Selectably quality level of a level measurement device with monitoring function

Abstract

A level measuring device for determining a level of a medium is described, which comprises an evaluation unit which is configured to generate a measurement signal on the basis of a reflection signal emitted from the level measuring device towards the medium in order to determine the level on the basis of a characteristic feature of the measurement signal and to monitor the determination of the level on the basis of the characteristic feature by means of a monitoring function. Here, the monitoring function has at least selectively a higher quality level or a lower quality level when determining the level.

Description

Technical Field

[0001] This invention relates to a level measuring device, a method for adjusting the level measuring device, and the use of the level measuring device. Background Technology

[0002] When commissioning level measurement devices, a large number of reference measurements are often required to ensure high reliability and / or measurement accuracy after the device is put into operation. In process industries, the requirements for level sensors are increasingly stringent, as they must not only perform the measurement task but also perform it reliably. Summary of the Invention

[0003] For level measuring devices, reliably performing measurement tasks means that the device can accurately determine the level within its accuracy class, or report a fault when it cannot definitively determine the level. Depending on the application, it is essential to ensure that the level sensor can reliably perform measurement tasks through commissioning before reliable operation can commence. To this end, plant operators need to approach different levels under process conditions to ensure reliable operation.

[0004] In particular, establishing the required process conditions has proven difficult in practice. For example, the temperature of a level sensor during commissioning differs from that after the process has been running for several hours. Another example is the presence of deposits or contaminants on the antenna of a radar level measuring device, which continuously alter the measurement signal during operation. Furthermore, some plant operators prefer to use water, for instance, instead of hazardous chemical mixtures during commissioning. Therefore, in practice, commissioning can never accurately represent the sensor application during operation. Due to these discrepancies, conventional level measuring devices exhibit safety deficiencies.

[0005] Throughout this description of the invention, the order of the method steps is presented in a manner that facilitates understanding of the method. However, those skilled in the art will recognize that many method steps can also be performed in different orders and lead to the same result. In this sense, the order of the method steps can be changed accordingly, and is therefore also disclosed.

[0006] According to one aspect, a level measuring device for determining the level of a medium is proposed, comprising an evaluation unit configured to:

[0007] - A digitally converted signal based on reflected signals, specifically based on the reflected portion of a signal emitted from the level measuring device toward the medium, generates a measurement signal to determine the level based on the characteristic features of the measurement signal; and

[0008] - The determination of level based on characteristic features by means of a monitoring function, wherein the monitoring function selectively has at least a higher quality level or a lower quality level when determining the level, and / or uses it for monitoring.

[0009] Here, the digital conversion signal can be an electrical signal generated by the level measuring device based on a reflected signal. The reflected signal can be the reflected portion of a transmitted signal emitted from the level measuring device toward the medium and received by the level measuring device.

[0010] The level measuring device may include a transmitting device configured to emit a signal toward a medium and a sensor unit configured to receive and digitally convert the reflected signal. Furthermore, the level measuring device may include an evaluation unit configured to convert the received and digitally converted signal into a measurement signal or echo curve. The evaluation unit is also configured to evaluate the measurement signal to determine the level based on the measurement signal, as described below. The transmitting device, sensor unit, and evaluation unit may, in particular, be implemented together as integrated hardware on the same circuit board or chip.

[0011] The level can indicate the distance of a level measuring device from the surface of a medium or filling material, wherein the medium is, for example, located in an open or closed container.

[0012] The measurement signal (also known as the echo curve) is generated by a digitally converted signal based on at least a portion of the reflected signal emitted from the level measuring device toward the medium. Different methods can be used to generate the measurement signal (or echo curve) depending on the measurement principle being applied (e.g., radar level measuring device, ultrasonic level measuring device, or guided radar level measuring device).

[0013] Therefore, for example, when using ultrasound for measurement, the measurement signal can be sampled directly after reception and electronic processing by a sufficiently fast A / D converter, for example, by filtering or amplifying the reflected signal. In radar measurement devices where the electromagnetic waves propagate at the speed of light, the measurement signal can be generated through additional steps. For example, the pulse propagation time method or the FMCW (frequency modulated continuous wave) method is suitable for this. What these two methods have in common is that the short propagation time of the signal can be detected through additional methodological steps. For example, in the FMCW method, the A / D converter can generate a so-called beat frequency curve, i.e., an intermediate frequency signal generated after mixing the transmitted and correspondingly received chirped signals. The measurement signal or echo curve can then be obtained from the logarithmic result of the Fourier transform of the beat frequency curve after A / D conversion. Typically, the portion of the signal reflected, particularly from the surface of the medium, can be detected by the level measuring device and recorded in a time-dependent manner to obtain the echo curve. This time correlation can be converted into the distance between the reflecting surface and the level measuring device by the speed of the signal and can be interpreted, for example, as the echo signal. Such measurement signals typically have multiple local maxima (also known as echoes).

[0014] All evaluations and determinations performed by the level measuring device can be performed on the entire digital conversion signal and / or the entire measurement signal, or on a portion of the corresponding digital conversion signal and / or the measurement signal, so as to enable evaluations and determinations to be performed with minimal computational resources.

[0015] For example, the transmitted signal of a level measuring device may include a pulse shape (e.g., in the case of a pulse radar level measuring device) or a signal with a linear frequency deviation (e.g., in the case of an FMCW radar level measuring device).

[0016] For example, if a strong signal is reflected due to the large surface area of ​​the medium, the amplitude of the measured signal will be correspondingly higher after the signal propagation time. This high amplitude of the local maximum value of the measured signal reflected from the surface of the medium can be defined as a characteristic feature of the measured signal used to determine the level.

[0017] Typically, liquids with high dielectric constants (DK values) reflect radar signals relatively strongly. Filler material surfaces that do not strongly reflect radar waves may be, for example, coarse-grained loose materials and / or liquids with low DK values ​​(dielectric constants), such as LPG (liquefied petroleum gas), oil, and solvents. Other local maxima or echoes may be caused, for example, by components or adhesives within the container, such as those disposed between the filler material surface and the transmitting element.

[0018] Due to interference, such as that generated during antenna coupling, the global maximum value of the measurement signal can often occur within close range of the radar level measuring device. This interference (e.g., so-called "antenna ringing") can be attributed to signal reflection from the horn antenna used as the transmitting antenna of the radar level measuring device, or caused by a so-called "dome" (e.g., a channel) in which the transmitter is arranged, and which, at least in some cases, is arranged at the top inside the container.

[0019] Since amplitude values ​​measured at close range of a radar level measuring device typically do not reflect any "useful information"—that is, cannot be attributed to reflections from the surface of the filling material—echoes from close range can be excluded from evaluation at the manufacturer's location, for example, through so-called "factory interference signal suppression." This close range can, for example, involve a measurement distance of less than 10 or 20 cm from the transmitter (e.g., from the transmitter chip). This suppression can be accomplished, for example, by subtracting a predetermined measurement signal curve from the measured signal before evaluating the measurement signal. The predetermined measurement signal curve, or reference echo curve, can substantially correspond to a measurement signal curve determined for an empty container, on a reference path, or in the open air.

[0020] Then, in other directions of the measurement signal, local maxima can be used to detect characteristic features used to determine the level, and other local maxima can represent other reflective surfaces or interferences within the detection range of the level measuring device through salient features of the measurement signal. Interference can be attributed to many different causes. Salient features can be local maxima in the measurement signal, which may specifically include amplitudes above a defined threshold and / or a defined threshold curve.

[0021] Since other objects can also reflect emitted signals and can act as interference, the measured signals must be evaluated in order to identify characteristic features and thus determine the distance between the medium and the level measuring device.

[0022] The measured signal can be visualized in a graph where the x-axis represents distance D linearly and the y-axis represents the amplitude A of the measured signal in dB.

[0023] The evaluation unit of the level measuring device can be configured to, in addition to determining the level, monitor the quality of the level determination based on characteristic features via a monitoring function to determine whether the measurement task for determining the level has been reliably solved. In other words, the level can be determined by periodically checking the quality of the measurement signal or the quality and / or evaluation of the characteristic features through the monitoring function. The monitoring function or evaluation unit can be configured to display errors and / or warnings when the level measurement or determination is determined to be unreliable.

[0024] For example, the monitoring function of a level measuring device can evaluate the amplitude value of a measurement signal. To this end, the monitoring function can compare the amplitude value of the measurement signal with a minimum amplitude and continuously monitor it. If the amplitude value of the measurement signal at the surface of the filling material (i.e., the amplitude value used to determine the characteristic feature of the level) is lower than this amplitude value by a fixed amount and / or a parameterized amount, the monitoring function generates an error signal (e.g., a fault message) and provides this error signal at the output of the evaluation unit. The level measuring device and / or evaluation unit can be configured such that the amplitude value of the monitored characteristic feature and the parameterized amount used for monitoring can be selected according to the current operating mode of the level measuring device, and / or they can be adjusted, for example, through parameterization.

[0025] Specifically, for the commissioning of level measuring devices, the fixed or parameterized values ​​of the amplitude values ​​used to check characteristic features can be selected to be higher than the corresponding values ​​in the normal operating mode of the level measuring device. This means that the level measuring device can more sensitively check the determination of characteristic features used to determine the level during commissioning, and / or provide corresponding error signals earlier when necessary than in the normal operating mode of the level measuring device.

[0026] In other words, the evaluation unit is configured to react more sensitively to any interference in the correctly determined measurement signal or any disturbances in the characteristic features themselves that may affect the characteristic features during the commissioning of the level measurement device via monitoring functions. This allows for optimization of the characteristic features used to determine the measurement signal or the parameters used to determine the level during commissioning, in order to achieve reliable operation in operating mode.

[0027] Therefore, in commissioning mode, the monitoring function can more sensitively monitor for influences and / or interferences that may impair the reliable determination of the level, and report them in the form of fault messages. These influences and / or interferences include, for example, fluctuations on the surface of the agitator and / or filling material within the detection range of the level measuring device, and / or the influence of the filling material on the irregular surface and / or temperature effects of the measured signal amplitude. Advantageously, during commissioning, for example due to fault messages, the parameter settings used to determine the characteristic features of the measured signal and / or the monitoring functions can be modified. Such parameter settings may involve, for example, modifications to the intensity of the transmitted signal and / or the average value of the measured signal, making the actual operation of the level measuring device not only safe but also reliable.

[0028] This means that, in operational modes, especially in parameterized modes, human intervention (such as during commissioning) can be largely avoided. Therefore, in particular, by selectively including different monitoring functions for determining sensitive mass levels, level measurement devices can be used in an improved manner for safety-critical applications.

[0029] In other words, the level sensor is configured to perform additional monitoring functions beyond the classic evaluation of the measurement signal, monitoring whether the measurement task has been reliably resolved. Due to the selectable different quality levels of the monitoring function, the level sensor is configured to react more sensitively to any malfunctions during sensor commissioning, allowing for adjustment of the parameter settings used to determine the level during commissioning if necessary. Therefore, the level measurement device is configured to periodically check the determination of the level by monitoring both the measurement signal itself and the evaluation of the measurement signal, adapting to commissioning and operating modes.

[0030] According to one aspect, the level measuring device is based on the determination of the propagation time of the transmitted signal; the level measuring device is particularly a radar level measuring device, an ultrasonic level measuring device, a guided radar level measuring device, or a guided microwave level measuring device.

[0031] In this specification, radar level measuring devices are typically used as examples to explain or elaborate on various aspects of the invention in more detail. However, in particular, the invention can be used with all level measuring devices that determine the level based on the propagation time of the signal.

[0032] A level measurement device based on signal propagation time (time of flight) may include: a transmitting device configured to transmit a signal toward a medium; and a sensor unit configured to receive reflected signals and digitally convert them, and determine the distance from the filling material based on the signal's propagation time, in order to determine the level of the medium. The level measurement device may also be a pressure sensor level measurement device, which monitors the level determination through monitoring functions with different mass levels.

[0033] According to one aspect, the evaluation unit is configured to selectively determine the level of the medium in either an operating mode or a commissioning mode, wherein the quality level of the monitoring function in the operating mode differs from that in the commissioning mode; and wherein the evaluation unit is specifically configured to switch between the operating mode and the commissioning mode by providing a switching signal to the level measuring device. During the commissioning of the level measuring device, so-called reference measurements can typically be performed. In this case, for example, filling and emptying a storage tank under process conditions, and monitoring the accuracy of the determination of the correct level by the level measuring device. Typically, the five levels determined by the level measuring device can be compared here with the actual levels determined independently of the level measuring device (e.g., manually determined). At the end of commissioning, the values ​​determined in this way (i.e., the independently determined values ​​and the values ​​determined by the level measuring device) can be specifically stored by the level measuring device for, for example, archiving.

[0034] If the level determined by the level measuring device matches the independently determined level, commissioning can be considered successful. During this commissioning, the monitoring function can monitor the level determination more sensitively with a higher quality level, so as to detect, for example, faults in the level determination. Advantageously, during commissioning, intervention can still be made, for example, through individual parameterization, regarding the level determination using the level measuring device, making the actual operation of the level measuring device in operating mode not only safe but also reliable. Thus, commissioning can be improved by using the level measuring device.

[0035] According to one aspect, the level measuring device includes a memory for storing the level determined by the level measuring device, and in particular, independently determined levels. Therefore, the level measuring device is configured to record both independently determined levels and levels determined by the level measuring device.

[0036] Alternatively or supplementarily, the level measuring device may be configured to monitor characteristic features of the measurement signal used to determine the level through a corresponding monitoring function, thereby recording the results of the monitoring function using at least one sub-function of the monitoring function. In particular, the monitoring results may be stored or recorded using the corresponding sub-function.

[0037] According to one aspect, the level measuring device is configured to determine the level periodically (i.e., at regular time intervals) or alternatively in an event-controlled manner (e.g., triggered by a trigger signal). If an independently determined level value corresponding to the level is determined, such a trigger signal can be provided to the level measuring device separately.

[0038] Alternatively or supplementarily, the level measuring device may be configured to perform the determination and / or storage and / or recording of a level determined by the level measuring device only at a specific predetermined level.

[0039] According to one aspect, the level measuring device is configured to determine characteristic values ​​for achieving monitoring functions through measurement, using which the corresponding quality level can be quantified. Examples of such characteristic values ​​may be the amplitude of a characteristic feature and / or related features. Another example may be the distance between a characteristic feature and / or related features and a threshold curve. Characteristic values ​​and / or related measurements can be provided for display to the user at the output of the level measuring device, and / or particularly displayed on the interface of the level measuring device (especially a graphical interface).

[0040] According to one aspect, the level measuring device is configured to determine the result of the monitoring function by determining an ideal characteristic value based on a corresponding metric and comparing the current characteristic value with the ideal characteristic value. The current characteristic value can be determined as a percentage of the ideal characteristic value and is specifically displayed as a percentage on the interface (particularly a graphical interface) of the level measuring device. If the monitoring function consists of multiple sub-monitoring functions (as further explained below), the individual sub-characteristic values ​​of each sub-monitoring function can be determined, and the total characteristic value can be determined by multiplying the sub-characteristic values. This total characteristic value can also be determined proportionally based on the ideal total characteristic value. This total characteristic value can be displayed to the user, particularly as a percentage, especially on the interface (particularly a graphical interface) of the level measuring device.

[0041] According to one aspect, the level measuring device is configured to check the level determination in operating mode at a quality level depending on the type of commissioning. That is, depending on the type of commissioning, the operating quality level in operating mode can include a value between a higher and lower quality level, or alternatively, other values ​​of the operating quality level. Advantageously, this can reflect the extent to which the function of the level measuring device has been tested under operating conditions, such that after a complete and successful test under operating conditions, the level measuring device operates in operating mode using a monitoring function with a lower quality level, for example, a lower requirement for level determination, compared to a lower quality level.

[0042] On one hand, the level measuring device is selectively configured to disable monitoring when the sensor is not operating under safe conditions. Thus, the level measuring device can operate in a highly available operating mode.

[0043] According to one aspect, the level measuring device includes an output module for outputting an error signal when the mass level determined by the level measuring device through monitoring functions and / or the characteristic value determined by measurement is insufficient to meet the selected mass level, particularly insufficient to meet reliable measurement requirements. The level measuring device can be configured to display the current characteristic value on a display of the level measuring device.

[0044] On one hand, the level measuring device is configured to specifically utilize a switch to selectively activate or deactivate the monitoring function.

[0045] On one hand, the level measuring device is configured to store the time trajectory of each current characteristic value in order to determine the deterioration of the characteristic value.

[0046] According to one aspect, the level measuring device is configured to display the degree of degradation of characteristic values ​​of the monitoring function and / or sub-monitoring function, wherein a currently determined characteristic value is compared with a reference characteristic value to at least display a reliable determination of the level, or a still acceptable determination of the level (where the level determination is about to fail), or a failure of the level determination, based on the comparison between the currently determined characteristic value and the reference characteristic value. In particular, the degree of degradation of the characteristic value can be displayed to display and / or trigger maintenance messages during operation of the level measuring device.

[0047] In particular, the degree of degradation of the characteristic value can be displayed on a color display in a manner corresponding to traffic lights.

[0048] To determine the degree of degradation, a comparison range between 100% and 70% of the reference characteristic value and the currently determined characteristic value can characterize a reliable determination of the level, and a comparison range between 40% and 50% can characterize a still acceptable determination of the level.

[0049] Alternatively or supplementarily, the currently determined characteristic value of the quality level of the monitoring function can be compared with a target curve to define the range assigned to the color display based on the difference between the currently determined characteristic value and the target curve. Specifically, the color display can show the quality determined by the level during the filling process (i.e., during rapid level changes).

[0050] According to one aspect, the level measuring device is configured to display the time interval until reliable determination fails and / or the level change until reliable determination fails by comparing the current characteristic value of the monitoring function or sub-monitoring function with a model-based characteristic value determined by the monitoring function or sub-monitoring function. Such a model may be an empirical model of characteristic value changes with temperature or an empirical model of characteristic value changes with level.

[0051] Alternatively or supplementarily, the model for the radar level measurement device can be based on the radar equations and / or on the distance A between the level and the level measurement device, in order to determine the prediction of the future amplitude of the characteristic features, where, according to A = 1 / r 4 The amplitude A of the reflected signal varies with distance r. For example, if a reflected signal with an amplitude of 100 dB exists at a distance of 1 m from the level measuring device, it can be determined using radar equations and / or by utilizing A = 1 / r during the filling period. 4 The assumed characteristic is determined by the direction of the amplitude A at a distance r to determine whether the amplitude of the reflected signal at a distance of 0.3m is sufficient to reliably stand out from the antenna ringing.

[0052] According to one aspect, the level measuring device is configured to check the corresponding level at a selected higher quality level using a monitoring function, so as to commission the level measuring device when approaching a defined level. This is achieved by activating a lower quality level of the monitoring function in the operating mode of the level measuring device, so that parameters specifically used for level determination are adapted to the operating mode during commissioning. For this commissioning, a reference measurement (i.e., commissioning when approaching a defined level) can be initiated on the level measuring device itself and / or remotely, for example, via a PC or smartphone coupled to the level measuring device in a wired and wireless manner.

[0053] According to one aspect, the monitoring function includes at least one monitoring sub-function, each sub-function selectively possessing a higher quality level and a lower quality level, so as to achieve a quality level of the monitoring function based on the respective selected quality levels of the monitoring sub-functions; and in particular, if at least one monitoring sub-function generates an error signal when monitoring level determination according to the quality level of the selected monitoring function, the evaluation unit is configured to generate an error signal to indicate an incorrect level determination. In other words, the monitoring function itself can consist of multiple individual sub-functions to advantageously monitor different characteristics of the measurement signal for level determination and / or the evaluation of the measurement signal. Advantageously, through appropriately adapted monitoring sub-functions, the monitoring of level determination can be adapted to different processes and operating conditions of the level measuring device.

[0054] According to one aspect, the evaluation unit is configured to achieve a quality level of the monitoring function based on multiple monitoring sub-functions determined by the characteristic features used to monitor the level; and / or to generate error signals based on multiple monitoring sub-functions with deviations from the determined characteristic features used to monitor the level, to indicate erroneous level determination. That is, by increasing the number of monitoring sub-functions with higher quality levels and correspondingly decreasing the number of monitoring sub-functions with lower quality levels, a higher quality level can be selected for the monitoring function without depending on the respective quality level of the monitoring sub-functions. Advantageously, when commissioning the level measuring device, especially under process conditions close to different levels, the level determination can be monitored more sensitively by increasing the number of monitoring sub-functions, so as to check the minimum detection reliability of the level.

[0055] According to one aspect, the level measuring device is configured to check the corresponding level through a monitoring function with multiple monitoring sub-functions, so as to commission the level measuring device when it approaches a defined level. The number of monitoring sub-functions used for commissioning the level measuring device is greater than the number in the operating modes of the level measuring device; and specifically, a higher or lower quality level is selected for the corresponding monitoring sub-function. Advantageously, a higher quality level can also be achieved by having more sub-functions of the monitoring function check the level determination. Therefore, the higher requirement for level determination during commissioning can be adapted to various conditions and processes using the level measuring device.

[0056] According to one aspect, the first sub-function of the monitoring function for determining the detection reliability of the characteristic feature monitors the amplitude of the characteristic feature in the measurement signal caused by the level of the medium; and in particular monitors the distance between the amplitude of the characteristic feature and the threshold curve of the measurement signal; and compared with the lower quality level of the first sub-function, the higher quality level of the first sub-function monitors a higher amplitude; and / or monitors the characteristic feature using a higher threshold curve.

[0057] In other words, the level measuring device is configured to evaluate the maximum amplitude of a characteristic feature of the measured signal, caused by a reflected signal from the surface of the filling material, through a first sub-function of the monitoring function. Here, the first sub-function compares the maximum amplitude of the characteristic feature with the minimum amplitude that should be continuously monitored corresponding to the selected mass level. When the maximum amplitude of the characteristic feature is lower than the minimum amplitude, the first sub-function of the monitoring function can output a fault message or an error message. The level measuring device is configured to allow selection of the minimum amplitude based on the operating type of the level measuring device. When commissioning the level measuring device (i.e., in commissioning mode), the minimum amplitude corresponding to the threshold can be selected to be higher than the minimum amplitude during periodic operation in operating mode. This means that the level measuring device monitors the determination of the level more sensitively during commissioning and can therefore report errors faster than during operation.

[0058] According to one aspect, the second sub-function of the monitoring function for the characteristic feature caused by the level of the medium predicts the next characteristic feature in the measurement signal based on the worst-case scenario of the measurement signal of the next measurement, in order to determine the prediction of detection reliability, wherein the lower quality level of the second sub-function monitors the amplitude of the next characteristic feature caused by the level of the medium; and / or monitors the distance between the amplitude of the next characteristic feature and the threshold curve; and in particular, the higher quality level of the second sub-function monitors a higher amplitude compared to the lower quality level of the second sub-function; and / or monitors the next characteristic feature using a higher threshold curve.

[0059] A level measuring device can determine the level based on a measurement signal, specifically by generating a measurement signal for determining the characteristic features of the level measurement signal using multiple individual measurement signals through recursive averaging. The recursive averaging can be a "global average" (Scharmittelung). A "global average" can be understood as the average of multiple corresponding values ​​from multiple measurement signals of different measurements, and a "recursive global average" can be understood as a partial average of the corresponding value of each current measurement signal with the previously averaged measurement value, where the previously averaged measurement signal is obtained by averaging the corresponding values ​​of previous measurement signals. Thus, the current measurement signal is included only in the predicted measurement signal in a weighted manner. For example, the corresponding current measurement signal is included in the recursive average with, for example, a 25% weight. A second sub-function of the monitoring function determines the worst-case scenario for the next reflected signal of the next measurement based on a model, so as to predict the measurement signal accordingly. In other words, it can therefore be described the maximum extent to which the measurement signal (especially the digitally converted measurement signal) can change based on the next measurement signal. When level changes or amplitude fluctuations are small, the measurement signal predicted in this way changes only moderately. On the other hand, corresponding to the diagnostic function, the second sub-function of the monitoring function estimates the worst-case scenario for the trajectory of the next measurement signal based on a model. An example of a worst-case scenario estimate based on a model could be that the subsequent reflected signal is adversely reflected, particularly due to surface movement of the filling material, so that any portion of the reflected signal attributable to the level does not reach the level measuring device. The characteristic features in the predicted measurement signal will decrease accordingly relative to the maximum amplitude, but it will not completely disappear due to the weighting of the continuous measurement signals by the recursive averaging.

[0060] Therefore, by utilizing the second sub-function, the minimum detection reliability can be predicted (particularly through the first sub-function) for the next level determination. The level measuring device can be configured to report a fault or error using the second sub-function only if the measurement signal predicted in this way has the following characteristics, which, according to the first sub-function, determine that the detection reliability is too low to produce a reliable and sufficiently accurate level determination when estimating the worst-case scenario for the next measurement signal for the next measurement. Thus, advantageously, by utilizing the second sub-function, it is possible to predict whether the measurement signal at the next level determination will have a quality appropriately selected to determine a reliable measurement value by modeling from the current measurement signal. If the quality (corresponding to the desired detection reliability) is not good enough, the level measuring device can be configured to indicate a fault.

[0061] According to one aspect, a third sub-function of the monitoring function for characteristic features caused by the level of the medium monitors at least one salient feature in the measurement signal and the amplitude difference between the characteristic feature and the characteristic feature, wherein each salient feature in the measurement signal is caused by further reflection of the transmitted signal; and compared with a lower quality level of the third sub-function, a higher quality level of the third sub-function monitors a higher amplitude difference between the characteristic feature and at least one salient feature of the measurement signal. When determining the level by a level measuring device, monitoring of salient features can improve the safe and reliable determination of the characteristic feature, thereby improving level determination.

[0062] Here, a significant characteristic of the measured signal may be the amplitude of the measured signal, particularly within a certain range, where the maximum value of the amplitude is greater than a specific threshold and / or above a specific threshold curve.

[0063] Advantageously, the third sub-function is used to monitor the increase of salient features in order to ensure the reliable determination of characteristic features.

[0064] According to one aspect, the fourth sub-function of the monitoring function monitors the occurrence of at least one salient feature in the measurement signal in order to identify the characteristic feature of the level; and compared with the lower quality level of the fourth sub-function, the higher quality level of the fourth sub-function monitors a greater distance between the characteristic feature of the level and at least one salient feature in the measurement signal and / or a greater difference between the amplitude of the characteristic feature of the level and the amplitude of at least one salient feature in the measurement signal.

[0065] Alternatively or supplementarily, the fourth sub-function can monitor the presence of salient features of the measured signal in a specific region. Here, salient features can be based on portions of the reflected signal caused by adhesions and / or contaminants on the wall.

[0066] Alternatively or supplementarily, the fourth sub-function can be configured to monitor different amplitude differences between characteristic features and salient features appearing in different regions of the measured signal. This means that different regions of the measured signal can be associated with different necessary differences in order to compare the amplitude of the characteristic feature with the amplitude of the salient feature.

[0067] A method for commissioning a level measuring device is proposed, wherein the level measuring device includes an evaluation unit that uses a monitoring function to monitor the determination of level based on characteristic features in a measurement signal, and wherein the monitoring function selectively includes at least a higher quality level and a lower quality level of the determined level, and the method includes the following steps:

[0068] - Activate the monitoring function used for level determination;

[0069] - Select a higher quality level for the monitoring function;

[0070] - By using a level measuring device, reference measurements of the level are performed at different levels of the medium using a monitoring function at a higher quality level;

[0071] - Compare the correlation between the corresponding material level and the corresponding output signal of the level measuring device to check reliable operation;

[0072] - Select a lower quality level for the monitoring function in order to put the level measurement device into operation.

[0073] On the one hand, this commissioning method can be used to check the level measuring device used for the corresponding task, and through the high quality level during commissioning, it is possible to safely and reliably determine the level in the operating mode even if the operating conditions in the operating mode are different from those during commissioning.

[0074] According to one aspect, the level measuring device is configured to adjust parameters used for level determination; and the adjustment method includes the following steps:

[0075] - Adjust the parameters used to determine the level in order to optimize the correlation between the corresponding level and the corresponding output signal of the level measuring device.

[0076] This enables the level measuring device to determine the level safely and reliably in operating mode.

[0077] According to one aspect, a method for calibrating the level measuring device is performed using one of the aforementioned level measuring devices. Since parameters can be adjusted after a reference measurement is performed using a higher quality level, this calibration method can be performed particularly easily using one of the aforementioned level measuring devices.

[0078] According to one aspect, a computer program including instructions is provided, which, when executed by a computer, cause the computer to perform one of the aforementioned methods. In particular, an evaluation unit may include such a computer to perform the method and / or at least one step of the method. This computer program may be part of operating software for debugging and / or operating the level measuring device. Alternatively or additionally, the computer program may be installed on a portable operating device such as a smartphone, mobile phone, or service module for operating and / or debugging the level measuring device.

[0079] Here, the computer program may be configured to compare a stored checksum based on stored parameters for operating the level measuring device with a currently calculated checksum based on current parameters for operating the level measuring device. Alternatively or additionally, the computer program may be configured not to automatically activate a debugging assistant configured to perform one of the above methods when the stored checksum equals the current checksum.

[0080] A machine-readable storage medium is provided on which the above-described computer program is stored. Therefore, the method can be easily implemented on various control and monitoring devices.

[0081] One of the aforementioned level measuring devices is presented for detecting the level of a medium and / or for process control. By using a set of level measuring devices, the production process can be monitored with particular reliability.

[0082] It should also be noted that the various embodiments described above and / or described below can be combined with each other. Attached Figure Description

[0083] Reference Figures 1 to 7 The exemplary embodiments of the present invention will be described below, and will be explained in more detail thereafter.

[0084] Figure 1 A flowchart for selecting a quality level is shown.

[0085] Figure 2 A flowchart for selecting monitoring sub-functions is shown.

[0086] Figure 3 A flowchart for selecting the operating mode is shown.

[0087] Figure 4 The measurement signal of the level measuring device, which has characteristic and significant features, is shown.

[0088] Figure 5 The measurement signal of the level measuring device is shown as a worst-case estimate with characteristic features.

[0089] Figure 6 The measurement signal of the level measuring device with a threshold curve is shown.

[0090] Figure 7 A flowchart for reliably commissioning a level sensor is shown. Detailed Implementation

[0091] Figure 1A simplified flowchart of the first control of a level measuring device having a discriminator 101 for selecting between an operating mode and a commissioning mode is shown. Here, the discriminator 101 can be switched between different operating modes, for example, by using a switching signal, an electrical switch, a GUI switch, or by triggering a button on the level measuring device control panel or operating unit. Specifically, the discriminator 101 can be configured to select between operating modes by selecting and providing corresponding configuration values ​​for a set of parameters. If the commissioning mode is selected, in step 102, a set of parameters for a monitoring function 103 is provided for a reference measurement (i.e., a measurement used to commission the level measuring device) so that commissioning is monitored by the monitoring function, which checks the correctness of level determination at a higher quality level compared to the operating mode. Alternatively, the operating mode can be selected using the discriminator 101 such that a set of parameters for the monitoring function in the operating mode is provided in step 104 of the monitoring function 103, so that the correctness of level determination is checked at a lower quality level in the operating mode.

[0092] Figure 2 A simplified flowchart of an alternative second control for a level measuring device with discriminator 101 is shown. If an operating mode is selected using discriminator 101, a monitoring function for level determination is selected to check for correct level determination at a lower quality level in operating mode. Alternatively, a commissioning mode can be selected using discriminator 101, which then activates sub-monitoring functions 202, 203, and 204 to check for correct level determination at a higher quality level in commissioning mode. Here, a higher or lower quality level can be selectively selected for each sub-monitoring function 202, 203, and 204 itself. In other words, in commissioning mode, the commissioning monitoring function can consist of multiple sub-functions to monitor more analysis and / or contributions for level determination compared to the operation in operating mode.

[0093] Figure 3 A simplified flowchart of an alternative third control for the level measuring device with discriminator 101 is shown. If an operating mode is selected using discriminator 101, monitoring function 301 for the operating mode is activated or selected. If a commissioning mode is selected using discriminator 101, monitoring function 302 for the commissioning mode is selected or activated to check the level determination at a higher quality level during commissioning compared to the operating mode.

[0094] Figure 4The time trajectory of the measurement signal 401 or echo curve 401 of the level measuring device is simplified, whereby the measurement signal 401 is based on the reflected signal emitted from the level measuring device toward the medium and then received again. The horizontal axis 406 is the time axis of the measurement signal, which is proportional to the distance from the level measuring device (which may be measured in meters), and the vertical axis 405 represents the amplitude of the measurement signal (e.g., in dB). Additionally, in Figure 4 The threshold curve 402 is marked with a dashed line in the graph. In the trajectory of the measurement signal 401, the characteristic feature 403 and salient feature 404 of the measurement signal are depicted as local maxima. The level can be determined based on the temporal position of the characteristic feature 403. The salient feature 404 can be defined as follows: the amplitude of the measurement signal is locally higher than the threshold curve 40 at that point. The salient feature 404 can be based on the portion of the interference reflected signal caused by interference, such as an installation within the container or multiple reflections between the level and the top of the container. Here, the characteristic feature 403 is also higher than the threshold curve 402. The distance between the maximum amplitude of the characteristic feature 403 and the threshold curve 402 can be defined as proportional to the detection reliability of the characteristic feature 402. The measure of detection reliability can be expressed as the distance from the threshold curve 402, in dB or as a percentage. The dB value determined based on the distance between the maximum amplitude and the threshold curve can be expressed as a percentage using a reference value. Therefore, it can be determined theoretically or empirically that, for example, a detection reliability of 120 dB corresponds to a 100% percentage value, while 0 dB corresponds to a 0% percentage value. The 120 dB reference value can correspond to the maximum possible detection reliability of the signal processing of the level measuring device.

[0095] The reliability of the detection can be monitored by comparing the distance between the maximum amplitude of characteristic feature 403 and the threshold curve 402 with a predefined minimum distance value using the first sub-monitoring function. When the distance falls below the minimum, the first sub-monitoring function can output an alarm signal and / or trigger an alarm.

[0096] Figure 5 The chart corresponds to Figure 4 The chart, and combined Figure 4The second sub-monitoring function is explained, which is used for the characteristic feature caused by the medium level and is based on a model-based worst-case scenario of the next measurement signal. Here, a prediction is made for the next characteristic feature 503 in the measurement signal to determine the prediction of detection reliability. The second sub-monitoring function determines the amplitude of the next characteristic feature 503 caused by the medium level. As explained in more detail above, the measurement signal 401 (based on the reflected signal emitted from the level measuring device toward the medium) may include a recursive averaging. Here, the recursive averaging of the measurement signal 401 can be performed in such a way that subsequent measurements are included in the average with, for example, a weight of 25%. Using the assumptions of the first model-based approach (which, for example, assumes that the (transmitted) signal is reflected onto the surface of the medium away from the level measuring device), the extent to which the characteristic feature 503 can change maximally can be determined. That is, possibly due to the moving surface, the subsequent level measurement or determination of the medium whose fill height is to be determined is adversely reflected, such that the signal portion attributable to the level does not reach the level measuring device (i.e., does not reach the sensor of the level measuring device).

[0097] Under the second model-based assumption (which assumes minimal level change or fluctuation), characteristic 503 will change only moderately. If the second sub-monitoring function estimates the worst-case scenario, a first model-based assumption is made. The amplitude of characteristic 503 estimated in this way can be compared with the threshold curve 402 to determine the minimum detection reliability for the next measurement, as a prediction. If the detection reliability used to estimate the adverse scenario (i.e., a predefined value for the predicted detection reliability) is too low to determine the level sufficiently reliably and accurately, a diagnostic function using the predicted detection reliability defined by the metric (Metrik) described herein can report a failure.

[0098] Here, through the second sub-monitoring function, the predicted detection reliability requirement is detected at a selected higher quality level using a correspondingly higher value predefined for the predicted detection reliability, or alternatively at a lower quality level using a lower value predefined for the predicted detection reliability. For example, the determination of characteristic features can be monitored at a higher quality level in commissioning mode. For example, the determination of characteristic features can be monitored at a lower quality level in the operation mode of the level measuring device.

[0099] Despite Figure 4 Compared to characteristic feature 403, the amplitude of characteristic feature 503 (corresponding to) Figure 5The amplitude of characteristic feature 503 decreases, but characteristic feature 503 can still be detected because, due to the recursive averaging of all consecutive converted measurement signals, the effect of a single worst-case estimate of the amplitude of characteristic feature 503 is only included with, for example, a weight of 25%. The final decrease in the amplitude of characteristic feature 503 can be estimated from the amplitude of characteristic feature 403, and... Figure 5 This reduction is described using characteristic feature 503. Figure 4 The salient feature 404 is unaffected by model-based assumptions, and therefore shifts to Figure 5 The salient feature is 504.

[0100] If the predicted detection reliability is determined to be below the threshold curve 402, a fault message can be generated, for example, to notify the monitoring results of the level determination via a second sub-function.

[0101] exist Figure 5 In the example, through Figure 4 The predicted characteristic feature 503 is estimated and depicted based on the maximum possible decrease in the amplitude of characteristic feature 401. In this worst-case scenario, the characteristic feature of level 403 is transformed into characteristic feature 503, while the significant feature 404 of the disturbance is transformed into significant feature 504. The second sub-monitoring function can detect, based on the first sub-monitoring function, that the next predicted characteristic feature 503 may have too low detection reliability in the next level determination, and additionally generate a fault message through the aforementioned third sub-function, because the significant feature of the disturbance may still exist and the amplitude difference of the characteristic features below the significant feature is too small.

[0102] Figure 6 The chart corresponds to Figure 4 The diagram illustrates, by way of example, the function of the first sub-function of the monitoring function. The measurement signal 401 includes a characteristic feature 601, the maximum amplitude of which differs from the distance of either the first threshold curve 602 or the second threshold curve 603. Here, compared to the second threshold curve 603, the first threshold curve 602, representing a higher quality level for the first sub-function of the monitoring function, may have a higher trend in terms of the amplitude or ordinate 405 of the characteristic feature 601.

[0103] Compared to comparing characteristic feature 601 with a second threshold curve 603 for the operating mode, comparing characteristic feature 601 with a first threshold curve 602 for monitoring allows for a higher level of quality inspection in the commissioning mode of the level measuring device via the first sub-function of the monitoring function. The first sub-monitoring function (which requires a minimum detection reliability) is more sensitive in determining the characteristic feature in commissioning mode compared to the operating mode. Therefore, the detection reliability determined during commissioning in commissioning mode, using a metric that measures the distance between the maximum value of characteristic feature 601 and the more offset first threshold curve 602, is generally lower than the detection reliability determined during sensor operation in operating mode.

[0104] Switching to the debug mode of the first sub-monitoring function can be accomplished using a parameter dataset. In this mode, the first sub-monitoring function is configured to monitor at a higher quality level. Therefore, in debug mode, the first monitoring function identifies potential influences that could affect the reliable determination of the level, and these influences can be reported as fault messages.

[0105] Figure 7 A flowchart of a method for commissioning a level sensor with particular reliability is shown in a simplified manner. In a first step 701, optionally, as part of the commissioning, the level sensor is assembled or installed at the measuring point (e.g., a storage tank) to determine the level of the medium, and if it is not already installed, it is electrically connected if necessary.

[0106] In the second step 702, the monitoring function for level determination in the debugging mode (i.e., the monitoring function with a selected higher quality level) is activated, and / or the parameters and / or configuration values ​​for the debugging mode of the monitoring function of the evaluation unit of the level measuring device are provided. Examples of such parameters and / or configuration values ​​may include, for example: the intensity of the transmitted signal and / or the intensity of the average value of the measured signal and / or the threshold curve and / or the higher threshold curve and / or the parameters and / or measurements of the evaluation algorithm, and their parameters for the monitoring function and / or evaluation parameters for detecting the characteristic features of the measured signal. Furthermore, as an optional step, a measurement point may be specified or adjustments may be made.

[0107] In the third step 703, the level measuring device operates at a correspondingly higher quality level in the commissioning mode. In other words, in addition to determining the actual level, the level measuring device also periodically checks the quality and / or characteristics of the measurement signal at a higher quality level through monitoring functions in the commissioning mode, so as to determine the level at a higher quality level.

[0108] In step 704, reference measurements for commissioning are performed, where, for example, five different levels of the medium in a container are actually set or reached, and the level measuring device determines the corresponding levels sequentially. If necessary, in the event of a fault message, the parameter values ​​used by the level measuring device to determine the level are modified based on the results of the monitoring function at a higher quality level, so that the level of the medium can be reliably determined in the operating mode, i.e., reliably determined at a lower quality level. Here, the selected quality level of the monitoring function and the detected faults are provided through a graphical user interface such as a display or at the interface. The reliable operation of the level measuring device in the operating mode can be checked by comparing the corresponding level with the corresponding output signal of the level measuring device. If necessary, step 704 can be repeated to reconfigure the level determination using new parameter values ​​(e.g., by modifying the emission intensity or adjusting the signal processing) so that commissioning is successfully completed in step 705 when commissioning is performed again.

[0109] In step 706, as an optional step of the method, it is possible to prevent alteration of the parameters of the level measuring device used to determine the level. Particularly for safety-critical applications of the level measuring device, it is recommended, for example, to use a password or PIN to protect the level measuring device from unauthorized access, thereby preventing alteration of the level measuring device's parameters and protecting the parameterization from being changed.

[0110] In step 707, the operating mode of the level measuring device for the current operation is selected, in which the monitoring function operates at a lower quality level. That is, for safety reasons, the monitoring function is still activated, but its operating sensitivity is lower than that during commissioning. Therefore, as during commissioning, manual intervention should be eliminated.

[0111] Cross-references to related applications

[0112] This application claims priority to European Patent Application No. 22,168,889.8, filed on April 19, 2022, the entire contents of which are incorporated herein by reference.

Claims

1. A level measuring device for determining the level of a medium, comprising an evaluation unit configured to: A measurement signal is generated based on a digitally converted signal of a reflected signal emitted from the level measuring device toward the medium, so as to determine the level based on the characteristic features of the measurement signal. The level of the medium is determined based on the characteristic features of the measured signal, and In addition to determining the level, the quality or accuracy of the level determination based on the aforementioned characteristics is monitored through a monitoring function to determine whether the measurement task for determining the level has been reliably resolved. in, The monitoring function, in determining the level, selectively has either a higher or lower quality level. The evaluation unit is configured to selectively determine the level of the medium in either an operating mode or a commissioning mode, wherein the quality level of the monitoring function in the operating mode differs from the quality level of the monitoring function in the commissioning mode. In the commissioning mode, the evaluation unit is configured to perform reference measurements of the level at different levels of the medium using the monitoring function at the higher quality level, and to compare the correlation between each level and the corresponding output signal of the level measuring device to check the reliable operation of the level measuring device. In the operating mode, the evaluation unit is configured to run the monitoring function at the lower quality level.

2. The level measuring device according to claim 1, wherein, The level measuring device is based on the determination of the propagation time of the transmitted signal.

3. The level measuring device according to claim 1, wherein, The level measuring device is a radar level measuring device, an ultrasonic level measuring device, or a guided radar level measuring device.

4. The level measuring device according to any one of claims 1-3, wherein, The evaluation unit is configured to switch between the operating mode and the commissioning mode using a switching signal provided to the level measuring device.

5. The level measuring device according to any one of claims 1-3, wherein, The monitoring function is configured to periodically check the quality of the measurement signal and / or the characteristic feature and / or the evaluation of the characteristic feature to determine the level.

6. The level measuring device according to any one of claims 1-3, wherein, The monitoring function or the evaluation unit is configured to indicate errors and / or warnings when the measurement or determination of the level is determined to be unreliable, and / or adjust the parameters used to determine the level.

7. The level measuring device according to any one of claims 1-3, configured to check the level accordingly at the selected higher quality level during commissioning of the level measuring device when it is close to a defined level, using the monitoring function.

8. The level measuring device according to claim 7, wherein, In the operating mode of the level measuring device, the lower quality level of the monitoring function is activated so that the parameters used to determine the level during the commissioning are adapted to the operating mode.

9. The level measuring device according to any one of claims 1-3, wherein, The monitoring function includes at least one monitoring sub-function, which selectively has a higher quality level and a lower quality level, respectively, so as to achieve the quality level of the monitoring function based on the selected quality level of the corresponding monitoring sub-function.

10. The level measuring device according to claim 9, wherein, The evaluation unit is configured to generate an error signal to indicate an incorrect determination of the level if at least one of the monitoring sub-functions generates an error signal when monitoring the determination of the level according to the selected quality level of the monitoring function.

11. The level measuring device according to claim 9, wherein, The evaluation unit is configured to: realize the quality level of the monitoring function based on a plurality of monitoring sub-functions for determining the characteristic features of the level, and / or generate an error signal based on a plurality of monitoring sub-functions for detecting deviations in the determination of the characteristic features of the level, to indicate an incorrect determination of the level.

12. The level measuring device according to claim 9, configured to check the corresponding level via a monitoring function having multiple monitoring sub-functions during commissioning of the level measuring device when approaching a defined level, wherein, The number of monitoring sub-functions used during the commissioning of the level measuring device is greater than the number of monitoring sub-functions used in the operating mode of the level measuring device.

13. The level measuring device according to claim 9, wherein, It allows you to select a higher or lower quality level for each corresponding monitoring sub-function.

14. The level measuring device according to claim 9, wherein, The first sub-function of the monitoring function for determining the detection reliability of the characteristic feature monitors the amplitude of the characteristic feature in the measurement signal caused by the level of the medium, and wherein, compared with the lower quality level, the first sub-function monitors whether the amplitude of the characteristic feature exceeds a higher threshold or applies a higher threshold curve at the higher quality level.

15. The level measuring device according to claim 9, wherein, Based on a model-based worst-case scenario of the measurement signal of the next measurement, a second sub-function of the monitoring function predicts the next characteristic feature in the measurement signal for the characteristic feature caused by the level of the medium to determine the prediction of detection reliability, wherein the second sub-function monitors the amplitude of the next characteristic feature caused by the level of the medium and / or the distance between the amplitude of the next characteristic feature and a threshold curve at the lower quality level, and monitors a higher amplitude and / or applies a higher threshold curve at the higher quality level compared to the lower quality level.

16. The level measuring device according to claim 9, wherein, The third sub-function of the monitoring function for the characteristic feature caused by the level of the medium monitors the difference between the amplitude of at least one significant feature in the measurement signal caused by further reflection of the transmitted signal and the amplitude of the characteristic feature, and wherein the third sub-function monitors a larger difference between the amplitude of the characteristic feature and the amplitude of the at least one significant feature in the measurement signal at the higher quality level compared to the lower quality level of the third sub-function.

17. The level measuring device according to claim 9, wherein, The fourth sub-function of the monitoring function for the characteristic feature caused by the level of the medium monitors the occurrence of at least one salient feature in the measurement signal to assist in identifying the characteristic feature of the level, and wherein, compared to the lower quality level of the fourth sub-function, the fourth sub-function monitors a greater distance between the characteristic feature of the level and the at least one salient feature in the measurement signal and / or a greater difference in amplitude between the characteristic feature and the at least one salient feature at the higher quality level.

18. A method for debugging a level measuring device, in, The level measuring device includes an evaluation unit that uses a monitoring function to monitor the determination of level based on characteristic features in a measurement signal, wherein the monitoring function selectively has at least a high quality level or a low quality level when determining the level, wherein the evaluation unit is configured to, in addition to determining the level, also monitor the quality of the level determination based on the characteristic features through the monitoring function to determine whether the measurement task for determining the level has been reliably resolved; wherein the monitoring function is configured to periodically check the quality of the measurement signal and / or the characteristic features and / or the evaluation of the characteristic features to determine the level; and wherein the monitoring function or the evaluation unit is configured to indicate errors and / or warnings when the measurement or determination of the level is determined to be unreliable, and / or adjust the parameters used to determine the level, the method comprising: Activate the monitoring function used to determine the level; Select the higher quality level of the monitoring function; The level measuring device performs reference measurements of the level in the commissioning mode using the monitoring function at the higher quality level at different levels of the medium. Compare the correlation between the corresponding material level and the corresponding output signal of the material level measuring device to check reliable operation; Select the lower quality level of the monitoring function to put the level measuring device into operation in the operating mode.

19. The method according to claim 18, wherein, The level measuring device is configured to adjust parameters for determining the level, and the method further includes: The parameters used to determine the level are adjusted to optimize the correlation between the corresponding level and the corresponding output signal of the level measuring device.

20. The method according to claim 18 or 19, wherein it is performed by the level measuring device according to any one of claims 1 to 17.

21. The use of the level measuring device according to any one of claims 1 to 17 for detecting the level of a medium and / or for process control.

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