectra - for example, remission spectra of individual modules. • The angle between the object and the path or marker can be reliably determined. • The distance between the object and the path or marker can be reliably determined.

[0104] Regarding further advantageous embodiments of the device, method and detector with evaluation unit according to the invention, reference is made to the general part of the description and to the attached claims to avoid repetition.

[0105] Finally, it should be expressly pointed out that the exemplary embodiments described above serve only to illustrate the claimed teaching, but do not limit it to these exemplary embodiments. Reference symbol list 1 object 2 Path 3 Detector, camera 4 Markers, Code 5 Detection area, reading window 6 evaluation unit 7 Graphical representation 8 Graphical representation 9 1. Light source 10 2. Light source 11 Additional light source 12 sub-areas 13 Control unit, superimposed control 14 Module 15 deflection mirrors 16 light sources 17 Optics

Claims

[1] Device for reliably determining the position of an object (1) with respect to a relative movement between the object (1) and a path (2), comprising: a detector (3) which is attached to or integrated into the object (1), at least one marker (4) arranged along the path (2), wherein the at least one marker (4) is detected by means of the detector (3) within its spatial detection range (5) to determine the position of the object (1) relative to the at least one marker (4), Generating means for providing a definable graphic representation (7, 8) or graphic representation sequence, wherein the graphic representation (7, 8) or graphic representation sequence is detected by means of the detector (3) within its spatial detection range (5), and Evaluation means for verifying a match or relationship between the provided graphical representation (7, 8) or graphical representation sequence with corresponding data detected by the detector (3) in order to verify whether software within the detector (3) is still functioning correctly or may be frozen or hanged or have a time shift or delay, wherein the generating means comprise a first light source (9) and a second light source (10), wherein the first light source (9) emits a definable first light color or a definable first light color spectrum and the second light source (10) emits a definable second light color or a definable second light color spectrum different from the first light color for illuminating a correspondingly colored graphic representation (7, 8) or graphic representation sequence provided by the generating means, such that, depending on the illuminating first or second light color or the illuminating first or second light color spectrum, the graphic representation (7, 8) or a part of the graphic representation is visible or not by means of the detector (3) with or in a predefinable intensity and / or color, and wherein the colored graphic representation (7, 8) and the at least one marker (4) are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker (4), characterized by , that the generating means have at least one additional light source (11) for illuminating at least one sub-area (12) of the at least one marker (4) and that the at least one additional light source (11) is designed to emit the first or second light color or the first or second light color spectrum or a third light color or a third light color spectrum different from the first or second light color onto the at least one sub-area (12) in such a way, that, in the case of a marker (4) illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker in the at least one partial area (12) illuminated by the at least one additional light source (11) with the second light color or the second light color spectrum or the third light color or the third light color spectrum, as produced by the first light color or the first light color spectrum with regard to intensity and / or color, is changeable by illumination by the at least one additional light source (11) with regard to the visibility produced by the first light color or the first light color spectrum in the at least one partial area (12) illuminated by the at least one additional light source (11) and / or that, in the case of a marker (4) illuminated by means of the 2nd light source with the 2nd light color or the 2nd light color spectrum, the visibility of the marker (4) in the at least one partial area (12) illuminated by means of the at least one additional light source (11) with the 1st light color or the 1st light color spectrum or the 3rd light color or the 3rd light color spectrum, which is produced by the 2nd light color or the 2nd light color spectrum with regard to intensity and / or color, can be changed by illuminating it by means of the at least one additional light source (11). [2] Device for reliably determining the position of an object (1) with respect to a relative movement between the object (1) and a path (2), comprising: a detector (3) which is attached to or integrated into the object (1), at least one marker (4) arranged along the path (2), wherein the at least one marker (4) is detected by means of the detector (3) within its spatial detection range (5) to determine the position of the object (1) relative to the at least one marker (4), Generating means for providing a definable graphic representation (7, 8) or graphic representation sequence, wherein the graphic representation (7, 8) or graphic representation sequence is detected by means of the detector (3) within its spatial detection range (5), and Evaluation means for verifying a match or relationship between the provided graphical representation (7, 8) or graphical representation sequence with corresponding data detected by the detector (3) in order to verify whether software within the detector (3) is still functioning correctly or may be frozen or hanged or have a time shift or delay, wherein the generating means comprise a first light source (9), wherein the first light source (9) emits a definable first light color or a definable first light color spectrum for illuminating a correspondingly colored graphic representation (7, 8) or graphic representation sequence provided by the generating means, such that, depending on the illuminating first light color or the illuminating first light color spectrum, the graphic representation (7, 8) or a part of the graphic representation is visible or not by means of the detector (3) with or in a predefinable intensity and / or color, and wherein the colored graphic representation (7, 8) and the at least one marker (4) are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker (4), characterized by, that the generating means have at least one additional light source (11) for illuminating at least one sub-area (12) of the at least one marker (4) and that the at least one additional light source (11) is designed to emit a second light color or second light color spectrum different from the first light color or light color spectrum onto the at least one sub-area (12) such that that, in the case of a marker (4) illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker (4) in the at least one partial area (12) illuminated by the at least one additional light source (11) with respect to intensity and / or color, as produced by the first light color or the first light color spectrum, can be changed by illuminating it with respect to intensity and / or color by the first light color or the first light color spectrum. [3] Device according to claim 1 or 2, characterized bythat the marker(s) (4) is or are realized by means of one or more codes (4) or Data Matrix codes (4), wherein several codes (4) or Data Matrix codes (4) may be realized in the form of a code tape. [4] Device according to any one of claims 1 to 3, characterized by , that the at least one sub-area (12) is formed by at least one strip-shaped area or by at least one element or module (14) of the marker (4) or that the at least one sub-area (12) is formed by an environment of at least one strip-shaped area, element or module (14) of the marker (4). [5] Device according to any one of claims 1 to 4, characterized by, that the at least one additional light source (11) is designed in such a way that it provides illumination corresponding to the shape of the at least one sub-area (12), for example strip-shaped or point-shaped illumination or illumination illuminating an area surrounding at least one strip-shaped area, element or module (14) of the marker (4). [6] Device according to any one of claims 1 to 5, characterized by , that the generating means include a control unit (13) for defining an illumination or illumination sequence of the 1st and / or 2nd light source (9, 10) for providing a change in the visibility of the at least one marker (4) or part of the at least one marker (4) by means of the detector (3). [7] Device according to any one of claims 1 to 6, characterized by, that the generating means include a control unit (13) for defining a time and / or a duration of illumination of the at least one sub-area (12) to be illuminated of the at least one marker (4) and / or an illumination sequence for the at least one sub-area (12) to be illuminated of the at least one marker (4) with the at least one additional light source (11). [8] Device according to any one of claims 1 to 7, characterized by , that the generating means have a control unit (13) for defining the 1st and / or 2nd light color or the 1st and / or 2nd light color spectrum of the 1st light source, the 2nd light source and / or the at least one additional light source (11). [9] Device according to any one of claims 1 to 8, characterized by, that the evaluation means, for example with an evaluation unit (6), are designed such that they a) check the at least one marker (4) for correctness by means of an algorithm, b) correct any change in the visibility of the marker (4) detected and produced by illumination with the at least one additional light source (11) in the at least one sub-area (12), which is recognized by the algorithm as an error, and c) determine a corrected sub-area (12), a corrected strip-shaped area or a corrected element or module (14) of the marker (4), for example a changed bit or several changed bits, by comparison with data read by the detector (3), so that the position, an angular position and / or a distance of the object (1) relative to the at least one marker (4) or to the path (2) can be calculated or determined. [10] Device according to any one of claims 1 to 9, characterized by, that the at least one additional light source (11) for illuminating the at least one sub-area (12) is designed at a definable distance (d) from an optical axis of the detector (3). [11] Device according to any one of claims 1 to 10, characterized by , that an illumination direction of the at least one additional light source (11) is realized parallel to an optical axis of the detector (3). [12] Device according to any one of claims 1 to 11, characterized by , that illumination with the at least one additional light source (11) is realized at an angle to the at least one marker (4). [13] Device according to any one of claims 1 to 12, characterized by that the detector (3) is a camera and / or that the object (1) is a vehicle. [14] Method for reliably determining the position of an object (1) with respect to a relative movement between the object (1) and a path (2), in particular carried out by means of a device according to one of claims 1 or 3 to 13, wherein a detector (3) is attached to the object (1) or integrated into the object (1), wherein at least one marker (4) is arranged along the path (2), wherein the at least one marker (4) is detected by means of the detector (3) within its spatial detection range (5) to determine the position of the object (1) relative to the at least one marker (4), wherein a definable graphic representation (7, 8) or graphic representation sequence is provided by means of generation means, wherein the graphic representation (7, 8) or graphic representation sequence is detected by means of the detector (3) within its spatial detection range (5), wherein a match or relationship between the provided graphic representation (7, 8) or graphic representation sequence and corresponding data detected by the detector (3) is verified using evaluation means to verify whether software within the detector (3) is still functioning correctly or is possibly frozen or has crashed or has a time shift or delay, wherein the generating means comprise a first light source (9) and a second light source (10), wherein the first light source (9) emits a definable first light color or a definable first light color spectrum and the second light source (10) emits a definable second light color or a definable second light color spectrum different from the first light color for illuminating a correspondingly colored graphic representation (7, 8) or graphic representation sequence provided by the generating means, such that, depending on the illuminating first or second light color or the illuminating first or second light color spectrum, the graphic representation (7, 8) or a part of the graphic representation is visible or not by means of the detector (3) with or in a predefinable intensity and / or color, and wherein the colored graphic representation (7, 8) and the at least one marker (4) are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker (4), characterized by , that the generating means have at least one additional light source (11) for illuminating at least one sub-area (12) of the at least one marker (4) and that the at least one additional light source (11) is designed and used to emit the first or second light color or the first or second light color spectrum or a third light color or a third light color spectrum different from the first or second light color onto the at least one sub-area (12), that, in the case of a marker (4) illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker produced by the first light color or the first light color spectrum with regard to intensity and / or color in the at least one partial area (12) illuminated by the at least one additional light source (11) with the second light color or the second light color spectrum or the third light color or the third light color spectrum is changed by illumination by the first light color or the first light color spectrum with regard to intensity and / or color in the at least one partial area (12) illuminated by the at least one additional light source (11) and / or that, in the case of a marker (4) illuminated by means of the 2nd light source with the 2nd light color or the 2nd light color spectrum, the visibility of the marker (4) in the at least one partial area (12) illuminated by means of the at least one additional light source (11) with the 1st light color or the 1st light color spectrum or the 3rd light color or the 3rd light color spectrum is changed by illumination by means of the at least one additional light source (11) with regard to intensity and / or color. [15] Method for reliably determining the position of an object (1) with respect to a relative movement between the object (1) and a path (2), in particular carried out by means of a device according to one of claims 2 to 13, wherein a detector (3) is attached to the object (1) or integrated into the object (1), wherein at least one marker (4) is arranged along the path (2), wherein the at least one marker (4) is detected by means of the detector (3) within its spatial detection range (5) to determine the position of the object (1) relative to the at least one marker (4), wherein a definable graphic representation (7, 8) or graphic representation sequence is provided by means of generation means, wherein the graphic representation (7, 8) or graphic representation sequence is detected by means of the detector (3) within its spatial detection range (5), wherein a match or relationship between the provided graphic representation (7, 8) or graphic representation sequence and corresponding data detected by the detector (3) is verified using evaluation means to verify whether software within the detector (3) is still functioning correctly or is possibly frozen or has crashed or has a time shift or delay, wherein the generating means comprise a first light source (9), wherein the first light source (9) emits a definable first light color or a definable first light color spectrum for illuminating a correspondingly colored graphic representation (7, 8) or graphic representation sequence provided by the generating means, such that, depending on the illuminating first light color or the illuminating first light color spectrum, the graphic representation (7, 8) or a part of the graphic representation is visible or not by means of the detector (3) with or in a predefinable intensity and / or color, and wherein the colored graphic representation (7, 8) and the at least one marker (4) are identical or the colored graphic representation sequence is formed by a sequence of representations of the marker (4), characterized by, that the generating means have at least one additional light source (11) for illuminating at least one sub-area (12) of the at least one marker (4) and that the at least one additional light source (11) is used to emit a second light color or second light color spectrum different from the first light color or light color spectrum onto the at least one sub-area (12) in such a way, that, in the case of a marker (4) illuminated by the first light source with the first light color or the first light color spectrum, the visibility of the marker (4) in the at least one partial area (12) illuminated by the at least one additional light source (11) with the second light color or the second light color spectrum is changed by illumination by the at least one additional light source (11) with regard to intensity and / or color.

Images