SYSTEMS AND METHODS FOR RECALIBRATING A MEASUREMENT INSTRUMENT

Systems and methods are provided for recalibrating a measurement instrument that includes a transducer coupled to a signal conditioning module. During an initial calibration of the measurement instrument, a transducer signal is recorded and stored to a non-transitory storage medium. During recalibration, the transducer is electrically disconnected from the signal conditioning module, and the recorded transducer signal is retrieved from the non-transitory storage medium and injected into the signal conditioning module to generate a measurement output. The measurement output may then be compared with a calibrated measurement to determine if the measurement instrument is out of calibration.

TECHNICAL FIELD

The technology described herein relates generally to measurement instruments recalibration.

BACKGROUND

The periodic recalibration of a measurement instrument, such as a flow meter, typically requires the instrument to be removed from the system in which it is being used and sent to a recalibration facility for comparison against a certified measurement standard. This process is often costly both in terms of the price for recalibration services and the time that the instrument is out of service while out for recalibration.

SUMMARY

Systems and methods are provided for recalibrating a measurement instrument that includes a transducer coupled to a signal conditioning module. During an initial calibration of the measurement instrument, a transducer signal is recorded and stored to a non-transitory storage medium. During recalibration, the transducer is electrically disconnected from the signal conditioning module, and the recorded transducer signal is retrieved from the non-transitory storage medium and injected into the signal conditioning module to generate a measurement output. The measurement output may then be compared with a calibrated measurement to determine if the measurement instrument is out of calibration.

A device for recalibrating a measurement instrument may include a processor configured to retrieve a recorded transducer signal from a non-transitory storage medium, wherein the recorded transducer signal is stored to the non-transitory storage medium during an initial calibration of the measurement instrument. The device may further include an output port configured to be coupled to the input port of a signal conditioning module of the measurement instrument in place of a transducer. The processor may be further configured to cause the recorded transducer signal to be injected from the output port into the signal conditioning module, whereby the recorded transducer signal causes the signal conditioning module to generate a measurement output for use in recalibrating the measurement instrument with reference to a calibrated measurement.

DETAILED DESCRIPTION

FIG. 1is a diagram of an example measurement instrument100that may be recalibrated using the systems and methods described herein. The example measurement instrument100includes a signal conditioning module102that is coupled to a transducer104. The transducer104receives a physical stimulus and generates a transducer signal in response to one or more physical parameters of the stimulus. For instance, in one example the transducer104may be a flow transducer that generates a transducer signal that is proportional to the flow velocity of a liquid or gas flowing through the transducer. In other examples, the transducer104may be responsive to other physical parameters, such as pressure, temperature, etc.

The signal conditioning module102receives the transducer signal through an electrical connection106to the transducer104. The electrical connection106may, for example, be any suitable type of connector, assembly, or circuitry that enables the transducer104to be electrically disconnected from and reconnected to the signal conditioning module102. The signal conditioning module102converts the transducer signal into a format that may be displayed or otherwise processed by the measurement instrument. For instance, an example signal conditioning module102may include amplification, analog-to-digital conversion and/or other circuitry suitable for converting the transducer signal into a desirable format for display or further processing. In certain examples, the signal conditioning module102may include a digital or analog display for displaying a measurement output.

In different examples, the measurement instrument100illustrated inFIG. 1may be a vortex flow meter, a magnetic flow meter, a CiDRA passive flow meter, an ultrasonic flow meter, a temperature transmitter with one or more well quantified transducers, or other type of measurement instrument with one or more discrete transducers. In embodiments, the measurement instrument100includes one or more transducers104that either do not have a degradation mechanism that would affect the accuracy of the measurement, or that have a statistically quantified degradation mechanism which may affect the accuracy of the measurement but can be accounted for with a known amount of uncertainty during recalibration.

FIG. 2is a diagram illustrating an example recalibration device200for recalibrating the measurement instrument100shown inFIG. 1. As shown, to utilize the recalibration device200, the transducer104is electrically disconnected from an input port of the signal conditioning module102, and an output port of the recalibration device200is electrically connected to the input port of the signal conditioning module102in place of the transducer104. For instance, in one example, a wire assembly connecting the signal conditioning module102to the transducer104may be disconnected from the transducer104and reconnected to the recalibration device200.

In operation, the recalibration device200is used to inject one or more stored transducer signals into the signal conditioning module102. The measurement(s) resulting from injection of the one or more stored transducer signals into the signal conditioning module102is then compared against one or more calibrated measurements to determine if the measurement instrument102,104is out of calibration. If out of calibration, the measurement instrument may be adjusted accordingly, and the process repeated until the measurement(s) resulting from injection of the one or more stored transducer signals match the calibrated measurement(s). For instance, in some examples the measurement(s) resulting from injection of the one or more stored transducer signals may be used to calculate one or more correction constants that are used to adjust the signal conditioning module.

In embodiments, the one or more stored transducer signals used during the recalibration process may be recorded during an initial calibration of the measurement instrument100. For instance, prior to being sold or deployed into the field, the measurement instrument100may be subject to a standard calibration procedure in which the measurement instrument100is subjected to a range of physical parameters and the resultant measurements are compared against and calibrated to a certified calibration standard(s). During this initial calibration procedure, the transducer signal(s) generated by the measurement instrument100may be recorded and stored with reference to the corresponding measurement(s) from the certified calibration standard(s).

As illustrated inFIG. 2, the stored transducer signal(s) from the initial calibration procedure may, for example, be stored to a local storage medium202and loaded into the memory of a recalibration device200or may be stored in a network storage medium204(such as cloud storage) and loaded to the recalibration device200via a wired or wireless network connection. The recalibration device200may then use the stored transducer signal(s) for recalibration by injecting the stored transducer signal(s) into the signal conditioning module102and comparing the resultant measurement(s) against the corresponding stored measurement(s) from the certified calibration standard(s).

FIGS. 3 and 4are block diagrams illustrating an example system and method for recalibrating a measurement instrument. More specifically,FIG. 3illustrates an example system and method300for storing calibration data during an initial calibration of the measurement instrument, andFIG. 4illustrates an example system and method400for using the stored calibration data for recalibrating the measurement instrument.

With reference first toFIG. 3, the illustrated example300shows the initial calibration of a measurement instrument302using a certified calibration standard304(i.e., another measurement instrument that has been certified to be calibrated to the applicable standard(s)). During the initial calibration, both measurement instruments302,304are subjected to one or more physical parameters306that the instruments are designed to measure. The resultant measurements307,308are compared and used for calibration of the measurement instrument302in the standard fashion. During this calibration process, the transducer signal(s)310generated by the instrument under calibration302is recorded and stored to a storage device312. In addition, calibrated measurement(s)308from the certified calibration standard304are also stored in the storage device312in relation to the corresponding transducer signal(s)310. For instance, in one embodiment, the recorded transducer signal(s)310and calibrated measurement(s)308may be related in a stored data structure314by storing the data308,310along with a corresponding time stamp(s), such that the transducer signal(s)310is matched with a calibrated measurement(s)308from the same instant in time. In embodiments, the transducer signal(s)310and calibrated measurement(s)308may be stored using a recording device or system, for example as described below with reference toFIGS. 5 and 7.

The illustrated example300shows a stored calibration data file having a data structure314that includes two recorded transducer signals (A and B) and two corresponding calibrated measurements (X and Y). It should be understood, however, that other examples could include more or fewer recorded signals and corresponding calibrated measurements. In addition, other examples may include measurement instruments302,304that generate measurements307,308in response to more than one transducer signal, and thus the stored calibration data file314may include calibrated measurements that correspond to two or more recorded transducer signals. In addition, in alternative embodiments, the stored calibrated measurement may be obtained from the measurement307of the instrument under calibration302(illustrated by the dotted arrow inFIG. 3), or the measurement307may be stored in the storage medium312along with the calibrated measurement308for comparison or other purposes during recalibration.

With reference now toFIG. 4, the illustrated example400shows the stored calibrated data file314, which was captured during initial calibration, being used to recalibrate the measurement instrument302after it has been deployed in the field. During recalibration400, the recorded transducer signal(s)402stored in the data file314is injected into the signal conditioning module404of the measurement instrument302to generate an instrument measurement output406. The stored calibration measurement408corresponding to the injected transducer signal402is then compared410to the instrument measurement output406to determine if the measurement instrument302is out of calibration. If out of calibration, appropriate calibration adjustments412are made to the measurement instrument302until the instrument measurement406matches the calibrated measurement408. For example, in certain embodiments, a difference between the stored calibration measurement408and the instrument measurement output406may be used to generate one or more calibration constants for adjusting the signal conditioning module404. Calibration constants may, for example, include a zero off-set, a slope and zero off-set, or a multi-point piecewise linearization.

In embodiments, the calibrated data file314may be stored in a storage medium and loaded into the memory of a recalibration device, for example as described above with reference toFIG. 2. In other embodiments, however, the data file314may be stored and injected into the signal conditioning module404of the measurement instrument302using other mechanisms, for example as described below with reference toFIGS. 10-12.

The illustrated example shows the injection of a single recorded transducer signal (A)402and a comparison410of the resultant instrument measurement406with a single stored calibration measurement (X)408. It should be understood, however, that other examples could include the injection of multiple recorded transducer signals (such as recorded transducer signals corresponding to a range of physical parameters that the instrument is designed to measure) and the comparison of the resultant instrument measurements406with multiple corresponding calibration measurements408. In addition, other examples may include an adjustment to the instrument measurement406prior to comparison410with the calibrated measurement408to account for any known statistically quantified degradation of the transducer(s) in the measurement instrument302being recalibrated.

FIGS. 5 and 6are block diagrams showing another example of a system for recalibrating a measurement instrument.FIG. 5depicts an example system500for recording a transducer signal during an initial calibration.FIG. 6depicts an example system600for using the recorded transducer signal to recalibrate the measurement instrument after it has been deployed in the field.

With reference first toFIG. 5, the illustrated system500includes a measurement instrument502under calibration, a recording device504, and a storage medium506. The measurement instrument502includes a transducer508and a signal conditioning module (not shown). The recording device504includes an analog-to-digital converter510and a processor512.

The measurement instrument502, as a complete unit, is subjected to a standard calibration by subjecting it to a full range of parameters514that the instrument is designed to measure while simultaneously recording its transducer signal, as well as the measurements515from a certified calibration standard(s) being subjected to the same parameters. During calibration, when the applied parameter514is deemed stable for calibration, the recording device504may be activated, for example using a digital command516. The digital command516may, for example, be generated by a user interface device, an external software input, an internal software signal from the measurement instrument502, or from another suitable source of digital commands. The command516instructs the processor512to initiate a recording sequence.

In the illustrated example, a recording sequence begins with the input command516being processed by the processor512, which commences an analog-to-digital signal conversion using the analog-to-digital converter (ADC)510. The analog-to-digital conversion may, for example, be initiated by the processor512sending a time synchronized digital command. The ADC510then begins converting the analog signal from the transducer508and returning a digital signal as a data stream to the processor512for timestamping and storage of the data stream. The ADC510samples and converts the transducer signal from an analog signal to a digital signal at a fixed sample rate and resolution, which may vary based on the requirements of the measurement instrument.

The processor512timestamps the received digital transducer signals and stores the digital transducer signals in the storage medium506in real time. As shown, the processor512may also receive measurements515from the certified calibration standard(s) and store the calibrated measurements in the storage medium506in relation to the corresponding transducer signals. The stored calibration data file may, for example, be identified by the starting time of the recording. The calibration data file may be archived after the recording sequence has ended, and represents the appropriate certified standard's reading derived for each data set recorded. The storage medium506may be a remote or local non-transitory storage medium. Examples of a remote storage medium506include an edge network storage and a cloud storage. A local storage medium506may, for example, include a variety of forms of digital storage devices.

The recording sequence ends when a digital command516is transmitted to the processor512to terminate the recording process. The processor512subsequently sends a digital command to the ADC510to stop further sampling and conversion, and the calibration data file is appropriately saved.

With reference now toFIG. 6, the illustrated system600includes a recalibration device602, as well as the measurement instrument502and storage medium506. The recalibration device602includes a processor604and a digital-to-analog converter606. The measurement instrument502includes a signal conditioning module608and a transducer (not shown).

During recalibration, a measurement instrument502is typically subjected to the full range of parameters that the instrument is designed to measure. The stored calibration data506(recorded by the system ofFIG. 5), however, enables periodic recalibrations to be performed without the need for a physical certified calibration standard or the need to generate the appropriate range of physical parameter(s). During this recalibration process600, the recalibration device602is used to inject the previously recorded transducer signal from the storage medium506into the signal conditioning module608, mimicking the transducer.

During recalibration, the measurement instrument602may be left in service, with the recalibration device602being used to inject the previously recorded data. In different embodiments, the recorded transducer signal may be injected into the measurement instrument502by connecting the recalibration device602to the signal conditioning module608in place of a disconnected transducer (e.g., as shown inFIG. 2), by connecting recalibration device602between the signal conditioning module608and the transducer (e.g., as shown inFIG. 10), by connecting the recalibration device602to an additional transducer input to the signal conditioning module608(e.g., as shown inFIG. 11), by utilizing a recalibration device602embedded within the measurement instrument502(e.g., as shown inFIG. 12), or by another suitable mechanism.

In the illustrated example, the injection of stored transducer signals by the recalibration device602is activated/deactivated using a digital command610. The digital command610may for example, be generated by a user interface device (e.g., a touchscreen display or other user interface device on the recalibration device), an external software input, an internal software signal from the measurement instrument502, or from another suitable source of digital commands. The digital command610instructs the processor604in initiate the signal injection sequence. In one embodiment, the recalibration procedure may be remotely actuated using a digital command610received through a wired or wireless connection to the recalibration device602. During a remotely actuated recalibration, the stored calibration data506may, for example, be transmitted to the recalibration device from a remote storage location or may be retrieved by the recalibration device from a cloud or edge network storage location

The signal injection sequence begins with the processor604processing the digital command610and selecting a calibration data file from the storage medium506that represents the desired transducer signal. The processor604sends the calibration file data to the digital-to-analog converter (DAC)606for conversion into an analog signal. Instructed by the processor604, the DAC606converts the calibration file data into an analog signal based on the included timestamp information, and injects the analog signal into the signal conditioning module608. The analog signal may be generated at the same sample rate and resolution to avoid loss in signal integrity. The output of the signal conditioning module608is then compared against the stored certified calibration measurements for the given data set506in order to make any necessary calibration adjustments to the measurement instrument502.

In certain embodiment, the components of the recording device504ofFIG. 5and the recalibration device602ofFIG. 6may be included in a single device, which may be used for both recording and recalibration. Other embodiments, however, may use difference devices for recording and for recalibration.

FIGS. 7 and 8are block diagrams showing an additional example of a system for recalibrating a measurement instrument. The example recalibration system illustrated inFIGS. 7 and 8is similar to the system depicted inFIGS. 5 and 6, but is modified to record and inject multiple simultaneous transducer signals. Specifically,FIG. 7depicts an example system700for recording multiple simultaneous transducer signals during an initial calibration, andFIG. 8depicts an example system800for using the multiple recorded transducer signals to recalibrate the measurement instrument after it has been deployed in the field.

With reference first toFIG. 7, the illustrated recording system700includes a master processor702that controls a plurality of recording sub-systems704,706,708. Each recording sub-system704,706,708includes a slave processor710and an analog-to-digital convertor712. Each recording sub-system704,706,708receives an analog transducer signal714from different ones of multiple transducers included in the measurement instrument under calibration. In other embodiments, multiple analog transducer signals714may be generated by a single transducer in a measurement instrument. For simplicity, the measurement instrument is not shown inFIG. 7.

As described above with reference toFIG. 5, the measurement instrument under calibration is subjected to a standard calibration by subjecting the measurement instrument and a certified calibration standard to a range of parameters. When the applied parameters are deemed stable for calibration, the recording system700may be activated by a digital command716that instructs the master processor702to start data recording. The digital command716may, for example, be generated by a user interface device, an external software input, an internal software signal from the measurement instrument, or from another suitable source of digital commands.

The master processor702transmits the start recording command to the slave processors710along with a reference clock time. The slave processors710then begin converting the received analog transducer signals714into digital transducer signals and storing the digital transducer signal data to a storage medium(s)718along with corresponding timestamp data, as described above with reference toFIG. 5. More specifically, the slave processors710initiate the analog-to-digital conversion, for example by sending time synchronized digital commands to the analog-to-digital converters714. The ADCs714then convert the analog transducer signals714and return digital transducer signals as data streams to the slave processors710. The slave processors710timestamp the received digital transducer signals and store them to the storage medium(s)718in real time. Although not shown inFIG. 7for simplicity, the slave processors710may also receive measurements from the certified calibration standard(s) and store the calibrated measurements in the storage medium(s)718in relation to the corresponding transducer signals. The recording sequence ends when a digital command716is received by the master processor702and forwarded to the slave processors710, which instruct the ADCs712to stop further sampling and conversion and save the calibration data file(s). The stored calibration file(s) may be identified by the starting time of the recordings and may be archived after the recording sequence has ended.

In different embodiments, the recording system700may store the calibration file(s) in a single or multiple data storage media718. The storage media718may be remote or local non-transitory storage. Examples of remote storage media include edge network storage and cloud storage. Examples of local storage media may include a variety of forms of digital storage devices.

With reference now toFIG. 8, the illustrated recalibration system includes a master processor802that controls multiple recalibration sub-systems804,806,808. Each recalibration sub-system804,806,808includes a slave processor810and a digital-to-analog convertor (DAC)812. Each recalibration sub-system804,806,808is used to inject one of multiple recorded transducer signals into the signal conditioning module of the measurement instrument under recalibration, mimicking the instrument's transducers. The measurement instrument under recalibration is not shown inFIG. 8for simplicity.

During recalibration, the measurement instrument may be left in service, with the recalibration system800being used to inject the previously recorded data into the signal conditioning module. The recorded transducer signals are injected into the measurement instrument by electrically connecting the analog output814of each recalibration sub-system804,806,808to multiple transducer inputs to the signal conditioning module. In an embodiment, the recalibration system outputs814may be connected to the signal conditioning module in place of disconnected transducers. In other embodiments, however, the recalibration system800may be included in a device that is connected between the measurement instruments transducers and signal conditioning module, or may be embedded within the measurement instrument.

In the illustrated example, the injection of stored transducer signals by the recalibration system800is activated/deactivated using a digital command816received by the master processor802. The digital command816may, for example, be generated by a user interface, an external software input, an internal software signal from the measurement instrument, or from another suitable source of digital commands. To initiate recalibration, the master processor802receives the digital command816to commence data injection and transmits the command to the slave processors810along with a reference clock time.

The slave processors810select one or more calibration data files from the storage media718that represent the desired transducer signals. The slave processors810then initiate the digital-to-analog conversion, sending the stored digital transducer data to the DACs812for conversion into analog transducer signals814. Instructed by the slave processors810, the ADCs812convert the calibration file data into analog signals814based on the included timestamp information, and inject the analog signals814into the signal conditioning module (not shown). The transducer signal814output from each recalibration sub-system804,806,808is synchronized with the other slave processors810for simultaneous, synchronous injection into the signal conditioning module, to ensure that no phase shifts in signals are introduced due to timing errors.

The output of the signal conditioning module is then compared against the stored certified calibration measurements for the given data set in order to make any necessary calibration adjustments to the measurement instrument.

In embodiments, the components of the recording system700ofFIG. 7may be included in a single recording device, and the components of the recalibration system800ofFIG. 8may be included in a single recalibration device. In certain embodiments, the components of the recording system700ofFIG. 7and the recalibration system800ofFIG. 8may be included in a single device that is used for both recording and recalibration. It should also be understood that although three sub-systems are illustrated in the examples shown inFIGS. 7 and 8, other embodiments may include more or less sub-systems to accommodate measurement instruments with more or less transducers.

FIG. 9is a flow diagram of an example method900for recalibrating a measurement instrument that includes a signal conditioning module and a transducer. The illustrated method900may, for example, be implemented using one or more of the systems described herein. At902, the transducer of the measurement instrument is electrically disconnected from the signal conditioning module. At904, a stored transducer signal is retrieved from a non-transitory storage medium, where the stored transducer signal is recorded during an initial calibration of the measurement instrument. At906, the recorded transducer signal is injected into the signal conditioning module to generate a measurement output. At908, the measurement output is compared with a calibrated measurement. At910, one or more parameters of the measurement instrument are adjusted based on the comparison between the measurement output and the calibrated measurement.

FIG. 10illustrates an example recalibration device1000that is connected between the signal conditioning module1010and transducer1020of a measurement instrument. In this example, the recalibration device1000includes switching circuitry (not shown) that is used to electrically disconnect the transducer1020from the signal conditioning module1010during a recalibration procedure, and inject recorded transducer signals into the signal conditioning module1010for recalibration using the methods described herein.

FIG. 11illustrates an example embodiment in which the recalibration device1100and transducer1110are connected to different input ports of the signal conditioning module1120of a measurement instrument. In this example, the recalibration device1100includes switching circuitry (not shown) that is used to electrically isolate the transducer1110from the signal conditioning module1120during a recalibration procedure and inject recorded transducer signals into the signal conditioning module1120for recalibration using the methods described herein.

FIG. 12illustrates an example embodiment in which the recalibration device1200is embedded within the signal conditioning module1210of the measurement instrument. Similar to the example shown inFIG. 10, this example recalibration device1200may include switching circuitry (not shown) that is used to electrically disconnect the transducer1220from the signal conditioning module1210during the recalibration procedure, and inject recorded transducer signals into the signal conditioning module1210for recalibration using the methods described herein. The recorded transducer signals may, for example, be stored in a memory device within the signal conditioning module1210or embedded recalibration device1200, or may be stored remotely, for example using cloud or other network storage.

In certain embodiments, the example recalibration devices illustrated inFIGS. 10-12may also be used for recording calibration data during the initial device calibration using the systems and method described herein.