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CN-113739958-B - Device and method for calibrating measured values

CN113739958BCN 113739958 BCN113739958 BCN 113739958BCN-113739958-B

Abstract

An apparatus is shown having an input arranged to read in an analog signal, an analog-to-digital converter arranged to convert the analog signal into a digital value, and a processor arranged to determine 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 measurement value from the calibrated digital value by means of a non-linear measurement function. In response to the calibration signal, the processor alters the linear calibration function based on an algorithm based on the nonlinear measurement function and a number of predetermined comparison measurements.

Inventors

  • Mathias cluller
  • TORSTEN LINDNER

Assignees

  • WAGO管理有限责任公司

Dates

Publication Date
20260505
Application Date
20210419
Priority Date
20200527

Claims (13)

  1. 1. An apparatus (130) for calibrating measurement values, comprising: An input (134) which is provided for reading in an analog signal; an analog-to-digital converter (300) arranged to convert an analog signal into a digital value, and A processor (800) arranged to determine a digital 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 Wherein the processor (800) is designed to derive a digital measurement value from the calibrated digital value by means of a nonlinear measurement function (m (y)); it is characterized in that the method comprises the steps of, The processor (800) is designed to change the linear calibration function (k (x)) as a response 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. 2. The apparatus (130) of claim 1, wherein the comparison measurement comprises two analog signals corresponding to known measurements.
  3. 3. The apparatus (130) of claim 2, wherein the changing includes iteratively adjusting the calibration function (k (x)).
  4. 4. A device (130) according to claim 3, wherein the iterative adjustment is interrupted in the following cases: The number of steps preset is reached, or the deviation between the known measured values and the measured values calculated by applying the adjusted calibration function (k (x)) meets a specific criterion, or An interrupt request is received.
  5. 5. The apparatus (130) of claim 4, wherein the processor (800) is designed to change the linear calibration function (k (x)) by determining a first value in a first flow and a second value in a second flow, multiplying a value assigned to the analog signal with the first value, adding the second value to a product of the value and the first value, or subtracting the second value from the product.
  6. 6. The device (130) according to claim 5, wherein the processor (800) is furthermore designed to determine the value by means of multiplying the digital value (x) with a third value and by means of adding or subtracting a fourth value.
  7. 7. An apparatus (130) for calibrating measured values has An input circuit (200) for a sensor (150) 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 (k 1 (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 (k 2 (y)) for outputting a second calibration value, A third functional block (500) for inputting the second calibration value and outputting a physical value of the sensor (150) based on the second calibration value, A fourth functional block (610) for comparing the physical value of the sensor (150) with a predefinable target value and outputting the comparison result, and -A correction function block (620) for changing the application-dependent second calibration function (k 2 (y)) based on the comparison result.
  8. 8. The apparatus of claim 7, wherein the sensor (150) is a temperature sensor.
  9. 9. Method for configuring an electronic measurement component located in the field downstream of a sensor (150), which electronic measurement component derives a calibration value from a sensor signal by means of a linear calibration function (k (x)) and derives a measurement value from the calibration value by means of a nonlinear measurement function (m (y)), the method comprising: -changing (1000) the linear calibration function (k (x)) based on a first sensor signal value and a second sensor signal value, the first sensor signal value and the second sensor signal value corresponding to a known measurement value.
  10. 10. The method according to claim 9, wherein the changing comprises iteratively adjusting the calibration function (k (x)), the iteratively adjusting being interrupted in the following case: The number of steps is preset, or the deviation between the known measured values and the measured values calculated by applying the adjusted calibration function (k (x)) meets a specific criterion, or An interrupt request is received.
  11. 11. The method according to claim 9 or 10, wherein the changing comprises determining a first value and determining a second value, multiplying the first value by a value assigned to the second sensor signal value, adding the second value to the product of the value and the first value, or subtracting the second value from the product.
  12. 12. A method according to claim 11, wherein the value is determined by means of multiplication of a third value determined from the second sensor signal value with a fourth value and by means of addition or subtraction of a fifth value.
  13. 13. The method of claim 12, wherein the first sensor signal value is zero or corresponds to a minimum absolute output value of the sensor (150).

Description

Device and method for calibrating measured values Technical Field The present invention relates to an apparatus and method capable of calibrating measurement values. More particularly, the present invention relates to an apparatus and method that enables calibration of measurements in the field. Background The measuring transducer can be calibrated to a specific measuring value range and/or specific measuring values on the production side. For example, a linear calibration function can be predefined on the production side, which assigns calibration values to the original values. If an event that occurs in the field deviates from the prediction of the implementation of a calibration on the production side, or deviates from the environment in which the calibration on the production side is applied, it may be necessary or advantageous to adapt the calibration on the user side in the field to the event that occurs. 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 nonlinear measurement function. Furthermore, the processor is designed to change the linear calibration function as a response 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 herein in the specification and claims refers in particular to an input/output module, i.e. an I/O module. The term "I/O module" as used within the scope of the present specification refers in particular to a module which can be connected in series on the front end or a module which is connected in series on the front end and which connects one or more field devices (for example sensors and/or actuators) to the front end and, if necessary (via the front end), to an upper control unit. Furthermore, the term "front-end" as used in the present description and in the claims refers to a modular assembly of field bus nodes, which has the task of making available the data and/or services of the I/O modules in series on the front-end via the field bus connected to said front-end. Furthermore, the term "input" as used in the description and claims refers in particular to an electrical connection via which electrical signals (for example voltage values and/or current values) can be read in (and thus further processed in the device). Furthermore, the concept "analog-to-digital converter" as used in the description and claims refers in particular to a circuit that determines which of the many value ranges an analog value falls into, and outputs a digital value corresponding to the respective value range. The digital value may be output, for example, as a bit string. Furthermore, the term "processor" as used in the specification and claims refers in particular to a circuit arranged to process instructions from a set of instructions 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 "nonlinear measurement function" as used in the description and in the claims refers in particular to nonlinear allocation rules (e.g. calculation rules) by means of which measured values can be allocated to digital values. The measured values can be reported quantitatively, for example, by means of physical parameters, such as the temperature level at a specific 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 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 can be received via a data interface, and which initiates a calibration procedure. The comparison measurement may comprise 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, so that the measured value to be produced is determined (within the measurement accuracy range), 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 the step of reducing, 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. If a predetermined number of step