阅读说明：本技术 用于校准测量值的装置和方法 (Device and method for calibrating measured values ) 是由 马蒂亚斯·克吕勒 托斯滕·林德纳 于 2021-04-19 设计创作，主要内容包括：示出了具有输入端、模数转换器和处理器的装置,所述输入端设置用于读入模拟信号,所述模数转换器设置用于将模拟信号转换为数字值,所述处理器设置用于确定数字的测量值。此外,所述处理器设置成,借助于线性的校准函数从所述数字值得出已校准的数字值,并且借助于非线性的测量函数从所述已校准的数字值得出数字的测量值。作为对校准信号的反应,所述处理器基于算法和一定数量的预定的比较测量值改变所述线性的校准函数,所述算法基于所述非线性的测量函数。(An arrangement is shown with an input provided for reading in an analog signal, an analog-to-digital converter provided for converting the analog signal into a digital value, and a processor provided for determining a digital measured value. Furthermore, the processor is configured to derive a calibrated digital value from the digital value by means of a linear calibration function and to derive a digital measured value from the calibrated digital value by means of a non-linear measurement function. In response to a calibration signal, the processor varies the linear calibration function based on an algorithm based on the non-linear measurement function and a number of predetermined comparison measurements.)

1. An apparatus (130) for calibrating measurements, comprising:

an input (134) provided for reading in an analog signal;

an analog-to-digital converter (300) arranged to convert the analog signal to a digital value; and

a processor (800) arranged to determine a numerical measurement value;

wherein the processor (800) is designed to derive a calibrated digital value from the digital value by means of a linear calibration function (k (x)); and is

Wherein the processor (800) is designed to derive a digital measured value from the calibrated digital value by means of a non-linear measuring function (m (y));

it is characterized in that the preparation method is characterized in that,

the processor (800) is designed to change the linear calibration function (k (x)) as a reaction to the calibration signal based on an algorithm based on the non-linear measurement function (m (y)) and a number of predetermined comparison measurements.

2. The device (130) of claim 1, wherein the comparison measurement comprises two analog signals corresponding to known measurements (970, 980).

3. The apparatus (130) of claim 2, wherein the changing comprises iteratively adjusting the calibration function (k (x)).

4. The apparatus (130) of claim 3, wherein the iterative adjusting is interrupted in the following case:

a predetermined number of steps is reached, or the deviation between the known measured values and the measured values (972, 982) calculated by applying the adjusted calibration function (k (x)) meets a specific criterion; or

A request for an interrupt is received.

5. The device (130) according to claim 4, wherein the processor (800) is designed to change the linear calibration function (k (x)) by determining a first value (a2) in a first procedure and a second value (b2) in a second procedure, by multiplying the value assigned to the analog signal with the first value, by adding the second value to the product of the value and the first value (a2), or by subtracting the second value (b2) from the product.

6. The device (130) according to claim 5, wherein the processor (800) is furthermore designed to determine the value by means of a multiplication of the digital value (x) with a third value (a1) and by means of an addition or subtraction of a fourth value (b 1).

7. An apparatus (130) having

An input circuit (200) for a sensor (150), in particular for a temperature sensor, for outputting an analog voltage,

an analog-to-digital converter, ADU (300), for inputting an analog voltage and outputting a digital value (x),

a first function block (410) for performing a first calibration of the digital value (x) with respect to the ADU (300) based on a first calibration function (k1(x)) for outputting a first calibration value,

a second function block (420) for applying a related second calibration to the first calibration value based on a second calibration function (k2(y)) for outputting a second calibration value,

a third function block (500) to input the second calibration value and to output a physical value of the sensor (150) based on the second calibration value,

a fourth function block (610) for comparing the physical value of the sensor (150) with a predeterminable nominal value and outputting the result of the comparison, an

-a correction function block (620) for changing the second calibration function (k2(y)) of application correlation based on the comparison result.

8. Method for configuring an electronic measurement component located in the field downstream of a sensor (150), which derives calibration values from the sensor signal by means of a linear calibration function (k (x)) and measurement values from the calibration values by means of a non-linear measurement function (m (y)), comprising:

changing (1000) the linear calibration function (k (x)) based on a first sensor signal value and a second sensor signal value, which correspond to known measurement values (970, 980).

9. The method according to claim 8, wherein said changing comprises iteratively adjusting said calibration function (k (x)), said iteratively adjusting being interrupted in case:

either a predetermined number of steps is reached or a deviation between the respective known measured value and the measured value (972, 982) calculated by applying the adjusted calibration function (k (x)) meets a specific criterion; or either

A request for an interrupt is received.

10. The method of claim 8 or 9, wherein the changing comprises determining a first value (a2) and determining a second value (b2), multiplying the first value by a numerical value assigned to the second sensor signal value, adding the second value (b2) to the product of the numerical value and the first value (a2), or subtracting the second value (b2) from the product.

11. Method according to claim 10, wherein the value is determined by means of a multiplication of a third value determined from the second sensor signal value with a fourth value (a1) and by means of an addition or subtraction of a fifth value (b 2).

12. The method of claim 11, wherein the first sensor signal value is zero or corresponds to a minimum absolute output value of the sensor (150).

Technical Field

The invention relates to a device and a method capable of calibrating measured values. More particularly, the present invention relates to an apparatus and method that enables calibration of measurements in the field.

Background

On the production side, the measuring transducer can be calibrated to a specific measured value range and/or a specific measured value. For example, a linear calibration function can be predefined on the production side, which assigns the calibration values to the original values. If an event occurring in the field deviates from the prediction of the calibration implementation for the production side or from the environment applied in the calibration for the production side, it may be necessary or advantageous to adapt the calibration in the field to the event occurring on the user side.

Disclosure of Invention

The first device according to the invention comprises an input provided for reading in an analog signal, an analog-to-digital converter, ADU, provided for converting the analog signal into a digital value, and a processor provided for determining a digital measured value, wherein the processor is designed to derive a calibrated digital value from the digital value by means of a linear calibration function and to derive a digital measured value from the calibrated digital value by means of a non-linear measurement function. Furthermore, the processor is designed to change the linear calibration function as a reaction to the calibration signal based on an algorithm based on the non-linear measurement function and a number of predetermined comparison measurements.

The term "device" as used in the description and claims herein refers in particular to an input/output module, i.e. an I/O module. The term "I/O module" is used within the context of the present description to refer in particular to a module that can be connected in series or already connected in series to a front end, which connects one or more field devices (e.g., sensors and/or actuators) to the front end and, if necessary (via the front end), to a superordinate controller. Furthermore, the term "front end" as used in the context of the present description and claims refers to a component of a modular fieldbus node whose task is to make the data and/or services of an I/O module, which is connected in series on the front end, available via the fieldbus connected to said front end.

Furthermore, the term "input" as used in the description and in the claims refers in particular to an electrical connection, by means of which electrical signals (for example voltage values and/or current values) can be read in (and thus further processed in the device). Further, the concept of "analog-to-digital converter" as used in the specification and claims refers, in particular, to a circuit that determines which of a plurality of value ranges an analog value falls into, and outputs a digital value corresponding to the corresponding value range. The digital values may be output as a bit string, for example.

Furthermore, the term "processor" as used in the description and in the claims refers in particular to a circuit arranged to process instructions from an instruction set assigned to said processor, wherein the order of said instructions (and, if necessary, the arguments assigned to said instructions) is predetermined by an algorithm executed by said processor. Furthermore, the term "non-linear measurement function" as used in the description and in the claims refers in particular to a non-linear assignment rule (e.g. a calculation rule) by means of which measured values can be assigned to digital values. The measured values can be reported quantitatively, for example, by means of physical parameters, such as the temperature at a particular location. The measured value may be, for example, a numerical value provided in digital form by the processor.

Furthermore, the term "calibration signal" as used in the description and in the claims refers in particular to a signal which can be triggered manually, for example by pressing a key on the housing of the device, or which can be received via a data interface and which initiates a calibration procedure.

The comparison measurement may include two analog signals corresponding to known measurements.

For example, a temperature sensor can be connected to the input and subjected (in time succession) to two known temperatures, in order to determine (within the measurement accuracy) the measured values to be generated, and the linear calibration function can be used to reduce or compensate for the deviation.

The changing includes iteratively adjusting the calibration function.

For example, in a step of tapering, the parameters of the calibration function can be adjusted until a sufficient agreement between the generated measured values and the generated physical values is achieved.

The repeated adjustment can be interrupted if a predetermined number of steps is reached, or if the deviation between the respective known measured value and the measured value calculated with the application of the adjusted calibration function meets a certain criterion, or if an interruption request is received.

For example, the iterative adjustment may be interrupted when the deviation is below a measurement accuracy limit of the sensor.

The processor can be designed to change the linear calibration function by determining a first value in a first procedure and a second value in a second procedure, to multiply the first value by a value assigned to the analog signal, to add the second value to the product of the value and the first value, or to subtract the second value from the product.

It is noted herein that the use of ordinal numbers such as "first", "second", etc., in the specification and claims does not determine a temporal order, but merely serve to distinguish one feature from another.

For example, the second value may be determined first in the second flow, followed by the first value in the first flow.

The processor may furthermore be designed to determine the value by means of a multiplication of the digital value with a third value and by means of an addition or subtraction of a fourth value.

The linear calibration function can thus be realized by two functions connected one after the other. For example, the first function can be permanently predefined on the production side and the signal path can be calibrated from the input (i.e. the measurement transducer), whereas the second function calibrates the signal path up to the input and is adjustable in the field.

For example, the sensor may be a resistance temperature sensor or a thermistor, for which a calibration of the signal path to the input may be necessary.

The second device according to the invention has an input circuit for a sensor, in particular for a temperature sensor, and also has an ADU for inputting an analog voltage and outputting a digital value, a first function block for performing a first calibration with respect to the ADU based on a first calibration function for outputting a first calibration value on the digital value, a second function block for performing a second calibration with respect to the first calibration value based on a second calibration function for outputting a second calibration value, a third function block for inputting the second calibration value and outputting a physical value of the sensor based on the second calibration value, a fourth function block for comparing the physical value of the sensor with a predeterminable nominal value and outputting a comparison As a result, the correction function block is configured to change the second calibration function of the application correlation based on the comparison result.

The functional blocks of the functions may be implemented by means of certain hardware, software or by means of a combination of certain hardware and software. The functional blocks are implemented, for example, by means of one or more signal processors.

According to the invention, a method for configuring an electronic measuring component located in the field downstream of a sensor, which electronic measuring component derives a calibration value from the sensor signal by means of a linear calibration function and a measured value from the calibration value by means of a non-linear measuring function, comprises changing the linear calibration function on the basis of a first sensor signal value and a second sensor signal value, which first sensor signal value and second sensor signal value correspond to known measured values.

The changing may comprise repeatedly adjusting the calibration function, the repeated adjustment being interrupted either when a preset number of steps is reached or when a deviation between each known measurement value and a measurement value calculated in case of applying the adjusted calibration function meets a certain criterion; or the iterative adjustment of interrupts upon receiving a request for an interrupt.

The altering may comprise determining a first value and may comprise determining a second value, multiplying the first value by a numerical value assigned to the second sensor signal value, adding the second value to a product of the numerical value and the first value, or subtracting the second value from the product.

The value may be determined by means of a multiplication of a third value determined from the second sensor signal value with a fourth value and by means of an addition or subtraction of a fifth value.

The first sensor signal value may be zero or correspond to the smallest absolute output value of the sensor.

The sensor signal value can be selected, for example, such that the value becomes zero or the absolute value of the value becomes minimal.

It goes without saying that the features already described in connection with the apparatus can also be features of the method and vice versa.

Drawings

The invention is explained in the following detailed description by way of example, wherein reference is made to the accompanying drawings in which:

fig. 1 shows a block diagram of a fieldbus system comprising a plurality of modular fieldbus nodes;

FIG. 2 shows a block diagram of a modular Fieldbus node, which includes a front end and a plurality of I/O modules, and which shows Fieldbus devices connected to the I/O modules;

FIG. 3 shows a block diagram of an I/O module equipped with an electronic measurement component;

FIGS. 4a and 4b show a flow for adjusting the parameters of a linear calibration function; and

fig. 5 shows a process of a method for configuring an electronic measurement component (downstream of a sensor) located in the field.

Identical or functionally similar elements in the figures are denoted by the same reference numerals.

Detailed Description

Fig. 1 shows a block diagram of a fieldbus system. The field bus system 10 comprises a superordinate control unit 20 and modular field bus nodes 100 which are connected to one another (in terms of signaling) via a field bus 30. The superordinate control unit 20 can be used both for monitoring and for controlling devices (not shown) controlled via the field bus system 10. When the superordinate control unit 20 monitors the devices, the superordinate control unit 20 can periodically or aperiodically receive status data from the field bus node 100, which describes the status of the devices and generates an error signal or an alarm signal if the status of the devices deviates (substantially) from a desired/permitted status or status range. When the superordinate control unit 20 controls the device (not only monitors but also) the superordinate control unit 20 can receive status data from the field bus node 100 periodically or aperiodically and determine the control data transmitted to the field bus node 100 taking into account the status data.

Fig. 2 shows a block diagram of a modular fieldbus node. The fieldbus node 100 comprises a front end 110 and two I/O modules 120, 130 cascaded to the front end 110. The sensors and actuators 140, 150, 160, 170 are connected to the I/O modules 120, 130 in terms of signals. During operation, the I/O modules 120, 130 read in sensor signals and generate status data from the sensor signals, which are transmitted to the front end 110 via the local bus 180. The front end 110 is able to process the status data locally and/or (if necessary in a modified form) forward the status data to the superordinate control unit 20. The superordinate control unit 20 (or the front end 110 in the case of local processing) is then able to generate control data taking into account the status data.

The control data generated by the superordinate control unit 20 can then be transmitted via the field bus 30 to (the same or) one (other) front end. The control data transmitted to the front end 110 (or generated by the front end 110) is then forwarded/transmitted (in an improved form if necessary) to the I/O modules 120, 130. The I/O modules 120, 130 receive the control data and output control signals corresponding to the control data at outputs connected to the actuators. The data communication between the components of the field bus system 10, the mapping of the sensor signals to the status data and the mapping of the control data to the control signals can be adapted to different use scenarios by the configuration of the field bus node 100.

Fig. 3 shows a block diagram of a device embodied as an I/O module according to the invention. The I/O module 130 includes inputs 132, 134. Sensor 150 is coupled to I/O module 130 via input 134. The sensor 150 may be, for example, a temperature sensor such as a resistance temperature sensor or a thermistor. Input 134 is coupled to input circuit 200. The input circuit 200 can be designed to apply a defined voltage at the sensor 150 or to generate a defined current through the sensor 150. The input circuit 200 can furthermore be designed to detect the current through the sensor 150 or to tap a voltage drop across the sensor 150 or to generate an analog voltage proportional to said current or voltage drop. The I/O module 130 further includes an ADU 300. The ADU 300 is designed to convert analog voltages to digital values.

The digital values are mapped to calibration values by the calibration function block 400. The calibration function block 400 applies a linear calibration function k (x), i.e. a calibration function of the form k (x) a · x + b, where x represents the value corresponding to the digital value. The calibration function block 400 may comprise function blocks 410, 420, wherein the function block 410 applies a first linear calibration function k1 ═ a1 · x + b1 to the values, and the function block 420 applies a second linear calibration function k2(k1(x)) ═ a2 · k1(x) + b2 to the output values of the function block 410, i.e. the results of the first linear calibration function.

The first linear calibration function k1(x) can be adapted to the ADU 300, for example, so that the result of the first linear calibration function (within the measurement accuracy range) requires no further calibration if the signal path to the input 134 is not disturbed. The second linear calibration function k2(k1(x)) is set accordingly to adapt the electronic measurement components of the I/O module 130 to the signal path to the input 134. Alternatively, only one linear calibration function can be provided without correlating the two linear calibration functions.

The calibration values are mapped to measurement values by the function block 500. The measured value can correspond to a physical variable, such as temperature. The mapping is performed by means of a non-linear measuring function, for example a second or higher order polynomial m (y) d + e · y + f · y2+ …, where y k2(k1 (x)). When a2 and b2 are 0, the non-linear measurement function will yield a correct measurement value when the signal path to the input 134 is not interfering. In the event of a disturbance in the signal path to the input 134, this disturbance can be reduced or compensated by a corresponding selection of a2 and b 2. The I/O module 130 is therefore designed to change the linear calibration function as a reaction to the calibration signal 700 based on an algorithm based on the non-linear measurement function and a number of predetermined comparison measurements.

The I/O module 130 may be equipped with keys 136 and the calibration signal 700 may be triggered by the run initiator via the control keys 136. Alternatively or additionally, the I/O module 130 may also be designed such that the calibration signal 700 can be triggered by the operation initiator when a corresponding message is received by the I/O module 130 (via the local bus 180). If the compare and correct function block 600 receives the calibration signal 700, the compare and correct function block 600 iteratively changes b2 and/or a2 until an interrupt criterion is met or until the run initiator interrupts the process.

The compare and correct function block 600 may include a function block 610 and a correct function block 620. The function block 610 can be provided to compare the measured values with predefinable setpoint values and to output the comparison result. The modification function block 620 may be arranged for changing (applying the relevant) the second linear calibration function k2(k1(x)) based on the comparison result.

The calibration function block 400, the function block 500 and the comparison and correction function block 600 may be implemented by means of deterministic hardware or by means of software executed on the processor 800.

Fig. 4a shows a sequence of two runs for adjusting a2 and b2, wherein in fig. 4b the first run is shown in the first row and the second run is shown in the second row. The first run determines a first comparison value 970 in step 910 and an initial value for b2 in step 920 (e.g., b2 ═ 0). In step 930 b2 is increased. The degree of improvement may be reduced in each step 930. For example, the degree of improvement may be half that in the previous step 930 in each subsequent step 930. Furthermore, there may be a latency (e.g., one second) between the loops.

If the measured value 972 is greater than the compared value 970 detected in decision block 940, then the last increase is withdrawn in step 950. If the maximum number of loops is reached, the flow may be interrupted at step 960. Furthermore, the process may be interrupted when the run initiator receives an interrupt signal. As shown in fig. 4b, the comparison value 970 can be selected such that the slope of the second linear calibration function k2(k1(x)), i.e. a2, has as little influence as possible on the calibration of the "compensation". The comparison value 970 may be selected, for example, such that k1(x) is close to zero (the first row is shown by a circle in fig. 4 b). This may be the case, for example, if the sensor signal value is zero or if it corresponds to the smallest absolute output value of the sensor.

On the second run, a second comparison value 980 is determined in step 910, and an initial value (e.g., a 2-0) is determined for "gain" a2 in step 920. In step 930 a2 is increased. The degree of improvement may be reduced in each step 930. For example, the degree of improvement may be half that in the previous step 930 in each subsequent step 930. Furthermore, there may be a latency (e.g., one second) between the loops.

If in decision block 940 it is detected that the measured value 982 is greater than the comparison value 980, then the last increase is withdrawn in step 950. If the maximum number of loops is reached, the flow may be interrupted at step 960. Furthermore, the process may be interrupted when the run initiator receives an interrupt signal. As shown in fig. 4b, the comparison value 980 may be selected such that the slope of the second linear calibration function k2(k1(x)), i.e. a2, has as great an influence as possible. The comparison value 980 may be selected, for example, such that k1(x) is almost maximal (the second row is shown by a circle in fig. 4 b). This may for example be the case when the sensor signal value is at a maximum.

Fig. 5 shows a process of a method for configuring an electronic measurement component located in the field downstream of the sensor 150. The method comprises a step 1000 of changing the linear calibration function k2(k1(x)) based on two sensor signal values corresponding to the measured values 972, 982.

List of reference numerals

10 field bus system

20 control unit

30 field bus

100 field bus node

110 front end/field bus coupler

120I/O module

130I/O module

132 input terminal

134 input terminal

140 field device

150 field device

160 field device

170 field device

180 local bus

200 input circuit

300A/D converter

400 calibration function block

410 function block

420 function block

500 function block

600 compare and correct function block

610 function block

620 correction function block

700 calibration signal

800 processor

910 step

920 step

930 step

940 decision

950 step

960 decision

970 compare values

972 measured value

980 comparison value

982 measured value

1000 steps.