# US 8,571,819 B2 · Coriolis mode processing techniques

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- Number: US 8,571,819 B2
- Document ID: US8571819B2
- Status: Granted
- Kind: B2
- Application number: 13/317,495
- Filed: 2011-10-19
- Published: 2013-02-14
- Granted: 2013-10-29
- Earliest claimed: 2005-07-11
- Assignees: Invensys Systems, Inc.
- Applicants: Manus P. Henry
- Inventors: Manus P. Henry
- Web page: https://patentgrep.com/patent/US8571819B2

## CPC

- G01F 1/84: Coriolis or gyroscopic mass flowmeters
- G01F 1/74: Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
- G01F 1/76: Devices for measuring mass flow of a fluid or a fluent solid material
- G01F 1/8436: {signal processing}
- G01F 1/8486: {with multiple measuring conduits}
- G01F 1/849: {having straight measuring conduits}
- G01F 15/024: {involving digital counting}
- G01N 9/002: {using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence)}
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Flowmeters are described in which a sensor signal received from a sensor that is attached to vibratable flowtube, so as to determine properties of a fluid within the flowtube, contains a drive signal component and a Coriolis mode component. The flowmeters are operable to determine drive parameters of the drive signal component, as well as Coriolis parameters of the Coriolis mode component. By analyzing the sensor signal based on the drive signal parameters, and not on the Coriolis signal parameters, the flowmeters are able to provide stable and accurate determinations of the properties of the fluid.

## Claims

### Claim 1

A Coriolis flowmeter comprising:
a flowtube having a fluid flowing therethrough, the flowtube being subject to a vibration, the vibration of the flowtube comprising at least a drive mode of vibration and a contaminant mode of vibration;
a sensor for outputting an observed signal representative of the vibration of the flowtube, the observed signal including a drive mode signal corresponding to the drive mode of vibration and a contaminant mode signal corresponding to the contaminant mode of vibration; and,
a transmitter for receiving the observed signal and determining a parameter of the fluid, the transmitter comprising:
a zero-crossing detector for detecting a plurality of observed zero-crossings of the observed sensor signal;
a frequency calculator operable to determine an observed signal frequency and an initial estimate of frequency of the contaminant mode signal, the observed signal frequency and the contaminant mode signal frequency being used to determine a parameter of fluid passing through the flowmeter.

### Claim 2 (depends on 1)

The Coriolis flowmeter as set forth in claim 1 further comprising a mode maximizer operable to generate at least a first characterization of the observed sensor signal, the first characterization maximizing the drive mode signal.

### Claim 3 (depends on 2)

The Coriolis flowmeter as set forth in claim 2 further comprising a determination system operable to determine the parameter of the fluid using at least the first characterization.

### Claim 4 (depends on 3)

The Coriolis flowmeter of claim 3, wherein the initial estimate of contaminant mode signal frequency is a predetermined function of the observed signal frequency.

### Claim 5 (depends on 1)

The Coriolis flowmeter of claim 1, wherein the mode maximizer is operable to generate a second characterization of the observed sensor signal, the second characterization of the observed sensor signal maximizing the drive mode signal.

### Claim 6 (depends on 5)

The Coriolis flowmeter of claim 5, wherein the determination system calculates the parameter of the fluid using the second characterization.

### Claim 7 (depends on 6)

The Coriolis flowmeter of claim 6, wherein a parameter calculator uses the second characterization to determine an estimate of an amplitude of oscillation of the contaminant mode signal and an estimate of a phase angle of the contaminant mode signal.

### Claim 8 (depends on 7)

The Coriolis flowmeter of claim 7, wherein the parameter calculator uses the first characterization to determine an estimate of an amplitude of oscillation of the drive mode signal and an estimate of an offset between a zero-crossing of the observed signal and a zero-crossing of the drive mode signal.

### Claim 9 (depends on 8)

The Coriolis flowmeter of claim 8, wherein the determination system calculates the parameter of the fluid using the estimate of the amplitude of oscillation of the drive mode signal and the estimate of the offset between the zero-crossing of the observed signal and the zero-crossing of the drive mode signal.

### Claim 10 (depends on 7)

The Coriolis flowmeter of claim 7, wherein the parameter calculator uses the estimate of an amplitude of oscillation of the drive mode signal and the estimate of an offset between a zero-crossing of the observed signal and a zero-crossing of the drive mode signal to calculate the estimate of an amplitude of oscillation of the contaminant mode signal and an estimate of a phase angle of the contaminant mode signal.

### Claim 11 (depends on 10)

The Coriolis flowmeter of claim 10, wherein the parameter calculator uses the estimate of the amplitude of oscillation of the contaminant mode signal and the estimate of the phase angle of the contaminant mode signal to calculate an improved estimate of the amplitude of oscillation of the drive mode signal and an improved estimate of the offset between the zero-crossing of the observed signal and the zero-crossing of the drive mode signal.

### Claim 12 (depends on 11)

The Coriolis flowmeter of claim 11, wherein the determination system calculates the parameter of the fluid using the improved estimate of the amplitude of oscillation of the drive mode signal and the improved estimate of the offset between the zero-crossing of the observed signal and the zero-crossing of the drive mode signal.

### Claim 13 (depends on 11)

The Coriolis flowmeter of claim 11, wherein the parameter calculator uses the improved estimate of the amplitude of oscillation of the drive mode signal and the improved estimate of the offset between the zero-crossing of the observed signal and the zero-crossing of the drive mode signal to calculate an improved estimate of the amplitude of oscillation of the contaminant mode signal and an improved estimate of the phase angle of the contaminant mode signal.

### Claim 14 (depends on 1)

The Coriolis flowmeter of claim 1, wherein the observed signal is not filtered before reaching the frequency calculator to minimize the effect of the contaminant mode signal.