DE102015226011A1 - Detection device for detecting at least one reflective element in a detection area, vehicle and method for detecting a detection area by means of a detection device - Google Patents

Abstract

The invention relates to a detection device (106) for detecting at least one reflective element (102) in a detection region (104). The detection device (106) comprises at least one exposure device for exposing the detection region (104) to light of a first frequency range and at least one image acquisition sensor for capturing an image of the detection region (104). The image acquisition sensor has at least one first pixel sensitive to the light of the first frequency range and a second sensitive second for light of a second frequency range deviating from the first frequency range.

Description

State of the art

The invention is based on a device or a method according to the preamble of the independent claims. The subject of the present invention is also a computer program.

There are known lightning-based cameras for the detection of persons with reflective safety vests.

Disclosure of the invention

Against this background, with the approach presented here, a detection device for detecting at least one reflecting element in a detection area, a vehicle, a method for detecting a detection area by means of a detection device, a device that uses this method, and finally a corresponding computer program according to the Main claims presented. The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

A detection device for detecting at least one reflective element in a detection region is presented, wherein the detection device has the following features:
at least one exposure device for exposing the detection region to light of a first frequency range; and
at least one imaging sensor for capturing an image of the detection area, wherein the imaging sensor has at least one first pixel sensitive to light of the first frequency range and a second pixel sensitive to light of a second frequency range different from the first frequency range.

By a reflective element, for example, a reflective strip on a garment, such as a safety vest, a retroreflector or a cat's eye can be understood. Light can here be understood as meaning both electromagnetic radiation that is visible to the human eye and electromagnetic radiation that is invisible to the human eye. In particular, light may be understood here to mean electromagnetic radiation which, in addition to a wavelength range which is visible to the eye, may further comprise wavelength regions adjoining thereto, in particular the infrared radiation and wavelength ranges assigned to the ultraviolet radiation. Thus, by light, for example, visible light, infrared light and / or ultraviolet light can be understood here. The exposure device may be, for example, a device for generating a light flash, in particular an infrared light flash. Depending on the embodiment, the image acquisition sensor can be a color, monochrome or infrared sensor or a combination of at least two of the three sensors mentioned. For example, the image pickup sensor can be realized as a CCD sensor. By a pixel, a single surface element of the image sensor can be understood. The pixel may, for example, comprise at least two subpixels. A detection region can be understood to be an area that can be detected by the detection device. For example, the light of the first frequency range may be infrared light and the light of the second frequency range may be visible light.

The approach presented here is based on the knowledge that a camera can be sensitive to image in the visible wavelength range as well as to the detection of a reflective element by means of an image sensor, which can be sensitive, for example, to light in a visible wavelength range and light in an invisible wavelength range. about a reflective protective vest, can be used.

With the help of such a multifunction camera with reflex marker detection, it is possible to reliably recognize persons in the context of autonomous machines as well as in the context of assistance systems for human-guided machines.

Thus, an additional separate camera for the detection of the reflective element can be dispensed with, d. that is, it is not necessary to expand an existing camera-based system with a dedicated camera to realize the detection function. This can save costs.

According to an embodiment, the exposure device may be configured to expose the detection region with infrared light as the light of the first frequency range. Additionally or alternatively, the second visible light pixel may be sensitive as the light of the second frequency range. By infrared light, a spectral range of electromagnetic waves between 1 mm and 780 nm can be understood. The visible light may be, for example, violet, blue, green, yellow, orange or red light or a light mixed from the six colors mentioned. By this embodiment, the detection device can be used both for detecting the reflective element and for Capture objects in the visible wavelength range.

It is advantageous if the image acquisition sensor further comprises at least one further sensitive light for one of the first frequency range and, additionally or alternatively, deviating from the second frequency range further frequency range further pixel. Thereby, the detection accuracy of the detection device can be improved.

According to a further embodiment, the image sensor and the exposure device may be arranged adjacent to each other or be arranged. As a result, the detection device can be made as compact as possible.

The approach described here also creates a vehicle with a detection device according to one of the preceding embodiments.

Furthermore, the approach presented here provides a method for detecting a detection area by means of a detection device according to one of the preceding embodiments, wherein the method comprises the following steps:
Providing an exposure signal to expose the detection area by the exposure means at an exposure time;
Reading in a first sensor signal provided by the image pickup sensor before or after the exposure time and / or a second sensor signal provided by the image pickup sensor at the exposure time; and
Generating an image representing the detection area using the first sensor signal and / or the second sensor signal.

The exposure signal may be, for example, an activation signal for activating the exposure device. Thus, the exposure device can be designed to emit a flash of light using the exposure signal, with which the detection area can be illuminated. The first or second sensor signal can each be an image of the detection area recorded by the image acquisition sensor as a function of activation of the exposure device. By way of example, the first sensor signal may be a recording of the detection area without illumination by the exposure device, in particular shortly before or after illumination, and the second sensor signal may be a recording of the detection area during illumination by the exposure device. Depending on the embodiment, the image generated in the step of generating may be an image in the visible wavelength range, an image in the non-visible wavelength range, in particular in the infrared range, or an image covering both wavelength ranges.

According to one embodiment, an RGB image may be generated in the step of generating. Depending on the embodiment, an infrared image or a monochrome image may additionally or alternatively be generated here. As a result, a range of functions of the detection device can be expanded with little effort.

According to a further embodiment, the method may comprise a step of evaluating the first sensor signal and the second sensor signal in order to detect a reflective element in the detection area. Additionally or alternatively, the method may include a step of generating a detection signal in response to a result of the evaluation. By way of the detection signal, a successful detection of a reflecting element in the detection area can be displayed. By using the sensor signals, the reflective element can be detected with high reliability.

It is also advantageous if, in the step of reading in, a first image recorded by the image acquisition sensor before or after the exposure time is read in as the first sensor signal and a second image taken by the image acquisition sensor at the exposure time as the second sensor signal. In this case, in the step of evaluating using the first sensor signal and the second sensor signal, a difference image can be generated from the first image and the second image. Finally, in the generating step, the detection signal may be generated when the difference image represents the reflective element. For example, a difference image can be understood to mean an image which can represent at least one object contained in the second image but not contained in the first image, in particular the reflective element. This embodiment enables reliable and accurate detection of the reflective element.

This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

The approach presented here also creates a device that is designed to perform the steps of a variant of a method presented here in appropriate facilities to drive or implement. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently.

For this purpose, the device may comprise at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting data or control signals to the sensor Actuator and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller or the like, wherein the memory unit may be a flash memory, an EPROM or a magnetic memory unit. The communication interface can be designed to read or output data wirelessly and / or by line, wherein a communication interface that can read or output line-bound data, for example, electrically or optically read this data from a corresponding data transmission line or output to a corresponding data transmission line.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the device. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

In an advantageous embodiment, the device is used to control a driver assistance system of a vehicle. For this purpose, the device can access, for example, sensor signals provided by the detection device or other environment sensors of the vehicle. It is controlled by actuators such as steering or brake actuators.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The sensor signals may, for example, be signals of a sensor of a motor vehicle or of sensors installed in a motor vehicle. The sensor signals may thus be signals of a gas sensor, for example a lambda probe, a pressure sensor, which is installed, for example, in a bumper, or an acceleration sensor, for example an ESP sensor. The control and / or data signals may be signals sent to a control unit, such as a brake or engine control unit. On the basis of these signals, the control unit can then decide whether, for example, a warning signal is output during a malfunction of the tested sensor and / or an emergency program is activated which activates certain units, such as brake actuators in the motor vehicle, and / or certain units of the motor vehicle are deactivated to bring about a safe operating state.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

1 a schematic representation of a vehicle according to an embodiment;

2 a schematic representation of a detection device according to an embodiment;

3 a schematic representation of a device according to an embodiment;

4 a schematic representation of a device according to an embodiment; and

5 a flowchart of a method according to an embodiment.

In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similar acting, wherein a repeated description of these elements is omitted.

1 shows a schematic representation of a vehicle 100 according to an embodiment. In front of the vehicle 100 is a person with a protective vest. The protective vest has exemplified two reflection strips as reflective elements 102 on. Here, the person is in a detection area 104 a detection device 106 of the vehicle 100 which is formed around the two reflective elements 102 capture. For this purpose, the detection device 106 for both light of a first frequency range, such as an infrared range, as well as light of a second frequency range, such as a visible wavelength range, sensitive. In addition, the detection device 106 trained to the detection area 104 to illuminate with the light of the first frequency range.

2 shows a schematic representation of a detection device 106 according to an embodiment. In the detection device 106 For example, it is a detection device as described above with reference to 1 is described. The detection device 106 includes an exposure device 200 for exposing the detection area 104 with the light of the first frequency range. At the exposure device 200 it is according to this embodiment, an infrared flash for illuminating the detection area 104 with infrared light. Furthermore, the detection device 106 with an image sensor 202 realized, which is designed to form an image of the detection area 104 take. For this purpose, the image pickup sensor 202 a first pixel 204 which is sensitive to the light of the first frequency range, and a second pixel 206 which is sensitive to a second frequency range deviating from the first frequency range. For example, the second pixel 206 sensitive to light in the visible wavelength range. In the detection area 104 it is a viewing area of the image sensor 202 and the exposure device 200 ,

According to the in 2 Embodiment shown are the image pickup sensor 202 and the exposure device 200 arranged adjacent to each other.

Examples are in the detection area 104 an object 210 without reflective mark and an object 212 with reflex mark.

According to an embodiment, the image pickup sensor comprises 202 at least one more pixel 208 which, depending on the exemplary embodiment, is sensitive to light of a further frequency range deviating from the first or second frequency range or from both frequency ranges.

According to a further embodiment, the detection device 106 with an optional processing logic 214 realized, which is adapted to an exposure signal at an exposure time 216 to the exposure device 200 to send. Here is the exposure device 200 designed to be using the exposure signal 216 the light of the first frequency range, here an infrared flash, to send out and thus the detection area 104 to illuminate. The image pickup sensor 202 is designed to be the detection area 104 at the time of exposure as well as shortly after or before the exposure time. This is how the image acquisition sensor detects 202 According to this embodiment, at the time of exposure, an infrared image 218 of the detection area 104 and shortly before or after the exposure time, a monochrome image 220 of the detection area 104 , Here represents the infrared image 218 about the object 212 with reflex mark, while the monochrome image 220 the object 210 without reflex mark. Alternatively, the image pickup sensor 202 be formed to capture an RGB image instead of the monochrome image.

Here is the processing logic 214 trained to the infrared image 218 evaluate and a detection signal 222 provided the evaluation of the infrared image 218 that gives the infrared image 118 the object 212 with reflex mark represents or depicts. The detection signal may thus indicate that a reflex mark has been detected.

According to one embodiment, the detection device 106 As a multifunction camera for mono or stereo operation with conventional functionality and an additional function for the detection of reflective elements such as safety vests by means of an infrared flash device as an exposure device 200 realized.

In this case, the detection device delivers 106 on the one hand conventional images, such as monochrome images or RGB images that can be used, for example, to locate or display images. On the other hand, the detection device 106 designed to additionally detect and locate people who wear reflective elements such as reflective strips on safety vests.

For this purpose, a recording setup is used in which the infrared sensitivity of the image sensor 202 is not the same over all individual pixels, whereby an active lighting, such as a flash, does not affect all pixels in the same way.

For example, the image pickup sensor 202 be realized with a special grid of pixels, ie a regular array of pixels, which is one of other pixels of the image sensor 202 have different infrared sensitivity.

Due to the different sensitivity, it is possible to synchronously produce two images of a scene with different frequency characteristics, which are the basis for different image processing tasks.

Such a detection device makes it possible to integrate the described detection function into existing camera applications without the need for another camera.

Depending on the embodiment, the detection device comprises 106 one or more image sensors 202 and one or more exposure devices 200 , for example in the form of infrared flash devices. The respective fields of view of the image sensor 202 and the exposure devices 200 , previously also called detection area, may overlap.

The pixels in the image acquisition sensor 202 For example, they are arranged as follows.

In the case of an RGB camera, the image pickup sensor includes 202 instead of RGGB (red, green, green, blue), for example, RGBI (red, green, blue, infrared) as a pixel.

In the case of a mono camera, the image pickup sensor includes 202 instead of YYYY, for example YIIY or YYYI or other variants, where Y stands for a brightness without filter or with bandpass for visible light and I for infrared pixels.

The pixels of the image sensor 202 are arranged from an RGGB image sensor, for example, as follows: R G → R G G B I B

Starting from a monochrome image sensor are the pixels of the image sensor 202 for example, arranged as follows: Y Y → Y I Y Y Y Y Y Y → Y I Y Y I Y

3 shows a schematic representation of a device 300 according to an embodiment. The device 300 For example, as part of a preceding based on 2 be implemented described further processing logic. The device 300 includes a delivery unit 302 for providing the exposure signal 216 as well as a read-in unit 304 configured to be responsive to providing the exposure signal 216 a first sensor signal provided by the image pickup sensor in picking up the detection area before or after the exposure timing 306 representing the monochrome image, for example, and a second sensor signal provided by the image pickup sensor in picking up the detection region at the exposure time 308 which, for example, represents the infrared image. A generation unit 310 the device 300 is designed to operate using the two sensor signals 306 . 308 an image representing the detection area 312 to create. This can be the picture 312 a combination of over the sensor signals 306 . 308 include image information provided. Depending on the embodiment, the generating unit 310 formed, for example, to generate an RGB image, an infrared image or a monochrome image or a combination of at least two of said three types of images.

4 shows a schematic representation of a device 300 according to an embodiment. In contrast to 3 includes the in 4 shown device 300 in addition to the providing unit and generating unit as described above with reference to FIG 3 described, an optional evaluation 400 , which is designed to analogously to the generating unit, the two sensor signals 306 . 308 from the reading unit 304 to receive and evaluate to detect a reflective element in the detection area, such as in 2 schematically represented object with reflex mark. For better visibility, the provisioning unit and the generation unit are in 4 Not shown.

Here is the evaluation unit 400 designed to be dependent on a result of in the evaluation unit 400 evaluation carried out a deployment signal 402 to generate that from an optional generation unit 404 the device 300 is used to detect the detection signal 222 to generate. For example, the evaluation unit generates 400 the provisioning signal 402 if the evaluation shows that the second sensor signal 308 represents an image of the detection area comprising the object with reflex mark. Thus, via the detection signal 222 a detected detection of the reflex mark can be displayed

According to one embodiment, the evaluation unit 400 designed to be using the two sensor signals 306 . 308 a difference image from the first image of the detection area recorded at the time of exposure and the second image of the detection area taken before or after the exposure time produce. Here, the evaluation unit 400 the provisioning signal 402 ready when the difference image represents the reflective element, here the object with reflective mark.

For example, the difference image shows the reflective element as a difference between the first and the second image when the reflective element is present in the detection area. If, on the other hand, no reflective element is present in the detection area, the image information of the first and the second image cancel each other out when the difference is formed in such a way that the difference image has no image information that can be classified as a reflective element. In this case, depending on the exemplary embodiment, the difference image is either an image comprising no image information or an image which only includes image information which, by virtue of its characteristic, for example its brightness value, can not be classified as reflective elements. In this way it can be determined by a suitable evaluation of the difference image, whether or not there was a reflective element in the detection area during the acquisition of the images used to form the difference image. For evaluating the difference image can be made of suitable image evaluation algorithms, as they can be used for example for object detection.

5 shows a flowchart of a method 500 according to an embodiment. The procedure 500 for detecting a detection range, for example, by means of a detection device, as described above with reference to 1 to 4 is described, carried out or controlled. This is done in one step 510 the exposure signal is provided to expose the detection area by the exposure means at the exposure time. In a further step 520 the reading in of the first sensor signal provided by the image recording sensor before or after the exposure time or of the second sensor signal or of the two sensor signals provided by the image recording sensor at the exposure time takes place. Finally, in one step 530 the image representing the detection area is generated using the first sensor signal or the second sensor signal or both sensor signals.

The steps 510 . 520 . 530 can be repeated continuously.

According to one embodiment, in an optional step 540 evaluated the two sensor signal to detect a reflective element in the detection area. If the evaluation reveals that the reflective element is in the detection area, then in a further optional step 550 generates a corresponding detection signal.

For example, in step 540 a difference image between an exposure without a flash and a timely to the first image taken lightning exposure generated. In the differential image reflectors, as they are applied for example on safety vests, visible. Further processing makes it possible, for example by means of suitable methods of pattern recognition, to classify in "safety vest" and "no safety vest".

Depending on the embodiment, the following functional primitives are conceivable.

A first function primitive FP (a) comprises a conventional image pickup function without flash. Here, the image pickup sensor, also called lmager, exposed. The different types of pixels are each assembled into an image, such as a monochrome image or an infrared image.

A second function primitive FP (b) is used to record an infrared image. For this purpose, the detection area is illuminated with an infrared flash. The imaging sensor is exposed, with the different types of pixels in turn being assembled into a monochrome image or infrared image.

Thus, by means of the method 500 Both conventional images such as monochrome or RGB images are recorded as well as reflective elements such as reflex markers are detected.

To detect the reflective element, two images are taken successively with the shortest possible time interval, once with flash and once without flash. The images are then sent to the further processing logic, which generates a detection result.

For example, at a time t = 0, the first function primitive FP (a) and at a further time t = 0 + x the second function primitive FP (b) is executed.

Alternatively, at time t = 0, the second function primitive FP (b) is executed. Accordingly, at time t = 0 + x, the first function primitive FP (a) is executed.

Depending on the required detection frequency, the sequence of the two function primitives can be different. After a respective sequence, a detection can take place.

Depending on the embodiment, either only FP (a) shots or both FP (a) and FP (b) shots of the pixels are provided.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims (12)

Detection device ( 106 ) for detecting at least one reflective element ( 102 ; 212 ) in a detection area ( 104 ), wherein the detection device ( 106 ) comprises the following features: at least one exposure device ( 200 ) for exposing the detection area ( 104 ) with light of a first frequency range; and at least one image acquisition sensor ( 202 ) for capturing an image of the detection area ( 104 ), wherein the image sensor ( 202 ) at least one sensitive to light of the first frequency range first pixel ( 204 ) and a second pixel sensitive to light of a second frequency range deviating from the first frequency range (US Pat. 206 ) having. Detection device ( 106 ) according to claim 1, wherein the exposure device ( 200 ) is formed around the detection area ( 104 ) with infrared light as the light of the first frequency range, and / or the second pixel ( 206 ) is sensitive to visible light as the light of the second frequency range. Detection device ( 106 ) according to one of the preceding claims, in which the image acquisition sensor ( 202 Furthermore, at least one additional pixel sensitive to light of a further frequency range deviating from the first and / or second frequency range (US Pat. 208 ) having. Detection device ( 106 ) according to one of the preceding claims, in which the image acquisition sensor ( 202 ) and the exposure device ( 200 ) are arranged adjacent to each other or can be arranged. Vehicle ( 100 ) with a detection device ( 106 ) according to one of the preceding claims. Procedure ( 500 ) for detecting a detection area ( 104 ) by means of a detection device ( 106 ) according to one of claims 1 to 4, wherein the method ( 500 ) comprises the following steps: providing ( 510 ) of an exposure signal ( 216 ) to the detection area ( 104 ) by means of the exposure device ( 200 ) to expose at an exposure time; Read in ( 520 ) one of the image sensor ( 202 ) before or after the exposure time provided first sensor signal ( 306 ) and / or one of the image sensor ( 202 ) at the exposure time provided second sensor signal ( 308 ); and generating ( 530 ) one of the detection area ( 104 ) representing image ( 312 ) using the first sensor signal ( 306 ) and / or the second sensor signal ( 308 ). Procedure ( 500 ) according to claim 6, wherein in the step of generating ( 530 ) an RGB image and / or an infrared image and / or a monochrome image is generated. Procedure ( 500 ) according to claim 6 or 7, with a step of evaluating ( 540 ) of the first sensor signal ( 306 ) and the second sensor signal ( 308 ) to a reflective element ( 102 ; 212 ) in the detection area ( 104 ) and / or a step of generating ( 510 ) of a detection signal ( 222 ) depending on a result of the evaluation ( 540 ). Procedure ( 500 ) according to claim 8, wherein in the step of reading ( 520 ) from the image sensor ( 202 ) recorded before or after the exposure time as the first sensor signal ( 306 ) and one of the image sensor ( 202 ) recorded at the exposure time as the second sensor signal ( 308 ), whereby in the step of evaluating ( 540 ) using the first sensor signal ( 306 ) and the second sensor signal ( 308 ) a difference image is generated from the first image and the second image, wherein in the step of generating ( 510 ) the detection signal ( 222 ) is generated when the difference image is the reflective element ( 102 ; 212 ). Contraption ( 300 ) with units ( 302 . 304 . 310 ; 400 . 404 ), which are adapted to the process ( 500 ) according to any one of claims 6 to 9 and / or to control. Computer program that is adapted to the procedure ( 500 ) according to any one of claims 6 to 9 and / or to control. A machine readable storage medium storing the computer program of claim 11.

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