US 7,912,661 B2 · Impedance analysis technique for frequency domain characterization of magnetoelastic sensor element by measuring steady-state vibration of element while undergoing constant sine-wave excitation

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.

Claims20

Dependent claims

Circuitry for characterizing a resonant behavior 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 steady state total sensor signal from the coil with the magnetoelastic sensor element positioned within the excitation field;
(c) a phase detection circuit for detecting phase of said steady state total sensor signal so measured;
and
(d) a processing unit for determining:
(i) a total measured impedance spectrum from said steady state total sensor signal so measured, and
(ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum characterizing the resonant behavior response of the sensor element, wherein
(iii) said reconstructed impedance spectrum is calculated by subtracting an impedance generally attributable to the coil during said providing said AC excitation signal, from said steady state total measured impedance.

5 more elements

A method for characterizing a resonant behavior response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the method comprising the steps of:

(a) providing an AC excitation signal to the coil;
(b) measuring a steady state total sensor signal from the coil with the magnetoelastic sensor element positioned within the excitation field within a spacing created by a winding of the coil;
(c) detecting the phase of said steady state total sensor signal so measured;
and
(d) automatically determining:
(i) a total measured impedance spectrum from said steady state total sensor signal so measured, and
(ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum characterizing the resonant behavior response of the sensor element, and
(iii) calculating said reconstructed impedance spectrum by subtracting an impedance generally attributable to the coil during said providing said AC excitation signal, from said steady state total measured impedance.

5 more elements

A non-transitory computer readable storage medium having stored thereon, program code for causing a computer processor to execute instructions for characterizing a resonant behavior response of a magnetoelastic sensor element during exposure to an excitation field generated by an interrogation coil, the program code comprising:

(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 steady state 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 steady state total sensor signal;
and
(d) a fourth program sub-code comprising instructions for automatically determining:
(i) a total measured impedance spectrum from said steady state total sensor signal so measured, and
(ii) a plurality of magnitude values representing the real part of a reconstructed impedance spectrum characterizing the resonant behavior response of the sensor element, and
(iii) instructions for calculating said reconstructed impedance spectrum by subtracting an impedance generally attributable to the coil during said providing said AC excitation signal, from said steady state total measured impedance.

5 more elements

Dependencies are inferred from the claim text.

Impedance analysis technique for frequency domain characterization of magnetoelastic sensor element by measuring steady-state vibration of element while undergoing constant sine-wave excitation

Life of this patent

Impedance analysis technique for frequency domain characterization of magnetoelastic sensor element by measuring steady-state vibration of element while undergoing constant sine-wave excitation

Life of this patent

Abstract

Claims20