Impedance analysis technique for frequency domain characterization of magnetoelastic sensor element by measuring steady-state vibration of element while undergoing constant sine-wave excitation
First Claim
1. Circuitry for characterizing the response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the circuitry comprising:
- (a) an excitation circuit for providing an AC excitation signal to the coil;
(b) a receive circuit for measuring a total sensor signal from the coil with the sensor element positioned within the excitation field;
(c) a phase detection circuit for detecting phase of said total sensor signal so measured; and
(d) a processing unit for determining;
(i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element.
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Accused Products
Abstract
Circuitry and program code adapted for carrying out an associated technique for characterizing the response of one or more magnetoelastic sensor elements during exposure to an excitation field generated by an interrogation coil: including: (a) measuring a total sensor signal from the coil with the sensor element positioned within the excitation field within a spacing created by a winding of the coil; and (b) automatically determining: (i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element. The reconstructed impedance spectrum for the sensor element, having been calculated by subtracting an impedance generally attributable to the coil during the time an AC excitation signal is provided, from the total measured impedance. Subtraction of coil impedance from total complex impedance is accomplished by separate subtraction of the real part and of the imaginary part, represented as follows
Re[Zs(ω)]=Re[Zt(ω)]−Re[Zc(ω)] Equation (12)
and
Im[Zs(ω)]=Im[Zt(ω)]−Im[Zc(ω)] Equation (13) where subscript “t” indicates total complex impedance, “s” indicates sensor element impedance, and “c” indicates coil impedance.
33 Citations
20 Claims
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1. Circuitry for characterizing the response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the circuitry comprising:
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(a) an excitation circuit for providing an AC excitation signal to the coil;
(b) a receive circuit for measuring a total sensor signal from the coil with the sensor element positioned within the excitation field;
(c) a phase detection circuit for detecting phase of said total sensor signal so measured; and
(d) a processing unit for determining;
(i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for characterizing the response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the method comprising the steps of:
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(a) providing an AC excitation signal to the coil;
(b) measuring a total sensor signal from the coil with the sensor element positioned within the excitation field within a spacing created by a winding of the coil;
(c) detecting the phase of said total sensor signal so measured; and
(d) automatically determining;
(i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A computer executable program code on a computer readable storage medium for use in characterizing the response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the program code comprising:
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(a) a first program sub-code comprising instructions for providing an AC excitation signal to the coil;
(b) a second program sub-code comprising instructions for measuring a total sensor signal from the coil with the sensor element positioned within the excitation field within a spacing created by a winding of the coil;
(c) a third program sub-code comprising instructions for detecting the phase of said total sensor signal; and
(d) a fourth program sub-code comprising instructions for automatically determining;
(i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element. - View Dependent Claims (16, 17, 18, 19)
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20. A method for characterizing the response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the method comprising the steps of:
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(a) measuring a total sensor signal from the coil with the sensor element positioned within the excitation field within a spacing created by a winding of the coil; and
(b) automatically determining;
(i) a total measured impedance spectrum from said total sensor signal so measured, and (ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum for the sensor element.
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Specification