DE102022102056A1 - Level measurement system and method for determining a level - Google Patents

Abstract

The invention relates to a fill level measuring device (40), a fill level measuring system (10) and a method for determining the fill level of a filling material (28) in a container (20). The fill level measuring system (10) has the container (20), wherein at least a first wall (22) of the container (20) has a multiplicity of retroreflectors (30), and a fill level measuring device (40). The procedure has the following steps:
placing a plurality of retroreflectors (30) on a first wall (22) of the container (20);
placing a sensor (42) on a second wall (24) of the container (20), the second wall (24) being disposed substantially opposite the first wall (22);
sending a signal (45) to a first subset (32) of the plurality of retroreflectors (30);
receiving the reflected signal (47) from a second subset (34) of retroreflectors (30), the second subset (34) consisting of the retroreflectors (30) of the first subset (32) returning the reflected signal (47); and
determining the fill level as a function of the first subset (32) of retroreflectors (30) and the second subset (32) of retroreflectors (30).

Description

field of invention

The invention relates to a filling level measuring system and a method for determining the filling level of a filling material in a container. Furthermore, the invention relates to a program element, a computer-readable medium and a use.

background

In at least some types of containers, determining a fill level can be difficult. Examples include a building rubble depot or containers in a recycling center, e.g. for cardboard boxes or bulky waste, or garbage containers. The filling material can be arranged in a very unstructured manner in these containers, so measuring methods such as filling level measurement or averaging a topology measurement can be complex.

Summary

It is the object of the invention to provide a device and a method which at least partially overcome the disadvantages of the prior art. This object is solved by the subject matter of the independent patent claims. Further developments of the invention result from the dependent claims and the following description.

• anordnen einer Vielzahl von Retroreflektoren an einer ersten Wand des Behälters; anordnen eines schwenkbaren Sensors an einer zweiten Wand oder einem Reflektorträger des Behälters, wobei die zweite Wand im Wesentlichen gegenüber der ersten Wand angeordnet ist;
• senden eines Signals an eine erste Untermenge aus der Vielzahl von Retroreflektoren; empfangen des reflektierten Signals von einer zweiten Untermenge von Retroreflektoren, wobei die zweite Untermenge aus den Retroreflektoren der ersten Untermenge besteht, die das reflektierte Signal zurücksenden; und
• bestimmen des Füllstands als eine Funktion der ersten Untermenge von Retroreflektoren und der zweiten Untermenge von Retroreflektoren.

One aspect relates to a method for determining a filling level of a filling material in a container using a filling level measuring system as described above and/or below, with the steps:

• placing a plurality of retroreflectors on a first wall of the container; arranging a pivotable sensor on a second wall or a reflector support of the container, the second wall being arranged substantially opposite the first wall;
• sending a signal to a first subset of the plurality of retroreflectors; receiving the reflected signal from a second subset of retroreflectors, the second subset consisting of the retroreflectors of the first subset returning the reflected signal; and
• determining the fill level as a function of the first subset of retroreflectors and the second subset of retroreflectors.

The method can be carried out, for example, using a fill level measuring device with a sensor and a large number of retroreflectors, the retroreflectors being matched to the sensor. For example, if radar waves are used in or by the sensor of the level gauge, the dimensions of the retroreflectors can be larger than for a sensor using light. The retroreflectors can be arranged in a container, in particular in or on a wall of the container. The retroreflectors ensure that a defined echo is created from the first wall for every possible beam angle of the sensor. The container can be, for example, a building rubble depot (with walls) or a container in a recycling center, e.g. for cardboard boxes or bulky waste, or also a garbage container, a garbage can or a silo of any shape.

The level gauge, or at least the sensor of the level gauge, can be arranged on a second wall of the container, essentially opposite the first wall. In at least some embodiments, the sensor may be pivotable. The fill level measuring device, or the sensor, can be arranged on the second wall at an angle, i.e. with a radiation angle, for example between 0° and 75°, in particular between 15° and 45° to the horizontal. The purpose of these aspects of the arrangement is that the sensor can send the signal to as many of the retroreflectors as possible within its signal transmission range—in the case of a pivotable sensor: within its pivoting range. Accordingly, the signal emission area can extend in the vertical direction from the bottom of the container—or also starting from a higher level—to an upper edge and/or a “maximum marking” of the container. The signal transmission range can be selected so wide in the horizontal direction that a certain "statistical averaging" can be achieved; i.e. the horizontal signal emission range should not be chosen so narrowly that a single object can cover (“shadow”) all retroreflectors at a certain height.

The retroreflectors that can be reached through the swivel range form the first subset. The first subset need not necessarily include all retroreflectors. The first subset can be determined by a first measurement or "calibration measurement", eg always after the container has been emptied. When the container is empty, the pivotable sensor can transmit the signal to all retroreflectors of the first subset and receive the reflected signal from all retroreflectors of the first subset. If the container is at least partially filled, then the pivotable sensor can send the signal in the directions of all retroreflectors of the first subset; In this case, however, some of the retroreflectors are covered by the filling material, so that not all of the retroreflectors in the first subset can send back the signal. Those retroreflectors that return the reflected signal form the second subset of retroreflectors. The filling level of the filling material in the container can then be determined as a function of the first subset and a second subset of retroreflectors. A simple example of such a function is, for example, a quotient of the number of retroreflectors in the first subset and the number of retroreflectors in the second subset. The function can be calculated in the evaluation unit. The evaluation unit can be arranged in the filling level measuring device, in particular the evaluation unit can be arranged in a common housing with the sensor.

With this device, not only can the determination of a filling level be greatly simplified, but the sensor and/or the evaluation unit can also be simplified compared to devices from the prior art. For example, when using a radar sensor, there is no need to determine the entire envelope curve for each point in space from the sensor to the container wall and beyond, just to ensure that the level echo is within the measuring range. In addition, materials that reflect poorly - such as paper, plastics, organic material such as leaves, etc. - no longer pose a problem, but rather help the efficiency of the measurement precisely because they do not return a reflected signal as clearly as one of the retroreflectors. This simplified evaluation of the sensor data and (e.g.) the simple formation of the quotient can also lead to a simplification of the evaluation unit and thereby contribute to reducing the energy requirement of the fill level measuring device.

In some embodiments, the function includes a quotient, in particular a weighted quotient, of the number of the first subset to the second subset of retroreflectors. It should be noted that the "number" of elements in a set is also called the cardinality of the set.

A simple determination of the fill level could then be carried out as follows: Assume K ₁ = 5 * 4 = 20 (5 elements wide, 4 elements high) as the cardinality of the first subset and K ₂ = 8 as the cardinality of the second subset, then the fill level results Q: $$\text{f}=1-\left({\text{K}}_2/{\text{K}}_1\right)=100\%-\left(\mathrm{8th}/20\right)=60\%$$

An alternative level measuring system, which is only set up to determine a limit level, could only have retroreflectors arranged at a certain height—the height of the limit level. Accordingly, the signal transmission range or pivoting range can be limited to only horizontal transmission or pivoting for such a “limit level measuring system”.

If retroreflectors are placed starting from a higher level than the bottom of the vessel, then the level calculation may be modified. If, as a modification of the above example, the lower row of retroreflectors is omitted (ie K ₁ = 5 * 3 = 15), then the level F can be calculated with an offset "off", for example as follows: $$\text{f}=1-\left({\text{K}}_{\text{2}}/\left({\text{<figure-callout id="1" label="K" filenames="DE102022102056A1\_0007.png" state="{{state}}">K</figure-callout>}}_{\text{1}}+\text{off}\right)\right)+\left({\text{K}}_{\text{2}}/\text{off}\right)$$

In some embodiments, the function is a weighted quotient of the signal intensity of the reflected signals from the first subset to the signal intensity of the reflected signals from the second subset of retroreflectors. This can be realized, for example, by illuminating the first wall with light, for example, and measuring the reflected light. The level can then be determined from the weighted quotient of the reflected light to the emitted light.

In some embodiments, the pivotable sensor is located in an upper portion of the second wall of the container. The beam angle of the sensor or the fill level measuring device can be arranged, for example, at an oblique angle in or on the second wall, so that the beam angle of the device eg from the bottom of the empty container to the edge of the opposite first wall of the container. The oblique angle or beam angle can be, for example, between 0° and 75°, in particular between 15° and 45°, to the horizontal, for example approximately 10%, 20%, 30% or 45% of the horizontal.

In some embodiments, the pivotable sensor is located at a location approximately less than 20%, less than 10%, less than 5%, less than 2%, less than 1%, or equal to 0% below a top edge of the second wall of the container. If the type of container allows it, the pivotable sensor can also be arranged above the upper edge of the second wall of the container.

In some embodiments, the signal from the sensor is sent using radar waves and/or using light. For example, the radar waves can be sent in a frequency range from 60 GHz to 300 GHz. The radar sensor can, for example, use a continuous signal, pulses or an FMCW principle (FMCW: frequency modulated continuous wave radar). This can be realized, for example, by only evaluating the envelope curve of the echo in the area of the wall where - e.g. during a first measurement - a retroreflector was detected. An advantage of using radar waves can be that the measurements are not very sensitive to pollution, especially when longer wavelengths are used.

For example, when using light, one or more frequencies between infrared and ultraviolet can be used. For example, the light can be sent continuously or in a pulsed manner. An advantage of using light can be a more cost-effective design of the retroreflectors and/or easier washability, especially if a film assumes the function of the retroreflectors.

Alternatively or additionally, a camera can be used. The number of measuring points will be determined e.g. by the number of pixels. The detection of whether the first wall is visible or not can be done - instead of by the retroreflectors - by a pattern on the wall (e.g. a grid) or by color coding (e.g. red-green checkered). In this embodiment, the fill level can be determined, for example, as a function of the number of visible and detected red squares.

In some embodiments, the sensor is designed as a mechanically and/or electronically pivotable sensor. Mechanical swiveling can be implemented using a motor, for example. Electronic swiveling can be implemented, for example, by means of "beam forming" (in the case of radar). Mechanical and/or electronic swiveling can be implemented, for example, using lighting systems such as those used in newer vehicles.

• einen schwenkbaren Sensor, der in dem Behälter an einer zweiten Wand angeordnet ist, wobei die zweite Wand im Wesentlichen gegenüber der ersten Wand angeordnet ist, und der dazu eingerichtet ist, ein Signal an eine erste Untermenge aus der Vielzahl von Retroreflektoren zu senden und ein reflektiertes Signal von der ersten Untermenge der Retroreflektoren zu empfangen; und
• eine Auswerteeinheit, welche dazu eingerichtet ist, den Füllstand zu bestimmen als eine Funktion der ersten Untermenge von Retroreflektoren und einer zweiten Untermenge von Retroreflektoren, wobei die zweite Untermenge aus den Retroreflektoren der ersten Untermenge besteht, die das reflektierte Signal zurücksenden.

One aspect relates to a fill-level measuring device that is set up to carry out at least parts of the method according to one of the preceding claims, the fill-level measuring device being based on:

• a pivotable sensor disposed in the container on a second wall, the second wall being disposed substantially opposite the first wall and configured to transmit a signal to a first subset of the plurality of retroreflectors and a reflected one receive signal from the first subset of retroreflectors; and
• an evaluation unit configured to determine the filling level as a function of the first subset of retroreflectors and a second subset of retroreflectors, the second subset consisting of the retroreflectors of the first subset that return the reflected signal.

In some embodiments, the fill level measuring device is designed as an autonomous field device. Such a self-sufficient field device can have a battery, a solar module and/or an accumulator, for example, and it can support wireless communication protocols. In at least some cases, low power consumption can be essential for the self-sufficient field device; this is also supported in the level measurement system described here.

One aspect relates to a filling level measuring system for determining a filling level of a filling material in a container. The filling level measuring system has the container, wherein at least a first wall of the container has a multiplicity of retroreflectors, and a filling level measuring device as described above and/or below. The retroreflectors can have a design that is matched to the filling level measuring device, in particular to its sensor system. If, for example, radar waves are used in the sensor of the level measuring device, the dimensions of the retroreflectors can be larger than in the case of a sensor that uses light. The sensor can, for example, be a high-frequency front end, in particular a radar sensor, an ultrasonic front end, a LiDAR or a laser front end. The number of retroreflectors can depend, for example, on the size of the container, on the type of filling material and/or on other factors. The retroreflectors can be designed, for example, as triple mirrors, as triple prisms or as lens-like designs. The retroreflectors ensure that a defined echo is created from the first wall for every possible beam angle of the sensor. The container can be, for example, a building rubble depot (with walls) or a container in a recycling center, for example for cardboard boxes or bulky waste, or a garbage container, a garbage can or a silo of any shape.

One aspect relates to the use of a filling level measuring system as described above and/or below to determine a filling level of a filling material in a container.

One aspect relates to a multiplicity of retroreflectors, which are designed to be arranged on at least a first wall of a container, the retroreflectors being matched to a sensor of a level measuring device as described above and/or below.

One aspect relates to a container having a multiplicity of retroreflectors as described above and/or below.

One aspect relates to a program element which, when it is executed on an evaluation unit of a filling level measuring device and/or on another processing unit, instructs the evaluation unit and/or the processing unit to carry out the method as described above and/or below.

One aspect relates to a computer-readable medium on which the program element described herein is stored.

It should also be noted that the various embodiments described above and/or below can be combined with one another.

For further clarification, the invention is described using the embodiments shown in the figures. These embodiments are meant to be exemplary only and not limiting.

character list

• 1 schematisch ein Füllstandmesssystem gemäß einer Ausführungsform;
• 2 schematisch ein Füllstandmessgerät gemäß einer Ausführungsform;
• 3 schematisch ein Füllstandmesssystem gemäß einer weiteren Ausführungsform;
• 4 schematisch ein Füllstandmesssystem gemäß einer weiteren Ausführungsform;
• 5a bis 5c schematisch eine Behälterwand gemäß einer weiteren Ausführungsform;
• 6 ein Flussdiagramm mit einem Verfahren gemäß einer Ausführungsform.

It shows:

• 1 schematically a level measurement system according to an embodiment;
• 2 schematically a fill level measuring device according to an embodiment;
• 3 schematically a level measurement system according to a further embodiment;
• 4 schematically a level measurement system according to a further embodiment;
• 5a until 5c schematically a container wall according to a further embodiment;
• 6 FIG. 12 is a flowchart showing a method according to an embodiment.

Detailed Description of Embodiments

1 12 schematically shows a fill level measurement system 10 according to an embodiment. The fill level measuring system 10 has a container 20 with a first wall 22 and a second wall 24. A plurality of retroreflectors 30 are arranged on the first wall 22 (not shown). On the second wall 24 of the container 20 in an upper region 26, in the vicinity of the upper edge 25, a filling level measuring device 40 is arranged, which has a mechanically and/or electronically pivotable sensor 42. The sensor 42 sends a signal 45 to the opposite first wall 22, in particular to the retroreflectors 30 arranged there. A reflected signal 47 is sent back from these retroreflectors 30 and received by the sensor 42. The container 20 has a filling material 28 in a lower region. If the signal 45 swings down and is reflected by the product 28, then the signal reflected from it is significantly less than the reflected signal 47 from the retroreflectors 30. Signals below a predefined signal strength can therefore be ignored and do not count as a "reflected signal 47 “, which is “positively relevant” for determining the fill level.

2 12 schematically shows a fill level measuring device 40 according to an embodiment. The fill level measuring device 40 has a sensor 42 with a transmitter 44 which is set up to transmit a signal 45 and a receiver 46 which is set up for receiving a reflected signal 47 . The transmitter 44 and the receiver 46 can (in an exemplary embodiment that is not shown here) have a common front end, for example if the sensor 42 is designed as a radar sensor, the transmitter 44 and the receiver 46 can have a common antenna (horn antenna, flat antenna, etc.) use. The level measuring device 40 also has an evaluation unit 48 which is connected to the sensor 42 and which is set up to determine the level based on the measured values of the sensor 42. The evaluation unit 48 can be outsourced, for example to a server. The fill-level measuring device 40 can, particularly when it is designed as an autonomous field device, contain additional components, eg a battery, a rechargeable battery, a communication module that can support wireless and/or wired protocols, displays and/or other components.

3 FIG. 1 schematically shows a filling level measuring system 10 according to a further embodiment. The fill level measuring system 10 has a container 20 and a sensor 42 which is arranged obliquely in an upper region 26, in the vicinity of the upper edge 25, of the second wall 24 of the container 20. In the exemplary embodiment shown, the sensor 42 is designed as a radar sensor. The sensor 42 emits a signal 45 in the direction of a first wall 22 . Retroreflectors 30 are arranged on and/or in the first wall 22 and send the signal 45 back to the sensor 42 as a reflected signal 47. The pivoting of the sensor 42 is shown as a multiplicity of signals 45 and reflected signals 47. If one of the signals 45 hits a filling material 28, it is not reflected or is reflected so weakly that it is not evaluated by the sensor 42 as a “reflected signal 47”.

A lower part of 3 shows echoes E1 - E5, as a function of an amplitude A over a distance d. It becomes clear that the echoes E1 - E3 are within a distance range that was determined, for example, by a first measurement with an empty container 20 . The determined distance range is represented by a rectangle. The echoes E4 and E5, which were reflected by the filling material 28, are outside the determined distance range. When using a radar sensor that can determine distances - for example an FMCW or a pulse sensor - this can be used to check the "reflected signal 47" for plausibility or to exclude non-evaluated reflected signals.

4 FIG. 1 schematically shows a filling level measuring system 10 according to a further embodiment. Same reference numerals as in 3 show the same or similar components. In 3 the container 20 and the fill level measuring device 40 with the sensor 42 are shown in a view from above. Here, the sensor 42 performs a horizontal pan, for example via an upper row of retroreflectors 30, so that a large number of signals 45 are sent back as reflected signals 47.

The lower part of 4 shows that all reflected signals 47 can be checked for plausibility because all echoes E1 - E6 are within a distance range that was determined, for example, by a first measurement on the empty container 20 .

5a until 5c 12 schematically show a first container wall 22 according to a further embodiment. The first container wall 22 has a plurality of retroreflectors 30 which (in 5a and 5b ) are arranged in four horizontal and five vertical rows.

5a shows a situation with an empty container 20. In the embodiment shown, a signal 45 can be sent to all retroreflectors 30. The 4×5 retroreflectors 30 shown thus form a first subset 32 of the retroreflectors 30 (K ₁ =20). Furthermore, when the container 20 is empty, all of the 4×5 retroreflectors 30 shown send back a reflected signal 47 as a second subset 34 (K ₂ =20). As expected, the fill level F is: $$\text{f}=1-\left({\text{K}}_{\text{2}}/{\text{K}}_{\text{1}}\right)=100\%-\left(20/20\right)=0\%$$

It should be noted that the first subset 32 need not include all of the retroreflectors 30 present. If fewer vertical rows of retroreflectors 30 are detected - e.g. only four instead of five rows - then the first subset 32 can include fewer retroreflectors 30, in this case 4×4. If fewer horizontal rows are detected, an offset can be expected; see the example below.

5b shows a situation with a container 20 in which a (very unstructured) filling 28 is arranged. In 5b only an upper boundary line of the filling material 28 is shown. The filling material 28 thus "shadows" part of the retroreflectors 30, ie only the retroreflectors 30 of a second subset 34 with a cardinality K ₂ =8 send back a reflected signal 47 (K ₂ =8); the retroreflectors 30 marked with an "X" do not return a reflected signal 47. This results in the filling level F: $$\text{f}=1-\left({\text{K}}_{\text{2}}/{\text{K}}_{\text{1}}\right)=100\%-\left(\mathrm{8th}/20\right)=60\%$$

Out of 5b It also becomes clear that in at least some embodiments a signal discriminator can be used: For example, the first retroreflector of the second row is only slightly "shadowed" by the filling material 28 and its reflected signal 47 is detected, while the second and fourth retroreflectors the second row is more “shadowed” by the filling material 28, so that its reflected signal is not recognized as part of the second subset 34.

An embodiment in which the first container wall 22 is not equipped with retroreflectors 30 up to a bottom of the container 20 is in 5c shown. In this case, an offset (off = 5) can be expected. Accordingly, the filling level F results in: $$\text{f}=1-\left({\text{K}}_2/\left({\text{<figure-callout id="1" label="K" filenames="DE102022102056A1\_0007.png" state="{{state}}">K</figure-callout>}}_{\text{1}}+\text{off}\right)\right)+\left({\text{K}}_{\text{2}}/\text{off}\right)=100\%-\left(\mathrm{8th}/\left(15+5\right)\right)+\left(20/5\right)=60\%$$

This example also makes it clear that a fill level of less than 25% with an arrangement of 5c can no longer be recognized.

6 shows a flow chart 100 with a method for determining a filling level of a filling material 28 in a container 20 by means of a filling level measuring system 10 as described above and/or below. In a step 102 a multiplicity of retroreflectors 30 are arranged on a first wall 22 of the container 20 . In a step 104 , a pivotable sensor 42 is placed on a second wall 24 of the container 20 , the second wall 24 being placed substantially opposite the first wall 22 . In a step 106 a signal 45 is sent to a first subset 32 of the plurality of retroreflectors 30 . In a step 108, the reflected signal 47 is received by a second subset 34 of retroreflectors 30, the second subset 34 consisting of the retroreflectors 30 of the first subset 32, which send the reflected signal 47 back. In a step 110 the fill level is determined as a function of the first subset 32 of retroreflectors 30 and the second subset 32 of retroreflectors 30 . In many cases, steps 106 - 110 can be carried out several times.

Reference List

10

level measurement system

20

container

22

first container wall

24

second container wall

25

Top edge of the second container wall

26

upper area of the second container wall

28

contents

30

retroreflectors

32

first subset of retroreflectors

34

second subset of retroreflectors

40

level gauge

42

sensor

44

Channel

45

signal

46

Recipient

47

reflected signal

48

evaluation unit

100

flow chart

102 - 110

steps

Claims (15)

Method for determining the level of filling material (28) in a container (20), with the steps: placing a plurality of retroreflectors (30) on a first wall (22) of the container (20); arranging a sensor (42) on a second wall (24) or a reflector support of the container (20), the second wall (24) being arranged substantially opposite the first wall (22); sending a signal (45) to a first subset (32) of the plurality of retroreflectors (30); receiving the reflected signal (47) from a second subset (34) of retroreflectors (30), the second subset (34) consisting of the retroreflectors (30) of the first subset (32) returning the reflected signal (47); and determining the fill level as a function of the first subset (32) of retroreflectors (30) and the second subset (32) of retroreflectors (30). procedure after claim 1 , wherein the function is a quotient, in particular a weighted quotient, of the number of the first subset (32) to the second subset (34) of retroreflectors (30). procedure after claim 1 , wherein the function is a weighted quotient of the signal intensity of the reflected signals (47) from the first subset (32) to the signal intensity of the reflected signals (47) from the second subset (34) of retroreflectors (30). A method according to any one of the preceding claims, wherein the sensor (42) is located in an upper portion (26) of the second wall (24) of the container (20). procedure after claim 4 , wherein the sensor (42) at a point approximately less than 20%, less than 10%, less than 5%, less than 2%, less than 1%, or equal to 0% below an upper edge of the second wall (24) of the container (20) is arranged. Method according to one of the preceding claims, in which the signal (45) from the sensor (42) is transmitted by means of radar waves and/or by means of light. Method according to one of the preceding claims, in which the sensor (42) is designed as a mechanically and/or electronically pivotable sensor. Level measuring device (40) which is set up to carry out at least parts of the method according to one of the preceding claims, the level measuring device (40) having: a sensor (42) disposed within said container (20) on a second wall (24) or reflector support, said second wall (24) or reflector support being disposed substantially opposite said first wall (22), and said arranged to transmit a signal (45) to a first subset (32) of the plurality of retroreflectors (30) and to receive a reflected signal (47) from the first subset (32) of retroreflectors (30); and an evaluation unit (48) which is set up to determine the fill level as a function of the first subset (32) of retroreflectors (30) and a second subset (34) of retroreflectors (30), the second subset (34) from the retroreflectors (30) of the first subset (32) which return the reflected signal (47). Level gauge (40) after claim 8 , wherein the level gauge (40) is designed as a self-sufficient field device. Level measuring system (10) for determining a level of a filling (28) in a container (20), the level measuring system (10) having: the container (20), at least a first wall (22) of the container (20) having a plurality of retroreflectors (30); and a level gauge (40). claim 8 or 9 . Use of a level measurement system (10) according to claim 10 for determining the filling level of a filling material (28) in a container (20). A plurality of retroreflectors (30) set up for arrangement on at least one first wall (22) of a container (20), the retroreflectors (30) pointing to a sensor (42) of a level measuring device (40). claim 8 or 9 are matched. Container (20) having a plurality of retroreflectors (30). claim 12 . Program element, which, if it is on an evaluation unit (48) of a level measuring device (40). claim 8 or 9 and/or is executed on another processing unit, the evaluation unit (48) and/or the processing unit instructs the method according to one of Claims 1 until 7 to perform. Computer-readable medium on which a program element according to the preceding claim is stored.

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