# US 11,906,335 B2 · Measuring system and method for measuring a measurement variable of a flowing fluid

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- Number: US 11,906,335 B2
- Document ID: US11906335B2
- Status: Granted
- Kind: B2
- Application number: 17/052,460
- Filed: 2019-04-11
- Published: 2021-05-13
- Granted: 2024-02-20
- Earliest claimed: 2018-05-02
- Assignees: Endress + Hauser Flowtec AG
- Applicants: Endress+Hauser Flowtec AG
- Inventors: Michael Kirst
- Web page: https://patentgrep.com/patent/US11906335B2

## CPC

- G01F 1/00: Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow (measuring a proportion of the volume flow G01F5/00)
- G01F 1/3259: {for detecting fluid pressure oscillations}
- G01F 1/3287: {circuits therefor}
- G01F 1/38: the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule
- G01F 1/42: Orifices or nozzles
- G01F 1/66: by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01F 1/8468: {vibrating measuring conduits}
- G01F 15/00: Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME

## Abstract

A measuring system includes: a lumen forming a flow path and a flow obstruction arranged in the flow path for effecting a disturbance in a flowing fluid; a sensor arrangement adapted to produce a first sensor signal and a second sensor signal; and transmitter electronics. The transmitter electronics are adapted to receive both the first and second sensor signals and to convert such into first and second sensor signal sampling sequences approximating the first and second sensor signals, respectively, the transmitter electronics further adapted using a digital adaptive filter to ascertain from the first sampling sequence a filter coefficients set and therewith to form a z-transfer function for filtering the second sampling sequence such that the z-transfer function is determined by the filter coefficients set, the signal filter and the second sampling sequence to produce a wanted signal sequence, to produce therefrom digital measured values representing a measurement variable.

## Claims

### Claim 1

A measuring system for measuring at least one measurement variable, changeable as a function of time, of a fluid flowing along a flow path with a predetermined flow direction, the measuring system comprising:
a tube arrangement comprising a lumen defining a first portion of the flow path, a second portion of the flow path disposed in a flow direction downstream of the first portion, and a third portion of the flow path disposed in the flow direction downstream of the second portion and a tube wall surrounding the lumen;
a flow obstruction arranged within the tube arrangement in the second portion of the flow path, the flow obstruction configured to effect a disturbance in the flowing fluid, the disturbance dependent on the at least one measurement variable and/or serving as a measurable effect dependent on the at least one measurement variable;
a first sensor arrangement configured to generate a first sensor signal having a first frequency spectrum influenced by the fluid flowing within the first portion;
a second sensor arrangement configured to generate a second sensor signal having a second frequency spectrum influenced by the fluid flowing within the third portion, the second frequency spectrum deviating from the first frequency spectrum and/or including at least one wanted component, the at least one wanted component including a spectral signal component influenced by the at least one measurement variable as regards at least one signal parameter; and
a transmitter electronics including a microprocessor and configured to:
receive the first sensor signal and convert such into a first sensor signal sampling sequence approximating the first sensor signal, the first sensor signal sampling sequence including a first sequence of digital sampled values, defined by SD1[m]=SD1[tm·fs1], using a first sampling rate, defined by fs1=1/(tm+1-tm)=1/Ts1, from the first sensor signal at different sampling points in time, given by tn=n·Ts1;
receive the second sensor signal and convert such into a second sensor signal sampling sequence approximating the second sensor signal, the second sensor signal sampling sequence including a second sequence of digital sampled values, defined by SD2[n]=SD2[tn·fs2] using a second sampling rate, defined by fs2=1/(tn+1-tn)=1/Ts2, from the second sensor signal at different sampling points in time, given by tn=n·Ts2, such that the second sensor signal sampling sequence approximates at least one wanted spectral signal component of the second sensor signal influenced by the at least one measurement variable;
using a digital adaptive filter, ascertain from the first sensor signal sampling sequence a wanted signal filter coefficients set including a set of N filter coefficients;
using the wanted signal filter coefficients set, generate a first z-transfer function of a wanted signal filter, defined as:
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wherein wk are the filter coefficients, the wanted signal filter being a digital filter adapted to filter the second sensor signal sampling sequence such that the first z-transfer function of the wanted signal filter is determined by the wanted signal filter coefficients set;
generate a wanted signal sequence, using the wanted signal filter and the second sensor signal sampling sequence, the wanted signal sequence being a sequence of digital function values defined by:
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to generate from the wanted signal sequence a measured values sequence, being a sequence of digital measured values representing the at least one measurement variable and following one after the other in time.

### Claim 2 (depends on 1)

The measuring system of claim 1, wherein the transmitter electronics is configured to determine the filter coefficients of the wanted signal filter coefficients set using a least mean squares algorithm and/or a recursive least squares algorithm.

### Claim 3 (depends on 1)

The measuring system of claim 1, wherein the transmitter electronics includes a memory configured to store at least the filter coefficients of the wanted signal filter coefficients set.

### Claim 4 (depends on 1)

The measuring system of claim 1, wherein the transmitter electronics is configured to repeatedly calculate a transversal filter coefficients set of M filter coefficients determining a second z-transfer function, defined by:
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of a transversal filter of the digital adaptive filter.

### Claim 5 (depends on 4)

The measuring system of claim 4, wherein the transmitter electronics is configured to ascertain the wanted signal filter coefficients set for the wanted signal filter from the transversal filter coefficients set of the transversal filter.

### Claim 6 (depends on 1)

The measuring system of claim 1, wherein the digital adaptive filter is configured to generate from the first sensor signal sampling sequence an estimated signal sequence, being a sequence of digital function values, defined by:
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calculated from the first sensor signal sampling sequence using a digital transversal filter such that the estimated signal sequence is at least at times equal to or at least approximately equal to the sensor signal sampling sequence or has a minimum of least squares residuals from the sensor signal sampling sequence under a best linear unbiased prediction.

### Claim 7 (depends on 1)

The measuring system of claim 1, wherein the transmitter electronics is configured to ascertain a frequency of the wanted component based on the wanted signal sequence.

### Claim 8 (depends on 1)

The measuring system of claim 1, wherein the at least one measurement variable includes a flow velocity and/or a volume flow rate of the fluid, and wherein the transmitter electronics is configured to determine the flow velocity and/or the volume flow rate of the fluid based on a frequency of the wanted component obtained from the wanted signal sequence.

### Claim 9 (depends on 1)

The measuring system of claim 1, wherein the second portion, or the flow obstruction formed therewith, is adapted to increase a flow velocity of the fluid flowing passed and/or through and/or to lessen a static pressure prevailing in the fluid flowing passed and/or through and/or to effect a pressure difference dependent on a volume flow rate along a measuring path formed by the first, second and third portions.

### Claim 10 (depends on 1)

The measuring system of claim 1, wherein the second portion, or the flow obstruction formed therewith, is adapted to induce vortices in the fluid such that a Kármán vortex street is formed in the fluid flowing downstream of the flow obstruction.

### Claim 11 (depends on 1)

The measuring system of claim 1, wherein the flow obstruction is formed by a diaphragm.

### Claim 12 (depends on 1)

The measuring system of claim 1, wherein the flow obstruction is formed by a prismatic bluff body.

### Claim 13 (depends on 1)

The measuring system of claim 1, wherein the flow obstruction is formed by a nozzle.

### Claim 14 (depends on 1)

The measuring system of claim 1, wherein:
the first sensor arrangement includes a pressure sensor disposed at the first portion; and/or
the second sensor arrangement includes a pressure sensor disposed at least partially at the third portion; and/or
the first sensor arrangement includes a microphone disposed at the first portion; and/or
the second sensor arrangement includes a microphone disposed at least partially at the third portion; and/or
the second sensor arrangement includes a sensor paddle protruding into the third portion; and/or
the first sensor arrangement includes two ultrasonic transducers, both disposed at the first portion; and/or
the second sensor arrangement includes two ultrasonic transducers, both disposed at least partially at the third portion; and/or
the transmitter electronics is electrically connected both with the first sensor arrangement and the second sensor arrangement; and/or
the second portion includes a prismatic bluff body; and/or
the second portion includes a diaphragm; and/or
at least the second portion includes a vibronic measuring transducer; and/or
a smallest distance between the first and third portions amounts to greater than three times a smallest caliber of the tube arrangement; and/or
a smallest distance between the first and third portions amounts to less than ten times a greatest caliber of the tube arrangement.

### Claim 15

A method for measuring at least one measurement variable, changeable as a function of time, of a fluid flowing along a flow path with a predetermined flow direction, the method comprising:
providing the flow path, which includes a first portion, a second portion disposed in the flow direction downstream of the first portion, and a third portion disposed in the flow direction downstream of the second portion, wherein within the second portion a flow obstruction is configured to effect a disturbance in the flowing fluid dependent on the at least one measurement variable and/or a measurable effect dependent on the at least one measurement variable;
enabling the fluid to flow along the flow path such that volume portions of the fluid flow from the first portion to the second portion and then to the third portion, wherein the flow obstruction of the second portion effects the disturbance;
generating a first sensor signal having a first frequency spectrum influenced by the fluid flowing within the first portion;
converting the first sensor signal into a first sensor signal sampling sequence of digital sampled values approximating the first sensor signal obtained from the first sensor signal at different, time-equidistant sampling points in time at a constant sampling rate;
generating a second sensor signal having a second frequency spectrum influenced by the fluid flowing within the second portion and/or within the third portion, wherein the second frequency spectrum deviating from the first frequency spectrum and/or includes at least one wanted spectral signal component influenced by the at least one measurement variable or the disturbance with respect to at least one signal parameter;
converting the second sensor signal into a second sensor signal sampling sequence of digital sampled values approximating the second sensor signal obtained from the second sensor signal at different, time-equidistant sampling points in time at a constant sampling rate, wherein the second sensor signal sampling sequence approximates at least one wanted spectral signal component of the second sensor signal influenced by the at least one measurement variable;
using the first sensor signal sampling sequence and a digital adaptive filter to determine from the first sensor signal sampling sequence at least one wanted signal filter coefficients set, including at least five filter coefficients and/or filter coefficients at least partially differing from one another;
using the wanted signal filter coefficients set to define a first z-transfer function of a wanted signal filter, the first z-transfer function defined as:
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wherein the wanted signal filter is a digital filter configured to filter the second sensor signal sampling sequence such that the first z-transfer function of the wanted signal filter is determined by the wanted signal filter coefficients set, wherein N is the number of filter coefficients, wk, and Ts2 is the sampling period of the second sensor signal;
using the second sensor signal sampling sequence and the wanted signal filter to generate a wanted signal sequence, wherein the wanted signal sequence is a sequence of digital function values calculated from the second sensor signal sampling sequence using the wanted signal filter, the wanted signal sequence; and
generating a measured values sequence from the wanted signal sequence, wherein the measured values sequence is a sequence of digital measured values representing the at least one measurement variable and following one after the other in time.

### Claim 16 (depends on 15)

The method of claim 15, wherein:
the filter coefficients of the wanted signal filter coefficients set are determined using an least mean squares algorithm and/or a recursive least squares algorithm; and/or
at least two of the filter coefficients of the wanted signal filter coefficients set differ from one another; and/or
the wanted signal filter coefficients set, or the wanted signal filter defined therewith, includes five or more filter coefficients; and/or
the sampling rate of the first sensor signal sampling sequence and the sampling rate of the second sensor signal sampling sequence are the same.

### Claim 17 (depends on 15)

The method of claim 15, further comprising recurringly and/or cyclically replacing a wanted signal filter coefficients set previously determined from the first sensor signal sampling sequence and used to determine the first z-transfer function of the wanted signal filter with a subsequent wanted signal filter coefficients set.

### Claim 18 (depends on 17)

The method of claim 17, wherein the replacing of the wanted signal filter coefficients set previously determined with the subsequent wanted signal filter coefficients set is repeated cyclically at an exchange rate such that the exchange rate is lower than the sampling rate of the first sensor signal sampling sequence and/or is lower than the sampling rate of the second sensor signal sampling sequence.

### Claim 19 (depends on 15)

The method of claim 15, wherein the digital adaptive filter comprises a digital transversal filter having a second z-transfer function defined as:
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wherein M is the number of transversal filter coefficients, w1k.

### Claim 20 (depends on 19)

The method of claim 19, further comprising determining the wanted signal filter coefficients set for the wanted signal filter from the transversal filter coefficients set of the transversal filter such that the wanted signal filter coefficients set includes the filter coefficients of the transversal filter coefficients set.

### Claim 21 (depends on 19)

The method of claim 19, further comprising generating an estimated signal sequence using the transversal filter and the first sensor signal sampling sequence, wherein the estimated signal sequence is a sequence of calculated digital function values from the first sensor signal sampling sequence using the digital transversal filter.

### Claim 22 (depends on 21)

The method of claim 21, further comprising:
determining the transversal filter coefficients set from filter coefficients defining the second z-transfer function of the digital transversal filter such that the estimated signal sequence of the first sensor signal sampling sequence approximates or predicts the first sensor signal sampling sequence such that the estimated signal sequence has a minimum of least squares residuals from the first sensor signal sampling sequence; and/or
determining the wanted signal filter coefficients set for the wanted signal filter from the transversal filter coefficients set of the transversal filter when the estimated signal sequence for a predetermined sample, or time, interval equals or at least approximately equals the first sensor signal sampling sequence such that the estimated signal sequence has a minimum of least squares residuals from the first sensor signal sampling sequence.

### Claim 23 (depends on 21)

The method of claim 21, further comprising generating an estimate error sequence in which a deviation between a sampling value of the first sensor signal sampling sequence and a function value of digital function values representing the estimated signal sequence.

### Claim 24 (depends on 23)

The method of claim 23, further comprising generating the estimate error sequence from the first sensor signal sampling sequence such that the digital function values calculated from the first sensor signal sampling sequence correspond to the estimate error sequence using an estimate error function determined by the second z-transfer function of the digital transversal filter using the transversal filter coefficients set.

### Claim 25 (depends on 19)

The method of claim 19, wherein:
the wanted signal filter coefficients set includes all M filter coefficients of the transversal filter coefficients set such that each filter coefficient of the transversal filter coefficients set is adopted as a filter coefficient of the wanted signal filter coefficients set and/or that; and/or
the wanted signal filter coefficients set, or the wanted signal filter defined therewith, includes a non-zero filter coefficient and/or a predetermined filter coefficient which the transversal filter coefficients set, or the transversal filter defined therewith, does not include, and/or
wherein the transversal filter coefficients set, or the transversal filter defined therewith, includes five or more filter coefficients; and/or
wherein the filter coefficients of the transversal filter coefficients set are determined using a least mean squares algorithm and/or using a recursive least squares algorithm.

### Claim 26 (depends on 15)

The method of claim 15, wherein the second sensor signal includes at least one wanted spectral signal component influenced by the at least one measurement variable as regards at least one signal parameter, including one of an amplitude, a frequency and a phase angle.

### Claim 27 (depends on 26)

The method of claim 26, wherein the second sensor signal sampling sequence includes, or approximates, the at least one wanted component.

### Claim 28 (depends on 27)

The method of claim 27, wherein the wanted signal sequence includes, or approximates, at least the wanted component.

### Claim 29 (depends on 15)

The method of claim 15, further comprising:
generating the first sensor signal using a first sensor arrangement disposed at least partially at the first portion and/or at least partially within the first portion; and
generating the second sensor signal using a second sensor arrangement disposed at least partially at the third portion and/or at least partially within the third portion.

### Claim 30 (depends on 15)

The method of claim 15, wherein effecting the disturbance in the fluid flowing through the second portion comprises:
increasing a flow velocity of the fluid flowing within the second portion; and/or
lessening a static pressure prevailing in the fluid flowing within the second portion; and/or
providing a pressure gradient dependent on a volume flow within the fluid flowing along the flow path; and/or
inducing vortices in the fluid flowing within the second portion as to form a Kámán vortex street in the fluid flowing downstream of the flow obstruction.

### Claim 31 (depends on 15)

The method of claim 15, wherein:
the first sensor arrangement includes a pressure sensor positioned at the first portion; and/or
the second sensor arrangement includes a pressure sensor positioned at the second and/or third portion; and/or
the second sensor arrangement includes a sensor paddle protruding into the third portion; and/or
the first sensor arrangement includes at least one ultrasonic transducer disposed at the first portion; and/or
the second sensor arrangement includes at least one ultrasonic transducer disposed at the second and/or third portion; and/or
the second portion includes a bluff body; and/or
the second portion includes a diaphragm; and/or
the second portion includes a tube arrangement of a vibronic measuring transducer, comprising two or more tubes and/or a line branching and/or a line junction.

### Claim 32 (depends on 15)

The method of claim 15, wherein the method is performed using a measuring system adapted to perform the method, the measuring system comprising:
a tube arrangement comprising a lumen defining the first portion of the flow path, the second portion of the flow path disposed in a flow direction downstream of the first portion, and the third portion of the flow path disposed in the flow direction downstream of the second portion and a tube wall surrounding the lumen;
the flow obstruction arranged within the tube arrangement in the second portion of the flow path, the flow obstruction configured to effect a disturbance in the flowing fluid, the disturbance dependent on the at least one measurement variable and/or serving as a measurable effect dependent on the at least one measurement variable;
a first sensor arrangement configured to generate a first sensor signal having a first frequency spectrum influenced by the fluid flowing within the first portion;
a second sensor arrangement configured to generate a second sensor signal having a second frequency spectrum influenced by the fluid flowing within the third portion, the second frequency spectrum deviating from the first frequency spectrum and/or including at least one wanted component, the at least one wanted component including a spectral signal component influenced by the at least one measurement variable as regards at least one signal parameter; and
a transmitter electronics including a microprocessor and configured to:
receive the first sensor signal and convert such into a first sensor signal sampling sequence approximating the first sensor signal, the first sensor signal sampling sequence including a first sequence of digital sampled values, defined by SD1[m]=SD1[tm·fs1], using a first sampling rate, defined by fs1=1/(tm+1-tm)=1/Ts1, from the first sensor signal at different sampling points in time, given by tn=n·Ts1;
receive the second sensor signal and convert such into a second sensor signal sampling sequence approximating the second sensor signal, the second sensor signal sampling sequence including a second sequence of digital sampled values, defined by SD2[n]=SD2[tn·fs2] using a second sampling rate, defined by fs2=1/(tn+1-tn)=1/Ts2, from the second sensor signal at different sampling points in time, given by tn=n·Ts2, such that the second sensor signal sampling sequence approximates at least one wanted spectral signal component of the second sensor signal influenced by the at least one measurement variable;
using a digital adaptive filter, ascertain from the first sensor signal sampling sequence a wanted signal filter coefficients set including a set of N filter coefficients;
using the wanted signal filter coefficients set, generate a first z-transfer function of a wanted signal filter, defined as:
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wherein wk are the filter coefficients, the wanted signal filter being a digital filter adapted to filter the second sensor signal sampling sequence such that the first z-transfer function of the wanted signal filter is determined by the wanted signal filter coefficients set;
generate a wanted signal sequence, using the wanted signal filter and the second sensor signal sampling sequence, the wanted signal sequence being a sequence of digital function values defined by:
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to generate from the wanted signal sequence a measured values sequence, being a sequence of digital measured values representing the at least one measurement variable and following one after the other in time.

### Claim 33 (depends on 32)

The method of claim 32, wherein the method is performed for setup and/or commissioning of the measuring system.