Level measuring device for determining the level or volume of filling material in a movable container

Abstract

A fill level measuring device configured for determining a fill level or volume of a filling material in a movable container, comprising a first sensor configured for a distance measurement, a second sensor configured for a position measurement or orientation measurement, and an evaluation unit configured to determine, by analyzing the position measurement or orientation measurement, whether the movable container has been moved since a previous fill level measurement, and to use, in a subsequent calculation of the fill level or volume from the distance measurement, a first calculation rule if the movable container has been moved since the previous measurement, and a second calculation rule if the movable container has never been moved since the previous measurement.

Description

TECHNICAL FIELD

[0001] The present invention relates to the determination of the level or volume of a filling material in a movable container. In particular, the invention relates to a level measuring device configured for determining the level or volume of a filling material in a movable container, the use of a level measuring device, a method for determining the level or volume of a filling material in a movable container, a program element and a computer readable medium. BACKGROUND

[0002] For determining the level or volume of a filling material in a movable container, a filling height can be measured using a level sensor. In addition to sensors which are immersed in the filling material, in particular non-contact measuring sensors are used. For this purpose, radar sensors, ultrasonic sensors or optical sensors can be used.

[0003] When calculating the filling volume of a granular bulk material, the topology of the filling material surface can be included in order to improve the accuracy of the measurement result. For this purpose, a sensor which scans the surface can be used in order to calculate the topology of the filling material surface therefrom.

[0004] Scanning the filling material surface increases the calculation effort and the energy consumption. However, in particular in the case of self-sufficient sensors, or in the case of sensors which are connected to a 4 to 20 mA two-wire cable, energy is a scarce good. Sensors of this type are also complex and expensive in terms of construction. SUMMARY

[0005] Against this background, it is an object of the present invention to provide good measurement results when determining the level or volume of a filling material in a movable container with less energy consumption or at lower costs.

[0006] A first aspect of the present invention relates to a level measuring device, in particular for process automation in an industrial environment, which is configured for determining the level or volume of a filling material in a movable container. The filling material can in particular be a bulk material. The level measuring device comprises a first sensor which is configured for distance measurement. Examples of such a first sensor are radar sensors, ultrasonic sensors or optical sensors which perform transit time measurements. The term "first sensor" is to be interpreted broadly.

[0007] A second sensor is provided, which is configured for a position measurement (i.e. for a heading or positioning measurement) or for an orientation measurement. Furthermore, an evaluation unit is provided, which is configured to determine, by analyzing the position measurement or the orientation measurement, whether the movable container has been moved since a previous filling level measurement. Furthermore, the evaluation unit is configured to use a first calculation rule in a subsequent calculation of the filling level or volume on the basis of a distance measurement, if the movable container has been moved since the previous measurement and if it is likely that further conditions are fulfilled. According to an embodiment, the further conditions are that the filling level or the distance has not changed by a predetermined first minimum since the previous measurement.

[0008] Furthermore, the evaluation unit is configured to use a second calculation rule, if the movable container has never been moved since the previous measurement.

[0009] In certain cases, the two calculation rules can be identical (see below). Usually, they are different.

[0010] In simple cases, the calculation rules are implemented in the form of a table, from which the respective result can be read. This saves calculation effort and thus energy. The calculation rules can be designed as a software component of the filling level sensor. For example, the first or the second calculation rule is a linearization rule in the form of a linearization table of the filling material, which determines the volume of the filling material depending on the filling level of the filling material in the container.

[0011] If the container has been moved since the previous measurement, it can be assumed that it has been loaded onto a transport device and thus tipped (inclined). If it is then re-erected for a subsequent measurement, the bulk material usually forms an inclined plane, the shape of which is taken into account in the first calculation rule.

[0012] If it is then filled in the erected state, this inclined plane will be converted into a stockpile cone. Conversely, if it is emptied (over a longer period of time), a discharge funnel can occur instead of an inclined plane. Accordingly, in the last two cases described above, a different calculation rule is used in the filling level or volume calculation, respectively. The order in which the calculation rules are used can be independent of the measurement results and the calculation rules can be used several times.

[0013] According to an embodiment, the evaluation unit is configured to use the first calculation rule in the calculation of the level or volume from the distance measurements only if the movable container has moved since the previous measurement and the level has not changed by a predetermined first minimum value. In this case, as mentioned previously, the surface of the bulk material is considered to form a sloping plane. According to a further embodiment, the evaluation unit is configured to use the second calculation rule in the calculation of the level or volume from the distance measurements if the movable container has moved since the previous measurement, but the level has increased or decreased by a first predetermined minimum value since the previous measurement.

[0014] In this case, for example, a stockpile cone or a discharge hopper can be considered to be formed.

[0015] According to a further embodiment of the application, the evaluation unit is configured to take into account whether the level has increased or decreased since the previous measurement when selecting the calculation rule. Depending on the extent of this increase or decrease of the level, a sloping plane, a discharge hopper, or, if the increase is rather small, still a sloping plane (possibly with a small cone or a small discharge hopper) can be considered, and the respective calculation rule corresponding to this case is selected.

[0016] At this point, it should again be noted that the level measurement device can use more than two such calculation rules. A simple example of this is calculation rules describing the following cases: sloping plane, discharge hopper, stockpile cone, or a mixture of sloping plane and stockpile cone, a mixture of sloping plane and discharge hopper, a mixture of flat filling plane and stockpile cone, a mixture of flat filling plane and discharge hopper, or even, in the simplest case, a flat, horizontally extending filling material surface.

[0017] According to a further embodiment, the first sensor and the second sensor are integrated in the level measurement device.

[0018] However, the second sensor can also be configured for position measurement and not be integrated in the level measurement device, but for example in the movable container. Alternatively, the position or location determination of the sensor can be achieved by mobile radio technology, for example in the sense of radio cell positioning via a mobile radio network.

[0019] In particular, the evaluation of the measurement data of the sensor can be carried out centrally on a server or in the cloud and not in the actual level measurement device.

[0020] According to a further embodiment of the application, the first sensor is a radar sensor, a sensor using guided microwaves, an ultrasonic sensor or a laser sensor or other optical sensor.

[0021] According to another embodiment, the filling material is a bulk material.

[0022] According to another embodiment, the second sensor is part of a radio network, for example a private W-Lan or LoRa network, or a public mobile radio network. The first sensor can also be part of such a radio network.

[0023] Another aspect of the application relates to a method for determining the level or volume of a filling material in a movable container. Typically, a distance measurement is made by the first sensor. Before, at the same time as or after this, a position measurement of the container is made, or an orientation measurement of the container or the first sensor is made. Next, the measurement data of the position measurement and / or the measurement data of the orientation measurement are analyzed in order to determine whether the movable container has moved since the previous level measurement. At the same time, it can be determined how much the level has changed since the previous measurement. If the movable container has moved since the previous measurement, a first calculation rule is used in the calculation of the level or volume from the distance measurement. If the movable container has moved since the previous measurement, possibly including the additional condition that the level has increased or decreased by a defined value, a second calculation rule is used in the calculation of the level or volume from the distance measurement.

[0024] In some cases, the two calculation rules are identical; but usually, they are different.

[0025] Another aspect of the application relates to a program element which, when executed on an evaluation unit of a level measuring device, instructs the evaluation unit to perform the above and below described method steps.

[0026] Another aspect of the application relates to a computer-readable medium having the above described program element stored thereon.

[0027] The term "process automation in an industrial environment" can be understood as a subfield of technology which encompasses all measures for operating machines and devices without human involvement. One goal of process automation is to automate the interaction of individual components of a plant in the chemical, food, pharmaceutical, petroleum, paper, cement, shipping or mining industry. For this purpose, a large number of sensors can be used which are particularly suitable for the specific requirements of the process industry, such as mechanical stability, insensitivity to contaminants, extreme temperatures, extreme pressures, etc. The measured values of these sensors are usually transmitted to a control room, in which process parameters such as filling level, limit level, flow, pressure or density can be monitored and settings of the entire plant can be changed manually or automatically.

[0028] One subfield of process automation in industrial environments relates to logistics automation. In the field of logistics automation, processes are automated within buildings or individual logistics installations by means of distance sensors and angle sensors. Typical applications are logistics automation systems for the baggage and cargo handling area of airports, the traffic monitoring area (toll systems), the trade area, parcel delivery or also the building security (access control) area. The common denominator of the examples listed previously is that in each case there is a need to combine presence detection with precise measurement of the size and position of objects. For this purpose, sensors based on the optical measurement principle by means of laser, LED, 2D camera or 3D camera can be used, which detect distances according to the time-of-flight principle (ToF).

[0029] Another subfield of process automation in industrial environments relates to factory / manufacturing automation. Examples of such applications can be found in many industries such as the automotive industry, the food industry, the pharmaceutical industry or the packaging industry in general. The aim of factory automation is to automate the production of goods by means of machines, production lines and / or robots, i.e. to operate without human intervention. The sensors used here and the specific requirements for measurement accuracy when detecting the position and size of objects are comparable to those in the logistics automation examples described above.

[0030] Further embodiments of the application will be explained below. The illustrations in the drawings are schematic and not to scale. Identical reference signs denote identical or similar elements in the following description of the figures. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A level measurement device according to a first embodiment is shown.

[0032] Figure 2 A level measurement device according to another embodiment is shown.

[0033] Figure 3 A level measurement device according to another embodiment is shown.

[0034] Figure 4 A flow chart of a method according to an embodiment is shown. DETAILED DESCRIPTION

[0035] Figure 1 A level measurement device 100 is shown, which is configured for determining the level or volume of a filling material 201 in a movable container 200. The movable container 200 comprises an outlet in the bottom, through which the filling material 201 can be discharged.

[0036] A level measurement device 104, which can perform a distance measurement (dashed line), is installed in the upper region of the movable container. The distance to the filling material surface 202 is measured by means of the distance measurement.

[0037] From Figure 1 It can be seen that, as a result of the container 200 being tilted and then re-erected, the filling material surface 202 forms a tilted plane.

[0038] Figure 2 A further embodiment is shown, in which a filling material surface 202 has formed a filling cone (Schüttkegel). The dashed line 203 shows the opposite case, in which a discharge funnel (Abzugstrichter) has formed. From Figure 2 It can be seen that the starting situation is Figure 1 a tilted plane, in which, after the movable container has been erected, the filling material is subsequently refilled (filling cone formation) or discharged (discharge funnel formation).

[0039] A so-called enterprise resource planning (ERP) system 107 is provided separately from the movable container, which communicates with the cloud-based system 106 in order to control the filling or emptying process and to evaluate the measurement data transmitted by the measurement device 104.

[0040] Figure 3 A further embodiment is shown, in which two evaluation units 103 are provided. The first evaluation unit 103 is integrated in the level measurement device 104 and is connected to the first sensor 101 and the second sensor 102. The measurement device can transmit measurement data to and receive parameterization data or control data from an external second evaluation unit 103 via a wireless interface 105. In particular, this external evaluation unit 103 can be integrated in the ERP system 107 or the cloud-based system 106.

[0041] In the application of movable bulk material silos and storage containers, there are different filling cone situations, which can depend on the respective transport situation of the silo / container. During transport (and when filling at the supplier), the silo / container is placed horizontally. It is then erected at the place of use. The bulk material is thus in a tilted plane in the container. During use, the silo / container is refilled in the upright state at the site. This results in a characteristic filling cone, which deviates completely from the state after the silo / container has been erected.

[0042] The linearization table can be stored, but this can lead to significant deviations from the actual situation in the case of very different filling cone situations.

[0043] According to an embodiment of the application, more than two linearization tables are stored, for example in the form of calculation rules, in order to thereby achieve a higher accuracy of the measured values. For this purpose, a level measuring device for distance measurement (for example radar, ultrasound, laser, etc.) comprises a position sensor which recognizes when the silo / container is tilted or stood upright for transport. In addition to the position sensor, it is also possible to use geographical data. By means of GPS or other satellite navigation systems, or by means of a cellular network, it can be determined whether the silo has been moved. If the position of the silo has changed, it can be assumed that the silo is being transported horizontally and, as a result, the corresponding linearization table is selected.

[0044] In Figure 1 embodiments, the movable container is transported horizontally during transport and rotated by 90° and stood upright at the site of use. As a result, a typical tilted plane of the bulk material in the silo is produced. The position sensor in the distance measurement recognizes the position change. As a result, linearization takes place using the appropriate linearization table (or calculation rule).

[0045] After the first emptying, the silo is refilled at the site. This can be seen in Figure 2 . By filling from above, a typical stockpile cone can be produced. The position sensor recognizes that the silo is not being emptied and the distance sensor recognizes that the level in the container has changed positively (rising). As a result, linearization now takes place using a second linearization table or calculation rule which is suitable for the stockpile cone.

[0046] There is also the case that the silo is transported with a lower level and subsequently refilled at the site after standing upright. As soon as the level measuring device recognizes that the level has risen by a certain percentage or a predetermined minimum value (i.e. a certain distance), the corresponding calculation rule is used.

[0047] Linearization can take place within the first sensor (distance measurement). As a further possibility, the pure distance value and the position of the sensor can be transmitted by wireless transmission to a cloud-based system, where linearization (calculation) and matching then take place (see Figure 3 ).

[0048] In the case of no position sensor and only location information (for example, geographical data), it is also possible to replicate in the cloud or in the sensor when the sensor detects the location data. If the movable container sends a new location, the movable container has been transported and the first calculation rule is used in order to calculate the level (or volume) from the distance value. If the distance value increases and the silo is located at the same location, the silo has been filled at the site and, as a result, the distance value is converted into a level or volume using the second calculation rule.

[0049] Since the position sensor integrated in the distance sensor provides additional information, a storage logic (evaluation circuit) can be provided so that always the calculation rule matching the actual situation is used. This ensures that the measurement value deviation is minimized by matching linearization.

[0050] Due to the additional information about the position, an evaluation circuit can be provided which always uses a calculation rule matching the actual situation. This ensures that the measurement value deviation is minimized by matching linearization.

[0051] By transmission to a cloud-based system, if the bulk material in the silo / container changes, in addition to the calculation rule matching the actual situation, also the bulk material density or medium type can be quickly and easily matched. Thus, also the free-flowing properties of different bulk materials can be taken into account.

[0052] Figure 4 A flow chart of a method according to an embodiment is shown. In step 401 a distance measurement is performed and in step 402 a position measurement and / or a location measurement is performed. Such a position and / or location measurement has already been performed before the distance measurement 401 and now in step 403 it is determined which calculation rule is to be used. This depends, among other factors, on whether the movable container has been tilted or moved since a previous measurement occurring before the measurement 401 or whether the level has changed significantly since the previous measurement. Then in step 404 the actual level or volume is calculated from the measurement data of the distance measurement 401 and the additional information about the position change and / or location change and possibly distance change since the previous measurement.

[0053] Further, it is to be noted that "comprising" and "including" do not exclude other elements or steps and the use of "a" or "an" does not exclude a plurality. Also, it is to be noted that a feature or step described with reference to one of the above exemplary embodiments can also be used with reference to another of the above exemplary embodiments. Reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

1. A level measuring device (100) which is configured for determining a level or volume of a filling material (201) in a movable container (200), comprising: a first sensor (101) which is configured for distance measurement; a second sensor (102) which is configured for position measurement or orientation measurement; an evaluation unit (103) which is configured to determine, by analyzing the position measurement or the orientation measurement, whether the movable container has moved since a previous level measurement; and to determine, in a subsequent calculation of the level or the volume from the distance measurement, whether the filling material forms a tilted plane if the movable container has moved since the previous measurement, and to use a first calculation rule, and to use a second calculation rule if the movable container has never moved since the previous measurement.

2. The level measuring device (100) according to claim 1, wherein the evaluation unit (103) is configured to use the first calculation rule in the calculation of the level or the volume from the distance measurement only if the movable container has moved since the previous measurement and the level or the distance has not changed by a predetermined first minimum value.

3. The level measuring device (100) according to claim 1, wherein, the evaluation unit (103) is configured to use the second calculation rule in the calculation of the level or the volume from the distance measurement if the movable container has moved since the previous measurement, but the level or the distance has increased or decreased by a first predetermined minimum value since the previous measurement.

4. The level measuring device (100) according to any one of claims 1 to 3, wherein the evaluation unit (103) is configured to consider whether the level or the distance has increased or decreased since the previous measurement when selecting one of the first calculation rule and the second calculation rule.

5. The level measuring device (100) according to any one of claims 1 to 3, wherein the first sensor (101) and the second sensor (102) are integrated in a level measuring apparatus (104).

6. The level measuring device (100) according to any one of claims 1 to 3, wherein the evaluation unit (103) is integrated in a level measuring apparatus (104).

7. The level measuring device (100) according to any one of claims 1 to 3, wherein the evaluation unit (103) is not integrated in a level measuring apparatus (104).

8. The level measuring device (100) according to any one of claims 1 to 3, wherein the first sensor (101) is a radar sensor, a sensor using a directed radar signal, an ultrasonic sensor, a laser sensor or a sensor using a time-of-flight measurement method.

9. The level measuring device (100) according to any one of claims 1 to 3, wherein the filling material is a bulk material.

10. The level measuring device (100) according to any one of claims 1 to 3, wherein The second sensor (102) is part of a radio network.

11. Use of a level measuring device (100) according to any one of claims 1 to 10 for determining a level or a volume of a filling material (201) in a movable container (200).

12. A method for determining a level or a volume of a filling material (201) in a movable container (200) by means of a level measuring device (100) according to any one of claims 1 to 10, comprising the following steps: performing a distance measurement; performing a position measurement or an orientation measurement; analyzing the position measurement or the orientation measurement in order to determine whether the movable container has moved since a previous level measurement; if the movable container has moved since the previous measurement, using a first calculation rule in a subsequent calculation of the level or the volume from the distance measurement; if the movable container has never moved since the previous measurement, using a second calculation rule in the calculation of the level or the volume from the distance measurement.

13. The method according to claim 12, wherein if the movable container has moved since the previous measurement and a certain event has occurred, using the second calculation rule.

14. The method according to claim 12, wherein if the movable container has moved since the previous measurement and a higher level than in the last measurement has occurred, using the second calculation rule.

15. A computer readable medium having stored thereon a program element where, The program element, when executed on an evaluation unit (103) of a level measuring device (100) according to any one of claims 1 to 10, instructs the evaluation unit to perform the following steps: if the movable container has moved since a previous measurement, using a first calculation rule in a calculation of the level or the volume from the distance measurement; if the movable container has never moved since the previous measurement, using a second calculation rule in the calculation of the level or the volume from the distance measurement.

Images