DE102014208206A1 - Method for controlling, parameterizing or calibrating a sensor unit used for lighting control - Google Patents

Abstract

A method for controlling, parameterizing and / or calibrating a sensor unit (10) used for illumination control, which has an image sensor (11) for acquiring digital image information and a controller (15) for evaluating the image information and producing a brightness signal (S) representing the daylight. comprises the following steps: providing a reference or control object (20, 30) and arranging this reference or control object (20, 30) in a region detected by the image sensor (11), acquiring image information representing the reference or control object (20, 30), evaluating the image information by the controller (15) and deriving control, parameterization or calibration information.

Description

The present invention relates to a method by means of which a sensor unit used for lighting control is to be activated, parameterized and / or calibrated. The sensor unit is a unit based on an image or pixel sensor that acquires and evaluates digital image information. Furthermore, the invention relates to a corresponding sensor unit.

The starting point for the invention are the current methods for regulating light, in which the light emitted by the luminaire is not directly determined with the aid of a sensor, but instead the area to be illuminated is detected. In this so-called look-down light control, a light sensor thus measures the illuminance in the area to be illuminated and generates a corresponding signal. A control or regulating unit can then keep constant the lighting level in the area by means of a corresponding activation of the luminaires on the basis of the measured value transmitted by the light sensor. This means that the luminaires are controlled in such a way that, for example, in a region to be illuminated, a constant brightness is present independently of the daylight incident from the outside. Such look-down sensors are typically mounted on the ceiling of a room to be illuminated.

The currently used light sensors usually have a simple photodiode as a transducer. Depending on the optics used, the measured value obtained here is proportional to the average reflected light quantity of the area observed or detected by the sensor and thus a measure of the illuminance in the room. This proportionality factor is typically assumed to be constant. Color or color temperature measurements are not possible with such sensors due to the system.

When commissioning a corresponding look-down light control, the actual illuminance in the detection range of the light sensor is initially measured with the aid of a special measuring device, a so-called lux meter, and the lighting is adjusted so that the required light level is achieved. The control unit is calibrated or enabled in this way to assign an illuminance to the measured value of the sensor and to keep it constant at the desired value during later operation.

However, this procedure only leads to a satisfactory result permanently if the reflection factor in the detection range of the sensor remains permanently constant. This reflection factor indicates how much light is reflected from a surface onto the sensor and thus depends on the objects located in the detection area. For example, if the reflection factor changes due to the use of a new floor covering, new furniture, changes in work equipment at the desk and the like, the sensor's reading also changes without any actual change in illuminance. This leads to a malfunction of the system, as this tries to compensate for the supposed change in light.

To avoid this problem, novel sensor units have been proposed in which a pixel sensor or a camera sensor is used as the transducer. In principle, therefore, these are image sensors which determine digital image information of an area detected by the optics of the sensor. By means of suitable optics and appropriate evaluation algorithms, a variety of information regarding the space to be illuminated can then be obtained. On the one hand, of course, information regarding the currently present brightness can be obtained, on the other hand, the information can also be used to detect the presence of persons, so that such systems simultaneously also represent a presence or movement sensor. Such a multifunctional sensor is for example in the DE 10 2012 207 170 A1 the applicant described.

A problem of such intelligent sensors, however, concerns the still required start-up with the help of the measuring instrument described above, the lux meter for setting the required light level. In order to be able to obtain correct brightness information on the basis of the image information, this sensor must also be calibrated during commissioning, since in turn the reflection properties influence the image and brightness level detected by the image sensor. Furthermore, an accurate light color or light color temperature measurement is only possible if the sensor has been calibrated accordingly.

The present invention is therefore based on the object to provide a novel possibility in particular for calibrating a correspondingly intelligent sensor available, which is easy and quick to implement.

The object is achieved by a method for controlling, parameterizing and / or calibrating a sensor unit used for lighting control with the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims. Furthermore, the object is achieved by a sensor unit having the features of claim 10.

The solution according to the invention is fundamentally based on the knowledge that, when using a correspondingly intelligent sensor unit which is based on an image sensor for acquiring digital image information, calibration does not necessarily have to take place with the aid of a lux meter. Instead, the sensor unit can already be enabled to measure the light level and the light color absolutely and correctly if, at least in the context of a calibration, it looks at a reference object with known properties and then evaluates the corresponding image data.

• a) Bereitstellen eines Referenz- oder Steuerobjekts und Anordnen dieses Referenz- oder Steuerobjekts in einem von dem Bildsensor erfassten Bereich,
• b) erfassen von Bildinformationen, welche dass Referenz- oder Steuerobjekt enthalten und
• c) Auswerten der Bildinformationen durch den Controller und Ableiten von Steuer-, Parametrier- oder Kalibrierinformationen.

The present invention therefore proposes a method for controlling, parameterizing and / or calibrating a sensor unit used for illumination control, wherein the sensor unit has an image sensor for acquiring digital image information and a controller for evaluating the image information and creating a signal representing the illumination situation, and wherein the method comprises the following steps:

• a) providing a reference or control object and arranging this reference or control object in an area covered by the image sensor,
• b) capture image information containing the reference or control object and
• c) evaluating the image information by the controller and deriving control, parameterization or calibration information.

• • einen Bildsensor zum Erfassen von digitalen Bildinformationen sowie
• • einen Controller zum Auswerten der Bildinformationen und Erstellen eines das Tageslicht repräsentierenden Helligkeitssignals

aufweist,
wobei der Controller dazu ausgebildet ist, beim Auswerten der von dem Bildsensor erfassten Bildinformationen ein in dem von dem Bildsensor erfassten Bereich angeordnetes Referenz- oder Steuerobjekt zu erkennen und aus den zugehörigen Bildinformationen Steuer-, Parametrier- oder Kalibrierinformation abzuleiten. Further, the invention proposes a sensor unit for use in the lighting control, which

• • an image sensor for acquiring digital image information as well
• A controller for evaluating the image information and creating a brightness signal representing the daylight

having,
wherein the controller is designed to detect a reference or control object arranged in the region detected by the image sensor when evaluating the image information acquired by the image sensor and to derive control, parameterization or calibration information from the associated image information.

Ultimately, it is therefore provided that the intelligent sensor recognizes and detects an object within the area detected by it, whose reflection and optionally further optical properties are known to it. This in turn means that when evaluating the image information, the controller can take into account the influence of the reflection of the light reflected from the reference object and can accordingly deduce the originally measured brightness values from the originally measured brightness information. As a result, the system can work self-adjusting and a complex commissioning using a lux meter is no longer necessary.

Preferably, the reference object is designed as simple as possible and designed such that it can be used in a variety of ways. In the simplest embodiment, therefore, the reference object can represent a simple sheet of white paper, which fulfills certain properties with respect to the reflection factor and the color. White paper, which is used for example by default for copying, is within certain limits suitable for this purpose and could accordingly be readily used as a reference object for carrying out the method according to the invention.

In this case, the system is preferably embodied such that the controller automatically recognizes when evaluating the image information that a corresponding reference object, with the aid of which a calibration is to be performed, is located in the region detected by the sensor unit. According to a preferred embodiment of the invention, it is therefore provided that the reference object is identified in a corresponding manner, so that this is automatically detected when evaluating the image information. One possibility for this would be, for example, to give the reference object, for example the paper, a characteristic form which is recognized immediately. However, it is particularly preferably provided that the reference object is printed with a corresponding identifier, which is embodied for example in the form of a barcode, a so-called QR code or another machine-readable identifier. As already mentioned, this marking is designed in such a way that, on the one hand, the sensor unit is able to recognize it, and on the other hand, enough white surface remains to carry out the actual measurement. At the same time, the idea of printing the reference object has the advantage that the resulting contrasts in the image acquired by the sensor allow more accurate information, which is required for the calibration of the sensor unit, to be obtained.

A particular advantage of the solution according to the invention is that, as indicated above, a recalibration can be carried out at any time. This may be necessary if other conditions arise due to changes in the environment that may affect the result sensed by the sensor unit. In such a case, the reference object can now be introduced in a simple manner into the region detected by the sensor unit, thereby initiating the calibration. In this case, preferably It can be provided that an object is successively positioned several times at different locations within the area covered by the sensor unit. Alternatively, several reference objects could be arranged at the same time. In both cases, this leads to an increase in the information on the basis of which the calibration is carried out, so that overall a better result is achieved.

It should also be noted that the procedure according to the invention not only used to calibrate the sensor unit but also, for example, based on the same principle, a control of the sensor unit could be performed. For example, it would be conceivable for the sensor unit to have different operating modes and to be able to switch between these different operating modes. For this purpose, it can now be provided that, in turn, a corresponding control object, which is detected as part of the image evaluation, is positioned in the detection area of the image sensor. The corresponding control information, which then ultimately cause the sensor unit to assume a particular mode of operation, may be coded - again, for example, in the form of a bar code - or otherwise graphically encoded. Also in this case, it is then provided that the controller automatically recognizes this as part of the evaluation of the image information and generates and carries out a corresponding control information based thereon.

Finally, it is known, for example, from the Applicant's application described above that individual regions can be defined within the detected image region of the sensor, which are evaluated and their information then used for light control. It was originally proposed that such areas are defined, for example, in the context of a corresponding user interface, that is, the sensor unit communicates with, for example, a PC or another operating device, via which then a corresponding definition of such areas is made. Again, however, the concept of the present invention could also be used for such purposes. That is, a corresponding control object, which in turn can be a suitably printed sheet of paper in the simplest way, is positioned in the detection range of the sensor and thereby defines, for example, the center of a corresponding evaluation area, which is then considered separately when evaluating the image data. The corresponding control information must in turn be coded accordingly by the printing or shaping of the control object and can then define, for example, the extent of the area and / or its shape.

Ultimately, therefore, the concept according to the invention can be used in many ways in order to control or parameterize a sensor unit using an image sensor in a wide variety of ways. In particular, however, brings the solution of the invention advantages in terms of calibration of the sensor with it, since now consuming measures for commissioning can be omitted.

The invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 schematically the arrangement of a sensor unit according to the invention in a room to be illuminated and the use of reference objects for calibrating the sensor unit;

2 the construction of a sensor unit according to the present invention;

3a and 3b conceivable reference objects for calibrating the sensor unit according to the inventive method and

4 the use of the inventive concept for specifying certain evaluation areas in the image area detected by the sensor.

1 shows first generally the arrangement of the sensor unit according to the invention in a room to be illuminated. The with the reference number 10 designated sensor unit is usually on the ceiling of the generally by the reference numeral 100 arranged to be illuminated space arranged. It is used to control light sources, not shown, with the help of the space 100 to be illuminated. In particular, these light sources, for example, a job 101 light that on the surface of a desk 105 is trained. There are other objects in the room, such as shelves 106 and the same, which influence the lighting situation due to their reflection properties. Furthermore, daylight can enter the room through a window, not shown in detail.

The usual regulation or control of the light sources takes place in that by means of a sensor, here by means of sensor unit according to the invention 10 detects the lighting situation and in particular those on the table surface or the workplace 101 present brightness is determined. On the basis of this information, the light sources are then controlled in such a way that, for example, permanently during a work period at the workplace 101 a desired brightness is present, which allows a comfortable working.

Compared to a classic look-down light sensor, which is directly related to the workplace to be evaluated 101 is directed and outputs a single brightness signal, is the more complex configured sensor unit 10 able to obtain more diverse information regarding the lighting situation. The structure of this sensor unit 10 is schematic in 2 a central element of which is a pixel or image sensor 11 is that an optic 12 is assigned, with image sensor 11 and optics 12 collectively capture digital image information regarding the captured image area. As in 1 shown is the optics 12 Preferably carried out such that there is a very large viewing angle and accordingly ideally the entire space is detected.

The of the image sensor 11 recorded data are then first through a processing unit 13 prepared and then through another unit 14 evaluated. The units 13 and 14 if necessary can work together in a corresponding controller 15 the sensor unit 10 be integrated, which is ultimately responsible for the output of the illumination situation representative signal S. This signal S, which corresponds in principle to the brightness signal detected by a simple light sensor, can then be used for further illumination control. As already mentioned, however, offers the use of the image sensor 11 with subsequent image data processing significantly more diverse options to obtain information regarding the lighting situation. At the same time, the image data may be used to obtain information regarding the presence of persons and the like.

Also with this intelligent and multifunctional sensor unit 10 However, the problem is that of the image sensor 11 initially do not represent absolute brightness information but only represent luminance values. These values depend strongly on, for example, the light emitted by the artificial light sources from the various surfaces of the room 100 is reflected. Without knowledge of these reflection properties, it is thus not possible to obtain absolute brightness and, in particular, information regarding the color or color temperature of the light on the basis of the luminance values.

Whereas so far special lux meters have been used for calibrating brightness sensors, now comes a much easier to perform procedure for calibrating the sensor unit 10 for use. As schematically in 1 is shown, the method is based on the idea within the sensor unit 10 or the camera with the optics 12 captured image area reference objects 20 to arrange whose properties are known. In particular, the reflection and color properties of these reference objects 20 known.

In the illustrated embodiment come as reference objects 20 in a simple way sheets of white paper for use. For example, it may be plain copy paper whose reflection factor and color properties are known. It is assumed here that correspondingly white copy paper has approximately the same properties with regard to the above-mentioned parameters.

That of the image sensor 10 captured image with respect to these reference sheets of paper 20 So now is influenced by the known properties of the paper (reflection factor and color). That is, the luminance values with respect to the image data of these sheets 20 allow to obtain absolute brightness and color information. Since at least approximately can be assumed that the lighting situation in the vicinity of the reference sheets of paper 20 is identical, thus becomes the sensor 10 able to detect how far the light reflected on other surfaces of the image area is affected. However, this in turn makes it possible to determine the absolute brightness and possibly also the color or color temperature of the light during later operation of the system from the luminance values with respect to these areas. For the calibration, therefore, it is no longer necessary to use a separate measuring device which is connected to the sensor unit 10 must be coupled, so that the calibration can be performed easily and quickly by the consumer.

Ideally, the reference objects are the leaves 20 executed in such a way that the controller 15 the sensor unit 10 when evaluating the image data the sheets automatically recognize so reference objects and performs a calibration. In a simple way, this can be realized by the leaves 20 are marked in a special way and this identification is recognized during image evaluation. This could be done, for example, by the leaves having a certain characteristic shape.

In a particularly preferred manner, however, the leaves 20 printed with certain characteristic identifiers. Two examples of this are in 3a and 3b represented, wherein in the variant according to 3a a bar code 21 and in the variant according to FIG. 3b, a so-called QR code is used. The advantage of this approach is also that the reference objects can be recreated at any time by: simply reprinted. This also represents a particular advantage of the present invention, since the reference objects are available at any time and, accordingly, at any time a recalibration of the sensor unit 20 can be performed by the user himself. Of course, the reference objects are also extremely inexpensive and easy to manufacture.

Ideally - as in 1 shown - for calibration of the sensor unit 10 several leaves at the same time 20 in from the sensor unit 10 arranged area. As already mentioned, the calibration according to the invention is based on the idea of deriving calibration parameters for the entire image area, ie for each pixel of the acquired image data, on the basis of the measurements of the reference objects. It is advantageous if several reference objects are in the detection range of the camera, since then the calibration parameters can be interpolated between the reference objects and thereby the measurement signal is further improved. Of course, it would also be conceivable to successively position a reference object at different positions, but this approach is more complex and associated with a greater amount of time.

Ultimately, therefore, the procedure according to the invention offers numerous advantages over previously known calibration methods. Thus, in particular due to the known properties of the reference objects eliminates the adjustment of the sensor by means of a separate lux meter. Rather, the system operates according to the invention self-adjusting, that is, even with changes in the environment, it is possible to keep the illumination level constant. This can be ensured by the fact that either the reference objects remain permanently in the detection range of the camera or in the event that a change is made, a new calibration is performed, which can be done very quickly.

In addition, the solution according to the invention also makes it possible to determine the light color temperature or the light color temperature much more accurately than is the case with the algorithms for an image sensor commonly used in digital cameras. These algorithms implicitly assume the presence of white or gray objects in the image. If these are not available, the color temperature measurement is faulty. While white or gray objects are commonly found in typical office environments, color illumination can prevent automatic recognition of those objects unless the white objects are uniquely identifiable by the sensor, as provided for in the present invention. recognizable.

Finally, another advantage is, in particular, that the method according to the invention does not require a hardware-based expansion of the known multifunctional sensor units. Ultimately, only image processing and recognition of certain objects need to be implemented in software accordingly, but this does not result in any significant additional costs in terms of manufacturing the sensor unit.

It should be noted that although the inventive concept has been explained in particular based on the idea of calibration of the sensor unit, the invention is actually much more versatile.

Thus, by means of appropriate codes on the sheets of paper, commands of all kinds could be transmitted to the system. It would be conceivable, for example, for the printed codes to represent specific commands which on the one hand are used to control the sensor unit or even an illumination system coupled to the sensor unit. In this case, it is essential that the codes through the sensor unit 10 recognizable, the color of the paper or its reflective properties are less important in this case. However, the simplest way to create these control objects is to print sheets accordingly.

Another possibility to use the principle according to the invention is shown schematically in FIG 4 shown again, where again the off 1 known room 100 is shown. With the help of two control objects, however, now not the sensor unit 10 calibrated but parameterized instead.

For example, with the help of the illustrated sheet 30 which is in the middle of the table 105 is placed and printed with a corresponding coding, it will be clarified that the corresponding area represents a workstation, which represents a special evaluation area in the evaluation for the subsequent brightness control. A second sheet 31 however, is in the door area 107 of the room and serves, for example, to define an area by determining the presence or movement of persons by evaluating the image information. This makes it very easy to use the sensor unit 10 be configured to receive a variety of information for the brightness control during later operation.

The inventive concept thus represents a further development by which the use according to multifunctional sensor units is significantly simplified and made more comfortable.

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

• DE 102012207170 A1 [0006]

Claims (16)

Method for controlling, parameterizing and / or calibrating a sensor unit used for lighting control ( 10 ), wherein the sensor unit ( 10 ) • an image sensor ( 11 ) for capturing digital image information and • a controller ( 15 ) for evaluating the image information and producing a daylight-representing brightness signal (S), and wherein the method comprises the following steps: a) providing a reference or control object ( 20 . 30 ) and arranging this reference or control object ( 20 . 30 ) in one of the image sensor ( 11 b) acquiring image information which the reference or control object ( 20 . 30 ), c) evaluating the image information by the controller ( 15 ) and derivation of control, parameterization or calibration information. Method according to Claim 1, characterized in that the reference or control object ( 20 . 30 ) has known color and / or reflection properties and based on the image information with respect to the reference or control object ( 20 . 30 ) a calibration of the sensor unit ( 10 ) he follows. Method according to Claim 2, characterized in that the calibration is based on a plurality of reference or control objects (preferably simultaneously arranged in the region detected by the image sensor) ( 20 . 30 ) is carried out. Method according to one of the preceding claims, characterized in that the reference or control object ( 20 . 30 ) has a shape characterizing a control command or surface property. A method according to claim 4, characterized in that the control command a setting of an operating parameter of the sensor unit ( 10 ) causes, for example, the selection of an operating mode or the marking of a specific area to be evaluated. A method according to claim 4, characterized in that the control command for driving with the sensor unit ( 10 ) connected bulbs serves. Method according to one of the preceding claims, characterized in that it is in the reference or control object ( 20 . 30 ) is a sheet of paper. A method according to claim 7, characterized in that the paper has a printing, by which it is coded as a reference object and / or control information. A method according to claim 8, characterized in that the printing is a bar code or a QR code. Sensor unit ( 10 ) for use in the lighting control, which • an image sensor ( 11 ) for capturing digital image information and • a controller ( 15 ) for evaluating the image information and creating a daylight-representing brightness signal (S), wherein the controller ( 15 ) is adapted to, when evaluating the image sensor ( 11 ) captured image information in the image sensor ( 11 ) Detected area arranged reference or control object and derive control, parameterization or calibration information from the associated image information. Sensor unit according to claim 10, characterized in that the reference or control object ( 20 . 30 ) has known color and / or reflection properties and the controller ( 15 ) is designed on the basis of the image information with respect to the reference or control object ( 20 . 30 ) a calibration of the sensor unit ( 10 ). Sensor unit according to claim 11, characterized in that the controller ( 15 ) is designed to calibrate on the basis of a plurality of reference or control objects (preferably simultaneously arranged in the area covered by the image sensor) ( 20 . 30 ). Sensor unit according to one of claims 10 to 12, characterized in that the controller ( 15 ) is designed on the basis of a shape or surface property of the reference or control object ( 20 . 30 ) generate a control command. Sensor unit according to one of claims 10 to 13, characterized in that it is in the reference or control object ( 20 . 30 ) is a sheet of paper. Sensor unit according to claim 14, characterized in that the paper has a printing, by which it is coded as a reference object and / or a control information. Sensor unit according to claim 15, characterized in that the printing is a bar code or a QR code.

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