METHOD AND SYSTEM FOR MEASUREMENT OF PARAMETERS OF A FLAT MATERIAL

• US 20090281764A1
• Filed: 04/20/2009
• Published: 11/12/2009
• Est. Priority Date: 03/29/2006
• Status: Active Grant

• Current Assignee: Dolphin Measurement System LLC
• Original Assignee: Dolphin Measurement System LLC
• Inventors: Waldman, Ellis S., Naidis, Eugene, Raykhman, Alexander M.
• Granted Patent: US 8,174,258 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01B 2210/44 with detectors on both sides of the object to be measured
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01B 7/06 for measuring thickness measuring during the manufacture of coatings C23C14/54
• CPC Class Codes: G01N 27/72 by investigating magnetic variables

Abstract

A system and method for measurement of parameters of a conductive material, include generating an oscillating electromagnetic field (EMF) interacting with a sample portion from a remotely positioned source; measuring values of components of impedance of the electromagnetic; populating a system of equations including a theory of electromagnetism-based mathematical model of the electromagnetic system; solving the system of equations to calculate values of a distance between the sample portion and the source, thickness of the sample portion in proximity to a point of projection of the source onto the sample portion and electromagnetic properties of the sample portion; outputting the calculated values as the measured values; and repeating the steps of generating, populating, solving, outputting and repeating using the calculated values for the step of populating in place of the measured component values.

Claims

1. A method for measurement of parameters of a conductive material, comprising the steps of:

generating an oscillating electromagnetic field (EMF) interacting with a sample portion of flat conductive material, from a source remotely positioned from the sample portion;

measuring values of components of impedance of an electromagnetic system including the source of the EMF and the sample portion;

populating a system of equations including a theory of electromagnetism-based mathematical model of the electromagnetic system and the measured component values;

solving the system of equations to calculate values of a distance between the sample portion and the source, thickness of the sample portion in proximity to a point of projection of the source onto the sample portion and electromagnetic properties of the sample portion;

outputting the calculated values as the measured values; and

repeating the steps of generating, populating, solving, outputting and repeating using the calculated values for the step of populating in place of the measured component values.

2. The method of claim 1 wherein the step of generating the oscillating electromagnetic field interacting with the sample portion of the material includes using a source comprising resistive, inductive and capacitive electrical elements.

3. The method of claim 1 wherein the step of measuring values of components of impedance of the electromagnetic system including the source of the electromagnetic field and the sample portion of the material includes setting at least one driving frequency for the source in the presence of the sample portion.

4. The method of claim 3 wherein the components of the impedance include magnitude and phase angle presented in the form of gain-frequency and phase-frequency characteristics of the electromagnetic system.

5. The method of claim 3 wherein the components of the impedance includes real and imaginary parts.

6. The method of claim 3 wherein the components of the impedance are the electromagnetic system'"'"'s inductance and resistance.

7. The method of claim 1 wherein the step of populating a system of equations includes determining an initial estimate of a positional coordinate and a thickness of the sample portion.

8. The method of claim 7 wherein the positional coordinate is a distance between the source and the point of projection on a surface of the sample.

9. The method of claim 1 wherein the step of populating a system of equations includes determining an initial estimate of parameters and characteristics of said electromagnetic system.

10. The method of claim 9 wherein said parameters include electrical conductivity and magnetic permeability of the material sample and said characteristics are the components of the theoretical impedance of said electromagnetic system obtained with no presence of any conductive material, and

further wherein the components of said theoretical impedance are predetermined during the construction of said measuring system.

11. The method of claim 9 wherein all initial estimate variables make a vector of initial estimates.

12. The method of claim 11 wherein in the rolling mill application of the present invention, the initial estimate of the material sample thickness and positional coordinate is obtainable prior to rolling by measuring with any linear dimension measuring means including but not limited to mechanical, acoustical, laser or electromagnetic devices,

such measurements implementing a calibrating function for any non-invasive thickness measuring gauge that does not include a mathematical model of the measurement process of the object of measurement in a measurement algorithm.

13. The method of claim 1 wherein the step of populating a system of equations includes measuring a value of a non-zero linear velocity of the sample portion.

14. The method of claim 13 wherein the step of populating a system of equations includes using material velocity as a known input of the mathematical model.

15. The method of claim 1 wherein the step of populating a system of equations includes building at least one correcting function meant for determining adequacy of said mathematical model.

16. The method of claim 15 wherein said correcting function is incorporated in said system of equations.

17. The method of claim 15 wherein said correcting function is applied to a solution vector of said system of equations.

18. The method of claim 15 wherein the step of creating includes application of a vector of initial estimated values for building said correcting function.

19. The method of claim 1 wherein the step of populating the system of equations includes monitoring changes in the values of the components of said theoretical impedance of the electromagnetic system.

20. The method of claim 19 further including monitoring changes in the values of the components of said theoretical impedance of the electromagnetic system by periodically switching a periodical excitation of the electromagnetic measuring circuit to feeding the same circuit with a direct current, thereby effectively nullifying the circuit'"'"'s ability of sensing surrounding conductive media and delivering at the circuit'"'"'s output a signal modulated by changes in the circuit'"'"'s coil resistance and circuits analog electronics transfer functions resulting from changes in the circuit surrounding temperature and ground potential.

21. The method of claim 19 wherein said monitored changes in the components of the theoretical impedance are used to modify the mathematical model of the electromagnetic system eliminating dependence of the solution vector on thermal or thermal drift and ground electrical potential disturbances accompanying the process of measurement.

22. The method of claim 1 wherein the step of solving the system of equations may include using a recursive numerical solver.

23. The method of claim 22 wherein the step of solving includes creating an initial guess vector comprised of all or some of the components of said vector of initial estimates to be used for feeding the numerical solver.

24. The method of claim 23 wherein the initial guess vector is subsequently replaced by a solution to said system of equations obtained in some preceding executed step of solving.

25. The method of claim 1 wherein said step of solving the system of equations may include using a set of formulas analytically representing the solution to said system of equations.

26. The method of claim 1 wherein said step of solving the populated system of equations is comprised of two operations and;

further wherein the first operation returns an approximate values for components of the solution vector; and

still further wherein the second operation returns accurate values for components of the solution vector.

27. The method of claim 26 further including using the approximate values of the vector of solution generated by the first procedure for inputting the second operation to return accurate components of the solution vector, thereby increasing computing speed of the method of the present invention.

28. The method of claim 26 further including using the approximate values of the vector of solution for generating the guess values vector inputting the numerical solver returning accurate components of the solution vector.

29. The method of claim 1, further comprising the step of recording the outputted values of the measured variables in a computer readable medium as a quality control record.

31. The method of claim 23, wherein the pair of sources are coaxially located on opposing sides of the sample portion.

34. The method of claim 26, wherein the material is metal and further wherein the compressive and tension forces are created in a rolling process.

30. A method for measurement of positional coordinates, thickness and electromagnetic parameters of a flat conductive material, comprising the steps of:

generating an electromagnetic system of oscillating electromagnetic fields interacting with the sample portion of the material from a pair of sources positioned remotely on opposing sides of the sample portion;

measuring component values of impedance of the electromagnetic system made by each remote source of electromagnetic field and the material sample;

populating a system of equations including the measured impedance component values and a theory of electromagnetism-based mathematical model of the electromagnetic system;

solving the system of equations to calculate values of the sample portion distance to each source of EMF, thickness of the sample material in proximity to a point of projection on the sample material by each source of EMF, and the sample material'"'"'s electromagnetic parameters;

outputting the calculated values;

repeating the steps of generating, measuring, populating, solving, outputting and repeating.

32. A method for adjusting the thickness of flat, electrically conductive material under compressive and tensile forces, comprising the steps of:

generating an oscillating electromagnetic field (EMF) interacting with a sample portion of flat, electrically conductive material, from a source remotely positioned from the sample portion;

measuring component values of impedance of an electromagnetic system including the source of the EMF and the sample portion;

populating a system of equations including the measured component values and a theory of electromagnetism-based mathematical model of the electromagnetic system;

solving the system of equations to calculate values of a distance between the sample portion and the source and thickness of the sample portion in proximity to a point of projection of the source in to the sample portion;

using the calculated values for adjusting compressive and/or tension forces on the material;

repeating the steps of measuring, populating, solving, using and repeating.

33. A method for recording quality control measurements of thickness of a flat conductive material, comprising the steps of:

generating an oscillating electromagnetic field (EMF) interacting with a sample portion of flat conductive material, from a source remotely positioned from the sample portion;

measuring component values of impedance of an electromagnetic system including the source of the EMF and the sample portion;

populating a system of equations including the measured component values and a theory of electromagnetism-based mathematical model of the electromagnetic system;

solving the created system of equations to calculate values of a distance between the sample portion and the source and thickness of the sample portion in proximity to a point of penetration of the sample portion by a normal vector to the source;

recording the calculated values on a computer readable medium; and

repeating the steps of measuring, populating, solving, outputting and repeating.

35. A system for measuring positional coordinates and thickness of a flat conductive material, comprising:

an electromagnetic source adapted for generating an oscillating electromagnetic field (EMF) interacting with a sample portion of flat conductive material, wherein the source is remotely positioned from the sample portion;

circuitry adapted for measuring component values of impedance of an electromagnetic system including the source of the EMF and the sample portion; and

a computing system for solving a system of equations including a theory of electromagnetism-based mathematical model of the electromagnetic system and the measured component values to calculate values of a distance between the sample portion and the source, thickness of the sample portion in proximity to a point of projection of the source onto the material sample portion and electromagnetic properties of the sample portion.