DE102017129641A1 - 3D sensor system with a free-form optics - Google Patents

Abstract

Described is a sensor system (100) and a method for three-dimensional capture of a scene (190). The sensor system comprises (a) illumination means (130) for illuminating the scene with an illumination light (131) along an illumination beam path; (b) a measuring device (115) for receiving measuring light (196) along a measuring light beam path, wherein the measuring light is at least partially backscattered by at least one object (195) illumination light and for measuring distances between the sensor system and the object based on a light transit time of Illumination light and the measuring light; (c) a data processing device (150) connected downstream of the measuring device for determining the three-dimensional characteristic of the scene based on the measured distances; and (d) a free-form optical system (140, 142) arranged in the illumination beam path and / or in the measurement light beam path, wherein the free-form optical system is configured such that (i) when placed in the illumination beam path, an illumination light intensity of the illumination light from the solid angle of the illumination light (Ii) in an arrangement in the measurement light beam path, a measurement light intensity of the measurement light depends on the solid angle of the measurement light beam path, so that a distance-based intensity loss of the illumination light and the measurement light is at least partially compensated. Furthermore, uses of the sensor system are described.

Description

Technical area

The present invention relates to a sensor system and a method for three-dimensional acquisition of a scene based on transit time measurements. Furthermore, the present invention relates to several uses of such a sensor system.

Background of the invention

For opening and / or closing of openings frequently operated by actuators closing body are used, which facilitate the handling of the respective closure body for operators or automatically operated without any action, for example, when an object to be passed the opening passes into the region of the opening. Such an opening may, for example, be a passageway in a building. A closure body may be, for example, a door or a gate.

In order to achieve a high level of operational reliability of automatically closing and closing closing bodies, it is known to detect the area in front of or within an opening which can be covered by a closing body by means of an optical sensor system. This can on the one hand be ensured that when shooting the opening accidentally an object, such as a person, is clamped by the closing body.

In addition, in some applications such a sensor system may cause automatic opening of the closure body or opening. In this context, it is also known that such a sensor system or a data processing device connected downstream of such a sensor system performs object recognition by means of known methods of image processing and only releases the opening when an object authorized to pass through the openings is in the area of the (still closed Opening). Such an object recognition can be for example a face recognition.

Out EP 2 453 252 B1 is known for the application of the monitoring of automatically opening doors and / or gates a 3D sensor system, which is based on the principle of transit time measurement of light rays emitted by illumination sources and detected after at least partial reflection or 180 ° backscatter from a light receiver become. Such sensor systems are commonly referred to as "time-of-flight" (TOF) sensor systems. However, TOF sensor systems have the disadvantage that with increasing distance d of the object to be detected, the intensity of the (backscattered) measuring light to be detected by a light receiver of the TOF sensor is weakened in two respects. In the case of a punctiform illumination light source without a special focus, this attenuation of the illumination light emitted by the illumination sources scales with 1 / d ^ 2, where d is the distance to the illumination light source. The same applies to the measuring light when a point of the object at which the illumination light is scattered isotropically, as a point light source. As a result, this leads to a 1 / d ^ 4 scaling of the intensity of the received measurement light. In the case of beamforming realized in any manner, for example focusing, of the illumination light, of the measuring light and / or in the case of non-isotropic scattering of the illumination light with a preferred emission of the measuring light in the direction of the light receiver, the intensity attenuation is correspondingly lower, but nevertheless contributes a significant loss of light output. This in turn leads to a correspondingly poor energy efficiency of a TOF sensor system.

It is an object of the present invention to provide an energetically efficient and nevertheless reliable three-dimensional detection of a scene which also includes relatively distant objects.

Summary of the invention

This object is solved by the subject matters of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a sensor system for three-dimensional acquisition of a scene is described. The described sensor system comprises (a) a lighting device for illuminating the scene with an illumination light along an illumination beam path; (b) a measuring device (b1) for receiving measuring light along a measuring light beam path, wherein the measuring light is at least partially backscattered by at least one object in the scene illumination light and (b2) for measuring distances between the sensor system and the at least one object based on a Light transit time of the illumination light and the measuring light; (C) a data processing device connected downstream of the measuring device for determining the three-dimensional characteristic of the scene based on the measured distances; and (d) a free-form optical system which is arranged in the illumination beam path and / or in the measurement light beam path. The freeform optic is configured such that (dl) when placed in the Irradiation beam path an illumination light intensity of the illumination light depends on the solid angle of the illumination beam path and (d2) in an arrangement in the measurement light beam path, a measurement light intensity of the measurement light depends on the solid angle of the measurement light beam path, so that a distance-based intensity loss of the illumination light and the measurement light is at least partially compensated.

The described sensor system, which is a so-called Time Of Flight (TOF) sensor system, is based on the knowledge that at least partially compensated by a suitably designed freeform optics of the scene geometry and the spatial angle dependent influences on the intensity distribution of the received measurement light. Illustratively, the free-form optics ensure that in an image of the scene generated by the received measurement light, there are neither (excessively) underexposed nor (excessively) overexposed portions. If the free-form optical system is located in the beam path of the illumination light, then a suitable space-angle-dependent intensity distribution of the illumination light ensures that the measurement light from each subarea of the scene strikes a light receiver of the measuring device with the most homogeneous possible intensity distribution. Alternatively or in combination, when the free-form optical system is located in the beam path of the measuring light, then a suitable collection of measuring light beams ensures or contributes to the measurement light striking the light receiver with the most homogeneous possible intensity distribution.

In other words, the free-form optical system in the illumination beam path ensures that the scene is illuminated or exposed with a lighting angle-dependent illumination intensity. In the measuring light beam path, the free-form optics ensures that the measuring light is collected differently depending on the room angle, in particular with a focusing dependent on the angle of the room. Both effects contribute to the fact that measuring light received by all partial areas of the scene is at least approximately the same in terms of its intensity. As a result, it can be avoided that there are underexposed and / or overexposed subregions of the measurement light in an image of the detected scene.

With the described free-form optics, a spatial angle-dependent intensity distribution of the illumination light or a spatial characteristic of the illumination light and / or a spatial angle-dependent collection of the measurement light intensity or spatial measurement light collection characteristic can be adjusted so that the intensity of the illumination light is just as high as it is for a Reliable detection of the respective spatial angle range associated with the subarea of the scene is required. As a result, only as much energy is required for the illumination as is necessary, so that the described sensor system is characterized by a good energy efficiency as a result.

It should be noted that with the described free-form optics, if required, it is also possible to compensate for (undesired) aberrations in the illumination beam path and / or the measurement light beam path. Such aberrations may originate from other optical components of the sensor system.

The term "scene" may in particular be understood to mean that spatial area which is optically detected by the sensor system. Objects in the scene are recognized by a suitable image analysis. For this purpose, the data processing device can make use of known methods for image evaluation and / or image analysis. The data processing device may accordingly be a special image processing processor and have one that is configured to apply known methods for image evaluation and / or image processing.

The term "object" can be understood as meaning any spatially physical structure which has a surface texture which leads to an at least partial reflection or scattering of illumination light and is therefore visible to the measuring device by the resulting measurement light. The object may be an object such as a motor vehicle or a living being such as a human. The object may be a static or static object with respect to the sensor system. Furthermore, the object may also move within, leave or enter the scene. Through a repeated scene capture, the movement of the object can be determined (by comparing the different location positions determined with different scene acquisitions) (according to the formula speed = distance / time). Here, depending on the application, the absolute value of the speed and / or the motion vector, i. additionally the direction of movement, be determined.

The term "illumination light" in this document means those electromagnetic waves which are emitted by a light source or a lighting unit of the illumination device and strike the relevant object of the scene. The "measuring light" are the electromagnetic waves scattered by or on the object (back), which are received by the measuring device or a light receiver of the measuring device and for the three-dimensional Evaluation of the scene, together with the corresponding TOF distance information, can be used.

The term "characteristic of a scene" can be understood as the entirety of all spatial structures and in particular all objects which are detected by the sensor system. The characteristic of the scene changes when (i) new objects enter the scene when (ii) objects already in the scene change their position and / or their visual appearance, in particular their optical scattering behavior, and / or if (iii) Object left the scene. In this case, some structures can be recognized as being relevant and other structures as being less or even irrelevant by the data processing device by means of image processing and / or image recognition.

In this document, the term "free-form optics" can be understood as any optical structure that modifies the beam path of light beams, which provides for a spatial angle-dependent modification of the intensity of the illumination light and / or for a space angle-dependent collection (the intensity of the measurement light). The freeform optics can be a static optic. This means that regardless of its current characteristic in different scene captures (and scene determinations or scene evaluations by the data processing device), the scene is always illuminated with the same spatial angle-dependent modification of the illumination light and / or detected with the same spatial angle-dependent modification of the measurement light. In other embodiments, the operating state may be modified, for example, by a change in the geometry and / or the internal structure of the freeform optics.

A free-form optics can consist of an optical element. Alternatively, a freeform optics can also consist of a plurality of optical elements connected in series and realized, for example, by means of a lens system.

The term "distance-based loss of intensity" can be understood as the reduction of the intensity of illumination light and / or measurement light which is caused by a widening of the cross section of the illumination light beams or of the measurement light beams (after a scattering or reflection on an object). In the case of a point light source without a special focus, this loss of illumination light scales with 1 / d ^ 2, where d is the distance to the point light source. The same applies to the measuring light when a point of the object at which the illumination light is scattered isotropically, as a point light source. As a result, this leads to a 1 / d ^ 4 scaling of the resulting measurement signal, which is given by the intensity of the received measurement light. In the case of beamforming realized in some manner, for example focusing, the illumination light, the measuring light and / or non-isotropic scattering of the illumination light with a preferred emission of the measuring light in the direction of the measuring device, the "distance-based intensity loss" is correspondingly lower in practice, however, still represents a significant loss, which reduces the energy efficiency of a TOF sensor. According to the invention, these losses are at least partially reduced or compensated by the free-form optics.

The terms "optical" and / or "light" may refer to electromagnetic waves having a particular wavelength or frequency or a particular spectrum of wavelengths or frequencies. In particular, the electromagnetic waves used can be assigned to the spectral range visible to the human eye. Alternatively or in combination, electromagnetic waves associated with the ultraviolet (UV) or infrared (IR) spectral regions may also be used. The IR spectral range can extend into the long-wave IR range with wavelengths between 3.5 μm to 15 μm, which can be detected by means of the light receiver of the sensor.

It should be noted that the compensation of the distance-based intensity loss according to the invention by means of the spatial angle-dependent intensity modification of illumination light and / or measurement light is not only possible for TOF sensor systems which illuminate the whole or at least larger subregions of the scene simultaneously. The free-form optics according to the invention can also be used optically profitably in TOF sensor systems, which scan the scene sequentially with an illumination light beam, for example a laser beam.

According to one exemplary embodiment of the invention, the sensor system also has a further free-form optical system, wherein the free-form optical system is arranged in the illumination beam path and the further free-form optical system is arranged in the measurement light beam path. By providing two separate and thus individually dimensionable free-form optics, illumination light and measurement light can each be optimally optimized independently of one another. In the case of variable free-form optics, both "lights" can be modified independently of one another adaptively with respect to their angular-angle-dependent intensity distribution.

It should be noted that all features described in this document or Variants of the freeform optics also apply to the further freeform optics.

According to a further exemplary embodiment of the invention, the free-form optical system has at least one reflective optical element, at least one refractive optical element and / or at least one diffractive optical element.

The term "reflective" or "reflection" is understood in this document to mean (at least partial) repelling of electromagnetic waves at an interface, with respect to a normal of this interface the angle of incidence of the incident electromagnetic wave being equal to the angle of reflection of the reflected electromagnetic wave , The reflective interface of the free-form optical system preferably has the highest possible reflection coefficient. This means that that portion of the electromagnetic wave which is not reflected by "angle of incidence = angle of reflection" is as large as possible and the proportion of the electromagnetic wave which absorbs or which is scattered in other directions is as small as possible. A reflective element may in particular be a mirror. The freeform optics can thus have at least one mirror (with a suitably curved surface).

The term "refractive" or "refraction" (or refraction) refers to the change in the propagation direction of an electromagnetic wave due to a spatial change in its propagation velocity, which is specifically described for light waves by the refractive index n of a medium. A refractive element of the described free-form optics may be a suitable shaped lens. Other optically refractive elements such as, for example, a (modified prism) can also be used in order to realize a suitable beam angle-dependent beam shaping of the illumination light and / or the measurement light.

The term "diffractive" or "diffraction" (or diffraction) in this context refers generally to the spatial deflection of an electromagnetic wave at structural obstacles. Such obstacles may be an edge, a hole or a one-dimensional, a two-dimensional or even a three-dimensional grid. The diffractive optical element can be, for example and preferably, a diffractive optical element (DOE), which advantageously permits a dynamic adaptation or adaptation of the space angle-dependent characteristic of the illumination light and / or the space angle-dependent characteristic of the measurement light.

According to a further exemplary embodiment of the invention, the free-form optical system has at least one spatially and / or structurally changeable optical element, wherein a change of the optical element leads to a change of the solid angle dependence of the illumination light intensity and / or the measurement light intensity.

Due to the described variability of the freeform optics, the solid angle dependency of the intensity distribution of illumination light and / or measurement light can be adapted to a change in the characteristic of the scene to be detected during operation of the sensor system such that all (relevant) objects in the scene are detected with high accuracy can. The described change of the free-form optics can thus be caused by the data processing device during the operation of the sensor system depending on the scene. Furthermore, the free-form optics can also be modified according to the principle of "try-and-error" or by other statistical, incremental or history-based optimization procedures. This can be done dynamically during a real operation of the sensor system or as part of a calibration by means of a detection of suitable reference objects.

A spatial change of the optical element can, for example, be a simple displacement and / or rotation of this optical element in a coordinate system of the sensor system and / or relative to other optical elements of the freeform optical system. This can be done preferably by means of an actuator in an automatic manner, wherein a control of the actuator from the data processing device or from any other with respect to the sensor device internal or external freeform control device can take place.

The variable optical element may also be an elastic element, for example a deformable mirror. Further, the elastic member may be a pressure-deformable member of an elastic optical material which changes its optical properties (reflection, diffraction and / or refraction behavior) under pressure.

For example, a structural change in a DOE can lead to a desired modification of the solid angle dependence of the illumination light and / or the measurement light. In addition, micromirror arrays known from the so-called Digital Light Processing (DLP) projection technology can also be used. Furthermore, so-called. Micro electro mechanical systems (MEMS) devices for a targeted movement of a plurality of optical elements, in particular micromirrors, can be used, so that it to a desired spatial angle-dependent intensity distribution of the illumination light and / or the measuring light comes.

According to a further exemplary embodiment of the invention, the free-form optical system and / or the illumination device is / are configured to provide the illumination light and / or the measurement light with a space-angle-dependent intensity distribution which at least approximately compensates an edge light drop, in particular a natural edge light drop according to the one brightness in an image when casting an evenly bright subject through a lens, the factor cos ^ 4 decreases relative to the brightness in the center of the image.

The natural edge light drop, which is described by the so-called cos ^ 4 (cosine high 4) law, depends in a known manner on the focal length of a lens used. In the case of the described TOF sensor system, such an objective can be used for imaging the illumination light onto the scene and / or for imaging the scene onto a light receiver of the measuring device. In the case of the use of lenses and preferably a common objective for both (emitted from a flat light source) illumination light and for (scattered by the area scene) measuring light without the described compensation of the natural marginal light waste would occur twice and the negative influence of cos The law would be correspondingly strong. Therefore, in the TOF sensor system in which both the illumination light and the measurement light pass through an objective, the compensation of the natural peripheral light drop by the free-form optical system described herein and / or illumination by the illumination device uneven across the scene contribute particularly to an improvement of the light intensity ratios ,

The compensation of the natural Randlichtabfalls by a suitable spatial angle-dependent intensity modification of illumination light and / or measurement light may be at least 30%, preferably 50%, more preferably 80% and even more preferably 90% or even 95%. These percentages refer (with a fixed focal length of the objective used) to the ratio between the intensities at the edge of the image of the scene imaged on the measuring device (for the measuring light), which (a) with the described compensation and (b) without the described compensation of natural edge drop occur. Accordingly, a 100% compensation would mean a complete elimination of the natural edge light drop. In the case of a (fictitious) scene, which diffuses the illuminating light equally strongly in all subareas, the brightness in an image would be the same in all subregions, the image being the (complete) image of the scene on a light receiver of the measuring device.

It should be noted that with regard to the brightness distribution of the illumination light in the scene in preferred embodiments, overcompensation of the natural edge light drop occurs. This overcompensation should be just so strong that the natural marginal light drop of the measuring light is just compensated so that it comes in the image of the scene shown on the measuring device to the best possible compensation of the natural Randlichtabfalls.

According to a further exemplary embodiment of the invention, the sensor system further has an illumination light control device coupled to the illumination device, which is configured to control the illumination device such that a characteristic of the illumination light which describes the dependence of the illumination intensity of the illumination light on the solid angle during operation of the sensor system is dynamically changeable.

Due to a dynamic variability of the characteristic of the illumination light, one and the same scene can be recorded multiple times under different lighting conditions (successively). As a result, different data sets of one and the same scene are available to the data processing device, so that by means of a suitable method of image analysis (by the data processing device) that data record can be used for determining the three-dimensional characteristic of the scene which most accurately reproduces the scene. Optionally, a "a priori knowledge" about the optical and / or geometric properties of objects located in the scene can be taken into account.

Furthermore, an optimal lighting characteristic can also be determined according to the "try-and-error" principle or by other statistical optimization procedures. This can be done dynamically during a real operation of the sensor system or as part of a calibration by means of a recognition of suitable reference objects (as in the above-described spatial and / or structural change of an optical element of the freeform optics).

In some embodiments, the 3D images of the scene recorded with different illumination characteristics can also be processed together, so that a comprehensive data set is available for a final determination of the 3D characteristic of the scene. In such joint processing can different subregions of the scene are characterized in that a first partial data record recorded in a first illumination characteristic is used for a first partial region and for a second subregion of the second partial data record recorded in a second illumination characteristic for determining the overall characteristic of the scene. Of course, more than three data sets can be used for the detection of the overall characteristic of the scene, which are each associated with a different lighting light characteristic.

According to a further exemplary embodiment of the invention, the data processing device is coupled to the illumination light control device and configured to evaluate the determined three-dimensional characteristic of the scene and to change the characteristic of the illumination light based on a result of this evaluation.

To put it clearly, the way in which the scene for a scene detection is illuminated as a function of the room angle depends on measurement and evaluation results which have been determined from a previous scene detection. The characteristic of the lighting is thus adapted dynamically based on measurement results of a previous scene capture. This means that, correctly speaking, not only a control of the lighting device but rather a regulation thereof takes place. This advantageously allows a particularly accurate adaptation of the scene illumination with regard to an optimal scene evaluation.

Appropriate control of the lighting device may depend on current environmental conditions, which are reflected in the result of the scene evaluation. Such environmental conditions may be weather conditions such as the presence of rain, snow, hail, fog, smoke, suspended particles, etc. in the scene.

According to a further exemplary embodiment of the invention, the result of the evaluation depends on the optical scattering behavior of at least one object contained in the scene. This has the advantage that, in addition to the distance-based compensation described above and according to the invention, any different scattering behavior and / or reflection behavior of different objects in the scene can also be taken into account, so that the measurement light with an at least approximately spatially uniform intensity distribution to a light receiver of the Measuring device hits. A brightness which is as uniform as possible over the light-sensitive surface of the light receiver favors precise distance measurement by the described TOF sensor system.

It should be noted that in many objects, the litter or. Reflection behavior depends on the wavelength or the frequency of the illumination light. Consideration of such a frequency dependence can advantageously contribute to a further improvement of the scene lighting and the subsequent scene evaluation.

1. (a) einer als Laser ausgebildeten Beleuchtungslichtquelle zum räumlichen Abtasten der Szene mit einem ausgesandten Laserstrahl-Beleuchtungslicht;
2. (b) einer zumindest annähernd punktförmigen Beleuchtungslichtquelle;
3. (c) einer Mehrzahl von einzelnen Beleuchtungslichtquellen, die insbesondere individuell ansteuerbar und jeweils einem bestimmten Raumwinkelbereich der Szene zugeordnet sind; und
4. (d) einer flächigen Beleuchtungslichtquelle, insbesondere mit einer über die Fläche nicht homogenen ausgesandten Leuchtintensität.

According to a further embodiment of the invention, the illumination device comprises at least one of the group consisting of

1. (a) a laser light source for spatially scanning the scene with an emitted laser beam illuminating light;
2. (B) an at least approximately punctiform illumination light source;
3. (c) a plurality of individual illumination light sources which are in particular individually controllable and each associated with a specific solid angle range of the scene; and
4. (D) a flat illumination light source, in particular with a non-homogeneous emitted over the surface luminous intensity.

A scanning the scene laser beam can be directed in a known manner via two rotatable mirrors with mutually non-parallel and preferably perpendicular to each other oriented axes of rotation to the respective point of the scene to be illuminated. Non-mechanical optical elements such as diffractive optical elements (DOEs) can also be used for such a (dynamically adaptive) deflection. The deflection can be controlled in particular by the illumination light control device described above. Also, a dynamic adaptation of the free-form lens by means of the above-described spatial and / or structural change of an optical element of the free-form lens can provide for a suitable beam deflection of the laser beam.

The at least approximately punctiform illumination light source may be a (sufficiently strong) semiconductor diode, for example a laser or light emitting diode. In order to illuminate the scene in a targeted manner, suitable beam-shaping systems and in particular the free-form optics described can be used. In order to realize an illumination of the scene which is uneven in dependence on the spatial angle, it is also possible to use suitable optical elements for beam deflection, beam splitting and / or beam merging.

The plurality of illumination light sources, which are also in particular laser or light-emitting diodes, can be controlled (in particular individually) by the illumination light control device described above. This advantageously allows an adaptively controlled or even regulated adjustment of the characteristic of the illumination light.

A flat light source can also be the source for a spatially-dependent, non-homogeneous intensity distribution. If it is a spatially homogeneously illuminated surface, suitable optical elements for beam deflection, beam splitting, beam merging and / or beam shaping, in particular (also) described freeform optics can be used to realize a spatial angle-dependent non-uniform illumination of the scene.

According to a further exemplary embodiment of the invention, the free-form optical system and / or the illumination device is or are configured to provide the illumination light with a beam cross-section deviating from a circular shape. As a result, in scenes which are "not round", inadequate illumination of corner areas of the scene can be avoided. Although inadequate illumination of the corner areas could possibly be prevented by an overall increased intensity of the illumination light, in this case, however, the middle areas of the scene would be overexposed, which would be very disadvantageous, at least from an energetic point of view.

In many embodiments or applications of the sensor system, it is advantageous if the illumination light has a rectangular beam cross section. Preferably, the beam cross-section is adapted to achieve as homogeneous as possible illumination to the shape of the scene to be detected. Suitable shaping of the beam cross-section can not only be achieved by a corresponding shaping of the illumination surface of the illumination device and / or configuration of the free-form optical system, the beam cross-section can also be suitably adapted by optical components such as mirrors and refractive optical elements (e.g., lens system). Diffractive optical elements (DOEs) can also be used, which optionally even allow a dynamic and / or scene-dependent shaping of the beam cross-section. In addition, micromirror arrays known from the so-called Digital Light Processing (DLP) projection technology can also be used. Even with so-called microelectromechanical systems (MEMS) devices, a large number of optical elements can be moved in such a way that a desired illumination angle dependent on the angle of illumination occurs.

According to a further exemplary embodiment of the invention, the measuring device has a light receiver with a multiplicity of pixels for receiving the measuring light, wherein first pixels in a first subregion of the light receiver have a first light sensitivity and second pixels in a second subregion of the light receiver have a second light sensitivity. In this case, the second light sensitivity is different from the first light sensitivity.

The unequal pixel sensitivity described may also help to ensure that in an image of the scene the difference between a brighter region and a darker region is not so great as to jeopardize reliable scene capture and / or scene evaluation by the computing device.

In some embodiments, light receivers are used in which the spatial distribution between first pixels and second pixels can be varied dynamically or adaptively. Such a variation may also be controlled by the data processing device and may depend on a result of a previous scene evaluation.

It should be noted that the term light sensitivity relates to the ability of the pixel in question to accumulate incident photons within a short exposure time. A different pixel sensitivity may e.g. by reducing the noise of individual pixels or zones of pixels. Since the noise is often correlated with the heat of the sensor, e.g. a higher sensitivity can be achieved for a part of the light receiver by means of a heat pump (for example a Peltier element). The more punctually this temperature change can be generated on the light receiver, the higher the energy efficiency of the sensor system can be. Thus, for example, imprint a temperature gradient over the light receiver in a specific embodiment, so that the coming of a more distant portion of the scene measuring light reaches a cooler zone of the light receiver.

According to a further exemplary embodiment of the invention, the measuring device further has a light receiver control device coupled to the light receiver, wherein the light receiver control device and the light receiver are configured in such a way that, in a modified operation of the sensor system, at least two pixels of the plurality of pixels become a higher-order pixel are summarized.

Such aggregation of pixels, also referred to as "binning", has the effect of increasing the number of photons of the measurement light collected during a scene acquisition of one pixel, in proportion to the number of pixels, at the expense of spatial resolution pixels summed up to a parent pixel. Due to the resulting increased photon accumulation per (superordinate) pixel, the light sensitivity per pixel is significantly increased. This reduces the so-called statistical photon noise, in particular with a weak measuring light, which improves the scene evaluation accuracy. A "binning" is therefore particularly advantageous for a weak measuring light when a high spatial resolution is not required.

Typically, at least some of the plurality of pixels are grouped together so that a certain number of pixels are combined into a higher-level pixel. The certain number may be, for example, (preferably) two, three, (preferably) four, six, (preferably) eight, or (preferably) nine. Of course, an even stronger summary of pixels is possible.

It should be noted that binning can also be carried out locally in only at least a partial area of the active areas of the light receiver via the surface of the light receiver. Although this leads to an inhomogeneous spatial resolution, which is not necessarily desired. However, the disadvantage of such an inhomogeneous spatial resolution is overcompensated in many applications by the increased photon accumulation (per pixel). A local "binning" can be done at least in some known light receivers without special electronic or apparatus elements simply by a corresponding control of the light receiver, which control determines the "binning" and thus the operating mode of the sensor system.

In preferred embodiments, a local "binning" is performed in such a way that, measured by the measuring device and / or learned by the data processing device, exactly those areas of the light receiver, which have received too little light energy in at least one previous scene detection, by a suitable control of the light receiver be combined by the light receiver control means in subsequent scene captures in a suitable manner to higher-level pixels. Such dynamically controlled or controlled "binning" may be performed during a normal operation of the sensor system (learned) and / or during the configuration of the sensor system, for example as part of a (first) installation, a maintenance, a cyclic or automatic re-configuration, etc. become.

At this point, it should be noted that with a non-square number of individual pixels combined into a superordinate pixel, the spatial resolution of the light receiver along different directions is different in each case if the individual pixels have a square shape. This can be exploited in some cases in an advantageous manner. Such an application is present, for example, when movement of an object of the scene along a previously known spatial direction is to be detected with increased accuracy. In such a case, the number of pixels arranged along a line perpendicular to this known spatial direction (as depicted on the light receiver) may be larger than the number of pixels arranged along a line perpendicular thereto. Then the spatial resolution along the direction of movement is greater than the spatial resolution perpendicular to the direction of movement and the motion profile of such a linearly moving object can be determined with a particularly high accuracy even with a comparatively weak measuring light.

According to a further embodiment of the invention, the measuring device comprises (a) one or the light receiver for receiving the measuring light and (b) a measuring unit connected downstream of the light receiver, which is configured to measure the light running time based on (i) a measurement of the time span between a transmission a pulse of the illumination light and the reception of the measurement light associated with the pulse and / or (ii) a measurement of a phase shift between a temporal modulation of the illumination light and an associated temporal modulation of the received measurement light. This has the advantage that the described sensor system can be realized in a suitable manner, depending on the particular application, by utilizing a respectively suitable TOF measuring principle. In some embodiments, the sensor system is configured in such a way that it is possible to switch between the two different measurement principles "pulse mode" and "phase measurement" flexibly or, if necessary, between the two different measurement principles.

Regardless of the measuring principle used, the light receiver has a light-sensitive surface which, as described above, is subdivided into a multiplicity of pixels. With or on each pixel those photons of the measurement light are accumulated, which originate from a certain solid angle region or the associated subregion of the scene. The measurement unit is used to run the runtime for each pixel associated light rays of the illumination light and the measuring light to determine.

According to a further exemplary embodiment of the invention, the sensor system further has a holder which is mechanically coupled at least to the measuring device, wherein the holder is designed such that the sensor system can be attached to a stationary holding structure with respect to the scene to be detected.

To put it clearly, the holder ensures that the described sensor system can be a stationary system which has a certain spatially fixed detection range and therefore always monitors the same scene, which of course can have a different scene characteristic at different times. By comparing different temporally spaced detections of the dependent of the orientation of the sensor system scene spatially stationary objects that are present in the scene can be detected in an image analysis and hidden in a further image analysis with respect to movement profiles. As a result, computing power can be saved and the energy efficiency of the described sensor system can be improved.

The stationary support structure may be directly or indirectly mechanically coupled to a device for controlling a coverage characteristic of an opening to be passed through the object by at least one closure body. In addition to a suitable guide or bearing of the closing body, this device preferably has an actuator for moving the closing body, in particular for moving the closing body between a closed position and an open position (and vice versa).

In the field of building security, the opening may be an entrance, for example for a person or a vehicle. The closure body may be a door, for example a front door or a garage door. The stationary support structure may be, for example, the stationary frame structure of an entrance, for example the frame of a door.

According to a further embodiment of the invention, the data processing device is further configured such that a coverage characteristic of an opening to be passed from an object is controllable by at least one closure body. As a result, the opening, which is, for example, an entrance (or an exit) of a building, can be automatically monitored in an energetically favorable manner, and by suitable actuation of an actuator, the closing body can be moved automatically between an open position and a closed position. For this purpose, the data processing device of the described sensor system can be coupled with the control of a known control system for a closing body.

In accordance with another aspect of the invention, a method of three-dimensionally capturing a scene is described. The described method comprises (a) illuminating the scene with an illumination light emitted by a lighting device along an illumination beam path; (b) receiving, by means of a measuring device, measuring light along a measuring light beam path, wherein the measuring light is at least partially backscattered by at least one object in the scene illumination light; (c) measuring, by means of the measuring device, distances between the sensor system and the at least one object based on a light transit time of the illumination light and the measurement light; and (d) determining the three-dimensional characteristic of the scene based on the measured distances by means of a data processing device downstream of the measuring device. According to the invention, a free-form optical system is arranged in the illumination beam path and / or in the measurement light beam path, wherein the free-form optical system is configured such that (i) an illumination light intensity of the illumination light depends on the solid angle of the illumination beam path in an arrangement in the illumination beam path, and (ii) in an arrangement in FIG A measurement light intensity of the measurement light depends on the spatial angle of the measurement light beam path in the measurement light beam path, so that a distance-based intensity loss of the illumination light and the measurement light is at least partially compensated.

The described method is also based on the knowledge that, due to suitably designed or configured free-form optics, the scene geometry and the spatial angle-dependent influences on the intensity distribution of the received measurement light can be at least partially compensated.

In the beam path of the illumination light, the free-form optics can provide a suitable space-angle-dependent intensity distribution of the illumination light so that the measurement light from each subarea of the scene strikes a light receiver of the measuring device with as homogeneous a distribution of intensity as possible. In the beam path of the measuring light, the free-form optics can provide a suitable space-angle-dependent collection of measuring light intensity, so that the measuring light also strikes the light receiver with the most homogeneous possible intensity distribution.

According to an embodiment of the invention, the method further comprises (a) detecting an object in the scene; (b) comparing the detected object with at least one comparison object stored in a database; and, (c) if the object agrees with a comparison object within predetermined permissible deviations, identifying the object as an object authorized for a particular action.

The approved action may, for example, be an authorized passage through an opening in a building, which opening is closed by a closure body prior to identification as an approved object and is opened only after successful identification by a corresponding movement of the closure body. The objects to be identified may preferably be persons and / or vehicles. Successful identification may be to control or activate a closure mechanism for a closure body prior to opening a building.

According to another aspect of the invention, there is described a use of a sensor system described above for controlling a coverage characteristic of an aperture to be passed through an object by at least one occlusion body.

The described use is based on the finding that a detection and evaluation of an optical scene made in an energy-efficient manner can be used advantageously in passages which can be closed by a closing body. This applies in particular to passages which have a closure or a covering characteristic which is controlled or at least co-controlled by the described sensor system. Since such sensor systems are usually supplied with energy by the closure systems for the closure bodies, it is particularly important to manage with a comparatively small amount of energy while still achieving reliable TOF scene evaluations.

As a result of the inventive use of the sensor system described above, larger distances can also be monitored in an energy-efficient manner, which naturally leads to earlier detection of an opening requirement of the closure body. This can be of great advantage, especially in the case of fast moving objects. Furthermore, the scene can be detected in an energy-efficient manner with a wider detection angle, which can lead, for example, to an early detection of transverse traffic moving transversely to the opening and thus to a more reliable detection of objects in the security area of the closure system. This can be suppressed in cross traffic unnecessary opening request.

According to one embodiment of the invention, the opening is an entrance or an exit, in particular an emergency exit in a building. By recognizing an existing, but possibly non-moving object in a passage area, an input or output monitors, in particular a blocked emergency exit detected, and the corresponding information to an affiliated system, for example, to a monitoring system, transmitted.

According to a further embodiment of the invention, the object is a person or a vehicle. In this case, the building may in particular be a house or a garage.

According to a further aspect of the invention, a use is described of a sensor system described above for detecting and / or controlling traffic flows of objects which move through a scene of the sensor system, the scene being determined by a spatial detection area of the sensor system.

This use is also based on the finding that an energy-efficient sensor system is important in traffic detection and / or traffic flow control, since this sensor system is typically constantly in operation and, moreover, a very high number of such sensor systems are typically used, in particular for larger traffic flows.

The objects relevant to the traffic flow in question can be, for example, persons, vehicles, products such as e.g. Be packages, suitcases, etc. Since a plurality or even a multiplicity of 3D sensors are usually used for such applications, energy savings have a particularly positive effect here.

It should be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments of the invention are described with apparatus claims and other embodiments of the invention with method claims. However, it will be apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features associated with a type of subject matter, any combination of features is contemplated different types of invention articles belong.

Before describing exemplary embodiments of the invention with reference to the drawings, some technical considerations related to the invention will be described here.

In general, TOF-based sensor systems can be subdivided into two fundamentally different classes both with regard to the illumination light and with regard to the measurement light, which can be combined as desired.

B1: The first alternative (B1) for the illumination is characterized in that the scene is scanned sequentially by means of a single illumination beam of high focus and low divergence (ie high collimation). For each position of the illumination light beam in the scene, a measurement of the duration of the illumination light and the measurement light is made. The scanning can be realized using movable optical components, in particular mirrors. Alternatively or in combination, for a sequential scanning of the scene with the illumination light beam, a solid can be used which manages without mechanically moving parts and has integrated photonic structures or circuits. With a suitable control of these structures, the illumination light beam is then directed to the desired location of the scene. Such a solid is for example off US 2015/293224 A1 known.

B2: The second alternative (B2) for lighting is characterized by the fact that the entire scene is illuminated (all at once and flatly). If necessary, the intensity of the illumination light in selected subregions of the scene can be (selectively) increased in order to enable improved 3D object detection at these locations. Such spatially uneven distribution of the intensity of the illumination light can be done without moving optical components, for example by means of a so-called. Diffractive optical element (DOE).

M1: A first alternative (M1) for the measurement is based on pulsed illumination light beams. The "travel time" of a light pulse on the receiver side for each pixel within a time window is determined and derived from the distance.

M2: The second alternative (M2) for the measurement is based on a temporal, preferably sinusoidal, modulation of the illumination light with a predetermined frequency, suitable values for this frequency depending on the expected transit time or the maximum acquisition distance. On the side of the light receiver, the phase difference is measured for each pixel and derived therefrom the distance information.

Both measuring principles M1 and M2 are based on an integration of the number of photons or the photoelectrons generated in the light receiver, which arrive on each pixel to be measured. In this context, it is obvious that an ever-present light or photon noise depends on the number of photons accumulated in a pixel. Therefore, the higher the number of accumulated photons, the more accurate the distance information obtained from the TOF measurement becomes.

Further advantages and features of the present invention will become apparent from the following exemplary description of presently preferred embodiments.

list of figures

• 1 shows the use of a sensor system for controlling a coverage characteristic of an opening by means of closing bodies formed as sliding doors.
• The 2a and 2 B illustrate a deformation of a designed as an elastic optical element freeform optics.
• 3 shows the use of a sensor system for detecting a traffic flow of transported on a conveyor belt objects.
• The 4a and 4b illustrate a collection of single pixels of a light receiver.
• The 5a to 5c show different beam cross sections of an illumination light to adjust the lighting to the shape of the scene to be detected.

Detailed description

It should be noted that the embodiments described below represent only a limited selection of possible embodiments of the invention. In particular, it is possible to suitably combine the features of individual embodiments with one another, so that a multiplicity of different embodiments are to be regarded as obviously disclosed to the person skilled in the art with the embodiment variants explicitly illustrated here.

1. (1) In Anbetracht der bei vielen Anwendungen von 3D Sensorsystemen großen Bedeutung eines energieeffizienten Betriebs lässt sich die auf den Lichtempfänger treffende optische Energie des Messlichts dadurch optimieren, dass je nach Ausprägung der Szene die Szene unterschiedlich (intensiv) beleuchtet wird.
2. (2) Für die meisten Anwendungen von TOF Sensorsystemen ist die zu erfassende Szene jedoch quaderförmiger oder kubischer Natur. Bekannte TOF Sensoren haben aber typischerweise einen Erfassungsbereich, der für alle erfassten Raumwinkel zumindest annähernd eine gleiche Reichweite hat. Die (Außen)Grenze des Erfassungsbereiches ist daher ein Teil einer Kugelschale (bei der alle Punkte den gleichen Abstand zu dem TOF Sensorsystem haben). Das in diesem Dokument beschriebene TOF Sensorsystem ist nun in der Lage, diese „Kugelschalenbegrenzung“ durch ein gezielte Erhöhung oder Reduzierung der Beleuchtungsintensität in ausgewählten Teilbereichen der Szene zumindest teilweise aufzugeben bzw. zu kompensieren. Durch eine durch eine Freiformlinse realisierte Reduzierung der Beleuchtungsintensität im Zentrum der Szene und eine Erhöhung der Beleuchtungsintensität gegen den Rand der Szene und insbesondere zu den Ecken hin, kann dieser mit dem vorstehend erläuterten cos^4 Gesetz beschriebene nachteilige Effekt reduziert und die für die Beleuchtung eingesetzte Energie optimal ausgenutzt werden.
3. (3) Ferner lassen sich bestimmte von der räumlich geometrischen Anordnung von Sensorsystem und zu erfassender Szene abhängige Teilbereiche der Szene pauschalisiert mit einer optimalen Intensität von Beleuchtungslicht „belichten“. So wird zum Beispiel ein TOF-Sensorsystem üblicherweise über der mittleren Höhe der zu beobachtenden Objekte (Menschen, Produkte, Fahrzeuge, usw.) montiert, damit bei einer Mehrzahl von Objekten eine unerwünschte Objektabschattung weniger problematisch ist. Dies bedeutet aber, dass in den meisten Fällen der obere Bereich der Szene größere Messdistanzen beinhaltet als der untere Bereich. Dieses Wissen um den Montageort des Sensorsystems in Bezug zu der erfassenden Szene kann zur weiteren Optimierung des Betriebs des beschriebenen Sensorsystems insbesondere in Hinblick auf die energetische Effizienz berücksichtigt werden, indem der obere Bereich der Szene durch die Verwendung der beschriebenen Freiformoptik entsprechend weniger stark beleuchtet bzw. „belichtet“ wird.
4. (4) Bei einer Lichtquelle, welche aus mehreren einzelnen Beleuchtungsintensität liefernden Elementen besteht, welche die gesamte Beleuchtungseinrichtung darstellen (z.b. ein Array von Laser- oder Leuchtdioden), kann eine raumwinkelabhängige Intensitätsverteilung von Beleuchtungslicht durch eine Variation der Helligkeit einzelner Elemente gegenüber anderen Elementen unterstützt werden. Diese Variation kann sowohl konstruktiv im Aufbau (z.B. Laser- oder Leuchtdioden mit unterschiedlicher Intensität) als auch durch die Art der Ansteuerung (via variablem Strom pro Laser- oder Leuchtdiode durch eine geeignete Elektronik, beispielshaft durch ein Einmessen bei der (Erst)Installation eingestellt) eingestellt werden. Ferner ist auch eine dynamische Einstellung der einzelnen Laser- oder Leuchtdioden während des Betriebs möglich. Dabei werden einfach diejenigen Laser- oder Leuchtdioden, welche Bereichen der Szene zugeordnet sind, die wenig Messlicht liefern, entsprechend stärker bestromt. Dies eignet sich besonders gut für das o.g. Beleuchtungsprinzip B2 in Kombination mit dem o.g. Messprinzip M1 oder M2.
5. (5) Bei Beleuchtungseinrichtungen, welche mit einem Beleuchtungslichtstrahl sequentiell die ganze Szene abtasten (scannen), ist zu jedem Zeitpunkt der jeweilige momentane Raumwinkel des Beleuchtungslichtstrahls bekannt. Durch Variieren der Intensität dieses Beleuchtungslichtstrahls abhängig vom jeweiligen Raumwinkel kann so die Beleuchtungsintensität abhängig von der Szenengeometrie (und bei optionaler dynamischer „Ergebnisregelung“ auch abhängig von der Reflexions- bzw. Streulichtmenge) für jeden Raumwinkel die bereits von der Beleuchtungseinrichtung ausgesandte Beleuchtungsintensität gezielt gesteuert werden. So kann eine statische Szene eingemessen werden, wobei die zu jedem Raumwinkel passende Intensität an Beleuchtungslicht eingelernt wird.
6. (6) Die vorstehend erläuterte und optionale dynamische Anpassung der Intensität an Beleuchtungslicht durch die Beleuchtungseinrichtung kann sowohl in Echtzeit als auch von „Frame zu Frame“ adaptiv erfolgen. Dabei wird für die Teile der Szene, von denen zu wenig Messlicht empfangen wird, unmittelbar die Intensität des entsprechenden Teil(Beleuchtungslichts) erhöht. Dies bedeutet, dass abhängig von den Ergebniswerten einer letzten Szenenerfassung für die nächste Szenenerfassung diejenigen Bereiche mit „Überbelichtung“ abgeschwächt beleuchtet und diejenigen mit „Unterbelichtung“ aufgehellt werden. Dieser Ansatz eignet sich besonders gut für das Beleuchtungsprinzip B1 in Kombination mit dem Messprinzip M1 oder M2.
7. (7) Eine Ausführungsform der Erfindung erreicht eine Energieeinsparung mittels einer dynamischen Beleuchtungsenergieoptimierung, wobei Beleuchtungsenergien von unterschiedlichen Wellenlängen bzw. Frequenzen verwendet werden. Dabei können beispielsweise abhängig von der Farbe des Objekts die Wellenlängen, die zu den intensivsten Reflexionen bzw. Lichtstreuungen führen, mit einer geringeren Intensität ausgesendet werden. Im Gegensatz dazu können andere Wellenlängen bzw. andere Wellenlängenbereiche mit geringerer Reflexion bzw. Streuung in dem Wellenlängenspektrum mit einer höheren Intensität vorhanden sein. So kann beispielsweise ein rotes Objekt so primär mit einem rotem Lichtanteil beleuchtet werden und der grüne und der blaue Lichtanteil werden (für den betreffenden Raumwinkel) reduziert, bevorzugt auf zumindest annähernd eine Intensität von Null. Dasselbe Prinzip kann auch im Verhältnis zwischen sichtbarem Licht und infraroten (IR) Licht angewendet werden.

Before the figures are described in detail in this section, some aspects of a number of embodiments are explained below.

1. (1) In view of the importance of energy-efficient operation in many applications of 3D sensor systems, the optical energy of the measurement light incident on the light receiver can be optimized by illuminating the scene differently (intensively) depending on the nature of the scene.
2. (2) However, for most applications of TOF sensor systems, the scene to be captured is cuboidal or cubic in nature. However, known TOF sensors typically have a detection range that has at least approximately the same range for all detected solid angles. The (outer) boundary of the detection area is therefore part of a spherical shell (where all points are equidistant from the TOF sensor system). The TOF sensor system described in this document is now able to at least partially abandon or compensate for this "spherical shell boundary" by selectively increasing or reducing the illumination intensity in selected subregions of the scene. By reducing the illumination intensity in the center of the scene realized by a free-form lens and increasing the illumination intensity towards the edge of the scene and in particular to the corners, this can be reduced with the above-described cos ^ 4 law and the lighting effect used Energy can be optimally utilized.
3. (3) In addition, certain subregions of the scene which are dependent on the spatial-geometric arrangement of the sensor system and the scene to be detected can be "exposed" in a generalized manner with an optimum intensity of illuminating light. For example, a TOF sensor system is typically mounted above the average height of the objects to be observed (people, products, vehicles, etc.) so that unwanted object shadowing is less problematic in a variety of objects. However, this means that in most cases the upper part of the scene contains larger measurement distances than the lower part. This knowledge about the mounting location of the sensor system with respect to the sensing scene can be taken into account for further optimizing the operation of the described sensor system, in particular with regard to the energy efficiency, by correspondingly less illuminating the upper area of the scene through the use of the free-form optics described. Is "exposed".
4. (4) In a light source consisting of a plurality of individual illumination intensity providing elements representing the entire illumination device (eg, an array of laser or light emitting diodes), a space angle-dependent intensity distribution of illumination light can be promoted by varying the brightness of individual elements over other elements , This variation can be both constructive in structure (eg laser or light emitting diodes with different intensity) as well as by the type of control (via variable current per laser or light emitting diode by a suitable electronics, for example by a calibration in the (initial) installation set) be set. Furthermore, a dynamic adjustment of the individual laser or LEDs during operation is possible. In this case, simply those laser or light emitting diodes, which are assigned to areas of the scene that provide little measuring light, are correspondingly more energized. This is particularly well suited for the above-mentioned lighting principle B2 in combination with the aforementioned measuring principle M1 or M2.
5. (5) For lighting devices which sequentially scan (scan) the entire scene with an illuminating light beam, the respective instantaneous solid angle of the illuminating light beam is known at all times. By varying the intensity of this illumination light beam as a function of the respective solid angle, the illumination intensity can thus be controlled in a targeted manner, depending on the scene geometry (and with optional dynamic "result control" also depending on the amount of reflection or scattered light) for each solid angle, the illumination intensity already emitted by the illumination device. Thus, a static scene can be measured, with the appropriate intensity for each solid angle is taught to illuminating light.
6. (6) The above-explained and optionally dynamic adaptation of the intensity of illumination light by the illumination device can be adaptive both in real time and from "frame to frame". In this case, for the parts of the scene from which too little measuring light is received, immediately the intensity of the corresponding part (illumination light) is increased. This means that, depending on the result values of a last scene capture for the next scene capture, those areas with "overexposure" are illuminated at a reduced level and those with "underexposure" are brightened. This approach is particularly well suited for the lighting principle B1 in combination with the measuring principle M1 or M2.
7. (7) An embodiment of the invention achieves energy saving by means of dynamic lighting energy optimization using illumination energies of different wavelengths or frequencies. In this case, depending on the color of the object, the wavelengths which lead to the most intense reflections or light scattering can be emitted at a lower intensity, for example. In contrast, other wavelengths or other wavelength regions with less reflection or scattering may be present in the wavelength spectrum with a higher intensity. Thus, for example, a red object can be illuminated primarily with a red light component and the green and blue light components are reduced (for the relevant solid angle), preferably to at least approximately zero intensity. The same principle can also be applied in the relationship between visible light and infrared (IR) light.

• (8) Das in diesem Dokument beschriebene Sensorsystem kann beispielsweise bei Durchgängen einsetzt werden, insbesondere bei Durchgängen, welche eine Verschlusscharakteristik aufweisen, die automatisch gesteuert wird (z.B. mittels Türen, Tore, Barrieren, Ampeln, etc.). Da die Sensorik für eine Durchgangssteuerung üblicherweise durch die vorhandenen Verschlusssysteme mit Energie versorgt wird, gilt es mit einer gegebenen Energiemenge möglichst viel sensorische Wirkung zu erzielen. Das in diesem Dokument beschriebene Sensorsystem erlaubt im Vergleich zu bekannten Sensorsystemen (i) eine Datenerfassung für größere Distanzen (früheres Erkennen einer Öffnungsanforderung, insbesondere bei schneller bewegenden Objekten), (ii) breitere Erfassungswinkel (z.B. frühzeitiges Erkennen und Verfolgen von Querverkehr) und/oder (iii) ein zuverlässigeres Erkennen von Objekten in einem Sicherheitsbereich des Verschlusssystems.
• (9) In einer weiteren Ausführungsform, welche sich vor allem für das Beleuchtungsprinzip B2 eignet, wird eine (zusätzliche) räumliche Variation des Beleuchtungslichts durch DOE's erreicht, welche auch als ein Teil der beschriebenen Freiformoptik angesehen werden können. Bei DOE's im Zusammenhang mit Lasersystemen kann so die maximale Beleuchtungsenergie ausgenutzt werden, weil diejenigen Anteile der Beleuchtungslichtstrahlen, welche mit geringerer Intensität auf die Szene treffen sollen, nicht einfach durch eine Maske ausgeblendet werden sondern deren Intensität durch das DOE auf andere Bereiche der Szene umverteilt wird. So kann die Energie des Beleuchtungslichts nahezu vollständig ausgenutzt werden. Derselbe Effekt der Konzentration von Beleuchtungslicht in einem Teilbereich der Szene (wenn auch mit tieferer Effizienz) kann auch durch Mechanismen erreicht werden, wie sie für Musterprojektionen verwendet werden, die für 3D Sensoren erforderlich sind, welche auf dem bekannten Prinzip der strukturierten Beleuchtung bzw. der sog. Streifenprojektion beruhen.
• (10) In einer weiteren Ausführungsform wird die zu erfassende Szene zunächst konventionell, insbesondere gemäß dem Beleuchtungsprinzip B2, beleuchtet. Nach einer Ermittlung der Distanzinformation der ganzen Szene werden in den folgenden Szenenerfassungen die „überbelichteten Regionen“ mit einer geringeren Beleuchtungsintensität beleuchtet. Insbesondere bei Sensorsystemen, die zeitliche Veränderungen von Objekten in der Szene detektieren sollen, kann das Sensorsystem an der unteren Grenze der Messbarkeit betrieben werden, solange die Szene (noch) statisch ist. Wenn jedoch eine Veränderung in der Szene (grob) erkannt oder zumindest vermutet wird, dann kann sofort mit einer Erhöhung der Beleuchtungsintensität reagiert werden, so dass die Szene beziehungsweise die Szenenveränderungen dann mit einer hohen Genauigkeit erfasst und ausgewertet werden können. Dieser Mechanismus kann sowohl für IR Sensorsysteme als auch für Sensorsysteme verwendet werden, die mit sichtbarem Licht arbeiten.

The information obtained in the context of a variable-frequency or wavelength variable illumination with respect to reflection or scattering properties with associated distance and solid angle can be of great advantage in a subsequent scene analysis of moving objects, as this simple objects can be detected and tracked, since the functional togetherness of spatial points on the reflection or scattering properties can be interpreted in addition grouping.

• (8) The sensor system described in this document can be used, for example, in passages, in particular in passages which have a locking characteristic which is automatically controlled (eg by means of doors, gates, barriers, traffic lights, etc.). Since the sensors for a passage control are usually powered by the existing closure systems with energy, it is necessary to achieve as much sensory effect with a given amount of energy. Compared to known sensor systems (i), the sensor system described in this document permits data acquisition for longer distances (earlier detection of an opening request, especially for faster moving objects), (ii) wider detection angles (eg early detection and tracking of cross traffic) and / or (iii) a more reliable detection of objects in a security area of the closure system.
• (9) In a further embodiment, which is particularly suitable for the illumination principle B2, an (additional) spatial variation of the illumination light is achieved by DOEs, which can also be regarded as part of the described free-form optics. In the case of DOEs in the context of laser systems, the maximum illumination energy can thus be utilized because those portions of the illumination light beams which are to hit the scene with less intensity are not simply masked out by a mask, but their intensity is redistributed by the DOE to other areas of the scene , Thus, the energy of the illumination light can be almost completely utilized. The same effect of concentration of illumination light in a sub-area of the scene (albeit with lower efficiency) can also be achieved by mechanisms used for pattern projections required for 3D sensors based on the well-known structured illumination principle so-called strip projection based.
• (10) In a further embodiment, the scene to be detected is first illuminated conventionally, in particular according to the illumination principle B2. After determining the distance information of the whole scene, in the following scene acquisitions the "overexposed regions" are illuminated with a lower illumination intensity. Particularly in sensor systems which are intended to detect temporal changes of objects in the scene, the sensor system can be operated at the lower limit of the measurability as long as the scene is (still) static. However, if a change in the scene is (grossly) detected or at least suspected, then an increase in the illumination intensity can be reacted immediately, so that the scene or the scene changes can then be detected and evaluated with high accuracy. This mechanism can be used for both IR sensor systems and visible light sensor systems.

In the following detailed description referring to the figures, features of different embodiments, which are the same or at least functionally identical to the corresponding features or components of another embodiment, are provided with the same reference numerals or with reference numerals, which in the last two digits are identical. In order to avoid unnecessary repetitions, features or components already explained on the basis of a previously described embodiment will not be explained in detail later.

1 shows the use of a sensor system 100 to control a Covering characteristic of an opening 184 depending on the characteristics of one of the sensor system 100 watched scene 190 , According to the embodiment shown here, the opening 184 an entrance opening for persons in a building or a garage entrance for motor vehicles. The corresponding input structure is denoted by the reference numeral 180 Provided. One in the scene 190 located object 195 should symbolize such a person or a motor vehicle.

The entrance structure 180 includes a stationary support structure 182 which a frame and a guide for two designed as a sliding closure body 186 represents. The sliding doors 186 can each by means of a motor 187 along the displacement directions represented by two thick double arrows. The control of the motors 187 takes place, as set out below, by means of the sensor system described in this document 100 ,

The sensor system 100 indicates (a) a TOF detection system 110 , (b) a data processing device 150 and (c) a database 160 , The TOF detection system 110 again, (a1) has a lighting device 130 for emitting illumination light 131 and (a2) a measuring device 115 , which are used for the acquisition and measurement of measuring light 196 responsible is. In accordance with the principle of a 3D TOF detection is the measuring light 196 at least partially of the object 195 backscattered illumination light 131 , In the in 1 illustrated architecture of the TOF detection system 110 indicates the measuring device 115 on (a2-i) a light receiver 120 and (a2-ii) a measuring unit 125 which the light receiver 120 is arranged downstream and which is adapted to measure a light transit time between the illumination device 130 emitted illumination light 131 and from the light receiver 120 received measurement light 196 , Furthermore, the measuring device 115 a light receiver control device 122 associated with the operation of the light receiver 120 in terms of different operating modes controls.

According to the embodiment shown here, the TOF detection system 110 are on the TOF detection system 110 assigned (a3) an illumination light control means 135 for controlling the operation of the lighting device 130 and (a4) a freeform optical controller 145 for controlling actuators 131 . 143 , by means of which the optical imaging properties of freeform optics 140 or. 142 can be targeted.

How out 1 can be seen, the sensor system 100 according to the embodiment shown here, two freeform optics 140 each one of two light sources or lighting units of the lighting device 130 are assigned and in the corresponding beam path of the respective illumination light 131 are located. According to the embodiment shown here, the two free-form optics 140 not static but can each mean a schematically illustrated actuator 141 be deformed. This changes the imaging properties of the freeform optics 140 and there arises a relation to the space angle-dependent intensity distribution of the illumination light, as it from the respective illumination unit of the Beleuchtungseirichtung 130 is emitted, modified intensity distribution of illumination light 131 as it is on the scene 190 meets and illuminates or illuminates. Through a targeted deformation of the elastic freeform optics 140 that of the freeform optics controller 145 caused by the relevant actuators 141 is performed, the spatial characteristics of the illumination light 131 as it is on the scene 190 impinges, in view of a desired space angle-dependent distribution of the intensity of the illumination light 131 in the scene 190 be set. In this case, the desired spatial angle-dependent distribution of the illumination light intensity is typically that intensity distribution at which the detection of the scene by the light receiver 120 and the signal processing by the downstream measuring unit 125 and the data processing device 150 as reliable and / or accurate as possible.

Regarding the further freeform optics 142 , which in the beam path of the measuring light 196 is arranged, the same principles of operation apply as in the two freeform optics 140 , Also the optical properties with respect to a modification of the intensity distribution of the measuring light 196 be about an actuator 143 from the freeform optical controller 145 controlled. Through a targeted deformation of the further free-form optics 142 becomes the spatial angle-dependent collection of the intensity of the measuring light 196 modified. This is preferably done in such a way that the measurement light distributed spatially with respect to its intensity is inhomogeneous 196 as it is (in 1 from below) on the freeform optics 140 meets, "homogenizes", so that the measuring light with a homogeneous distribution of intensity as possible on the light receiver 120 meets.

It should be noted that the solid angle dependence of the illumination light and the measurement light described here can also be realized by only one type of free-form optics. For example, the whole "solid angle modification" only with the freeform optics 140 or only with the freeform optics 142 respectively. It should also be noted that the Freeform optics 140 and 142 instead of elastic refractive optical elements can also be realized with other optical elements, for example by means of diffractive and / or reflective optical elements.

It is further pointed out that the illumination light and the measuring light can be guided at least partially through the same free-form optics.

In the TOF detection system 110 are in particular all optical components of the sensor system 100 contain. This also applies to the freeform optics 140 and 142 as well as the actuators 141 or. 143 which over in 1 for reasons of clarity not shown holding structures on a housing of the TOF detection system 110 are attached. By means of a holder 111 is at least the TOF detection system 110 at the stationary support structure 182 mounted in a mechanically stable and spatially fixed manner. The entire sensor system is preferred 100 (in contrast to the representation of 1 ) is constructed as a module which is within a compact design adjacent to the TOF detection system 110 also the data processing device 150 as well as the database 160 having.

According to the embodiment shown here, the light receiver control device 122 the light receiver 120 to work in a particular one of at least two different modes of operation. In the various operating modes, for example, caused by a previous scene evaluation by means of the data processing device 150 , individual pixels of the light receiver 120 have a different sensitivity or a different efficiency with respect to an accumulation of photons. Also a below based on the 4a and 4b described scene-dependent summarization of pixels of the light receiver 120 can from the light receiver control device 122 be initiated or controlled.

On to the data processing device 150 via an interface 152 passed external control signal 152a can be used to control the operation of the data processing device 150 at least partially dependent on external information. In particular, via the control signal 152a an "a priori knowledge" about an object 195 for an improved evaluation of the captured scene 190 and in particular for improved object recognition.

According to the exemplary embodiment illustrated here, the illumination device illuminates 130 which may be, for example, an array of individually controllable laser or light-emitting diodes, the scene 190 and therefore also in the scene 190 located object 195 with a pulsed and thus temporally modulated illumination light 131 , The illumination light controller 135 is configured, the lighting device 130 such that a characteristic of the illumination light 131 indicating the dependence of the illumination intensity of the illumination light 131 from the solid angle (in which the illumination light 131 on the freeform optics 140 meets) during operation of the sensor system 100 is dynamically changeable.

The space angle-dependent intensity distribution of the illumination light 131 is in 1 not shown for reasons of clarity. To ensure that the intensity of the backscattered measuring light is as uniform as possible 196 To reach (as it meets the light receiver), those solid angles of the scene 190 , which are associated with a larger measuring distance, illuminated more than other solid angles, which are associated with a smaller measuring distance.

The illumination light controller 135 can the characteristic of the illumination light 131 also with regard to further (non-spatial) properties of the illumination light 131 for example, its (a) wavelength, (b) spectral intensity distribution, (c) polarization direction, and (d) intensity distribution for different polarization directions. These further properties can be selected such that they contribute to the most reliable and accurate object recognition possible. Again, a "a priori knowledge" about optical properties of the object 195 be taken into account.

It should be noted that the lighting device 130 next to the in 1 Lighting units shown may also have other lighting units that the scene 190 illuminate from another angle. Likewise, the two lighting units or it can also be just one lighting unit outside the housing of the TOF detection system 110 arranged and thus of the light receiver 120 be further spaced. This does not change the principles of the TOF measurement.

According to the exemplary embodiment illustrated here, the detected optical scene is based on this 3D data 190 with the data processing device 150 evaluated using suitable methods of image evaluation. This can include several pictures, which of the scene 190 under different lighting conditions or different Lighting characteristics were recorded, used together.

According to the embodiment shown here, the sensor system 100 able to perform an object detection. This is done by the data processing device 150 to one in the database 160 stored record of reference objects that correspond to selected objects that are authorized to open 184 to happen. This means that at a suitable approach of the object 195 to the entrance 184 the sliding doors 186 only be opened when the detected object 195 at least approximately coincident with one of the stored reference objects. This clearly indicates that in the use of the sensor system described here 100 the coverage characteristic of the object 184 also depends on the result of an object-based access control.

The 2a and 2 B illustrate a deformation of a designed as an elastic optically refractive element freeform optics. 2a shows the optical element 240a in a first operating state, which is characterized by a first spatial structure. According to the embodiment shown here, the first operating state is characterized by the fact that apart from any existing internal voltage from the outside (by an actuator) no force or no pressure on the freeform optics 240a is exercised. The corresponding (not warped) coordinate system is in 2a in the optical element 240a shown.

2 B shows the optical element, which now with the reference numeral 240b is provided, in a second (strained) operating state, which is characterized by a second spatial structure that is different from the first spatial structure. It is obvious that this also changes the light shaping properties, in particular with regard to a modification of the intensity distribution of illuminating light or measuring light passing through.

The second operating state is set by a force or a pressure on the optical element from the outside (from an actuator, not shown) 240b is exercised. The corresponding (warped) coordinate system of the optical element is in 2 B illustrated. The dimensions or lengths of the freeform optics changed with respect to the first state along the coordinate axes 240b are illustrated by coordinate axes of different lengths.

3 shows a further use or a further use of the sensor system 100 , For clarity, is in 3 only the TOF detection system 110 of the sensor system 100 shown.

According to the embodiment illustrated here, the TOF detection system detects 110 a traffic flow of (different) objects 395a . 395b . 395c . 395d and 395e , which are on a conveyor belt 398 and along the direction of movement represented by an arrow through a scene 390 move through. Reliable knowledge of the number and / or type of objects 395a to 395e can be used in the field of logistics for traffic flow control. Only one example of such a control of a traffic flow is the control of the luggage transport in an airport. It can also labels on the objects 395a - 395e determine the type of each object. It should be noted, however, that use in an airport is just one example of a variety of other traffic control applications.

The 4a and 4b illustrate combining single pixels of a light receiver configured as a semiconductor or CCD chip 420a or. 420b , The light receiver 420a has a plurality of light-sensitive or photon-collecting pixels 422a on. According to the embodiment shown here are the pixels 422a the full spatial resolution of the light receiver 420a associated with which resolution through the semiconductor architecture of the chip 420a is predetermined.

At the light receiver 420b each are four of the light-sensitive pixels (for a full resolution) to a parent pixel 422b (for increased photon accumulation per pixel at the expense of reduced spatial resolution). Illustratively, a pixel collects 422b compared to a single pixel 422a a fourfold amount of light on. Such "binning" of pixels reduces the required (minimum) intensity of the detected measurement light needed to evaluate the corresponding image area of the scene. Since the intensity of the measurement light depends directly on the intensity of the illumination light, binning reduces the intensity of the illumination light and thus reduces the energy consumption of the sensor system.

The described "binning" can also dynamically by a corresponding control of one and the same light receiver 420a or. 420b will be realized. In this case, the light receiver is operated either in a first operating mode (with full resolution) or in a second operating mode (with photon-collecting combined pixels). A switch between different ones Operating modes can be controlled by external control signals. Alternatively or in combination, such switching may also depend on the result of a scene evaluation, so that the "binning" mode of operation is regulated for a next scene capture.

It should be noted that more than two different modes of operation, each with a different strong summary of pixels can be used. Furthermore, it is possible to combine a different number of individual pixels into a higher-order pixel in different partial areas of the light receiver. Then, individual portions of the scene with higher spatial resolution (and less photon accumulation) and other portions of the scene with lower spatial resolution (and higher photon accumulation) can be detected. The described local and differently strong grouping of pixels can be carried out dynamically or adaptively in exactly the subregions in which a particular object is currently located.

The 5a to 5c show different beam cross sections of an illumination light to adjust the lighting to the shape of the scene to be detected. An in 5a illustrated first illumination light 531a has a substantially circular beam cross-section and is preferably suitable for "round scenes". However, for most applications which do not detect (and evaluate) a "round scene", a beam cross section deviating from a circular shape is suitable. In 5b is a lighting light 531b shown with an elliptical beam cross-section. 5c shows an illumination light 531c with a rectangular beam cross section. As already mentioned above, the beam cross-section can be adapted by a corresponding shaping of the free-form optics and optionally also by a suitable operation of the illumination device. Diffractive optical elements (DOEs) can also be used, which optionally even allow a dynamic and / or scene-dependent shaping of the beam cross-section.

It is noted that the term "comprising" does not exclude other elements and that the "on" does not exclude a plurality. Also, elements described in connection with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

LIST OF REFERENCE NUMBERS

100

sensor system

110

TOF detection system

111

holder

115

measuring device

120

light receiver

122

Light receiver controller

125

measuring unit

130

lighting device

131

Illumination light / illumination beam path

135

Illumination light control means

140

Freeform optics

141

actuator

142

further freeform optics

143

another actuator

145

Freeform optics controller

150

Data processing device

152

interface

152a

external control signal

160

Database

180

input structure

182

stationary holding structure

184

Opening / entrance

186

Closing body / sliding door

187

engine

190

scene

195

object

196

Measuring light / measuring light beam path

240a

Freeform optics / optically refractive element in the 1st state

240b

Freeform optics / optically refractive element in the 2nd state

390

scene

395a-e

objects

398

conveyor belt

420a / b

Light receiver / sensor chip

422a

pixel

422b

parent pixel / pooled pixel

531a

Illuminating light with round cross section

531b

Illuminating light with elliptical cross-section

531c

Illumination light with rectangular cross section

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• EP 2453252 B1 [0005]
• US 2015293224 A1 [0086]

Claims (21)

A sensor system (100) for three-dimensionally capturing a scene (190) comprising the sensor system (100) an illumination device (130) for illuminating the scene (190) with an illumination light (131) along an illumination beam path (131); a measuring device (115) for receiving measuring light (196) along a measuring light beam path (196), wherein the measuring light (196) is at least partially backscattered by at least one object (195) in the scene (190) illumination light (131) and for measuring distances between the sensor system (100) and the at least one object (195) based on a light transit time of the illumination light (131) and the measurement light (196); a data processing device (150) connected downstream of the measuring device (115) for determining the three-dimensional characteristic of the scene (190) based on the measured distances; and a free-form optical system (140, 142) which is arranged in the illumination beam path (131) and / or in the measurement light beam path (196), wherein the free-form optical system (140, 142) is configured such that (i) when arranged in the illumination beam path (131), an illumination light intensity of the illumination light (130) depends on the solid angle of the illumination beam path (131) and (ii) in the case of an arrangement in the measurement light beam path (196), a measurement light intensity of the measurement light (196) depends on the solid angle of the measurement light beam path (196), so that a distance-based intensity loss of the illumination light (131) and the measurement light (196) is at least partially compensated. A sensor system (100) according to the preceding claim, further comprising another freeform optics (142), wherein the free-form optical system (140) is arranged in the illumination beam path (131) and the further free-form optical system (142) is arranged in the measuring light beam path (196). Sensor system (100) according to one of the preceding claims, wherein the free-form optical system (140, 142) comprises at least one reflective optical element, at least one refractive optical element and / or at least one diffractive optical element. Sensor system (100) according to one of the preceding claims, wherein the free-form optics (140, 142) at least one spatially and / or structurally changeable optical element (240a, 240b), wherein a change of the optical element (240a, 240b) to a change of Solid angle dependence of the illumination light intensity and / or the measurement light intensity leads. Sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) and / or the illumination device (130) is configured to provide the illumination light (131) and / or the measurement light (196) with a space angle-dependent intensity distribution, which Edge light drop at least approximately compensated, in particular a natural Randlichtabfall according to which a brightness in an image when imaging a uniformly bright subject through a lens by the factor cos ^ 4 compared to the brightness in the center of the image decreases. The sensor system according to claim 1, further comprising an illumination light control device coupled to the illumination device, configured to control the illumination device such that a characteristic of the illumination light, which is the illumination light Dependence of the illumination intensity of the illumination light (131) on the solid angle describes, during an operation of the sensor system (100) is dynamically changeable. A sensor system (100) according to any one of the preceding claims, wherein the data processing means (150) is coupled to the illumination light controller (135) and configured to evaluate the determined three-dimensional characteristic of the scene (190) and based on a result of that evaluation the characteristic of the scene To change illumination light (131). A sensor system (100) according to the preceding claim, wherein the result of the evaluation depends on the optical scattering behavior of at least one object (195) contained in the scene (190). A sensor system (100) according to any one of the preceding claims, wherein the illumination means (130) comprises at least one of (a) a laser illumination light source spatially scanning the scene with a transmitted laser beam illumination light; (B) an at least approximately punctiform illumination light source; (c) a plurality of individual illumination light sources which are in particular individually controllable and each associated with a specific solid angle range of the scene; and (d) a planar illumination light source, in particular with a luminous intensity which is not homogeneous over the surface. Sensor system (100) according to one of the preceding claims, wherein the freeform optics (140, 142) and / or the illumination device (130) is configured to provide the illumination light (131) with a beam cross section (531b, 531c) deviating from a circular shape , Sensor system (100) according to one of the preceding claims, wherein the measuring device (115) comprises a light receiver (120, 420a) having a plurality of pixels (422a) for receiving the measuring light (196), wherein first pixels in a first subregion of the light receiver have first Lichtsensitivität and second pixels in a second portion of the light receiver having a second Lichtsensitivität, wherein the second Lichtsensitivität is different from the first Lichtsensitivität. A sensor system (100) according to any one of the preceding claims, wherein the measuring means (115) further comprises a light receiver controller (122) coupled to the light receiver (120), wherein the light receiver controller (122) and the light receiver (120) are configured in that in a modified operation of the sensor system (100) at least two pixels of the plurality of pixels (422a) are combined to form a higher-order pixel (422b). Sensor system (100) according to one of the preceding claims, wherein the measuring device (115) one or, if referring back to one of the two preceding claims, the light receiver (120) for receiving the measuring light (196) and a measurement unit (125) connected downstream of the light receiver (120) and configured to measure the light propagation time based on (a) a measurement of the time span between a transmission of a pulse of the illumination light (131) and the reception of the measurement light (196) belonging to the pulse and / or (B) a measurement of a phase shift between a temporal modulation of the illumination light (131) and an associated temporal modulation of the received measurement light (196). Sensor system (100) according to one of the preceding claims, further comprising a holder (111), which is at least mechanically coupled to the measuring device (115), wherein the holder (111) is formed such that the sensor system (100) at a reference on the scene to be detected (190) stationary support structure (182) is attachable. A sensor system (100) according to any one of the preceding claims, wherein the data processing means (150) is further configured to control a coverage characteristic of an opening (184) to be passed by an object (195) by at least one closure body (186). A method of three-dimensionally capturing a scene (190) comprising the method Illuminating the scene (190) with an illumination light (131) emitted by a lighting device (130) along an illumination beam path (131); Receiving, by means of a measuring device (115), measuring light (131) along a measuring light beam path (131), wherein the measuring light (131) is at least partially backscattered by at least one object (195) in the scene (190) illumination light (131); Measuring, by means of the measuring device (115), distances between the sensor system (100) and the at least one object (195) based on a light transit time of the illumination light (131) and the measurement light (196); and Determining the three-dimensional characteristic of the scene (190) based on the measured distances by means of a data processing device (150) connected downstream of the measuring device (115); wherein a freeform optics (140, 142) is arranged in the illumination beam path (131) and / or in the measurement light beam path (196), wherein the freeform optics (140, 142) is configured such that (I) in an arrangement in the illumination beam path (131), an illumination light intensity of the illumination light (131) depends on the solid angle of the illumination beam path, and (ii) in the case of an arrangement in the measurement light beam path (196), a measurement light intensity of the measurement light (196) depends on the solid angle of the measurement light beam path (196), so that a distance-based intensity loss of the illumination light (131) and the measurement light (196) is at least partially compensated. A method according to the preceding claim, further comprising Detecting an object (195) in the scene (190); Comparing the detected object (195) with at least one comparison object stored in a database (160); and, if the object (195) agrees with a comparison object within predetermined permissible deviations, identifying the object (195) as an object (195) permitted for a particular action. Use of a sensor system (100) according to one of the preceding Claims 1 to 15 for controlling a coverage characteristic of an opening (184) to be passed by an object (195) through at least one closure body (186). Use according to the preceding claim, wherein the opening (184) is an entrance or an exit, in particular an emergency exit in a building. Use according to one of the two preceding claims, wherein the object (195) is a person or a vehicle. Use of a sensor system (100) according to one of the preceding Claims 1 to 15 for detecting and / or controlling traffic flows of objects (395a - 395e) moving through a scene (190) of the sensor system (100), the scene (190) being determined by a spatial detection range of the sensor system (100).

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