Method for monitoring oscillation characteristics in a coriolis, flow, measuring device

• US 8,950,274 B2
• Filed: 11/14/2012
• Issued: 02/10/2015
• Est. Priority Date: 11/15/2011
• Status: Active Grant

• Current Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Inventors: Scherrer, Remy
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): KERAMET-AMIRCOLA, MOHAMMED E
• Application Number:
  US13/676,192
• Publication Number:
  US 20130160565A1
• Time in Patent Office: 818 Days
• Field of Search: 738/613.55, 73/110.8, 73/110.9, 73/121.2, 731/521.8, 738/613.54, 732/52, 732/68, 738/634.4, 702/45, 702/48
• US Class Current: 73/861.355
• CPC Class Codes: G01F 1/66 by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
• CPC Class Codes: G01F 1/8436 signal processing
• CPC Class Codes: G01F 25/10 of flowmeters

Abstract

A method for monitoring oscillation characteristics in a Coriolis, flow measuring device and to a correspondingly formed, Coriolis, flow measuring device in the case of which an excited oscillatory system is simulated with a digital model, which has at least one fittable parameter. The simulating includes, in such case, excitating the digital model in the same manner as the oscillatory system, calculating a simulation response variable of the simulated oscillations according to the digital model, and, performed over a plurality of signal modulations, iterative conforming of the at least one, fittable parameter in such a manner that the simulation response variable interatively approaches the response variable. Furthermore, it is ascertained whether a corresponding limit value is exceeded by the at least one, interatively ascertained parameter value for the at least one, fittable parameter or by at least one variable derived from the at least one, iteratively ascertained parameter value.

Claims

1. A method for monitoring oscillation characteristics in a Coriolis, flow measuring device, which is insertable into a pipeline, said Coriolis, flow measuring device including an oscillatory system excitable to execute mechanical oscillations, wherein the oscillatory system has at least one measuring tube, through which a medium can flow, said method comprising:

exciting the oscillatory system by at least one exciter to execute mechanical oscillations according to an excitation input signal, which exhibits temporary signal modulations occurring in time intervals;

registering by sensor at least one response variable of the caused mechanical oscillations of the oscillatory system;

simulating the excited oscillatory system with a digital model, which includes at least one fittable parameter; and

ascertaining whether a corresponding limit value is exceeded by the at least one, interatively ascertained parameter value for the at least one, fittable parameter or by at least one variable derived from the at least one, interatively ascertained parameter value;

wherein said simulating the excited oscillatory system with a digital model includes;

exciting the digital model in the same manner as the oscillatory system;

calculating a simulation response variable of the simulateoscillations according to the digital model; and

,

performed over a plurality of signal modulations, iterative conforming of the at least one, fittable parameter in such a manner that the simulation response variable iteratively approaches the response variable.

2. The method as claimed in claim 1, wherein:

in the step of ascertaining, that at least one parameter value of the respective fittable parameter is applied as interatively ascertained parameter value, in the case of which the associated simulation response variable has converged toward the response variable to a predetermined minimum measure.

3. The method as claimed in claim 1, wherein:

the temporary signal modulations of the excitation input signal are, in each case, formed by a temporary frequency- and/or amplitude change of the excitation input signal.

4. The method as claimed in claim 1, wherein:

the temporary signal modulations occur periodically in the excitation input signal.

5. The method as claimed in claim 1, wherein:

the temporary signal modulations are, in each case, formed by a temporary amplitude change of the excitation input signal.

6. The method as claimed in claim 1, wherein:

the steps of exciting, registering by sensor, simulating and ascertaining are performed in parallel with a flow measurement.

7. The method as claimed in claim 1, wherein:

the response variable is formed by a velocity of the oscillation and the simulation response variable by a velocity of the simulated oscillation.

8. The method as claimed in claim 1, wherein:

the digital model of the excited oscillatory system is based on a transfer function of the following form;

9. The method as claimed in claim 1, wherein:

the excitation input signal has a frequency, which essentially corresponds to the resonant frequency of the oscillatory system.

10. The method as claimed in claim 9, wherein:

the digital model of the excited oscillatory system is based on a transfer function present in digital representation and the digital representation of the transfer function includes as a component at least the following function Hsens(z) derived from an amplitude model;

11. The method as claimed in claim 1, wherein:

the digital model of the excited oscillatory system is based on a transfer function present in digital representation and the digital representation of the transfer function includes at least the following function H_lp(z) as a component, wherein the function H_lp(z) provides a delay and a low-pass filtering, which occur in the case of real, digital signal processing of the response variable;

12. The method as claimed in claim 1, wherein:

in the case of iterative approaching of the simulation response variable to the response variable, per iteration time interval, the amplitudes of the velocity of the oscillation and the velocity of the simulated oscillation present at at least two different points in time during the associated iteration time interval are used as operative comparison variables, wherein, at one of the two, different points in time, the amplitudes of the velocity of the oscillation and the velocity of the simulated oscillation are settled.

13. The method as claimed in claim 1, wherein:

the fittable parameters of the digital model are formed by the stiffness K₀ and by the quality factor Q or by two variable derived from the stiffness K₀ and the quality factor Q.

14. A Coriolis, flow measuring device, which is insertable into a pipeline, said Coriolis, flow measuring device comprises:

an oscillatory system excitable to execute mechanical oscillations and including at least one measuring tube, through which a medium can flow; and

at least one exciter;

at least one oscillation sensor;

an electronics,

said electronics being adapted to operate said at least one exciter and to evaluate a sensor signal of said at least one oscillation sensor;

said electronics, said at least one exciter and said at least one oscillation sensor are formed in such a manner that

said oscillatory system is excitable by the at least one exciter to execute mechanical oscillations according to an excitation input signal

and that at least one response variable of the caused mechanical oscillations of said oscillatory system is registrable by the at least one oscillation sensor, wherein;

said excitation input signal exhibits temporary signal modulations occurring in time intervals, and

said electronics is adapted to simulate said excited oscillatory system with a digital model, including at least one fittable parameter by;

exciting the digital model in the same manner as said oscillatory system,

calculating a simulation response variable of the simulated oscillations according to the digital model and

performing over a plurality of signal modulations an iterative conforming of the at least one fittable parameter in such a manner that the simulation response variable interatively approaches the response variable, and

said electronics is adapted to ascertain whether a corresponding limit value is exceeded by the at least one, interatively ascertained parameter value for the at least one fittable parameter or by at least one variable derived from the at least one, interatively ascertained parameter value.