U.S. patent application number 17/229958 was filed with the patent office on 2021-10-21 for methods, circuits and systems for obtaining impedance or dielectric measurements of a material under test.
The applicant listed for this patent is TransTech Systems, Inc.. Invention is credited to Adam D. Blot, Manfred Geier, Andrew J. Westcott.
Application Number | 20210325326 17/229958 |
Document ID | / |
Family ID | 1000005569428 |
Filed Date | 2021-10-21 |
United States Patent
Application |
20210325326 |
Kind Code |
A1 |
Blot; Adam D. ; et
al. |
October 21, 2021 |
METHODS, CIRCUITS AND SYSTEMS FOR OBTAINING IMPEDANCE OR DIELECTRIC
MEASUREMENTS OF A MATERIAL UNDER TEST
Abstract
Certain disclosed methods include: transmitting an excitation
signal into the MUT and transmitting a reference signal to a set of
magnitude and phase (M/P) detectors; receiving the response signal;
separately comparing a magnitude and phase for each of the
excitation signal and the reference signal with corresponding
detection ranges for a first one of the M/P detectors; separately
comparing a magnitude and phase for each of the response signal and
the reference signal with corresponding detection ranges for a
second one of the M/P detectors; iteratively adjusting the
excitation signal until the response signal has both a magnitude
and a phase within the corresponding detection ranges for the
second M/P detector; and iteratively adjusting the reference signal
until the reference signal has both a magnitude and a phase within
the corresponding detection ranges for the first and the second M/P
detectors.
Inventors: |
Blot; Adam D.; (Altamont,
NY) ; Geier; Manfred; (Oakland, CA) ;
Westcott; Andrew J.; (Troy, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TransTech Systems, Inc. |
Latham |
NY |
US |
|
|
Family ID: |
1000005569428 |
Appl. No.: |
17/229958 |
Filed: |
April 14, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63010791 |
Apr 16, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 27/028
20130101 |
International
Class: |
G01N 27/02 20060101
G01N027/02 |
Claims
1. A method of characterizing a response signal for detecting
physical characteristics of a material under test (MUT), the method
comprising: transmitting an excitation signal into the MUT using a
transmitting electrode on a sensor array and transmitting a
reference signal to a set of magnitude and phase (M/P) detectors;
receiving the response signal from the MUT via a receiving
electrode on the sensor array based on the excitation signal;
separately comparing a magnitude and phase for each of the
excitation signal and the reference signal with corresponding
detection ranges for a first one of the M/P detectors; separately
comparing a magnitude and phase for each of the response signal and
the reference signal with corresponding detection ranges for a
second one of the M/P detectors; iteratively adjusting the
excitation signal until the response signal has both a magnitude
and phase within the corresponding detection ranges for the second
M/P detector; and iteratively adjusting the reference signal until
the reference signal has both a magnitude and a phase within the
corresponding detection ranges for both the first and second M/P
detectors.
2. The method of claim 1, wherein the first M/P detector provides a
reading of the magnitude and phase of the excitation signal and the
reference signal, and wherein the second M/P detector provides a
reading of the magnitude and phase of the reference signal and the
response signal.
3. The method of claim 2, wherein the readings are obtained by a
computing device configured to control the iterative adjustment of
the excitation signal and the reference signal.
4. The method of claim 2, wherein the reading for each of the
excitation signal, the reference signal and the response signal
comprises separate magnitude and phase components.
5. The method of claim 1, wherein iteratively adjusting the
excitation signal comprises adjusting an amplification and phase of
the excitation signal.
6. The method of claim 1, further comprising, after verifying that
the excitation signal produces a response signal with a magnitude
and phase within the corresponding detection ranges for the second
M/P detector: analyzing data obtained from both the first and the
second M/P detectors using a data model about physical
characteristics of the MUT to detect at least one physical
characteristic of the MUT, wherein the analyzing comprises
correlating impedance or dielectric values from the data obtained
from both the first and the second M/P detectors with an
impedance-to-physical characteristic correspondence table or a
dielectric-to-physical characteristic correspondence table.
7. The method of claim 1, further comprising converting the
reference signal, the excitation signal and the response signal
from analog format to digital format prior to separately comparing
the reference signal, the excitation signal and the response signal
with the corresponding detection ranges for the first and second
M/P detectors.
8. The method of claim 1, wherein the transmitting electrode
comprises a single transmitting electrode.
9. The method of claim 8, wherein: a) the receiving electrode
comprises a single receiving electrode that surrounds the
transmitting electrode, or b) the receiving electrode comprises a
plurality of receiving electrodes, and wherein the method further
comprises switching between the plurality of receiving electrodes
for the response signal using an electrode switch.
10. The method of claim 1, wherein the excitation signal and the
reference signal are both generated by a signal generator with a
common control signal, and wherein the excitation signal and the
reference signal have a common frequency and a distinct magnitude
and/or phase.
11. A system configured to characterize a response signal for
detecting physical characteristics of a material under test (MUT),
the system comprising: a sensor array for communicating with the
MUT; a set of magnitude and phase (M/P) detectors; a signal
generator coupled with the set of M/P detectors and the sensor
array; and a computing device configured to control processes
including: initiating: a) transmission of an excitation signal into
the MUT with a transmitting electrode on the sensor array and b)
transmission of a reference signal to the set of magnitude and
phase (M/P) detectors; receiving a response signal from the MUT via
a receiving electrode on the sensor array based on the excitation
signal; separately comparing a magnitude and phase for each of the
excitation signal and the reference signal with corresponding
detection ranges for a first one of the M/P detectors; separately
comparing a magnitude and phase for each of the response signal and
the reference signal with corresponding detection ranges for a
second one of the M/P detectors; iteratively adjusting the
excitation signal until the response signal has both a magnitude
and a phase within the corresponding detection ranges for the
second M/P detector; and iteratively adjusting the reference signal
until the reference signal has both a magnitude and a phase within
the corresponding detection ranges for the first and the second M/P
detectors.
12. The system of claim 11, wherein the computing device is further
configured to: compute an electromagnetic property of the MUT based
on the measured magnitude and phase for the response signal and the
reference signal; and correlate the electromagnetic property with a
physical property of the MUT based on a physical model of the MUT
or a laboratory test of the MUT, wherein the electromagnetic
property comprises one or more of: impedance, susceptance,
permittivity or admittance.
13. The system of claim 11, wherein the first M/P detector provide
a reading of the magnitude and phase of the excitation signal and
the reference signal, and wherein the second M/P detector provides
a reading of the magnitude and phase of the reference signal and
the response signal.
14. The system of claim 13, wherein the readings are obtained by
the computing device configured to control the iterative adjustment
of the excitation signal and the reference signal.
15. The system of claim 13, wherein the reading for each of the
excitation signal, the reference signal and the response signal
comprises separate magnitude and phase components.
16. The system of claim 11, further comprising, after verifying
that the excitation signal produces a response signal with a
magnitude and phase within the corresponding detection ranges for
the second M/P detector and the reference signal has a magnitude
and phase within the corresponding detection ranges for the first
and second M/P detectors: analyzing data obtained from both the
first and the second M/P detectors using a data model about
physical characteristics of the MUT to detect at least one physical
characteristic of the MUT, wherein the analyzing comprises
correlating impedance or dielectric values from the data obtained
from both the first and the second M/P detectors with an
impedance-to-physical characteristic correspondence table or a
dielectric-to-physical characteristic correspondence table.
17. The system of claim 11, further comprising converting the
reference signal, the excitation signal and the response signal
from analog format to digital format prior to separately comparing
the reference signal, the excitation signal and the response signal
with the corresponding detection ranges for the first and second
M/P detectors.
18. The system of claim 11, wherein the transmitting electrode
comprises a single transmitting electrode, wherein the receiving
electrode comprises a single receiving electrode that surrounds the
transmitting electrode.
19. The system of claim 11, wherein the receiving electrode
comprises a plurality of receiving electrodes, and wherein the
system further comprises an electrode switch coupled with the
computing device, wherein the computing device is configured to
switch between the plurality of receiving electrodes for the
response signal using the electrode switch.
20. The system of claim 11, wherein the excitation signal and the
reference signal are both generated by the signal generator with a
common control signal, and wherein the excitation signal and the
reference signal have a common frequency and a distinct magnitude
and/or phase.
Description
PRIORITY CLAIM
[0001] This application claims priority to U.S. Provisional Patent
Application No. 63/010,791, filed on Apr. 16, 2020, which is herein
incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The disclosure relates generally to circuits, systems, and
methods for determining characteristics of a material under test
(MUT) by generating and measuring electric signals at a specific
frequency or over a range of frequencies to measure the dielectric
properties of that MUT. The dielectric characteristics can then be
correlated to a physical property or properties of the MUT such as
density or moisture.
BACKGROUND
[0003] The use of electrical impedance measurements to quantify
physical characteristics of construction, manufacturing, and
biological materials is the basis of an increasing number of
techniques, including impedance tomography and impedance
spectroscopy. An important factor in successfully characterizing an
MUT is the ability to obtain accurate and repeatable measurements
of electromagnetic properties of an MUT (e.g., the electrical
impedance, admittance, capacitance, permittivity, etc.) of that
MUT. These measured values are subsequently converted to
information about the dielectric properties of the MUT. However,
conventional approaches for obtaining electrical data for
characterizing MUTs can be both inaccurate and insufficiently
repeatable.
SUMMARY
[0004] All examples and features mentioned below can be combined in
any technically possible way.
[0005] The present application presents an electronic circuit and
measurement system for generating electric excitation signals at a
specific frequency or over a range of frequencies that enable
accurate measurements of response signals after excitation of the
MUT. The transmitted and response signals can be used to compute
the impedance and dielectric properties of the MUT.
[0006] Particular approaches involve generating and measuring
electric signals at a specific frequency or over a range of
frequencies to measure the impedance or the dielectric signature of
that MUT. The measurement of electrical impedance to quantify
physical properties of construction, manufacturing, or biological
materials is the basis of a variety of measurement techniques
including impedance tomography and impedance spectroscopy. One
requirement to successful characterization of an MUT is the
accurate and repeatable measurements of the electrical impedance
(or admittance) signature, which subsequently is converted to
information about the dielectric properties of the MUT, which in
turn can be correlated with physical (non-electrical) properties of
the MUT. Other electromagnetic characteristics can be used to
successfully characterize an MUT in various implementations.
Various particular implementations include an electronic circuit,
measurement system, and method for generating electric excitation
signals at a specific frequency or over a range of frequencies that
provide accurate measurements of the electric signals in response
to this excitation of the MUT for computation of the impedance and
dielectric signal properties of the MUT.
[0007] The subject matter of U.S. Pat. Nos. 5,900,736, 6,414,497,
6,803,771, 7,219,024, 9,465,061, and 9,805,146; as well as: US
Patent Publication No. 2009/0270756, US Patent Publication No.
2012/0130212; US Patent Publication No. 2013/0307564, US Patent
Publication No. 2014/0266268, US Patent Publication No.
2014/0278300, US Patent Publication No. 2015/0137831, US Patent
Publication No. 2015/0212026, US Patent Publication No.
2018/0128934, US Patent Publication No. 2018/0172612; Provisional
U.S. Patent Application No. 62/161,9275 (filed on Jan. 25, 2018);
and Provisional U.S. Patent Application No. 62/661,682 (filed on
Apr. 24, 2018) describe impedance-related techniques for
determining characteristics of materials, and are each incorporated
by reference herein in its entirety.
[0008] The methods, electronic circuits and systems of the present
subject matter relate to the measurement of the impedance as it
varies with the dielectric properties of the MUT, as well as
electronic devices and/or components for performing such
measurements at a specific frequency or over a range of
frequencies, with provisions for the characterization of the
excitation (also referred to as "transmit"), the response (also
referred to as "received"), and reference signals to produce a
measured signal within a desired range of the electronic measuring
components over the frequency range, based upon the magnitude or
strength and phase shift of the measured signal for the specific
frequency or range of frequencies.
[0009] In some cases, a method of characterizing a response signal
for detecting physical characteristics of a material under test
(MUT) includes: transmitting an excitation signal into the MUT
using a transmitting electrode on a sensor array and transmitting a
reference signal to a set of magnitude and phase (M/P) detectors;
receiving a response signal from the MUT via a receiving electrode
on the sensor array based on the excitation signal; separately
comparing a magnitude and phase for each of the excitation signal
and the reference signal with corresponding detection ranges for a
first one of the M/P detectors; separately comparing a magnitude
and phase for each of the response signal and the reference signal
with corresponding detection ranges for a second one of the M/P
detectors; and iteratively adjusting the excitation signal until
the response signal has both a magnitude and a phase within the
corresponding detection ranges for the second M/P detector; and
iteratively adjusting the reference signal until the reference
signal has both a magnitude and a phase within the corresponding
detection ranges for the first and the second M/P detectors.
[0010] In additional cases, a system is configured to characterize
a response signal for detecting physical characteristics of a
material under test (MUT). In these cases, the system can include:
a sensor array for communicating with the MUT; a set of magnitude
and phase (M/P) detectors; a signal generator coupled with the set
of M/P detectors and the sensor array; and a computing device
configured to control processes including: initiating: a)
transmission of an excitation signal into the MUT with a
transmitting electrode on the sensor array and b) transmission of a
reference signal to the set of magnitude and phase (M/P) detectors;
receiving a response signal from the MUT via a receiving electrode
on the sensor array based on the excitation signal; separately
comparing a magnitude and phase for each of the excitation signal
and the reference signal with corresponding detection ranges for a
first one of the M/P detectors; separately comparing a magnitude
and phase for each of the response signal and the reference signal
with corresponding detection ranges for a second one of the M/P
detectors; iteratively adjusting the excitation signal until the
response signal has both a magnitude and a phase within the
corresponding detection ranges for the second M/P detector; and
iteratively adjusting the reference signal until the reference
signal has both a magnitude and a phase within the corresponding
detection ranges for the first and the second M/P detectors.
[0011] Particular aspects of the present subject matter provide
electronic circuits, systems, and methods to apply an electronic
circuit which: 1) generates an excitation signal and a reference
signal at a specific frequency or over a range of frequencies; 2)
applies the excitation a signal to a material under test (MUT)
(which may include one or more subcomponents); 3) characterizes the
response signal with respect to the reference signal; 4) determines
the magnitude and phase relationship between the response signal
produced in presence of the MUT relative to the reference signal;
5) computes the impedance and dielectric properties of the MUT (and
in some cases, subcomponents); and 6) applies the measured
dielectric properties to a physical model to correlate the
measurement to a physical property or properties of the MUT (or a
sample of the MUT that has been subjected to engineering testing to
determine desired information about physical properties). The
approaches described herein can include characterization methods
for the measuring circuit board and sensor system, as well as a
method to collect information in the form of electrical quantities
with the circuit board and a sensor system.
[0012] Various embodiments of the disclosure relate generally to an
electronic circuit and system for the measurement of the impedance
to electric current through sensing system in communication with a
material under test (MUT) and subsequent extraction of the
dielectric properties of the MUT. In some cases, the system
includes a circuit having magnitude and phase detectors to measure
the change in magnitude or strength and phase difference between a
reference signal and an excitation (or transmit) signal and between
the reference signal and the response (or received) signal produced
by the transit of the excitation signal through the MUT. The system
can include at least one computing device configured to control the
generation of the excitation and reference signals, to evaluate the
measured signal levels, and to adjust excitation and/or reference
signals to produce input signals to the magnitude and phase
detectors and other circuit components that result in best
performance of these detectors and components. Circuits according
to various embodiments can include a signal strength determiner
and/or phase determiner for determining the phase shift between the
excitation signal, the reference signal, and the response signal
specific to the MUT. The strength and phase determiner may be
combined in a single circuit component. According to various
embodiments, the measured difference in signal strength and phase
are used to compute the (complex) electrical impedance and
dielectric properties of the MUT. This (MUT/system-specific)
impedance or the (MUT-specific) dielectric property can be
correlated with a physical property or properties of the MUT. The
system may be operated at a single frequency, or over a range of
frequencies.
[0013] In some particular embodiments, a system can include: a
signal generator which generates the excitation signal and the
reference signal; an excitation electrode connected with the signal
generator and in electrically conductive or non-conductive contact
with a material under test (MUT); a receiving electrode in
electrically conductive or non-conductive contact with the material
under test (MUT) which is part of the return path of the excitation
current flowing from the excitation electrode through the MUT to
the receiving electrode as the response signal; a reference signal
which is compared to the excitation signal and the response signal
at the receive electrode by a magnitude detector and/or phase
detector; and at least one computing device connected with the
signal generator, the signal strength determiner(s) and/or phase
determiner(s) for the excitation and reference signals and for the
response and reference signals, the at least one computing device
configured to: send a control signal to the signal generator to
initiate and conduct an excitation signal to the MUT via the
excitation electrode and to the excitation-to-reference strength
and phase determiner at a selected frequency or over a range of
frequencies.
[0014] Implementations may include one of the following features,
or any combination thereof.
[0015] In some particular embodiments, the at least one computing
device receives digitized strength and phase data from analog to
digital converters connected to the output of the strength and/or
phase determiner(s) and communicates the data to another computing
device to be used to compute the measured impedance or dielectric
property, and to correlate impedance or dielectric property with a
physical model of the MUT to quantify a physical property or
properties of the MUT.
[0016] In particular aspects, the computing device is further
configured to: compute an electromagnetic property of the MUT based
on the measured magnitude and phase for the response signal and the
reference signal; and correlate the electromagnetic property with a
physical property of the MUT based on a physical model of the MUT
or a laboratory (or engineering) test of the MUT, wherein the
electromagnetic property comprises one or more of: impedance,
susceptance, permittivity or admittance.
[0017] In some particular embodiments, the at least one computing
device provides the computation of the measured impedance or the
dielectric property to be correlated with a physical model of the
MUT to quantify a physical property or properties of the MUT.
[0018] In some particular embodiments, the at least one computing
device provides the controlling function for the signal
generator(s), switch(es), and other controllable elements of the
circuit.
[0019] In particular aspects, the first M/P detector provide a
reading of the magnitude and phase of the excitation signal and the
reference signal, and the second M/P detector provides a reading of
the magnitude and phase of the reference signal and the response
signal.
[0020] In certain cases, the readings are obtained by a computing
device configured to control the iterative adjustment (via the
signal generator) of the amplitude and phase of the excitation
signal and the reference signal.
[0021] In some implementations, the reading for each of the
excitation signal, the reference signal and the response signal
comprises separate magnitude and phase components.
[0022] In particular cases, the iteratively adjusting includes
adjusting an amplification of the excitation signal and/or the
reference signal.
[0023] In some aspects, a method further includes, after verifying
that the excitation signal produces a response signal with a
magnitude and phase within the corresponding detection ranges of
the second M/P detector and a reference signal with a magnitude and
phase within the corresponding detection ranges for both the first
and the second M/P detectors: analyzing data obtained by the first
and second M/P detectors using a data model about physical
characteristics of the MUT to detect at least one physical
characteristic of the MUT.
[0024] In certain aspects, the analyzing includes correlating
impedance or dielectric values for the MUT with an impedance
value-to-physical characteristic correspondence table or a
dielectric value-to-physical characteristic correspondence table.
In some implementations, the correspondence table(s) are developed
using a physical model of the MUT or by physical sampling or
engineering evaluations of the MUT.
[0025] In particular implementations, a method further includes
converting the reference signal, the excitation signal and the
response signal from analog format to digital format prior to
separately comparing the reference signal, the excitation signal
and the response signal with the corresponding detection ranges for
the first and second M/P detectors.
[0026] In some cases, the transmitting electrode includes a single
transmitting electrode.
[0027] In certain aspects, the receiving electrode includes a
single receiving electrode that surrounds the transmitting
electrode.
[0028] In particular implementations, the receiving electrode
includes a plurality of receiving electrodes, and the method
further includes switching between the plurality of receiving
electrodes for the response signal using an electrode switch.
[0029] In some aspects, the excitation signal and the reference
signal are both generated by a signal generator with a common
control signal, and the excitation signal and the reference signal
have a common frequency and a distinct magnitude and/or phase.
[0030] Particular aspects of the present subject matter provide a
system to generate electric signals at a specific frequency or over
a range of frequencies and with varying levels of strength or
magnitude to secure impedance or dielectric measurements on a
Material Under Test (MUT) which then can be correlated with
physical properties of the MUT. The system may include: at least
one computing means which can receive parameters for a physical
model of the MUT (and/or physical/engineering testing data about
the MUT) and digitize data for the computation of the impedance or
dielectric properties of the MUT; transmit control signals to the
at least one signal generator and circuit components; and transmit
data to a user interface; the at least one signal generator which
generates two electric signals at a specific frequency or over a
range of frequencies and at various amplitudes and phases of which:
an excitation signal which is transmitted to an electrode in
electrically conducting or non-conducting communication with the
MUT and to the first of the at least two magnitude and phase
detectors; and a reference signal which is transmitted to one of
the at least two of the first magnitude and phase detector and the
second of the at least two magnitude and phase detectors. The
excitation signal which is transmitted to an electrode in
communication with the MUT, produces a current through the MUT
which is collected at least one receiving electrode which is in
electrically conducting or non-conducting communication with the
MUT and where the current is converted to a voltage (referred to as
the received) signal that is transmitted to the second of the at
least two magnitude and phase detectors. The magnitude and phase of
the excitation signal relative to the reference signal from one of
the at least two magnitude and phase detectors is transmitted as
digital data to the at least one computing means. The magnitude and
phase of the received signal relative to the reference signal from
another of the at least two magnitude and phase detectors is
transmitted as digital data to the at least one computing means.
The at least one computing means processes the digitized magnitude
and phase data. The at least one computing means transmits the
processed data to a user interface which communicates the desired
physical properties of the MUT. The material under test may be a
soil.
[0031] Optionally, the material under test may be any material
under test that produces a complex impedance spectrum when excited
with methods of Electrical Impedance Spectroscopy (EIS). The
specific frequency or range of frequencies applied may, in
particular, fall within the range of 10 kHz to 100 MHz, and in some
cases, 100 KHz to 100 MHz. In additional cases, a method comprises:
at least one signal generator generating an electric excitation
signal under control of an at least one computing means at a
specific frequency or over a range of frequencies at specific
amplitude within a range of amplitudes and a fixed phase whose
voltage signal is transmitted to an electrode in communication with
a material under (MUT) and produces an electric current through the
MUT to a receiving electrode which is in electrically conducting or
non-conducting communication with the MUT. The current collected at
the receiving electrode is converted to a voltage signal (received
signal) which is transmitted to one of the at least two magnitude
and phase detectors where the at least one computing means
determines if the amplitude of the received signal falls within the
design amplitude input range of the magnitude and phase detector.
If the amplitude of the received signal is not within the desired
range for the magnitude and phase detector and the magnitude of the
received signal relative to the reference signal is not within the
desired tolerance band of the target magnitude, the computing means
adjusts the amplitude of the excitation signal until the measured
level is within the desired range and tolerance band. If the
amplitude of the received signal is within the desired input
amplitude range for the magnitude and phase detector and the
magnitude of the received signal relative to the reference signal
is within the tolerance band around the target magnitude, the
excitation amplitude is fixed and the at least one computing means
then instructs the at least one signal generator to generate
electric signals at a fixed frequency or over a range of
frequencies at a specific phase within a range of phases and at the
fixed amplitudes. The electric signal with varying values of phase
is transmitted to an electrode in electrically conductive or
non-conductive communication with the MUT and produces a current
through the MUT which is collected at a receiving electrode which
is in electrically conductive or non-conductive communication with
the MUT. The current collected at the receiving electrode is
converted to a voltage signal (received signal) which is
transmitted to one of the at least two magnitude and phase
detectors where the at least one computing means determines if the
phase of the received signal falls within the design input phase
range of the amplitude and phase detector. If the phase of the
received signal is not within the desired range for the magnitude
and phase detector is not within the desired tolerance band around
the desired target phase output, the computing means adjusts the
phase of the excitation signal until the phase of the received
signal is within the desired range and within the desired tolerance
band. If the phase of the received signal is within the desired
phase input range for the level and phase detector and within the
desired tolerance band, the amplitude and phase are fixed and used
for the values of the electric excitation signal which is measured
by the other of the at least two magnitude and phase detectors. The
at least one computing means then directs the at least one signal
generator to generate a reference signal whose amplitude and phase
fall within the design ranges of the one of the at least two
magnitude and phase detectors used to measure the received signal
and is adjusted to produce the magnitude and phase outputs within
the desired tolerance band about the target magnitude and phase of
the one of the at least two magnitude and phase detectors used to
measure the received signal. The at least one computing means
receives and processes the digitized magnitude and phase
measurement from the at least two magnitude and phase detectors for
the excitation signal and the received signal. The at least one
computing means transmits the processed data to a user interface
which communicates the desired physical properties of the MUT.
[0032] Various approaches can be used to determine electromagnetic
properties of the MUT, including, e.g., one or more of: impedance,
susceptance, permittivity or admittance.
[0033] Two or more features described in this disclosure, including
those described in this summary section, may be combined to form
implementations not specifically described herein. The system and
in particular its computing device may be configured to carry out
the methods described herein. Further variants of the described
methods result from the intended use of the described system and
its components.
[0034] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other
features, objects and advantages will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE FIGURES
[0035] FIG. 1. shows an illustration of a phase and magnitude
spectrum over the range of frequencies of interest for a typical
soil tested with a typical embodiment of an impedance measurement
system.
[0036] FIG. 2 Shows and illustration of the Keysight E4990A
Impedance Analyzer.
[0037] FIG. 3 shows a general configuration of a sensor system
including an impedance measurement circuit according to various
embodiments of the disclosure.
[0038] FIG. 4 shows an alternate configuration of a sensor system
including an impedance measurement circuit with selected circuit
elements according to various embodiments of the disclosure
[0039] FIG. 5. shows an alternate configuration of a sensor system
including an impedance measurement circuit with selected circuit
elements according to various embodiments of the disclosure and an
alternate sensor configuration.
[0040] FIG. 6 is a flow diagram illustrating processes according to
various implementations.
[0041] FIG. 7 is a flow diagram illustrating processes according to
various additional implementations.
[0042] It is noted that the drawings of the various implementations
are not necessarily to scale. The drawings are intended to depict
only typical aspects of the disclosure, and therefore should not be
considered as limiting the scope of the implementations. In the
drawings, like numbering represents like elements between the
drawings.
DETAILED DESCRIPTION
[0043] The various circuits, systems, methods, and procedures
described herein are related to the generation of electric signals
at a single frequency or over a range of frequencies for measuring
the impedance or dielectric properties of a material under test
(MUT). The frequency or range of frequencies is selected on the
basis of the properties of the MUT for an impedance-spectroscopic
analysis for the determination of physical properties of the MUT.
In certain implementations, a single frequency is adequate for
tomographic analysis, e.g., as described in US Patent Publication
Nos. 2016/0161624, and 2018/0128934, and U.S. Pat. Nos. 9,465,061,
9,804,112, and 10,324,052; or for the determination of physical
properties of selected materials that act as pure capacitors, such
as hot mix asphalt, as described in U.S. Pat. Nos. 5,900,736,
6,414,497, and 6,803,771.
[0044] However, for a more complex MUT such as a soil, an
impedance-spectroscopic analysis over a range of frequencies is
required, e.g., as described in U.S. Pat. Nos. 7,219,024,
9,465,061, 9,805,146, and 10,161,893. Each of the afore-mentioned
applications, publications and issued patents is hereby
incorporated by reference in its entirety.
[0045] While certain example implementations are described with
reference to determining electromagnetic properties of an MUT such
as impedance, various approaches can be used to determine
additional, or alternative, electromagnetic properties of the MUT,
including, e.g., one or more of: susceptance, permittivity or
admittance.
[0046] Commonly labeled components in the FIGURES are considered to
be substantially equivalent components for the purposes of
illustration, and redundant discussion of those components is
omitted for clarity.
[0047] While one example MUT described in this disclosure is a
soil, the various circuits, systems, methods and procedures
described herein are applicable to any material under test that has
a complex impedance spectrum, e.g., where Electrical Impedance
Spectroscopy (EIS) may be applied. For example, U.S. Pat. No.
9,465,061 describes a method of conducting an in-process inspection
of solid materials with EIS. In certain cases, there is a need to
conduct in-process inspections and characterizations of fluids, as
suggested by U.S. Pat. Nos. 9,372,183, 9,389,175, and 9,797,855.
U.S. Pat. No. 9,389,175 applies an optical detection system, and
U.S. Pat. Nos. 9,372,183 and 9,797,855 apply impedance flow
cytometry, which counts and characterizes cells. Each of the
afore-mentioned US patents is incorporated by reference in its
entirety. Additional publications discuss various electromagnetic
methods of characterizing dairy products (e.g., milk) and other
foods such as olive oil, fruits, vegetable oils, cookies, pork, and
fish. In all these examples, the complex impedance spectrum extends
over a broad range of frequencies. This is shown in FIG. 1,
illustrating corresponding Phase and Magnitude graphs over a
frequency range for a typical soil tested with a conventional
impedance soil measurement system. This broad range of frequencies
makes it difficult to secure accurate measurements that can be used
to correlate the measured impedance spectrum with a physical
property or properties of the MUT, for example, density (or
compaction level) and/or moisture level for a soil.
[0048] A typical range of frequencies of interest for soils is from
about 10 kHz to approximately 100 MHz, and in particular cases,
from about 100 kHz to about 100 MHz. These ranges of frequencies
have been shown to provide an impedance spectrum that can be used
to correlate with physical properties such as density (compaction
level) and moisture level of the soil. As can be seen in FIG. 1,
the values of the phase (e.g., about 45 degrees up to about 70
degrees) and magnitude (e.g., about -5 DB to about 5 DB) over the
range of frequencies is very large. These values are used to
compute the complex impedance of the MUT over the frequency range
of interest. In order to secure accurate data over the entire range
of frequencies, a very sophisticated (and expensive) instrument is
typically required. One such instrument is the Keysight
Technologies E4990A Impedance Analyzer, an image of which is shown
in FIG. 2. This Impedance Analyzer is a 30-pound (14 kg) instrument
that is about 17.0-in wide, 9.3-in high and 11.7-in deep (432
mm.times.239 mm.times.296 mm) and requires laboratory environmental
conditions to function effectively. As such, the conventional
systems and approaches are unwieldy in practical, field use
scenarios. To address these shortcomings in conventional systems
and approaches, various disclosed implementations provide circuits,
systems, and methods for use in the field and/or production
environment that are able to secure comparable levels of data
accuracy from an MUT over the desired frequency range. Other
approaches to satisfying this objective are presented in US Patent
Publication No. 2014/0266268 and U.S. Pat. No. 10,330,616 (each
incorporated by reference in its entirety).
[0049] While certain frequency ranges of interest are described
herein, other ranges and sub-ranges may also be of interest. For
example, the systems and approaches described herein can be
applicable to investigating soils in frequencies around 32 kHz,
e.g., 32 kHz+/-10 kHz, 15 kHz or 20 kHz.
[0050] Various commercially available electronic components are
described as examples relating to the various embodiments of the
disclosure. These are used only for illustrative purposes. Other
such components may be used as selected by one skilled in the
art.
[0051] Referring to FIG. 3, a schematic depiction of a measurement
system (or simply, system) 100 is shown according to various
implementations. In some cases, the measurement system 100
interacts with (or includes) a plurality of elements (or,
sub-systems). In various implementations, system 100 includes a
circuit to generate electric signals at a specific frequency (or
over a range of frequencies), along with controls (e.g., control
software such as program code) to communicate with the other
elements of an overall measurement system. As shown in FIGURE (FIG.
3, the measurement system 100 is configured to interact with a
sensor system 200, which in turn communicates with a MUT 210.
System 100 is configured to receive a physical model 300, which in
some example cases is the physical model of the MUT 210, e.g.,
soil. That is, the physical model 300 can include a physical soil
model where the MUT 210 includes soil.
[0052] Additionally, the sensor system 200 can communicate with an
interface (e.g., user interface) 400, which can be local or remote
relative to the system 100. In some cases, the interface 400
enables a user or other operator to communicate desired physical
attributes for testing of the MUT, e.g., for soil this could
include density and/or moisture.
[0053] In various implementations, the sensor system 200 includes a
central excitation electrode (TX 201) surrounded by a concentric
coplanar ring including a receiving electrode (RX 202). In some
cases, the design of the sensor is described in U.S. Pat. Nos.
5,900,736 and 7,219,024. In some cases, the electrodes 201, 202 are
in direct physical contact with the MUT 210 (e.g., as described
with respect to the sensor system in U.S. Pat. No. 5,900,736). In
other cases, the electrodes 201, 202 are offset (separated) from
the MUT 210 (e.g., such that a gap or standoff is present between
the electrodes 201, 202 and the MUT 210, as is described with
respect to the sensor system in in U.S. Pat. No. 7,219,024). The
sensor system 200 and MUT 210 present a resistive and/or capacitive
load on the circuit of the measurement system 100. The system 100
is configured to account for and accommodate for the load
characteristics in the sensor system 200 and MUT 210 in order to
secure accurate readings of the change in the magnitude and phase
of the response signal (received at RX 202) compared to the
excitation signal (sent via TX 201).
[0054] The physical model of the MUT (e.g., soil) 300 is used in
setting the parameters of the circuit in system 100. U.S.
Provisional Patent Application No. 62/661,682 describes a system
and method for securing a physical model of soils for use with
system 100.
[0055] Certain implementations may replace the physical model
and/or supplement the physical model of the MUT 300 with testing
data about physical characteristics of the MUT 300, e.g., an ASTM
test determining physical characteristics of the MUT 300.
[0056] Interface 400 can include any conventional interface, e.g.,
a user interface, to enable a user such as a human user or other
communication system to communicate physical properties of the MUT
210 from the measurement system 100, along with enabling data
logging such as data about time and/or location of the measurement.
Example interfaces can include a laptop computer, a tablet, a smart
phone, or a dedicated user interface that is connected (e.g.,
physically and/or wirelessly) with the measurement system 100. In
any case, the interface 400 is configured to communicate data from
the measurement system 100 in real time, e.g., in a field-testing
environment.
[0057] As shown in FIG. 3, in various implementations, system 100
can include at least one computing device (e.g., processor and/or
memory) 10 that is configured to receive data from external
systems, e.g., to receive the physical (MUT) model 300, as well as
send and receive data to/from the interface system 400. In some
cases, the physical (MUT) model 300 includes information about a
desired frequency range and expected values of the impedance
spectrum for a response from the MUT 210. In certain aspects,
information about the desired frequency range needed and the
possible range of measured magnitudes and phases of the impedance
spectrum are obtained from prior field testing or laboratory
testing with a system as described in U.S. Provisional Patent
Application No. 62/661,682. The computing device 10 sends a control
signal 11 to a signal generator 12 and receives digital data 18, 19
about on the magnitude (level) and phase of the generated signal
from respective magnitude and phase (M/P) detectors (e.g., TX and
RX) 15 and 17. The (TX) M/P detector 15 compares the excitation TX
signal 13 with a reference signal 14, both generated by the signal
generator 12. The (RX) M/P detector 17 compares the reference
signal 14 with the receive (response) RX signal 16 (received at
electrode RX 202). The excitation voltage signal 13 causes current
flow from the TX electrode 201 on the sensor, through the MUT 210,
to the receiving electrode RX 202, where it is measured as the
voltage (response) signal 16 at the RX level and phase detector 17.
The (digital) output signals from the magnitude and phase (M/P)
detectors 15 and 17 are transmitted to the computing device 10. The
computing device 10 includes a processor for processing the
magnitude and phase data, and a communication system (e.g.,
conventional wireless and/or wireless communication system) for
sending the results as an output, e.g., at interface 400.
[0058] FIG. 4 is a schematic depiction of a system 500 according to
various additional implementations. Commonly labeled features
within the FIGURES can represent the same or similar components,
separate descriptions of which may be omitted. In some cases, the
system 500 includes at least one computing device 510, which can
include at least one processor and/or a memory. In certain
implementations, the computing device 510 includes a digital signal
controller, e.g., similar to a dsPIC33F 16-bit Digital Signal
Controller. However, other microprocessors may be used in
additional implementations. In particular implementations, system
500 further includes a signal generator 104, such as a dual channel
Direct Digital Synthesis (DDS) chip. The signal generator 104 is
connected to the computing device 510 and is configured to receive
control instructions as described herein. In particular examples,
the signal generator 104 includes a device such as an Analog
Devices AD9958. In some cases, multiple single-channel signal
generator chips may be used in place of, or in addition to a
dual-channel ship. The signal generator 104 is configured to
generate two signals at the same frequency at different levels
(magnitudes, or strengths): an excitation (TX) signal 107, and a
reference signal 114. In various implementations, the amplitudes
(or, magnitudes) of the signals, as well as the phases, are
separately set at different values for the excitation signal 107
and the reference signal 114. In certain implementations, system
500 includes an amplifier 105 for amplifying the excitation signal
107 and transmitting an amplified (TX) signal 106 to the transmit
electrode 201 of the sensor system 200 and to a (TX) magnitude and
phase (M/P) detector 109. An example amplifier 105 can include an
AD4870 (from Analog Devices) or a similar device. In certain
implementations, the computing device 501 sends an amplifier
control signal 103 to control the amplifier 105, e.g., in
amplifying excitation signal 107. In the example embodiment of
system 500 shown in FIG. 4, an additional magnitude and phase (M/P)
detector 115 is shown for detecting the response signal 121 from
the response (receiving) electrode 202. In some cases, the M/P
detector 115 is a similar model/make as M/P detector 109, however,
in other cases, these M/P detectors are distinct types. In some
cases, the M/P detector 115 is an AD8302 or similar device. In
practice, the computing device 510 instructs the signal generator
104 to generate the reference signal 114 and the excitation (TX)
signal 107. The reference signal 114 is transmitted to the (TX) M/P
detector 109 and also to the response M/P signal detector (RX) 115.
The excitation voltage signal 107, once amplified and transmitted
as TX signal 106, produces current flow from the TX electrode 201
on the sensor system 200, through the MUT 210, to the receiving
electrode RX 202. The response signal 121 (in response to the
excitation) is measured at the response M/P detector (RX) 115. In
certain cases, the two M/P detectors 109, 115 (e.g., including an
AD8302) produce analog output signals proportional to the
logarithmic amplitude ratio (also referred to as magnitude) of and
the phase difference between, respectively, the (TX) excitation
signal 106 and the reference signal 114 (in M/P detector 109), and
the (RX) receive signal 121 and the reference signal 114 (in M/P
detector 115). In various implementations, these two magnitude and
phase analog signals 110, 111, 116, 117, one set for each of
magnitude and phase detectors (TX 109 and RX 115), are converted to
digital signals by an analog to digital converter (ADC) 114 prior
to being transmitted back to the computing device 510 (e.g., for
storage, processing, output to a user interface 400, etc.). In this
example embodiment of system 500, the analog to digital converter
(ADC) 114 can include Maxim MAX 1239 analog-to digital converter or
similar device, that accepts the two sets of analog magnitude and
phase signals and converts them to digital signals for transmission
to the computing device 510.
[0059] As noted herein, the amplitude of the excitation signal 107
generated with the signal generator 104 may be amplified by the
amplifier 105. In some cases, after passing through the amplifier
105, the TX (voltage) signal 106 is measured with the M/P detector
109 and also applied to the TX (excitation) electrode 201 on the
sensor system 200. This TX signal 106 causes a current flow through
the MUT 210, which is detected at the receive electrode (RX) 202,
where it is transmitted as the measurable voltage (RX) signal 121
to (RX) M/P detector 115. The amplitude of the receive (RX) signal
121 is dictated by the amplitude of the (TX) signal 106 and the
dielectric properties of the MUT 210. By changing the amplitude of
the TX signal 106 in either the signal generator 104 or the
amplifier 105 (e.g., via instructions from computing device 510),
the amplitude of the receive (RX) signal 121 measured by the M/P
detector 115 is changed. In various implementations, the computing
device 510 is configured (e.g., programmed) to adjust the amplitude
of the output (TX) signal 106 (e.g., via adjustment to the DDS
control signal 102 and/or the amplifier control signal 103) until
the receive (RX) signal 121 detected at the M/P detector 115 falls
within one or more predefined ranges (e.g., an input range for the
M/P detector 115, as well as a distinct, but overlapping input
range for the M/P detector 109). In some cases, adjusting the
receive (RX) signal 121 to fall within one or more range(s) of the
(RX) M/P detector 115 may necessitate a (TX) signal 106 that would
fall outside the range of the (TX) M/P detector 109. In these
cases, additional measures of proportionate attenuation of the
stronger (TX) signal 106 would be required, e.g., by an attenuator
before M/P detector 109 (not shown). In various implementations,
the phase of the excitation (TX) signal 107 from the signal
generator 104 is independently adjusted by the DDS Control signal
102, in order to adjust the phase of the receive (RX) signal 121.
In other implementations, e.g., where the M/P detector 115 has a
broad acceptable phase range (e.g., such as where the M/P detector
115 includes an AD8302 chip), the computing device 510 need not
independently adjust the phase of the excitation (TX) signal 107.
In particular cases, the amplitude and phase of the reference
signal 114 is specifically defined for TX and RX measurements
within the input range specified for the M/P detectors (e.g.,
Analog Devices input specifications for the AD8302 chip).
[0060] In various implementations, the ability to independently set
the amplitude of the excitation and reference signals to enhance
performance and compatibility of measured signals with the signal
input range of the magnitude and phase detectors significantly
improves the accuracy of data about the MUT 210, as compared with
conventional approaches. In the illustration of system 500 (FIG.
4), the function of magnitude and phase detection is performed by
M/P detectors 109, 115 (e.g., Analog Devices AD8302 or other
comparable magnitude and phase detectors). Having two comparisons
against the reference signal (excitation (TX) 106 vs. reference 114
and receive (RX) 121 vs. reference 114) enables the computing
device 510 to compute the complex ratio of excitation (TX) voltage
signals and response (RX) voltage signals, expressed in terms of
magnitude (e.g., logarithmic amplitude ratio) and phase difference
as:
M.sub.TX-REF-M.sub.RX-REF=M.sub.TX-RX
P.sub.TX-REF-P.sub.RX-REF=P.sub.TX-RX
[0061] where M.sub.TX-REF is the magnitude of the TX signal 107
relative to the reference signal 114;
[0062] where M.sub.RRX-REF is the magnitude of the RX signal 121
relative to the reference signal 114;
[0063] where M.sub.Tx-Rx is the magnitude of the TX signal 107
relative to the RX signal 121;
[0064] where P.sub.TX-REF is the phase of the TX signal 107
relative to the reference signal 114;
[0065] where P.sub.RRX-REF is the phase of the RX signal 121
relative to the reference signal 114; and
[0066] where P.sub.TX-RX is the phase of the TX signal 107 relative
to the RX signal 121.
[0067] After calculating the magnitude and phase differences
between the excitation 107 and response 121 signals, the computing
device 510 is configured to compare those magnitude and phase
differences with the physical model of the MUT (e.g., soil) 300 to
determine physical properties of the MUT. As noted herein the
physical model of the MUT 300 can include magnitude and phase
correspondence information (e.g., tables, correlations, etc.) with
physical properties of an MUT. For example, for particular MUT
types (e.g., soil), the physical model 300 includes magnitude
and/or phase ranges for signal responses that correspond with
particular physical properties or characteristics of the MUT. In
particular examples, density or moisture content values or ranges
are correlated with distinct magnitude and/or phase values or
ranges, such as those calculated by the computing device 510 using
the approaches described herein.
[0068] The measured magnitudes M.sub.TX-REF and M.sub.RX-REF and
phases P.sub.TX-REF and P.sub.RX-REF can also be used to
characterize the measurement systems described herein (e.g.,
measurement system 100 in FIG. 3, measurement system 500 in FIG. 4,
and measurement system 600 in FIG. 5) when replacing an unknown MUT
with an object of known electrical properties. For example, in
combination with information regarding components of the
measurement systems (from additional independent measurements
and/or component specifications), the measurement of materials of
known electrical properties, such as polyethylene, glass, G9
composite, and graphite, enables calibration and establishment of a
model for conversion of impedance data to dielectric
properties.
[0069] FIG. 5 shows an additional system 600 according to various
implementations. System 600 can include a number of components
described with respect to other systems disclosed herein, e.g.,
measurement systems 100 (FIG. 3) and 500 (FIG. 4). In certain
implementations, system 600 includes the measurement system 500
shown and described with reference to FIG. 4. However, in contrast
to the depiction in FIG. 4, system 600 includes a distinct sensor
system 200A that includes an RX switch 205 in communication with
computing device 510. In certain implementations, the electrodes in
sensor system 200A also differ from the electrodes in sensor system
200 (FIG. 4). That is, electrodes 201, 202, 203 in sensor system
200A are arranged in a linear (or semi-circular) array of sensors.
This arrangement of the sensors permits an examination of the
spatial or tomographic distribution of physical properties of the
MUT 210. In this example implementation, the sensor system 200A
includes one excitation electrode (TX) 201 and two distinct receive
(RX) electrodes 202 and 203. A similar electrode arrangement is
illustrated in US Patent Publication No. 2018/0128934 and U.S. Pat.
Nos. 9,465,061 and 9,804,112 (all incorporated by reference
herein). In various implementations, the excitation electrode (TX)
201 is always active while one active receive electrode (selected
from the receive (RX) electrodes 202 or 203), is selected via a
control signal 130 from the computing device 510 and the RX switch
205. The volumes of the MUT that are measured differ between the
measurement with transmitting electrode (TX) 201 and receiving
electrode (RX) 202 versus measurement with transmitting electrode
(TX) 201 and receiving electrode (RX) 203. Applying the teachings
of U.S. Pat. Nos. 9,465,061 and 9,804,112, the impedance spectrum
of different volumes of the MUT 210 may be determined and
correlated to physical properties of those volumes
[0070] In various implementations, the computing devices (e.g.,
computing device 10, FIG. 3, or computing device 510, FIGS. 4 and
5) can be configured to adjust the TX signal and RX signal to
improve the accuracy of detecting one or more physical
characteristics of the MUT 210. In particular cases, the computing
devices disclosed herein are configured to match the input
excitation signal (e.g., excitation (TX) signal 13 or excitation
(TX) signal 106) and receive signal (e.g., receive (RX) signal 16
or receive (RX) signal 121) to the design range of the M/P
detectors (e.g., M/P detectors 15, 17 in FIG. 3 and M/P detectors
109, 115 in FIGS. 4 and 5), as well as adjust the reference signals
(e.g., reference (REF) signal 14 in FIG. 3 and (REF) signal 114 in
FIGS. 4 and 5) to obtain precise and accurate data from the MUT 210
by keeping the (TX) signal 106, the (RX) signal, and the (REF)
signal 114 all within the input specifications for the (TX) M/P
detector 109 and the (RX) M/P detector 115.
[0071] FIG. 6 is a flow diagram illustrating processes in a method
according to various implementations. In some cases, the method
includes characterizing an excitation signal, for example, to
detect physical characteristics of an MUT. In particular cases, the
method also includes detecting (or characterizing) at least one
physical characteristic of the MUT using the excitation signal(s).
As will be evident, processes described with reference to FIG. 6
can be applied to any of the systems disclosed herein, e.g.,
measurement system 100, measurement system 500 and/or measurement
system 600. Turning to FIG. 6, processes can include:
[0072] Process P1: transmitting an excitation signal (e.g.,
excitation signal 13 or excitation signal 107) into the MUT 210
using a transmitting electrode (e.g., TX 201) on a sensor array
(e.g., sensor system 200, 200A) and transmitting a reference signal
(e.g., REF 14 or REF 114) to a set of magnitude and phase (M/P)
detectors (e.g., M/P detectors 15, 17 or M/P detectors 109, 115).
In certain cases, as noted herein, the excitation signal (e.g.,
excitation signal 13 or excitation signal 107) and the reference
signal (e.g., REF 14 or REF 114) are both generated by a signal
generator (e.g., signal generator 12 or signal generator 104) with
a common control signal (e.g., control 11, control 102), where the
excitation signal and the reference signal have a common frequency
and a distinct magnitude and/or phase.
[0073] Process P2: receiving a response signal (e.g., receive
signal 16 or receive signal 121) from the MUT 210 via a receiving
electrode (e.g., RX 202 or RX 203) on the sensor array (e.g.,
sensor system 200, 200A) based on the excitation signal (e.g.,
excitation signal 13 or excitation signal 107).
[0074] Decision D1: separately comparing a magnitude and phase for
the response signal (e.g., response signal 16 or response signal
121) and the reference signal (e.g., REF 14 or REF 114) with
corresponding detection ranges for a second one of the M/P
detectors (e.g., M/P detector 17 or M/P detector 115). As described
herein, the second M/P detector (e.g., M/P detector 17 or M/P
detector 115) provides a reading (e.g., to computing device 10 or
510) of the magnitude and phase of the reference signal (e.g., REF
14 or REF 114) and the response signal (e.g., response signal 16 or
response signal 121). The reading for each of the reference signal
(e.g., REF 14 or REF 114) and the response signal (e.g., response
signal 16 or response signal 121) includes separate magnitude and
phase components (e.g., FIGS. 4 and 5).
[0075] If No to Decision D1, process P3 includes adjusting the
excitation signal (e.g., excitation signal 13 or excitation signal
107), e.g., by increasing or decreasing the amplitude or magnitude
of that signal, e.g., via a control signal 102 to the signal
generator (e.g., signal generator 13 or signal generator 104). In
certain implementations, as illustrated in the embodiments in FIGS.
3 and 4, the computing device (e.g., computing device 10 or
computing device 510) adjusts the amplification of the excitation
signal (e.g., excitation signal 107), e.g., generating TX signal
106.
[0076] If Yes to Decision D1, Decision D2 includes separately
comparing a magnitude and phase for the reference signal (e.g., REF
14 or REF 114) with corresponding detection ranges for each of a
first one of the M/P detectors (e.g., M/P detector 15 or M/P
detector 109) and a second one of the M/P detectors (e.g., M/P
detector 17 or M/P detector 115). As described herein, the first
M/P detector (e.g., M/P detector 15 or M/P detector 109) provides a
reading (e.g., to computing device 10 or 510) of the magnitude and
phase of the excitation signal and the reference signal, and the
second M/P detector (e.g., M/P detector 17 or M/P detector 115)
provides a reading (e.g., to computing device 10 or 510) of the
reference signal and the response signal. In some cases, the
reading for each of the received excitation signal, the reference
signal and the response signal includes separate magnitude and
phase components (e.g., FIGS. 4 and 5).
[0077] If No to Decision D2 (meaning that reference signal deviates
from range of both the first and second M/P detectors), proceed to
process P4, which includes adjusting the magnitude and/or phase of
the reference signal (e.g., REF 14 or REF 114). As with the
decision loop D1, negative responses to decision loop D2 can
trigger iterative adjustment of the reference signal until both the
response signal requirements (Decision D1) and the reference signal
requirements (Decision D2) are satisfied.
[0078] A Yes response to Decision D2 means that the response signal
(e.g., receive signal 16 or receive signal 121) and the reference
signal (e.g., REF 14 or REF 114) have both a magnitude and a phase
within the corresponding detection ranges for the second M/P
detector (e.g., M/P detector 17 or M/P detector 115), and the
reference signal (e.g., REF 14 or REF 114) has a magnitude and
phase with the corresponding detection ranges for both the first
and second M/P detectors (e.g., M/P detectors 15 and 17 or M/P
detectors 109 and 115). In this case, process P5 can include
analyzing the response signal data from the second M/P detector
(e.g., M/P detector 17 or M/P detector 115) and the reference
signal (REF 14 or REF 114) using a data model (e.g., physical model
300) about physical characteristics of the MUT 210 to detect at
least one physical characteristic of the MUT 210. In particular
cases, this analysis includes correlating impedance or dielectric
values in the response signal (e.g., receive signal 16 or receive
signal 121) with a response signal-to-physical characteristic
correspondence table (e.g., in physical model 300).
[0079] One or more of the above-noted processes can be modified
according to the various implementations described herein. For
example, signals such as the reference signal, the excitation
signal and the response signal can be converted from analog format
to digital format prior to separately comparing those signals with
the corresponding detection ranges for the first and second M/P
detectors 109, 115, e.g., as illustrated in FIGS. 4 and 5. Even
further, in cases where the sensor system (e.g., sensor system
200A) includes a plurality of distinct receiving electrodes (e.g.,
RX 202, RX 203), approaches can include switching between receiving
electrodes (e.g., RX 202 or RX 203) for the response signal using
an electrode switch (e.g., RX switch 205, FIG. 5).
[0080] FIG. 7 is a flow diagram illustrating processes in an
additional method of detecting a physical characteristic of an MUT
210 using one or more systems herein. In various implementations,
the method is performed by execution of program code or other
programmable instructions at a processor such as the processor(s)
in the computing device 10 of FIG. 3 or the computing device 510 of
FIGS. 4 and 5.
[0081] In particular implementations process P101 includes
obtaining a physical model of the MUT 300, e.g., as a data file or
set of data files, via one or more communications media. The
physical model of the MUT 300 includes the frequency range over
which impedance and/or dielectric data must be secured from the MUT
210 in order to correlate that impedance and/or dielectric data
with one or more physical properties of the MUT 210. The model 300
can also include information about the amplitudes of the excitation
signal and reference signal for collecting data about the MUT
210.
[0082] In process P102, the computing device (e.g., computing
device 10 or computing device 510) transmits a control signal
(e.g., control signal 11 in FIG. 1 or control signal 102 in FIGS. 4
and 5) to a signal generator (e.g., signal generator 12 or 104) to
initiate generation of excitation and reference signals (e.g.,
signals 13 and 14, or signals 107 and 114) at a frequency and
amplitude (or over a range of frequencies and amplitudes) within a
predefined range(s) of amplitudes and phase for the M/P detectors
(e.g., M/P detectors 15, 17 or M/P detectors 109, 115). In certain
implementations, information about the desired frequency range and
the possible range of measured magnitudes and phases of the
impedance spectrum is obtained from prior field testing or
laboratory testing with a system as described in U.S. Provisional
Patent Application No. 62/661,682, previously incorporated by
reference herein. In the case of measurement system 500 (FIGS. 4
and 5), the computing device can also be configured to send an
amplifier control signal 103 to the amplifier 105 for amplifying
the excitation signal 107.
[0083] Also in P102, in response to the control signals from the
computing device, the signal generator (e.g., signal generator 12
or 104) generates an excitation signal 13 (FIG. 3) or 107 (FIGS. 4
and 5), and in particular cases, the amplifier 105 (FIGS. 4 and 5)
amplifies the excitation signal, according to the commanded
frequency, amplitude and phase dictated by the control signals. The
TX signal (e.g., TX signal 13, FIG. 3, or TX signal 106, FIGS. 4
and 5) is applied to the excitation electrode 201 in the sensor
system 200 (FIGS. 3 and 4) or 200A (FIG. 5). The current produced
by the excitation signal passes through the MUT 210 and is detected
at the receiving electrode 202 (FIGS. 3 and 4) or multiple
receiving electrodes 202, 203 (FIG. 5). The detected current at
receiving electrode(s) is converted to the (received) voltage
signal (e.g., RX signal 16 in FIG. 3 or RX signal 121 in FIGS. 4
and 5), which is measured in M/P detector(s) (e.g., M/P detector 17
in FIG. 3 or M/P detector 115 in FIGS. 4 and 5). The M/P detector
produces magnitude and phase data about the RX signal. In the
illustrations in FIGS. 4 and 5, the magnitude and phase detector is
configured to produce analog output voltages. In these cases, the
voltages, which are proportional to the measured magnitude and
phase, are converted to digital signals in the analog to digital
converter 114 and transmitted to the computing device 510 101. In
FIG. 3, the M/P detector 17 transmits the signals to the computing
device 10.
[0084] In P103, the amplitude of the receive signal (e.g., receive
signal 16 in FIG. 3 or receive signal 121 in FIGS. 4 and 5) is
compared to the specified amplitude input range of the M/P detector
(e.g., M/P detector 17 in FIG. 3 or M/P detector 115 in FIGS. 4 and
5). If the measured magnitude, which quantifies the amplitude of
the receive signal (e.g., receive signal 16 in FIG. 3 or receive
signal 121 in FIGS. 4 and 5) relative to the commanded amplitude of
the reference signal (e.g., REF signal 14 in FIG. 3 or REF signal
114 in FIGS. 4 and 5), indicates that the amplitude of the receive
signal is not within the specified range, P101 and P102 are
repeated with a different amplitude of the excitation signal (106).
In P104, the excitation amplitude is adjusted to bring the
amplitude of the receive signal (e.g., receive signal 16 in FIG. 3
or receive signal 121 in FIGS. 4 and 5) within the specified input
range of the M/P detector (e.g., M/P detector 17 in FIG. 3 or M/P
detector 115 in FIGS. 4 and 5), for example, to produce a desired
quality of the magnitude output signal. In some cases, this
includes keeping the measured magnitude of the (TX) signal 106, the
(RX) signal, and the (REF) signal 114 all within the input
specifications for the (TX) M/P 109 and (RX) M/P 115. Otherwise,
the procedure moves to process P105 if the measured phase of the
(TX) signal 106 or the (RX) signal are outside of the specified
phase range limitations for the M/P detector 115, or to process
P107 if phase adjustments are not necessary.
[0085] In P107, the computing device (e.g., computing device 10 or
computing device 510) adjusts the phase of the signal generated by
the signal generator (e.g., signal generator 12 or 104) to match
the phase of the signal required for the specified range of the M/P
detector (e.g., M/P detector 17, FIG. 3 or M/P detector 115, FIGS.
4 and 5). The data from the last reading from process P105 provides
the initial value of phase for process P106.
[0086] In P106, the measured receive signal (e.g., RX signal 16,
FIG. 3, or RX signal 121, FIGS. 4 and 5) is compared to the
specified input phase range for the magnitude and phase detector
(e.g., M/P detector 17, FIG. 3 or M/P detector 115, FIGS. 4 and 5).
If the measured phase is not with in the specified input range of
the RX M/P 115 or the TX M/P 109, P106 is repeated with a different
phase of the excitation signal (e.g., TX signal 13, FIG. 3 or TX
signal 106, FIGS. 4 and 5) with the magnitude of the excitation
signal fixed. In P108, the phase is adjusted to bring the phase of
the receive signal (e.g., RX signal 16, FIG. 3, or RX signal 121,
FIGS. 4 and 5) within the specified input range of the phase
detector (e.g., M/P detector 17, FIG. 3 or M/P detector 115, FIGS.
4 and 5). Otherwise, the process moves to Process P109.
[0087] At this point, the frequency, amplitude and phase of the
excitation signal (e.g., TX signal 13, FIG. 3 or TX signal 106,
FIGS. 4 and 5) and receive signal (e.g., RX signal 16, FIG. 3, or
RX signal 121, FIGS. 4 and 5) are fixed. In P109, the reference
signal (e.g., REF 14, FIG. 3 or REF 114, FIGS. 4 and 5) is adjusted
for the receive (RX) magnitude and phase measurement. The amplitude
and phase of this signal is selected to be within the respective
specified input ranges of the magnitude and phase detector 115
(e.g. the specifications of the Analog Devices AD8302) such that
the amplitude of the reference signal is as close as possible to
the amplitude of the receive (RX) signal and the phase difference
is 90.degree., where the phase difference can be detected with
highest precision.
[0088] In P110, the measured magnitude and phase of the receive
signal (e.g., RX signal 16, FIG. 3, or RX signal 121, FIGS. 4 and
5) are compared to target output magnitude and phase of the level
and phase detector (e.g., M/P detector 17, FIG. 3 or M/P detector
115, FIGS. 4 and 5). If the measured magnitude and phase from
detector (e.g., M/P detector 17, FIG. 3 or M/P detector 115, FIGS.
4 and 5) is not within specified tolerance bands based on the
signal to noise ratios around the target magnitude and phase, P109
is repeated with a magnitude and phase of the reference signal
(e.g., REF 14, FIG. 3 or REF 114, FIGS. 4 and 5) that is increased
or decreased to match the target values. Otherwise, the procedure
is continued in P110.
[0089] In P110, the reference signal (e.g., REF 14, FIG. 3 or REF
114, FIGS. 4 and 5) is adjusted for the excitation (TX) magnitude
and phase measurement. The amplitude and phase of this signal is
selected to be within the respective specified input ranges of the
magnitude and phase detector (e.g., M/P detector 15, FIG. 3 or M/P
detector 109, FIGS. 4 and 5) such that the amplitude of the
reference signal is approximately equal to the amplitude of the TX
signal and the phase difference is 90.degree., where the phase
difference can be detected with sufficient precision.
[0090] In P112, the measured magnitude and phase of the excitation
signal (e.g., TX signal 13, FIG. 3 or TX signal 106, FIGS. 4 and 5)
are compared to target output magnitude and phase of the level and
phase detector (e.g., M/P detector 15, FIG. 3 or M/P detector 109,
FIGS. 4 and 5). If the measured magnitude and phase from detector
109 is not within specified tolerance bands based on the signal to
noise ratios around the target magnitude and phase, P111 is
repeated with different amplitude and phase of the reference signal
(114). Otherwise, the procedure is repeated with a different
frequency within the specified range of frequencies starting in
Process P102 or completed in Process P112.
[0091] The computation of the magnitude and phase of the excitation
signal 106 relative to the receive signal 121 is described herein.
These values are used to compute the measured impedance or
dielectric properties over the range of frequencies to correlate
with the physical properties of interest for the MUT.
[0092] The functionality described herein, or portions thereof, and
its various modifications (hereinafter "the functions") can be
implemented, at least in part, via a computer program product,
e.g., a computer program tangibly embodied in an information
carrier, such as one or more non-transitory machine-readable media,
for execution by, or to control the operation of, one or more data
processing apparatus, e.g., a programmable processor, a computer,
multiple computers, and/or programmable logic components.
[0093] A computer program can be written in any form of programming
language, including compiled or interpreted languages, and it can
be deployed in any form, including as a stand-alone program or as a
module, component, subroutine, or other unit suitable for use in a
computing environment. A computer program can be deployed to be
executed on one computer or on multiple computers at one site or
distributed across multiple sites and interconnected by a
network.
[0094] Actions associated with implementing all or part of the
functions can be performed by one or more programmable processors
executing one or more computer programs to perform the functions of
the calibration process. All or part of the functions can be
implemented as, special purpose logic circuitry, e.g., an FPGA
and/or an ASIC (application-specific integrated circuit).
Processors suitable for the execution of a computer program
include, by way of example, both general and special purpose
microprocessors, and any one or more processors of any kind of
digital computer. Generally, a processor will receive instructions
and data from a read-only memory or a random access memory or both.
Components of a computer include a processor for executing
instructions and one or more memory devices for storing
instructions and data.
[0095] In various embodiments, components described as being
"coupled" to one another can be joined along one or more
interfaces. In some embodiments, these interfaces can include
junctions between distinct components, and in other cases, these
interfaces can include a solidly and/or integrally formed
interconnection. That is, in some cases, components that are
"coupled" to one another can be simultaneously formed to define a
single continuous member. However, in other embodiments, these
coupled components can be formed as separate members and be
subsequently joined through known processes (e.g., fastening,
ultrasonic welding, bonding).
[0096] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a", "an" and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0097] When an element or layer is referred to as being "on",
"engaged to", "connected to" or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to", "directly connected to" or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0098] Spatially relative terms, such as "inner," "outer,"
"beneath", "below", "lower", "above", "upper" and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
[0099] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *