Drag pointer for calculating a process measurement

Description

Field of the invention

[0001] The invention relates to process measurement technology. In particular, the invention relates to a trailing pointer configured to calculate a process measurement variable, a measuring device having such a trailing pointer, a measuring device-external display and / or evaluation unit comprising such a trailing pointer, a method for calculating a process measurement variable, a program element, and a computer-readable medium. Technical background

[0002] In modern process measurement technology, and especially when using standalone, wireless measuring devices, the power supply is often limited. Therefore, it is important to find a compromise between high measurement accuracy and the lowest possible energy consumption. For example, measurement accuracy can be increased by performing as many individual measurements as possible, although this is associated with relatively high energy consumption. On the other hand, energy consumption can be reduced by measuring less frequently.

[0003] EP 3 517 902 B1 describes a method for determining and displaying a remaining filling or emptying time of a container.

[0004] US 9,642,086 B1 describes a method and system for reducing power consumption in network-connected metering units using prediction.

[0005] US 2010 / 0141423 A1 describes a wireless sensor network and a corresponding data acquisition method. Summary of the invention

[0006] It is an object of the present invention to increase the accuracy in the output of values ​​of process measured variables.

[0007] This problem is solved by the features of the independent patent claims.

[0008] Further developments of the invention result from the dependent claims.

[0009] A first aspect of the invention relates to a measuring device-external display and evaluation unit according to claim 1, which is a mobile PC, a tablet, a smartphone, or a wearable device, and has a trailing pointer configured to calculate a process measurement variable. The trailing pointer is a control unit arranged outside the actual measuring device. For example, it can be arranged in a mobile phone or other user device.

[0010] The trailing pointer has a computing unit that is configured to approximately calculate a past temporal development of the value of the process measurement variable from process measurement data of a measuring device, as well as to calculate the current value of the process measurement variable from the past temporal (calculated) development.

[0011] The computing unit is configured to compare the calculated current value of the process measurement variable with a current value of the process measurement variable that can be traced back to current process measurement data. The computing unit is configured to instruct the measuring device to transmit process measurement data to an external receiver by means of energy-saving long-range communication or short-range communication if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable that can be traced back to the current process measurement data by more than a predetermined threshold. The computing unit is configured not to instruct the measuring device to transmit process measurement data to the external receiver if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable that can be traced back to the current process measurement data by less than a predetermined threshold.

[0012] The value of the process measurement variable can be, for example, a fill level, pressure, or flow rate. Process measurement data refers to the actual measurement data recorded by the measuring device, which is then converted into the value of the process measurement variable.

[0013] In other words, the computing unit is configured to approximately calculate the temporal development of the measured value (e.g., the fill level, pressure, or flow rate) from the measuring device's past process measurement data. This will typically result in a smooth, continuous temporal progression, rather than a stepped progression defined by individual measurement points. From this temporal progression, the computing unit can then calculate the current value of the process measurement variable. This is a prognosis, prediction, or estimation.

[0014] Approximately calculating the past temporal development of the value of a process variable involves, for example, recognizing a process variable pattern or trend. For example, the processing unit can detect that a fill level is rising continuously and linearly because the container is being filled at a constant rate. Likewise, it can detect when the container is being emptied continuously and at a constant rate. In this case, it will also generate a straight line, but this time with a negative slope.

[0015] According to the invention, the computing unit is configured to compare the calculated current value of the process measurement variable with a current value of the process measurement variable which is attributable to current process measurement data.

[0016] In other words, the computing unit compares the (theoretical, predicted) calculated measured value with an actually measured measured value.

[0017] According to the invention, the computing unit is configured to instruct the measuring device to transmit process measurement data to an external receiver if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable attributable to the current process measurement data by more than a predetermined threshold value.

[0018] The measuring device only transmits new, current process measurement data to the external receiver if the last measured value deviates significantly from the calculated value, i.e., if the trailing pointer is "out of control." This can occur, for example, if the container was initially filled and this filling process was then stopped. In this case, the trailing pointer would continue to move "upward," thus indicating that the fill level is continuing to rise. If a new measurement then reveals that this is not the case and the fill level is no longer changing, a new measured value (process measurement data) is transmitted to the external receiver.

[0019] According to the invention, the computing unit is configured not to instruct the measuring device to transmit process measurement data to the external receiver if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable attributable to the current process measurement data by less than the predetermined threshold value.

[0020] If it turns out that the drag indicator continues to provide a good forecast of the fill level, no new measured value is transmitted.

[0021] All this ensures that a measured value is only transmitted when it is also necessary to adjust the slave pointer. However, if the slave pointer continuously provides good estimates for the measured values, no new, current measured values ​​are transmitted.

[0022] According to a further embodiment, the approximate calculation of the past temporal development of the value of the process measurement variable comprises generating a mathematical or graphical description of the past temporal development. Such a description of the past temporal development makes it easy to make predictions for the future or estimate current measured values.

[0023] According to the invention, the trailing pointer is implemented in a user's terminal.

[0024] For example, the trailing pointer is configured to receive the process measurement data wirelessly from the measuring device.

[0025] According to a further embodiment, the process measurement variable is a fill level of a container or a volume of a filling material in a container. According to a further embodiment, the process measurement data is fill level measurement data from a level measuring device.

[0026] For example, a measuring device, for example a level measuring device, a point level sensor, a pressure measuring device or a flow measuring device, which has a drag pointer as described above and below.

[0027] According to a further aspect of the present invention according to claim 6, a measuring device and a measuring device-external display and / or evaluation unit are specified, which has a trailing pointer as described above and below.

[0028] A further aspect of the present invention relates to a method according to claim 7 for calculating a process measurement variable using a display and / or evaluation unit external to the measuring device, in which method a past temporal development of the value of the process measurement variable is first approximately calculated from process measurement data of a measuring device. Subsequently, the current value of the process measurement variable is calculated from the past, calculated temporal development. The calculated current value of the process measurement variable is compared with a current value of the process measurement variable that is attributable to current process measurement data.The method comprises a further step of instructing the measuring device, by means of energy-saving long-range communication or short-range communication, to transmit process measurement data to an external receiver if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable attributable to the current process measurement data by more than a predetermined threshold. The computing unit is configured not to instruct the measuring device to transmit process measurement data to an external receiver if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable attributable to the current process measurement data by less than a predetermined threshold.

[0029] A further aspect of the present invention relates to a program element according to claim 8 which, when executed on the computing unit of the above-described measuring device-external display and / or evaluation unit, instructs the computing unit to carry out the steps described above.

[0030] A further aspect of the present invention relates to a computer-readable medium according to claim 9, on which a program element as described above is stored.

[0031] Further embodiments of the present disclosure are described below with reference to the figures. Where the same reference numerals are used in the following description of the figures, they denote identical or similar elements. The representations in the figures are schematic and not to scale. Fig. 1 shows measurement intervals of two sensors. Fig. 2 shows measurement intervals of two sensors. Fig. 3 shows a temporal fill level curve. Fig. 4 shows level measurements for the Fig. 3 shown time course. Fig. 5 shows the temporal course of sensor measured values ​​as well as an approximately calculated temporal development of these measured values. Fig. 6 shows a measuring system according to an embodiment. Fig. 7 shows another representation of a measuring system. Fig. 8 shows a flowchart of a method according to an embodiment. Detailed description of embodiments

[0032] Fig. 1 shows a diagram showing the temporal progression of a fill level over a week. During the work week, Monday to Friday, the fill level decreases gradually and remains constant on Saturdays and Sundays.

[0033] Reference numeral 105 shows the time course of measurement intervals of a measuring device (sensor) without experience. The measurement intervals have a constant time interval, regardless of whether the fill level changes or not.

[0034] Reference numeral 106, on the other hand, shows the temporal distribution of measurement intervals of a self-learning sensor that has already gained experience. The self-learning sensor is intelligent enough to determine when the next measurement should be taken. Thus, it can save energy by foregoing measurements.

[0035] However, if the sensor does not measure a change in the measured value because the distance between adjacent measuring intervals has been increased, rapid level changes may sometimes only be detected late.

[0036] Fig. 2 shows a similar diagram as Fig. 1 , this time with regard to radio transmission. Reference numeral 107 again shows the actual fill level curve, and reference numeral 105 the measuring intervals. Reference numeral 106 shows the phases of transmission of the measured values ​​(radio transmission). The energy required for radio transmission of the measured values ​​is considerable and places a heavy strain on the energy of a self-sufficient sensor. The radio module can now be programmed so that it is activated for radio transmission depending on the measured values, for example, depending on changes in the measured value. This technology makes it possible to measure the fill level at regular intervals. However, the measured value is only transmitted to the cloud, for example, if there are significant changes.

[0037] Users who wish to remotely read the measured value will not receive any information about level changes during periods when no measurement is being taken or when no wireless transmission is taking place. As a result, there may be a significant discrepancy between the externally displayed level and the actual level.

[0038] Fig. 3 und 4 are intended to show how the measured value can be stored in stages in the cloud or on another measuring device or external storage.

[0039] Fig. 3 This shows the actual course of the fill level over time. The fill level initially rises linearly and then falls again. Then it rises linearly again.

[0040] Fig. 4 Shows the recorded measured values ​​that can be transmitted from the measuring device to the cloud. Since these measured values ​​are only recorded at specific times, the level measurement curve has a stepped progression. Since the measured value is displayed to the user directly from the cloud, the user also receives it in steps, with the corresponding deviation from the actual value. This deviation can only be reduced by increasing the measurement rate or increasing the wireless transmission rate.

[0041] However, the deviation can also be reduced by storing data in the measuring device, in the central storage (cloud) or, according to the invention,

[0042] A level pattern or trend is detected in the user's terminal device. Such a level pattern can, for example, be a specific gradient of a measurement curve (even an unchanged measured value contains a gradient of 0). The external processing unit in the central memory promptly follows the detected level pattern (process measurement pattern or trend), thereby increasing the accuracy of the display for the user.

[0043] With this method it is possible to reduce the radio rate while still increasing the displayed measurement accuracy.

[0044] This makes it possible to save sensor energy by reducing the wireless transmission rate without causing a significant difference between the displayed measured value and the actual fill level. In particular, the measuring device can be configured to only transmit measurement data when the value of the process variable exceeds the tolerance, i.e., deviates too far from the predicted value ("calculated current value of the process variable").

[0045] The trailing pointer features an intelligent measured value memory that uses past historical data to predict or extrapolate the measured value as accurately as possible to the current point in time based on the previous fill level pattern and / or time (time of day / day of week) and / or weather data. For example, a typical measured value history for a given time of day is displayed in the cloud. The display follows a trailing pointer in the cloud, which has learned how the history might develop from historical data. To save energy from, for example, battery-operated sensors, a measured value is only transmitted from the sensor if the measured value deviates significantly from the expected value.

[0046] The sensor transmits the measured values ​​via a radio connection as soon as the measured value is outside a tolerance band.

[0047] This shows Fig. 5 a measured value curve as determined in the measuring device. The sensor creates a curve through the measuring points (in this case a jagged curve, since the measured values ​​do not lie on a common straight line) and averages the measured values ​​accordingly (see dashed curve). A tolerance band is applied to this average. If a measured value deviates so far from the average that a predetermined tolerance range of, for example, 1% or 5%, or 10 to 25% in non-critical systems, is exceeded, a radio transmission of the measured value to the cloud is initiated. In one example, the cloud is the VEGA Inventory System (VIS). Radio transmission refers to energy-saving long-range communication, such as LoRa or NB-IoT. Short-range communication, such as Bluetooth or WLAN, can also be used, particularly within an industrial site. Transmission can also take place via WirelessHART.

[0048] In the cloud, or, according to the invention, in a terminal device, the last received measured value is compared with the historical measurement data. The cloud, or, according to the invention, a terminal device, is able to recognize a pattern with this data and adjusts the averaging of the measured value and the associated measurement uncertainties. This is shown in the lower part of the Fig. 5 to see.

[0049] Using the predetermined fill level pattern, the cloud is now able to determine the future measured value curve and approximate it in the time between the last transmitted measured value and the next transmitted measured value. For example, a constant gradient in the measured value curve can be used as a characteristic value. It is also possible to use the time of day, the day of the week, a valve position or even weather data as characteristic values. Many characteristic values ​​are possible, although this is just a selection of the many possibilities. The tolerance range and measurement uncertainty can be specified by the manufacturer. However, it is also possible for these to be set by the customer. A self-learning setting is also possible, provided sufficient data is available.

[0050] In Fig. 6 a measuring system is shown which does not fall within the scope of the claims, which uses the method described above

[0051] implemented. In the lower part of the Fig. 6 the measurement curve of a level sensor is shown over time.

[0052] This level sensor operates autonomously and is therefore battery-operated, transmitting the measured values ​​wirelessly to a higher-level central computer. This higher-level central computer is shown in the image above and is configured like a cloud storage system with the appropriate intelligence and computing power. One example of such a cloud solution is the VIS.

[0053] Users can now access the data in the cloud using their display device. These display devices include central control systems (PLCs), field display devices such as the DIS 82, network-capable computers, as well as mobile PCs, tablets, smartphones, or wearables. The display devices are available in the Fig. 6 shown on the right.

[0054] The following describes the operation of the measuring system up to time T. The sensor monitors a river level. This river level remains constant over a long period of time. The sensor detects that the measured value is largely constant and does not exceed the tolerance threshold. The sensor therefore reduces the radio transmission frequency to conserve energy.

[0055] The cloud also detects that the fill level is changing according to a specific pattern, or the cloud receives this pattern from the sensor. The cloud thus updates the measured value from the last measured value at time (T-1) up to time (T) with the known pattern.

[0056] A user reading the measured value on the display device sees the approximate fill level at a time between (T-1) and T, along with the measurement accuracy, if any. The following describes the operation starting at time (T+1). In the example of river level monitoring, the water level suddenly rises sharply due to heavy rain. The sensor detects that the measured value is outside the tolerance range. It triggers the wireless module to transmit the measured value to the cloud.

[0057] With further measurements, the sensor attempts to recognize a new pattern and redefine the tolerance range in order to reduce the energy-intensive radio transmission again.

[0058] A new current measurement value arrives in the cloud at time (T+1). The cloud computer abandons the known pattern for calculating the mean and adjusts the new mean accordingly. When a new measurement value is received at time (T+2), the cloud computer attempts to recognize a new pattern and follows it until the next measurement value is transmitted.

[0059] The user receives an approximate estimate of the actual measured value until time T+1. From the moment the measured value exceeds the tolerance, the user may receive a warning message. From this time T+1, the display is also adjusted, and the user always receives the most accurate level values ​​possible with maximum energy savings.

[0060] Fig. 7 shows another representation of the measuring system. The measuring system comprises a measuring device 102 with a computing unit 104. This measuring device can communicate with the cloud 101. Furthermore, an external display and / or control device 103 is provided, which can also communicate with the cloud. The trailing pointer can be installed both in the measuring device 102 and in the cloud 101 or, according to the invention, in the user-side terminal 103.

[0061] Fig. 8shows a flowchart of a method according to one embodiment. In step 801, process measurement data is acquired by a measuring device. A computing unit, which can be located directly in the measuring device, in the cloud, or, according to the invention, in a user terminal, calculates process measurement variables from this acquired process measurement data and then calculates an approximation function from these process measurement variables, which results in a continuous curve in a graphical representation that approximates the measured values ​​in the form of an averaging (step 802). In step 803, a further measured value is then estimated from this by continuing this averaging over time. In other words, a current value of the process measurement variable is calculated (but not measured) from the past temporal development of the process measurement variable.

[0062] In step 804, this calculated theoretical value is compared with a current measured value, and a decision is made as to whether a new measured value needs to be transmitted or not. The former will be the case if the difference between the predicted measured value and the actual measured value exceeds a certain threshold, and vice versa.

[0063] This allows the frequency of the radio transmission to be reduced, which leads to significant energy savings.

[0064] Additionally, it should be noted that "comprising" and "having" do not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered limitations.

Claims

1. Measuring-device-external display and evaluation unit (103), which is a mobile PC, a tablet, a smartphone or a wearable, comprising a slave pointer (103), configured to calculate a process variable, comprising: a computing unit, configured to approximately calculate a past temporal progression of the value of the process variable from process measurement data of a measuring device (102); calculate the current value of the process variable from the past temporal progression; wherein the computing unit is further configured to compare the calculated current value of the process variable with a current value of the process variable derived from current process measurement data; wherein the computing unit is further configured to instruct the measuring device (102) to transmit process measurement data to an external receiver (101) via energy-efficient long-range communication or short-range communication when the calculated current value deviates from the current value derived from current process measurement data by more than a predetermined threshold value; wherein the computing unit is arranged not to instruct the measuring device (102) to transmit process measurement data to the external receiver (101) if the calculated current value of the process measurement variable deviates from the current value of the process measurement variable, which is attributable to the current process measurement data, by less than a predetermined threshold value; wherein the computing unit is further configured not to instruct the measuring device (102) to transmit process measurement data to the external receiver (101) when the calculated current value deviates from the current value derived from current process measurement data by less than the predetermined threshold value.

2. Measuring-device-external display and evaluation unit (103) according to claim 1, wherein the approximate calculation of the past temporal progression of the value of the process variable comprises detecting a process variable pattern or trend.

3. Measuring-device-external display and evaluation unit (103) according to one of the preceding claims, wherein the approximate calculation of the past temporal progression of the value of the process variable comprises generating a mathematical or graphical representation of the past temporal progression.

4. Measuring-device-external display and evaluation unit (103) according to one of the preceding claims, where the process variable is a fill level of a container or a volume of a filling material.

5. Measuring-device-external display and evaluation unit (103) according to one of the preceding claims, wherein the process measurement data are fill level measurement data of a fill level measuring device (102).

6. Measuring device (102), and a measuring-device-external display and / or evaluation unit (103) according to one of the preceding claims.

7. Method for calculating a process variable using a measuring-device-external display and / or evaluation unit according to one of claims 1 to 5, comprising the following steps: approximately calculating a past temporal progression of the value of the process variable from process measurement data of a measuring device; calculating the current value of the process variable from the past temporal progression; comparing the calculated current value of the process variable with a current value derived from current process measurement data; instructing the measuring device (102), via the computing unit and by means of energy-efficient long-range or short-range communication, to transmit process measurement data to an external receiver (101) when the calculated current value deviates from the value derived from current process measurement data by more than a predetermined threshold value; wherein the computing unit is configured not to instruct the measuring device (102) to transmit process measurement data to the external receiver (101) when the deviation is less than the predetermined threshold value.

8. Program element which, when executed on the computing unit of a measuring-device-external display and / or evaluation unit according to any one of claims 1 to 5, instructs the computing unit to perform the following steps: approximately calculating a past temporal progression of the value of the process variable from process measurement data of a measuring device; calculating the current value of the process variable from the past temporal progression; comparing the calculated current value of the process variable with a current value derived from current process measurement data; instructing the measuring device (102) to transmit process measurement data to an external receiver (101) when the calculated current value deviates from the value derived from current process measurement data by more than a predetermined threshold value; wherein the computing unit is configured not to instruct the measuring device (102) to transmit process measurement data to the external receiver (101) when the deviation is less than the predetermined threshold value.

9. Computer-readable medium on which a program element according to claim 8 is stored.