Localization system and localization method with markers having holographic optical elements

Abstract

The invention discloses a concept for improved differentiation between an object marked with an optoelectronically detectable marker and a person marked with an optoelectronically detectable marker, in which holographic optical elements are introduced into a two-dimensionally planar marker, at which ambient light is reflected back with sufficiently high intensity even at high scattering angles relative to the surface normal of the two-dimensionally planar marker.For this purpose, it is proposed to detect light reflected by holographic optical elements (HOE; 21, 22, 23) applied to the marker (20) in an optoelectronic sensor (32) and to generate a two-dimensional reflection image, and to carry out an evaluation of the spectrally resolved local intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor (32) in an image processing device (34) and to determine, on the basis of the evaluated intensity distribution, a position and orientation assigned to the object (40) and a position and orientation assigned to the person, in each case relative to the optoelectronic detection device (30).

Description

Technical FieldThe present invention relates to a localization system and a localization method which is based on angle-dependent reflection measurements of holographically optical elements as part of markers to be localized.Prior ArtDifferent positioning methods can be used for determining the position and / or orientation of objects. Optical object recognition, for example, frequently uses geometric structures of high contrast, which can be recognized in a simple, accurate and reliable reproducible manner. Examples of these are optoelectronically detectable color-contrasted markings which consist of differently dimensioned geometric symbols or shapes, such as lines or polygons, for example, and gaps lying therebetween, so that the luminance difference at the boundaries between shapes and gaps is as high as possible. Such markings can have a one-dimensional coding (for example bar codes or bar codes) or a two-dimensional coding (for example data matrix codes, QR codes or Ace codes), each with a different payload density. The data encoded in a marker can be read mechanically using optical readers, such as cameras or camera scanners, for example, and can be further processed electronically.Markers can be equipped with holographic optical elements (HOE) to increase the information density. Examples of such markers are disclosed, for example, in the publications US 2021 / 0248338 A1, PT 99405 A, CZ 2004-1136 A3 and U.S. Pat. No. 10 885 413 B1.Disclosure of the InventionThe present invention provides a localization system and a localization method, each having the features of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent claims.A localization system for differentiating between an object marked with an optoelectronically detectable marker and a person marked with an optoelectronically detectable marker comprises an optoelectronic detection device. This has an optoelectronic sensor and an image processing device coupled to the optoelectronic sensor. The optoelectronic sensor is designed to detect light emanating from holographically optical elements applied to the markers and to generate a two-dimensional reflection image, wherein the light is reflected back onto the optoelectronic sensor by the holographic optical element. The image processing device is designed to perform an evaluation of the spectrally resolved local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor and to determine a position and orientation assigned to the object and a position and orientation assigned to the person, in each case relative to the optoelectronic capture device, on the basis of the evaluated intensity distribution.A localization method for differentiating between an object marked with an optoelectronically detectable marker and a person marked with an optoelectronically detectable marker comprises the steps of: detecting light emanating from holographically optical elements applied to the marker by means of an optoelectronic sensor of an optoelectronic detection device, wherein the light is reflected back to the optoelectronic sensor by the holographic optical element; generating a two-dimensional reflection image by the optoelectronic sensor from the detected reflected light; evaluating the spectrally resolved local intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor; and determining a position and orientation assigned to the object and a position and orientation assigned to the person, in each case relative to the optoelectronic detection device, on the basis of the evaluated spectrally resolved local intensity distribution.The localization device and / or the localization method is preferably designed to distinguish an object from a person by a primary color of the outgoing light. Preferably, a variation of the base color codes the direction. In one variant, the base color additionally or alternatively encodes a group of people and / or an object group. For example, the primary color red codes the group person, in this case the light red direction codes to the left and the dark red direction codes to the right. In one variant, color ranges, for example from bright red to medium red, code a group of people and / or an object group.Holographic optical elements (HOEs) are optically active structures whose functional principle is based on holography. In the case of an HOE, the imaging properties of a hologram are utilized or a conventional optical system is realized by a hologram, so that light waves can be deflected, divided, focused and / or widened. HOEs can also be formed, for example, as extremely thin film foils which can split incident light into its spectral colors. However, only the light beams that are incident within a specific wavelength range are diffracted in this case. By using HOEs, diffraction maxima can be generated which arise due to constructive interference of light waves at the HOEs.In contrast to conventional optics, in HOEs, a deflection of the light is realized not by refraction, but by diffraction at the volume grating. In this case, the HOEs can be manufactured both for transmission and for reflection and make new designs possible by means of a free selection of angle of incidence and angle of reflection or angle of diffraction. The holographic diffraction grating is exposed, for example, into a thin, photosensitive film. As a result of the volume diffraction, a characteristic wavelength and angle selectivity or else filter function can additionally be assigned to an HOE. Depending on the recording condition, for example a wavelength or an angle, only light from defined directions and with defined wavelengths is diffracted at the structure of the HOE.Advantages of the InventionAccording to some embodiments of the localization system and the localization method, the optoelectronic detection device can furthermore have a memory, which is coupled to the image processing device and stores a multiplicity of comparison and / or training data for the detected two-dimensional reflection images in a database. This enables a quick and reliably reproducible localization of the object from known reference data.According to various embodiments of the localization system and of the localization method, the image processing device can furthermore perform object recognition of structures of a contrast code of the marker recorded in the two-dimensional reflection image captured by the optoelectronic sensor. The combination of contrast codes such as QR codes with holographic optical elements enables the implementation of redundant detection mechanisms, which improves robustness with respect to interference sources, reduces susceptibility to incorrect determinations and increases the accuracy of the position and distance determination.According to several embodiments of the localization system and the localization method, at least one of the holographic optical elements applied to the marker may have a holographic deflector with high angle selectivity at low elevation angles with respect to the surface of the marker. This enables the implementation of a warning function in the case of inadequate detectable effective area of the marker in unfavorable orientations.According to some embodiments of the localization system and the localization method, the color depth of the optoelectronic sensor may be at least 8 bits. This advantageously increases the spatial and angular resolution of the position and orientation determination.According to a number of embodiments of the localization system and the localization method, the optoelectronic detection device can have one or more image processing systems as optoelectronic sensors, in particular color cameras with a color depth of at least 8 bits and a resolution of at most 640x480 pixels. The use of holographic optical elements (HOEs) advantageously leads to a substantially higher accuracy with at the same time lower resolution of the image processing systems and thus lower requirements for the objectives used. The evaluation of images of lower resolution furthermore requires a substantially lower computing capacity. Because computationally expensive pattern or object recognition can be replaced by evaluating the spectrally resolved local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor, the computational capacity used falls further.In some such embodiments, one or more of the optoelectronic sensors can each have an objective and optionally an externally controllable exposure source. The use of an integrated externally controllable exposure source can advantageously improve robustness with respect to interference light without the need for a complex exposure system.In addition, in some variant embodiments, the evaluation electronics for evaluating the spectrally resolved local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor can be integrated into the respective image processing system. The image processing systems may be coupled together in the form of a stereo camera or an omnidirectional camera. This enables the acquisition of further information about the spatial arrangement of a plurality of HOEs.The image processing systems do not have to have a high resolution and a high light sensitivity, so that large and thus cost-intensive objectives can be dispensed with.According to some embodiments of the localization system and the localization method, at least one of the holographic optical elements applied to the marker can have an optical function, such that a changing distance of the detection device from the object is indicated by a color change and / or a change in the intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor. As a result, a distance determination can be carried out more precisely.According to some embodiments of the localization system and the localization method, at least one of the holographic optical elements applied to the marker can have an optical function, such that a changing object orientation for dedicated angle ranges is indicated by a color change and / or a change in the intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor. This makes it possible to determine the object orientation more precisely.According to some embodiments of the localization system and the localization method, at least two of the holographic optical elements applied to the marker can have duplicated optical functions for improving the reliability of a determination of the distance of the detection device from the object and / or a determination of the object orientation for dedicated angular ranges. This advantageously enables a particularly robust determination of the distance and object orientation, since the evaluated back reflections of the at least two holographically optical elements can be checked for plausibility with respect to one another.According to some embodiments of the localization system and the localization method, at least one of the holographic optical elements applied to the markers used for identifying the object can reflect light of a previously defined wavelength, so that one-to-one identification of the object and thus the delimitation of the object from humans is made possible. For example, specific spectral wavelength ranges can be used exclusively on markers provided for objects, so that color coding is possible for discriminating between activated and non-activated detection elements.According to some embodiments of the localization system and the localization method, at least two of the holographic optical elements applied to the markers can be designed such that a unique signature can be derived over a wide capture angle range, for example over a capture angle range of at least 120° in azimuth and elevation.According to some embodiments of the localization system and the localization method, at least two of the holographic optical elements applied to the markers used for identifying the object can be designed such that a clear classification of the object can be determined from the light reflected back when the position and / or orientation of the object is changed. For example, different distinguishable classification rules of detected objects can result from predefined sequences of specific changes at defined wavelengths.The above embodiments and developments can be combined with one another as desired, insofar as appropriate. Further embodiments, developments and implementations of the invention also include combinations of features of the invention described above or below with respect to the exemplary embodiments, which combinations are not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.Brief Description of the DrawingsFurther features and advantages of the invention are explained below with reference to the figures. The following are shown: FIG. 1 : an exemplary illustration of an optoelectronically detectable marker in the form of a QR code; FIG. 2 : shows a schematic illustration of an optoelectronically detectable marker in the form of a QR code with holographic optical elements superimposed on the coding, according to one embodiment; FIG. 3 : shows a schematic illustration of the optoelectronic detection of the marker of FIG. 2 with the aid of a localization system according to one embodiment; FIG. 4 : an exemplary diagram of a two-dimensionally resolved optoelectronic measurement signal distribution of the holographic optical elements of the marker of FIG. 2 in a localization system of FIG. 3 ; FIG. 5 : shows a further exemplary diagram of a two-dimensionally resolved optoelectronic measurement signal distribution of the holographic optical elements of the marker of FIG. 2 in a localization system of FIG. 3 ; FIG. 6 : shows a flow diagram of a localization method for determining the location and position of an object identified by an optoelectronically detectable marker according to one embodiment; FIG. 7 : exemplary structures for redundant holographic optical elements on an optoelectronically detectable marker according to one embodiment; FIG. 8 : shows a schematic illustration of an optoelectronically detectable marker in the form of a QR code of holographic optical elements superimposed with the coding and a holographic deflector according to a further embodiment; FIG. 9 : shows a schematic illustration of an optoelectronically detectable marker in the form of a QR code with holographic optical elements superimposed on the coding according to a further embodiment; FIG. 10 : shows a schematic plot of the reflection intensity maxima along the distance from the optoelectronically detectable marker of FIG. 9 ; and FIG. 11 : shows a schematic plot of the frequency-dependent reflection intensity along the distance from the optoelectronically detectable marker of FIG. 9.DESCRIPTION OF EMBODIMENTSFIG. 1 shows an exemplary illustration of an optoelectronically detectable marker in the form of a QR code 10. The polygons are contrasted by optoelectronically detectable colors with gaps lying between them, so that the luminance difference at the boundaries between shapes and gaps is as high as possible. Such markings can have a one-dimensional coding (for example bar codes or bar codes) or a two-dimensional coding (for example data matrix codes, QR codes or Ace codes), each with a different useful information density. The data encoded in such a marker can be read mechanically and processed electronically using optical readers, such as cameras or camera scanners.A location and / or position determination of objects which have been marked by such optoelectronically detectable markers can be error-prone and often inaccurate. The accuracy of the location and / or position determination often varies with the distance of the marked object and with the illumination conditions in the respective environment. The determination of the angular orientation, i.e. the spatial orientation with respect to the optical reading device, can likewise be greatly impaired. As the distances become greater, optoelectronic detection devices with a higher resolution may be required. The recognition and localization of the patterns on such markers requires the use of complex object recognition algorithms that require a high computational capacity.By using markers equipped with holographic optical elements (HOEs), the localization of the objects marked therewith can be improved. In particular, but not exclusively, the position detection can be significantly improved by an optimized angle orientation determination. Better angular resolution, potentially better spatial resolution, lower costs due to less good camera resolution, computationally favorable and fast determination of the position, and possible extensions of existing localization solutions can be achieved by using optoelectronically detectable markers in the form of one- or two-dimensional planar contrast codes, such as bar codes, bar codes, data matrix codes, QR codes or Ace codes, holographically optical elements (HOE) superimposed with the code.FIG. 2 shows an example of such an optoelectronically detectable marker 20 with a contrast coding, here a QR code 10. The number, size, shape, type and position of the HOEs 21, 22 and 23 is shown in FIG. 2 only by way of example. It is possible to provide more or less than three HOEs 21, 22 and 23 with a different size, shape and / or position on the marker 20.The optical function of a hologram arises by diffraction of incident optical wavefronts at a diffraction grating in the volume of the holographic film. The diffraction grating was previously exposed in a recording process into the volume of the holographic film. The diffraction grating is formed in accordance with an interference pattern generated by two optical recording wavefronts as a modulation of the refractive index in the holographic film. The interference pattern is generated by the superposition of two coherent recording waves in the volume of the holographic film. The interference of the two recording wavefronts forms in the volume of the holographic film an interference grating which is permanently impressed into the volume of the holographic film by the exposure process. The parameters of the recording process (wavefront shape, spectral properties, intensity distribution and duration) determine the properties of the diffraction grating produced. HOEs can be produced, for example, as hologram structures by holographic wavefront printing, as taught, for example, in the publication DE 10 2017 218 544 A1.FIG. 3 shows a schematic illustration of the optoelectronic detection of the marker 20 of FIG. 2 with the aid of a localization system 1. the localization system 1 comprises an optoelectronic detection device 30, such as a video camera, a camera scanner or a similar device. Reflected ambient light emitted by the marker 20 and in particular by the HOEs 21, 22 and 23 is recorded via a suitable detection optical unit 31 and fed to an optoelectronic sensor 32. The optoelectronic sensor 32 may be, for example, a CCD sensor, a CMOS sensor, an active pixel sensor (APS), a photodiode array, or another suitable electromagnetic radiation detector with spatial resolution. The optoelectronic detection device 30 can have, for example, one or more color cameras as optoelectronic sensors 32 with a resolution of at most 640 x 480 pixels. The optoelectronic sensors 32 can each have an objective lens and an externally controllable exposure source.The image captured by the optoelectronic sensor 32 is transferred to an image processing device 34, which carries out an evaluation of the captured image and transfers the evaluation result to an output interface 35 of the capturing device 35. The image processing device 34 may be, for example, a microprocessor, a graphics processor, an ASIC, an FPGA, or any other suitable computing device. The output interface 35 may be, for example, a display or another user interface. It may also be possible for the output interface 35 to establish a communication connection to a further device to which the evaluation result of the image processing device 34 is transmitted via the output interface 35.The optoelectronic detection device 30 can also have a memory 33, such as a ROM, a RAM or another type of data memory, in which, on the one hand, configuration parameters and operating software for the operation of the detection device 35 and in particular of the image processing device 34 are stored. Secondly, comparison and / or training data can be stored in a database in the memory 33, which database allows the image captured by the optoelectronic sensor 32 to be matched with known images or optoelectronic capture signatures of markers in different positions, orientations and / or positions.The optoelectronic detection device 30 serves on the one hand for the general identification and localization of an object marked with a marker 20 on the basis of contrast coding, such as the QR code 10, for example, object detection of the structures of the QR code 10 recorded in the image detected by the optoelectronic sensor 32 is carried out in the image processing device 34 and a comparison with known QR codes is carried out, for example by comparison with known QR codes stored in a database of the memory 33. Subsequently, by determining the size, spacing and mutual orientation of the patterns and structures of the QR code 10, it is possible to draw conclusions as to the orientation in space.Additionally or alternatively, the image captured by the optoelectronic sensor 32 may receive back-reflected light from the HOEs 21, 22, and 23. In addition to the geometric position of the structure of the HOEs 21, 22 and 23, the position and orientation of the object relative to the optoelectronic detection device 30 can be encoded by the color of the backscattered light. FIGS. 4 and 5 show two exemplary diagrams of two-dimensionally resolved optoelectronic measurement signal distributions P 1 and P 2 of the HOEs 21, 22 and 23 of the marker 20 of FIG. 2 by an optoelectronic detection device 30 of the localization system 1 of FIG. 3.HOEs are structures which are written into a photo-optical layer and redirect the incident light. Depending on how the structure of the HOE is designed, the optical function can be determined, for example a scattering hologram, a retroreflector, a mirror, a concave mirror or a lens. HOEs can also have a high angular or wavelength selectivity in terms of their function. For example, the components of white light are scattered to different extents in different spatial directions. Therefore, the orientation of the HOE relative to the illumination source can be encoded by the backscattered wavelength and determined with the aid of the image captured by the optoelectronic sensor 32 of an optoelectronic detection device 30. In this case, the spectrally resolved local intensity distribution P of three back reflections A, B and C of different HOEs 21, 22 and 23 can be imaged bijectively onto the location function F of the HOEs 21, 22 and 23 on a marker 20, measured at azimuth α and elevation β relative to the surface of the marker 20. For example, in FIG. 4, the location function F(α1, β1) can be deduced from the spectrally resolved local intensity distribution P1[I(A),I(B), I(C)] of the location-dependent intensities and colors on the two-dimensional image of the optoelectronic sensor 32. Analogously, for example, in FIG. 5, the location function F(α2, β2) can be deduced from the spectrally resolved local intensity distribution P2[I(A),I(B), I(C)] of the location-dependent intensities and colors on the two-dimensional image of the optoelectronic sensor 32.An optoelectronic sensor 32 of an optoelectronic detection device 30 can have a color depth of at least 8 bits, for example. This means that the optoelectronic sensor 32 can distinguish between approximately 16 million color nuances. As a result, a very precise angle measurement of both the azimuth angle α and the elevation angle β can be carried out with the optoelectronic detection device 30. Because a plurality of HOEs 21, 22 and 23 positioned differently on the marker 20 respectively generate unique, linearly independent color patterns on the optoelectronic sensor 32, the respectively associated angular orientation of the marker 20 can be encoded uniquely. If the orientation of the object or the position of the optoelectronic detection device 30 relative to the object and thus also the orientation of the marker 20 relative to the optoelectronic detection device 30 changes, the wavelengths of the light backscattered by the HOEs 21, 22 and 23 shift. This also makes it possible to draw conclusions about the change in position.The localization system can additionally have a light source 50, which can be provided as a separate device or as part of the detection device 30. The light source 50 can emit white light W onto the marker 20 in a targeted manner, for example, so that the position of the illumination and recording optics is known a priori. The determination of the location and angular orientation of the marker 20 on the basis of the back reflection patterns in the image of the optoelectronic sensor 32 thereby becomes simpler and more reliable. In addition, the light emitted by the light source 50 can be modulated, so that a clear assignment of the backscattered light and an improvement of the signal-to-noise ratio can be achieved via a lock-in mechanism.The HOEs 21, 22 and 23 can have optimized optical functions, such as, for example, a retroreflectivity with a limited angular range, scattering functions with a high angular selectivity, or any combination of these functions. Furthermore, the HOEs 21, 22 and 23 can be designed for light outside the visible range, such as in the UV or infrared range.FIG. 7 shows, by way of example, that specific patterns and / or specific color combinations of HOEs can be used, so that the determination of the distance of the detection device 30 from the marker 20 can be improved with regard to color, shape and size by way of pattern recognition. The angular selectivity of holograms enables an angular change or the object orientation in space to be encoded precisely. For example, one and the same optical function can be applied multiple times on the marker surface. The matching of wavelengths and intensities of the redundant optical functions can implement a control functionality. The optical function of the surfaces can alternatively also be selected for this purpose such that the intensities of the light diffracted back must differ. The deflection function can also be designed in opposite directions, for example, so that a point-symmetric intensity distribution of the back-diffracted light is thereby obtained. If the position of the marker 20 relative to the detection device 30 changes, this distribution must also change point-symmetrically. Regions that address different wavelengths can be arranged symmetrically or asymmetrically, whereby the color composition of the reflected light likewise changes symmetrically or asymmetrically when the position of the marker 20 changes. Oppositely directed arrangements of deflectors can be used to improve the estimation accuracy of the marker distance via the distance of the intensity maxima of the reflected light. Analogous advantages in the detection accuracy can also be achieved in the azimuth angle if the deflector structures are applied to the marker 20 rotated by 90°.The object position in space can also be extracted by using specific patterns as shown in the examples of FIGS. 9, 10 and 11. In one embodiment, a pattern may consist of, for example, circular holographic deflectors 25 arranged concentrically. They redirect light in such a way that an intensity maximum for a specific wavelength is obtained at a specific distance. It can be seen in FIG. 10, for example, that the holographic deflector 25 with the largest radius shows an interference pattern R with an interference maximum at a distance d 3 of the detection device 30 from the marker 20. Likewise, it can be seen that the holographic deflector 25 with the mean radius shows an interference pattern R with an interference maximum at a distance d 2 of the detection device 30 from the marker 20. Finally, it can be seen that the holographic deflector 25 with the smallest radius shows an interference pattern R with an interference maximum at a distance d 1 of the detection device 30 from the marker 20. FIG. 11 shows the associated wavelength-dependent intensity distributions P of the different wavelengths f1, f2 and f3 of the concentric holographic deflectors 25 as a function of the respective distances d1, d2 and d3. If the distance of the marker 20 from the detection device 30 is varied, this can therefore be read directly in the image detected by the optoelectronic sensor 32 at changing intensities of the rings and wavelengths.In a further implementation possibility, a plurality of markers 20 can be used in spatially predefined proximity to one another. For example, two, three or more markers 20 can be attached to the bumper of a car, the HOEs 21, 22, 23 of which can be designed with optical functions in such a way that incident light of different wave lengths is fanned out in different spatial directions. If the markers are then detected, for example, by a second vehicle approaching from behind, the distance between the two vehicles can be encoded as a function of the detected color(s) in the various markers 20. When the vehicle is moving vertically centrally, both markers 20 simultaneously change color.Problems in the position and location determination of markers 20 with HOEs 21, 22 and 23 can occur if the markers are detected at very low elevation angles. In this case, the effectively detectable area goes to zero. Detection and evaluation of the reflection images is thus unreliable and may not be possible at all starting from a specific elevation critical angle. Figure 8 shows how such problems can be alleviated by special holographic structures 24 printed on the marker 20. By using holographic structures 24, for example frame deflectors rotating around the QR code 10, which retroreflect light at very low elevation angles, a boundary alignment is indicated by the light scattered back. When the elevation angle reaches a critical range, the light reflected back from the frame deflector appears with particularly high intensity in the image captured by the optoelectronic sensor 32. As a result, the detection device 30 can recognize that the orientation of the marker 20 no longer permits reliable position and / or position determination with sufficient certainty.The orientation can be encoded by the intensity distribution and the spectral composition of the holographic structures 24, such as a revolving frame deflector. For example, the color of the frame director may change from green to red in the transition region to the critical region, or the back-reflected image of the frame director may change from a green rectangle to a red stop symbol.FIG. 6 schematically shows a flow diagram of a localization method M for differentiation between an object marked with an optoelectronically detectable marker 20 and a person marked with an optoelectronically detectable marker 20. The localization method M can be realized, for example, with a localization system 1 as shown in FIG. 3 by way of example.In a first step M 1, light reflected by holographically optical elements HOE; 21, 22, 23 applied to the marker 20 is detected by means of an optoelectronic sensor 32 of an optoelectronic detection device 30, the color depth of which is at least 8 bits, for example. In a second step M 2, a two-dimensional reflection image is generated by the optoelectronic sensor 32 from the detected reflected light. An image processing device evaluates the spectrally resolved local intensity distribution in the two-dimensional reflection image acquired by the optoelectronic sensor 32 in a step M 3. This means that the intensities of different colors recorded in the reflection image are determined in a spatially resolved manner according to length and height in the reflection image. This can be done, for example, by comparing the two-dimensional reflection image with a plurality of comparison and / or training data stored in a database for the acquired two-dimensional reflection images. Finally, in a step M 4, a position and orientation of the object can be determined relative to the optoelectronic detection device 30 on the basis of the spectrally resolved local intensity distribution evaluated in step M 3.Optionally, in a further step M 5, object recognition of structures of a contrast code 10 of the marker 20 recorded in the two-dimensional reflection image captured by the optoelectronic sensor 32 can be carried out.In summary, the present invention relates to a concept for improved location and position determination of an object characterized by an optoelectronically detectable marker, in which holographically optical elements are introduced into a two-dimensional planar marker, at which ambient light or light of a dedicated additional light source is reflected back with sufficiently high intensity even at high scattering angles with respect to the surface normal of the two-dimensional planar marker. This enables a very precise position determination of the marker with respect to all solid angles, since the holographic optical elements generate reflection patterns in an optoelectronic detection device which can be distinguished depending on the angle and are linearly independent, and on the basis of which it is possible to draw conclusions about the position, location and orientation of the marker and thus about the corresponding position, location and orientation of the object identified thereby.This is advantageous in particular in safety technology, for example in production. By using optoelectronically detectable markers, it is possible to reliably distinguish between objects such as machines, vehicles and robots, on the one hand, and persons, on the other hand. In addition to spatial patterns, the reflected spectrum of the optoelectronically detectable markers can be used for one-to-one identification of an object, for example via an increased information density by color coding. Furthermore, dynamic color envelopes can enable one-to-one object classifications during a movement of an object. In this case, the location of the exposure source, the location of the image processing and the location of the markers can be decoupled from one another.The opto-electronically detectable markers advantageously make it possible to introduce an additional level of security by personalizing the markers on the basis of their one-to-one reflection behavior. This can serve, for example, for implementing a personalized payment and / or access restriction system. Grouping in the personalized markers also enables categorization of recognized persons also from the distance and without specific action instructions to the persons.The concept can be supplemented by the implementation of special two-dimensionally planar patterns and / or shapes of the holographic optical elements, such that the intensity of the back-reflected ambient light generates color-dependent intensity maxima depending on the distance of the marker from the optoelectronic detection device. In addition, special holographic optical deflection elements with retroreflectivity maxima at very high scattering angles with respect to the surface normal of the two-dimensionally flat marker can also be provided, so that the detection of such intensity maxima in the optoelectronic detection device indicates an indication that a critical angular range has been reached in which a marker orientation can no longer be ensured with sufficient certainty on account of the excessively low detectable marker surface.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 2021 / 0248338 A1

[0003] U.S. Pat. No. 10,885,413 B1

[0003] DE 10 2017 218 544 A1

[0030]

Claims

Localization system (1) for differentiation between an object (40) marked with an optoelectronically detectable marker (20) and a person marked with an optoelectronically detectable marker (20), having: an optoelectronic detection device (30), which has: an optoelectronic sensor (32), which is designed to detect light emanating from, in particular diffracted and / or reflected and / or backscattered, holographically optical elements (HOE; 21, 22, 23) applied to the markers (20) and to generate a two-dimensional reflection image; and an image processing device (34), which is coupled to the optoelectronic sensor (32) and is designed to perform an evaluation of the spectrally resolved local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor (32) and to determine a position and / or orientation assigned to the object (40) and a position and / or orientation assigned to the person, in each case relative to the optoelectronic capture device (30), on the basis of the evaluated intensity distribution.Localization system (1) according to claim 1, wherein the optoelectronic detection device (30) has one or more color cameras as optoelectronic sensors (32) with a resolution of at most 640x480 pixels.Localization system (1) according to claim 1 or 2, wherein one or more of the optoelectronic sensors (32) of the image processing device (34) each have an objective and an externally controllable exposure source.The locating system (1) according to any one of claims 1 to 3, wherein at least one of the holographic optical elements (21, 22, 23) applied to the marker (20) has a holographic deflector (24) with high angular selectivity at low elevation angles with respect to the surface of the marker (20).The localization system (1) according to any one of claims 1 to 4, wherein the color depth of the optoelectronic sensor (32) is at least 8 bits.Localization system (1) according to one of Claims 1 to 5, wherein at least one of the holographically optical elements (21, 22, 23) applied to the marker (20) has an optical function such that a changing distance of the detection device (30) from the object is indicated by a colour change and / or a change in the intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor (32).Localization system (1) according to one of Claims 1 to 6, wherein at least one of the holographically optical elements (21, 22, 23) applied to the marker (20) has an optical function, such that a changing object orientation for dedicated angle ranges is indicated by a colour change and / or a change in the intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor (32).Locating system (1) according to one of Claims 6 and 7, wherein at least two of the holographic optical elements (21, 22, 23) applied to the marker (20) have duplicated optical functions for improving the reliability of a determination of the distance of the detection device (30) from the object and / or a determination of the object orientation for dedicated angular ranges.Locating system (1) according to one of Claims 1 to 8, wherein at least one of the holographic optical elements (21, 22, 23) applied to the markers (20) used for identifying the object (40) reflects light of a previously defined wavelength, such that one-to-one identification of the object (40) and thus the delimitation of the object (40) from humans is made possible.Localization system (1) according to one of Claims 1 to 9, wherein at least two of the holographic optical elements (21, 22, 23) applied to the markers (20) are designed in such a way that a unique signature can be derived over a wide capture angle range.Localization system (1) according to one of Claims 1 to 10, wherein at least two of the holographic optical elements (21, 22, 23) applied to the markers (20) used for identifying the object (40) are designed in such a way that a clear classification of the object can be determined from the light reflected back when the position and / or orientation of the object (40) is changed (dynamic color change of a plurality of fields must follow rules).Localization method (M) for differentiation between an object (40) marked with an optoelectronically detectable marker (20) and a person marked with an optoelectronically detectable marker (20), having the steps: detecting (M1) light emanating from, in particular diffracted and / or reflected and / or backscattered from, holographically optical elements (HOE; 21, 22, 23) applied to the markers (20) by means of an optoelectronic sensor (32) of an optoelectronic detection device (30); generating (M2) a two-dimensional reflection image by the optoelectronic sensor (32) from the detected reflected light; evaluating (M3) the spectrally resolved local intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor (32); and determining (M4) a position and / or orientation assigned to the object and a position and / or orientation assigned to the person, in each case relative to the optoelectronic detection device (30), on the basis of the evaluated spectrally resolved local intensity distribution.Localization method (M) according to Claim 12, wherein the evaluation (M3) of the spectral and / or local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor (32) comprises comparing the two-dimensional reflection image with a multiplicity of comparison and / or training data stored in a database for the captured two-dimensional reflection images.Localization method (M) according to one of Claims 12 and 13, further having the steps: carrying out (M5) object detection of structures of a contrast code (10) of the marker (20) recorded in the two-dimensional reflection image captured by the optoelectronic sensor (32).Localization method (M) according to one of Claims 12 to 14, wherein at least one of the holographic optical elements (21, 22, 23) applied to the marker (20) has a holographic deflector (24) with high angle selectivity at low elevation angles with respect to the surface of the marker (20).Localization method (M) according to one of Claims 12 to 15, wherein the color depth of the optoelectronic sensor (32) is at least 8 bits.Localization method (M) according to one of Claims 12 to 16, wherein at least one of the holographic optical elements (21, 22, 23) applied to the marker (20) has an optical function, such that a changing distance of the detection device (30) from the object is indicated by a change in the spectral and / or local intensity distribution in the two-dimensional reflection image detected by the optoelectronic sensor (32).Localization method (M) according to one of Claims 12 to 17, wherein at least one of the holographic optical elements (21, 22, 23) applied to the marker (20) has an optical function, such that a changing object orientation for dedicated angle ranges is indicated by a change in the spectral and / or local intensity distribution in the two-dimensional reflection image captured by the optoelectronic sensor (32).Localization method (M) according to one of claims 17 and 18, wherein at least two of the holographic optical elements (21, 22, 23) applied to the marker (20) have duplicated optical functions for improving the reliability of a determination of the distance of the detection device (30) from the object and / or a determination of the object orientation for dedicated angular ranges.

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