US 2006/0124740 A1 · Magnetic field response measurement acquisition system

Abstract

Magnetic field response sensors designed as passive inductor-capacitor circuits produce magnetic field responses whose harmonic frequencies correspond to states of physical properties for which the sensors measure. Power to the sensing element is acquired using Faraday induction. A radio frequency antenna produces the time varying magnetic field used for powering the sensor, as well as receiving the magnetic field response of the sensor. An interrogation architecture for discerning changes in sensor's response frequency, resistance and amplitude is integral to the method thus enabling a variety of measurements. Multiple sensors can be interrogated using this method, thus eliminating the need to have a data acquisition channel dedicated to each sensor. The method does not require the sensors to be in proximity to any form of acquisition hardware. A vast array of sensors can be used as interchangeable parts in an overall sensing system.

A magnetic field response measurement acquisition system, comprising:

one or more inductively powered magnetic field response sensors, wherein one or more attributes of the one or more sensor responses correspond to one or more measured unrelated physical states and further wherein said one or more attributes are selected from the group consisting of amplitude, frequency and bandwidth;
antenna means for transmitting magnetic fields to power said one or more sensors and for receiving magnetic field responses from said one or more sensors;
an interrogation means for regulating said magnetic field transmission from and reception to said antenna means, and for analyzing said one or more sensor response attributes received from said one or more sensors, wherein said interrogation means can interrogate multiple sensors concurrently using a single acquisition channel, does not require that said signals from said one or more sensors be transmitted as modulated signals on a radio frequency carrier, and can concurrently acquire measurements of more than one unrelated physical state from each said sensor;
wherein said antenna means is a single switching antenna, and further wherein said interrogation means comprises the following steps:
(a) at the lower limit of a predetermined range, transmitting a radio frequency harmonic for a predetermined length of time from said antenna;
(b) switching said transmission mode of said antenna off;
(c) turning the receiving mode of said antenna on;
(d) rectifying the received response from said sensor to determine its amplitude;
(e) storing the amplitude, Ai(t), of said rectified response and the frequency, ωi(t) , of said transmitted radio frequency harmonic;
(f) switching the receiving mode off and the transmission mode on;
(g) shifting the transmitted radio frequency harmonic by a predetermined amount;
(h) transmitting the harmonic for a predetermined length of time;
(i) switching the transmission mode off;
(j) switching the receiving mode on;
(k) rectifying the received response from said sensor to determine its amplitude;
(l) storing the amplitude, Ai(t), of said rectified response and the frequency, ωi(t) , of said transmitted radio frequency harmonic;
(m) comparing said amplitude, Ai, to the two previously recorded amplitudes, Ai−1 and Ai−2;
(n) if said previous amplitude, Ai−l, is greater than said amplitude, Ai, and the previous amplitude, Ai−1, is greater than the amplitude prior to it, A1−2, storing said amplitude, Ai−1, as the amplitude inflection and the corresponding frequency, ωi−1, for the current frequency sweep;
(o) subtracting An(t), obtained n harmonic steps prior to that of i−2, from amplitude inflection, A1−1(t), obtained in step (n) and storing inverse 1/(Ai−(t)-An(t)) as corresponding to response bandwidth;
(p) comparing said attributes of amplitude, frequency and the value corresponding to bandwidth steps (n) and (o) with attributes of next subsequent sweep of said sensor;
and
(q) once amplitude inflection has been reached, continuing the sweep to said next sensor.

19 more elements

Facts

Application

11/305,854Filed 16 Dec 2005

Priority

30 Apr 2003

Published

15 Jun 2006

Term ends

Not estimatedThe source records don’t support an estimate.

Classification14 codes

G01L 19/086
Means for indicating or recording, e.g. for remote indication: for remote indication
B60C 11/243
Wear-indicating arrangements: tread wear sensors, e.g. electronic sensors
B60C 23/0449
Wheel or tyre mounted circuits: passive transducers, e.g. using surface acoustic waves, backscatter technology or pressure sensitive resonators
G01D 21/00
Measuring or testing not otherwise provided for

Family

Application60/467,844Us provisional application · filed 30 Apr 2003

Application60/467,840Us provisional application · filed 1 May 2003

Application60/467,841Us provisional application · filed 1 May 2003

Application60/467,113Us provisional application · filed 1 May 2003

Application60/467,839Us provisional application · filed 1 May 2003

Application60/467,842Us provisional application · filed 1 May 2003

Application60/467,112Us provisional application · filed 1 May 2003

Application60/467,194Us provisional application · filed 1 May 2003

Application10/839,445Continuation · filed 30 Apr 2004

Application11/305,854Continuation · filed 16 Dec 2005

US 2005/0007239 A1Published application

US 7,086,593 B2Related patent

US 7,159,774 B2Related patent

US 2006/0124740 A1This patent

From the US filing history. Foreign family members aren’t listed.

Magnetic field response measurement acquisition system

Life of this patent

Magnetic field response measurement acquisition system

Life of this patent

Abstract

Claims20