DE102023106317A1 - Field device with a first sensor and a second sensor - Google Patents

Abstract

Field device set up for process automation in industrial or private environments, with a first sensor for level detection and a second sensor for vibration or acceleration detection of the container. A control unit calculates the level of the medium from the detected vibration/acceleration, or a density/mass of the medium from the detected level, limit level or pressure and the detected vibration/acceleration.

Description

Field of the invention

The invention relates to field devices for process automation in industrial or private environments. In particular, the invention relates to a field device with a first sensor and a second sensor, a method for calculating a fill level of a medium, a density of the medium or a mass of the medium, a program element and a computer-readable medium.

background

In process automation in industrial or private environments, field devices are used to monitor the fill levels of containers, for example. In addition to level radar measuring devices, such as free-radiating radar sensors or level sensors, limit level sensors are also used, for example in the form of vibrating rods, tuning forks, capacitive or conductive sensors, but also sensors that use guided waves for measurement or pressure sensors.

In this case, adhesions to the sensor or the container can lead to falsified measurement results. Especially for self-sufficient sensors that do not have an external power supply, the energy requirement should be as low as possible in order to achieve a long service life.

Summary

It is an object of the present invention to provide a field device for process automation in industrial or private environments, which provides precise measurements and is characterized by the lowest possible energy consumption. For example, a more precise measurement can also be carried out and/or more information can be provided about a measured value.

This object is achieved by the features of the independent patent claims. Further developments of the invention emerge from the subclaims and the following description of embodiments.

A first aspect of the present disclosure relates to a field device that is configured for process automation in an industrial or private environment. The field device has a first sensor that is configured to detect a fill level, a limit level or a pressure of a medium in a container. In addition, it has a second sensor that is configured to detect a vibration and/or an acceleration of the container. In addition, a control unit is provided that is configured to calculate the fill level of the medium from the detected vibration and/or the detected acceleration, or to calculate a density or a mass of the medium from the detected fill level, the detected limit level or the detected pressure, and the detected vibration and/or the acceleration.

The control unit can also be programmed for both calculations. The field device can therefore measure the level of the medium in two ways, with the first sensor and with the second sensor. If the field device knows the level in the container, it can determine the density or mass of the medium by using the known level and the detected vibration and/or acceleration that the container experiences at the location where the field device is attached.

For this purpose, it can be helpful to first carry out a calibration, i.e. to record a dependency between the fill level of the container and the vibration/acceleration.

According to one embodiment of the present disclosure, the field device further comprises a wired and/or wireless interface that is configured to transmit the detected fill level or the detected pressure of the medium, as well as the detected vibration and/or acceleration, to an external evaluation unit. This external evaluation unit can be an external computing unit or a cloud.

According to a further embodiment of the present disclosure, the field device has a field device housing in which both the first sensor and the second sensor are arranged. Typically, during the measurement, the field device housing is firmly connected to the container so that the container vibration/container acceleration can be measured.

According to a further embodiment of the present disclosure, the control unit is configured to trigger a measurement by the first sensor less frequently than a measurement by the second sensor. This proves to be advantageous in particular when the energy consumption of the first sensor for such a measurement is higher than the energy consumption of the second sensor.

According to a further embodiment of the present disclosure, the control unit is configured to record a fill level vibration profile during filling or emptying of the container using both the first sensor and the second sensor, from which a fill level can be calculated from a vibration and/or acceleration recorded by the second sensor. This procedure corresponds to the calibration described above. This can optionally also be strengthened in the learning phase by additional information from another system.

According to a further embodiment of the present disclosure, the control unit is configured to infer a decrease in the density of the medium from an increase in the amplitude of the detected vibration with a constant filling quantity, for example based on the information from a filling level sensor. Alternatively or additionally, the control unit can be configured to infer a decrease in the density of the medium from an increase in the amplitude of the detected vibration with a constant mass. This can be the case, for example, when the medium foams. Likewise, foaming of the medium and/or foam formation of the medium can be detected in this way. Alternatively or additionally, the control unit can be configured to infer a change in the density of the medium from an increase in the amplitude of the detected vibration, for example when the filling quantity remains the same or changes. This can be the case, for example, when the medium changes or when the medium is at least partially replaced. For example, the medium in a container can change: at a point in time A, a medium or product with density A can be in a container, and after emptying and refilling with a medium B and density B, the density can have changed accordingly, possibly with the same fill level. This can be recorded by the two sensors and output or displayed.

According to a further embodiment of the present disclosure, the control unit is configured to conclude from an increase in the amplitude of the detected vibration (for example with the second sensor) with the type of medium remaining the same that the fill level has decreased or that a funnel, a bridge or a cavity has formed in the medium, for example because the first sensor has not detected a fill level change.

A further aspect of the present disclosure relates to a method for calculating a fill level of a medium, a density of a medium or a mass of a medium, in which a vibration and/or an acceleration of the container in which the medium is located is detected, for example by a second sensor. The fill level of the medium is then calculated from the detected vibration and/or the detected acceleration, or the density or the mass of the medium is calculated, specifically from a previously measured fill level of the medium, a limit level of the medium or a pressure of the medium and the detected vibration and/or the detected acceleration.

Another aspect of the present disclosure relates to a program element that, when executed on a control unit of a field device described above, instructs the field device to perform the steps described above.

Another aspect of the present disclosure relates to a computer-readable medium on which a program element as described above is stored.

The term “process automation in an industrial environment” can be understood as a branch of technology that includes measures for operating machines and systems 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 sectors. A variety of sensors can be used for this purpose, which are particularly adapted to the specific requirements of the process industry, such as mechanical stability, insensitivity to contamination, extreme temperatures and extreme pressures. Measured values from these sensors are usually transmitted to a control room, in which process parameters such as fill level, limit level, flow, pressure or density are monitored and settings for the entire plant can be changed manually or automatically.

A sub-area of process automation in the industrial environment concerns the logistics automation of plants and the logistics automation of supply chains. With the help of distance and angle sensors, processes inside or outside a building or within a single logistics plant are automated in the field of logistics automation. Typical applications include logistics automation systems in the area of baggage and freight handling at airports, in the area of traffic monitoring (toll systems), in retail, in parcel distribution or in the area of building security (access control). What the examples listed above have in common is that presence detection in combination with precise measurement of the size and location of an object is required by the respective application. Sensors based on optical measuring methods using lasers, LEDs, 2D cameras or 3D cameras that measure distances according to the time of flight (ToF) principle can be used for this purpose.

Another area of process automation in the industrial environment concerns factory/production automation. Applications for this can be found in a wide variety of industries such as automobile manufacturing, food production, the pharmaceutical industry or in the packaging sector in general. The aim of factory automation is to automate the production of goods using machines, production lines and/or robots, i.e. to allow it to run without human involvement. The sensors used here and the specific requirements with regard to measurement accuracy when recording the position and size of an object are comparable to those in the previous example of logistics automation.

The terms used in the claims should be construed to give them the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article "a" or "the" in introducing an element should not be construed to exclude a plurality of elements. Similarly, the mention of "or" should be construed to include a plurality of elements, so that the mention of "A or B" does not exclude "A and B" unless it is clear from the context or the preceding description that only one of A and B is meant. Further, the phrase "at least one of A, B and C" is to be understood as one or more elements from a group of elements consisting of A, B and C, and not to be construed to require at least one of each of the listed elements A, B and C, whether A, B and C are related as categories or otherwise. Furthermore, the mention of “A, B and/or C” or “at least one of A, B or C” should be interpreted to include any single entity of the listed elements, e.g. A, any subset of the listed elements, e.g. A and B, or the entire list of elements A, B and C.

Further embodiments of the invention are described below with reference to the figures. If the same reference symbols are used in the following description of the figures, they denote the same or similar elements. The representations in the figures are schematic and not to scale.

Short description of the characters

• 1 shows a measurement setup with a field device according to an embodiment.
• 2A shows a container with a field device at a first fill level.
• 2B shows the container of 2A at a second filling level.
• 3A shows the container of 2A with a first filling material.
• 3B shows the container of 2A with a second filling material.
• 4A shows the container of 2A during transport.
• 4B shows the container of 2A during transport, but with a different filling material.
• 5 shows a flowchart of a method according to an embodiment of the present disclosure.

Detailed description of embodiments

1 shows a measuring system with a field device 100, an external evaluation unit 105 and a cloud 107.

The external evaluation unit 105 and the field device 100 can communicate with each other and exchange data wirelessly and/or wired (via the communication interfaces 121, 122 of the field device 100 or 123, 124 of the external evaluation unit).

The field device 100 has a field device housing 106 in which the first sensor 101 and the second sensor 102 are located. The first sensor 101 is used to detect a fill level, a limit level or a pressure of a medium in a container and is, for example, a fill level radar sensor, an ultrasonic sensor, a TDR sensor, a limit level sensor, a radar sensor, a laser sensor or a lidar sensor.

The second sensor 102 is used to detect a vibration and/or an acceleration of the container, and is therefore a vibration or acceleration sensor, for example in the form of a piezo sensor or gyroscope. However, the terms first sensor and second sensor are to be interpreted broadly.

The two sensors 101, 102 are connected to a control unit 103, which can receive and process the measurement data from the two sensors. A communication module 104 is also connected to the control unit 103, which provides a wireless and/or wired communication interface, such as this is represented by the antenna 121 and the communication port 122.

Corresponding connections 123, 124 are also located in the external evaluation unit 105.

The field device 100 can therefore be designed as a level sensor in combination with a vibration/acceleration sensor.

The 2A and 2B show two measurement scenarios. 2A shows a container 108 in which a filling material 109 is located. The container 108 is, for example, a silo on which there is a motor 110 that is set up to empty and/or shake the container. As a rule, such silos 108 are connected to a system (conveyor screw, rotary valve, ...) for removal. In addition, as described, a vibrator can be attached to ensure a better flow of material. Filling the silo or tank can also generate vibrations. In the case of liquids, pumps or agitators can also generate vibrations.

The corresponding vibrations on the field device depend on the respective vibration sources, the container itself and the current fill level of the container.

If the container is relatively well filled, as in 2A As shown in Figure 1, the second sensor of the field device 100 measures only a relatively weak vibration (amplitude). However, if the container is less full, as shown in Figure 1, 2B As can be seen, the second sensor is a much stronger vibration.

In a first embodiment, the field device learns a level-dependent vibration pattern of the silo 108. This means that the field device stores the corresponding vibration patterns (measured by the second sensor (vibration sensor, acceleration sensor, ...)) for each measured level (for example, measured by the first sensor (radar, LIDAR, ...)) and derives a "vibration profile" from them.

If the level sensor (first sensor) fails, for example due to adhesion to the antenna, the field device can still derive the current level from the recorded vibration data/acceleration data. This results in higher availability for level measurement.

If it is a self-sufficient, battery-operated sensor, the fill level can only be determined with the second sensor (vibration sensor) after the learning phase. This is more energy efficient and increases the running time until the battery needs to be changed. In an extended procedure, the field device can verify the measurement with the radar (first sensor) at certain intervals for safety reasons.

In another embodiment, the field device waits until a vibration is detected and only then starts the measurement (by the first sensor and/or the second sensor). This could also lead to an extension of the battery life, since it can be assumed that without vibration (since no filling or emptying) the fill level does not change.

The field device can also be set up to detect buildup. The learned level vibration profile can also be used to determine how strong buildup is on the silo/container wall, or whether it is present. In practice, this means that bridges/funnels and rat holes can be detected early on. The plant operator can then take countermeasures early on and thus increase plant availability.

In addition, this evaluation can also detect a defect in the silo/container/tank, as the vibration pattern changes accordingly.

According to a further embodiment, the density/mass of the filling material can be detected or determined from the combination of the level and vibration sensors. All of this can be done in the sensor and/or the cloud.

This is in the 3A and 3B shown. In 3A there is a relatively heavy filling material in the container 108, so that the field device 100 detects only relatively small vibrations. In the case of 3B there is a lighter filling material in the tank, so that the field device 100 detects stronger vibrations, although in both cases the same vibrator 110 is used, so the source of the vibration is identical.

This results in clear advantages. On the one hand, incorrect fillings can be detected, which can occur, for example, if the wrong product has been delivered. If, for example, the same product is always stored in a tank, the evaluation of the fill level vibration profile can be used to detect when a different product with a different density has been filled in. Product identification can also be carried out, for example at a plaster distributor. Thanks to a large database with information on fill level vibration patterns depending on the product, the field device can use the recorded fill level vibration profile to deduce and display the correct product. Furthermore, the fill level can also be determined from the associated density in the form of a mass indication, for example in tons. The information could also be used to identify or document the product quality in the silo. If stored for too long and/or incorrectly, the product might be harder or heavier, which could lead to a different vibration pattern.

Another embodiment relates to transportable containers that are transported to the customer by vehicle, for example plaster silos for construction sites. This is described in the 4A and 4B shown.

The vibration/acceleration sensor (second sensor) is active when the silo is tilted during travel and records a vibration/acceleration pattern. The mass in the silo can be determined from this data and enough historical or calculated or simulated data. This means that the mass can be recorded during the journey to the customer and when the system is set up on site, the mass is displayed in the system at the corresponding fill level. This enables a higher level/weight measurement accuracy.

As a result, the logistics of the silos can be simplified and made more efficient. For example, the silo can be transported directly from one construction site to the next if the remaining mass has been reliably determined and the filling quantity is still sufficient. Previously, it was necessary for the truck to first drive back to the factory to be weighed there.

5 shows a flow chart of a method according to an embodiment. In step 501, the vibration and/or acceleration of a container in which the filling material is located is recorded. In step 502, the filling level of the medium is calculated from the recorded vibration and/or the recorded acceleration. In step 503, the density or mass of the medium is calculated from the filling level of the medium recorded by a filling level sensor, a limit level of the medium or a pressure of the medium, as well as the recorded vibration and/or the recorded acceleration. In step 504, the measurement data is forwarded to a cloud that is connected to a logistics control center, for example.

Claims (12)

Field device (100) configured for process automation in an industrial or private environment, comprising: a first sensor (101) configured to detect a fill level, a limit level or a pressure of a medium in a container; a second sensor (102) configured to detect a vibration and/or an acceleration of the container; a control unit (103) configured to calculate the fill level of the medium from the detected vibration and/or the detected acceleration, or a density or a mass of the medium from the detected fill level, the detected limit level or the detected pressure and the detected vibration and/or the detected acceleration. Field device (100) to Claim 1 , wherein the first sensor (101) is a level radar sensor, a radar sensor, an ultrasonic sensor, a laser sensor, a lidar sensor or a limit level sensor. Field device (100) to Claim 1 or 2 , wherein the second sensor (102) is a vibration or acceleration sensor. Field device (100) according to one of the preceding claims, further comprising: a wired or wireless interface (104) configured to transmit the detected fill level or pressure of the medium, as well as the detected vibration or acceleration, to an external evaluation unit (105). Field device (100) according to one of the preceding claims, further comprising: a field device housing (106) in which the first sensor (101) and the second sensor (102) are arranged. Field device (100) according to one of the preceding claims, wherein the control unit (103) is configured to trigger a measurement by the first sensor (101) less frequently than a measurement by the second sensor (102). Field device (100) according to one of the preceding claims, wherein the control unit (103) is configured to detect a fill level vibration profile during filling or emptying of the container using both the first sensor (101) and the second sensor (102), from which a fill level can be calculated from a vibration and/or acceleration detected by the second sensor (102). Field device (100) according to one of the preceding claims, wherein the control unit (103) is configured to conclude from an increase in the amplitude of the detected vibration with an increasing filling quantity that there is a decrease in the density of the medium; and/or wherein the control unit (103) is configured to conclude from an increase in the amplitude of the detected vibration with a constant mass and/or an increasing filling quantity that there is a decrease in the density of the medium; and/or wherein the control unit (103) is arranged to conclude a change in the density of the medium from an increase in the amplitude of the detected vibration. Field device (100) according to one of the preceding claims, wherein the control unit (103) is configured to conclude from an increase in the amplitude of the detected vibration, with the type of medium remaining the same, a decrease in the fill level or the formation of a funnel, a bridge or a cavity in the medium. Method for calculating a fill level of a medium, a density of the medium or a mass of the medium, comprising the steps: Detecting a vibration and/or an acceleration of a container in which the medium is located; Calculating the fill level of the medium from the detected vibration and/or the detected acceleration; or Calculating the density or the mass of the medium from a fill level of the medium, a limit level of the medium or a pressure of the medium and the detected vibration and/or the detected acceleration. Program element which, when executed on a control unit (103) of a field device (100), instructs the field device to perform the following steps: Detecting a vibration and/or an acceleration of a container in which the medium is located; Calculating the fill level of the medium from the detected vibration and/or the detected acceleration; or Calculating the density or the mass of the medium from a fill level of the medium, a limit level of the medium or a pressure of the medium and the detected vibration and/or the detected acceleration. Computer-readable medium on which a program element is Claim 11 is stored.

Images