U.S. patent application number 16/557203 was filed with the patent office on 2020-06-25 for synthetic data collection method for full matrix capture using an ultrasound array.
The applicant listed for this patent is BWXT Technical Services Group, Inc.. Invention is credited to Nicholas J. Borchers, Daniel T. MacLauchlan, Steven J. Younghouse.
Application Number | 20200200715 16/557203 |
Document ID | / |
Family ID | 51259118 |
Filed Date | 2020-06-25 |
View All Diagrams
United States Patent
Application |
20200200715 |
Kind Code |
A1 |
Younghouse; Steven J. ; et
al. |
June 25, 2020 |
SYNTHETIC DATA COLLECTION METHOD FOR FULL MATRIX CAPTURE USING AN
ULTRASOUND ARRAY
Abstract
A method for efficiently achieving full-matrix ultrasonic data
capture which includes the steps of providing an ultrasound array
apparatus, the ultrasound array apparatus further comprising a
probe, collecting data over a plurality of inspection locations,
generating a plurality of data matrices, each of the data matrices
reflecting data collected at the locations, and collecting,
initially, a subset of a quantity of data needed for reconstruction
of each of the inspection locations. In the method, as the probe
moves from collection location to collection location, a data
matrix at a prior collection location is gradually filled in as the
probe moves to subsequent collection locations. In certain
embodiments physical scanning of a probe with few elements is
replaced by electronically scanning using an array with many
elements.
Inventors: |
Younghouse; Steven J.;
(Forest, VA) ; MacLauchlan; Daniel T.; (Lynchburg,
VA) ; Borchers; Nicholas J.; (Blacksburg,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BWXT Technical Services Group, Inc. |
Lynchburg |
VA |
US |
|
|
Family ID: |
51259118 |
Appl. No.: |
16/557203 |
Filed: |
August 30, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15966399 |
Apr 30, 2018 |
10401328 |
|
|
16557203 |
|
|
|
|
13760172 |
Feb 6, 2013 |
9958420 |
|
|
15966399 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 15/8915 20130101;
G01N 2291/106 20130101; G01N 29/262 20130101; G01S 7/52085
20130101 |
International
Class: |
G01N 29/26 20060101
G01N029/26; G01S 15/89 20060101 G01S015/89; G01S 7/52 20060101
G01S007/52 |
Claims
1. A method for efficiently achieving full-matrix ultrasonic data
capture comprising: (a) providing an ultrasound array apparatus,
the ultrasound array apparatus comprising a probe, the probe
adapted for positioning over a test piece; (b) collecting data over
a plurality of locations; (c) generating a plurality of data
matrices, each of the data matrices reflecting data collected at
the locations; (d) collecting, initially, a subset of a quantity of
data needed for reconstruction at each of the locations; and (e)
collecting data from location to location, gradually filling in a
data matrix at a prior location as the probe moves to subsequent
locations.
2. The method of claim 1, wherein the ultrasonic array has k
positions and m elements and no more than (k+m-1) element firings
are required and no more than ( k m ) + m ( m - 1 ) 2 ##EQU00007##
waveforms are required to be collected in order to collect all the
data needed for reconstruction.
3. The method of claim 1, wherein the probe has a plurality of
elements, each of the elements having an element pitch, further
comprising the step of setting the scan increment equal to element
pitch.
4. The method of claim 1, wherein the probe is moved along a
direction of the ultrasonic array to generate the plurality of data
collection locations.
5. The method of claim 3, wherein a large array is employed.
6. The method of claim 5, wherein collection of data over the
plurality of locations is accomplished by electronically
transmitting and receiving on a subset of the elements, then
incrementing the subset in order to electronically increment the
data collection location.
7. The method of claim 1, wherein the ultrasound array is operating
in pitch-catch mode.
8. The method of claim 7, wherein the array has k positions and m
elements and a subset of transmit elements and a subset of receive
elements are fired in order to fill the matrix at each
position.
9. The method of claim 8, wherein no more than 2(k+m-1)-1 firings
are required and no more than k(2m-1)+(m-1).sup.2 waveforms are
required to be collected in order to collect all the data needed
for reconstruction.
10. The method of claim 1, wherein data collection increment is a
unit fraction of element pitch such that collection increment is
equal to pitch divided by L.
11. The method of claim 10, wherein the array has k positions and m
elements and no more than k+L(m-1) element firings are required and
no more than ( k m ) + L m ( m - 1 ) 2 ##EQU00008## waveforms are
required to be collected in order to collect all the data needed
for reconstruction, with the proviso that k>L for both of the
equations herein.
12. The method of claim 1, wherein the collected data is reused.
Description
CLAIM OF PRIORITY
[0001] This application is a continuation of U.S. Pat. Application
No. 15,966,399, filed Apr. 30, 2018, now U.S. Pat. No. 10,401,328,
which is a continuation of U.S. patent application Ser. No.
13/760,172, filed Feb. 6, 2013, and now U.S. Pat. No. 9,958,420
issued May 1, 2018, the disclosures of which are incorporated by
reference herein.
FIELD AND BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates generally to the field of data
collection, and in particular to a new and useful method for
achieving full matrix capture and processing of waveform data by
employing an ultrasound array apparatus.
2. Description of the Related Art
[0003] In ultrasonic testing, very short ultrasonic pulse-waves
with center frequencies ranging typically from 0.1 to 15 MHz and,
occasionally, up to 50 MHz are launched into materials to detect
internal flaws or to characterize materials. The technique is also
commonly used to determine the thickness of a tested object, for
example, to monitor pipe wall corrosion.
[0004] Ultrasonic testing is often performed on steel and other
metals and alloys, though it can also be used on concrete, wood and
composites, albeit with lower resolution. It is a form of
non-destructive testing used in many industries.
[0005] Two basic methods of receiving the ultrasound waveform are
pulse-echo and pitch-catch. In pulse-echo mode the transducer
performs both the sending and the receiving of the pulsed waves as
the "sound" is reflected back to the device. The reflected
ultrasound comes from an interface such as the back wall of the
object or from an imperfection within the object. The diagnostic
machine typically displays these results in the form of a signal
with amplitude representing intensity of the reflection and arrival
time of the reflection representing distance. In pitch-catch mode
separate transducers are employed to transmit and receive the
ultrasound.
[0006] There are a number of benefits to ultrasound testing. This
testing method provides high-penetrating power, which allows the
detection of flaws deep in the part being analyzed. It is also a
high sensitivity form of testing, permitting the detection of
extremely small flaws. Generally only one surface needs to be
accessible for ultrasound testing. The method provides greater
accuracy than other nondestructive methods in determining the depth
of internal flaws and the thickness of parts with parallel
surfaces. It provides some capability of estimating the size,
orientation, shape and nature of defects. It is generally
nonhazardous to operations or to nearby personnel and has no effect
on equipment and materials in the vicinity. It is also capable of
portable as well as highly-automated operation.
[0007] One type of ultrasound testing is known as phased array
ultrasound. For this type of testing the probe(s) are comprised of
a plurality (array) of elements, each of which can transmit and/or
receive ultrasound independently. By combining the transmitted
waves from each individual element a composite sound beam is
created. This beam may be steered and/or focused in an arbitrary
manner by applying short time delays across the elements and then
firing the elements together. In an analogous manner a receive
array may be set to be sensitive to incoming ultrasound from a
particular angle and/or focal depth by applying a set of short
delays across elements and subsequently adding together
contributions from all elements.
[0008] Matrix capture of ultrasonic information is a powerful
technique for inspection which uses the same array probes as phased
array ultrasound. The method is distinct, however. Matrix capture
is achieved, for example, by firing each array element in
succession and recording the received waveforms at all elements for
each firing. The resulting collected data at a given inspection
location forms a matrix of waveforms for which each waveform is
associated with one transmit-receive element pair. By acquiring all
data for every transmit/receive element pair over the array,
virtual ultrasonic scans at arbitrary angles can be reconstructed
at any time after data has been collected by applying the
appropriate set of short delays to the recorded waveforms and then
adding all signals together (using a computer, for instance).
[0009] Matrix capture is identified as distinct from phased array
in the following manner. In the phased array method, at a given
inspection location the appropriate set of short delays is applied
to all waveforms during transmit and receive phases, and at that
time waveforms from all array elements are summed together. Only
the final result is stored. In the matrix capture method all
waveforms corresponding to every combination of transmit and
receive element at each inspection location are stored in a data
matrix. At any subsequent time in post-processing the appropriate
set of short delays are applied to the stored waveforms and all
waveforms in the matrix are summed together in order to effectively
create a steered and/or focused beam of ultrasound.
[0010] Known matrix capture techniques, however, have an inherent
and significant disadvantage, namely the need for storing a large
amount of data. All waveforms for all transmit/receive pairs must
be stored for every scan location.
[0011] By way of an illustration, each waveform typically requires
1000 time points to be collected, each point requiring one byte.
For a 32-element array this means that (32).sup.2, or 1024,
waveforms must be collected. At 1000 bytes each, this collection
results in 1 MB of data stored for each scan location. Even a small
scan will require on the order of 100 times 100, or 10,000, scan
locations. This collection of data will result in total data
storage of about 10 GB. For the case of a pulse-echo inspection
with a probe containing m elements the number of waveforms that
must be collected per scan location, including reciprocity
considerations, is:
Number of waveforms per inspection location ( pulse - echo ) = m (
m - 1 ) 2 . ##EQU00001##
This requirement strains data storage needs, and also can place a
practical limitation on scan speed because it can be difficult to
rapidly move so much data.
[0012] Gains in efficiency can be realized by a method in which
scan and/or index increments are set equal to element pitch or unit
fractions thereof. In this case a large fraction of the collected
data at one location is (theoretically) identical with data
collected at neighboring locations.
[0013] One illustrative example involves a situation in which the
array probe is operating in pulse-echo mode and has three elements.
The probe will be moved to three separate positions along the same
direction as the ultrasonic array. At any given position, in order
to accumulate data from all transmit-receive pairs with a standard
method of data capture then
m ( m + 1 ) 2 = 3 4 2 = 6 ##EQU00002##
waveforms must be recorded. Additionally, each of the three
elements must be fired once. In order to collect all data for the
three probe positions a total of 9 element firings are needed and
18 waveforms must be collected.
[0014] This situation is illustrated in FIG. 1, in the section
marked "Standard Data Collection." A set of tables are shown, each
representing the data matrices for a probe at subsequent inspection
locations (shown in the upper left) corresponding to a 3-element
array moving in increments of one element pitch. Tables from left
to right represent data matrices which need to be filled in each
subsequent location (A, B, C). Tables from top to bottom represent
these same arrays at subsequent probe locations (A, B, C). The data
required at each location is a set of waveforms corresponding to
each transmit-receive pair. The letters in the tables represent the
probe location at which data is collected. For standard collection,
at each probe location (A, B, and C), all data for reconstruction
at that respective location is collected.
[0015] In the case where the probe is moved along the array
direction at a step size equal to the element pitch, if the
elements are fired 9 times and 18 waveforms are collected then much
of the data is redundant.
[0016] Thus, a need exists for a method of capture of waveform data
that is efficient and overcomes the above deficiencies, including,
but not limited to, redundancies and strain on storage
capacity.
SUMMARY OF THE INVENTION
[0017] The present invention addresses known deficiencies in the
art and is drawn to a new and efficient method of data collection
that effectively employs ultrasound technology.
[0018] Accordingly, one aspect of the present invention is to
provide a means for achieving full matrix capture by efficiently
employing an ultrasound array apparatus.
[0019] Embodiments of the present invention provide a method for
efficiently achieving full-matrix ultrasonic data capture which
includes the steps of providing an ultrasound array apparatus, the
ultrasound array apparatus further comprising a probe, moving the
probe over a plurality of collection locations, generating a
plurality of data matrices, each of the data matrices reflecting
data collected at the locations, and collecting, initially, a
subset quantity of data needed for reconstruction of each of the
collection locations. In the method, as the probe moves from one
collection location to the next, a data matrix at a prior
collection location is gradually filled in as the probe moves to
subsequent collection locations.
[0020] Accordingly, one aspect of the present invention is drawn to
a method for efficiently achieving full-matrix ultrasonic data
capture comprising: (a) providing an ultrasound array apparatus,
the ultrasound array apparatus comprising a probe, the probe
adapted for positioning over a test piece; (b) collecting data over
a plurality of locations; (c) generating a plurality of data
matrices, each of the data matrices reflecting data collected at
the locations; (d) collecting, initially, a subset of a quantity of
data needed for reconstruction at each of the locations; and (e)
collecting data from location to location, gradually filling in a
data matrix at a prior location as the probe moves to subsequent
locations.
[0021] Accordingly, another aspect of the present invention is
drawn to a method for efficiently achieving full-matrix ultrasonic
data capture comprising: (A) providing a two-dimensional ultrasound
array apparatus, the ultrasound array apparatus comprising a probe,
the probe adapted for scanning and the probe comprising scan
increments and nominal scan boundaries; (B) moving the probe over a
plurality of inspection locations; (C) generating a plurality of
data matrices, each of the data matrices reflecting data collected
at the inspection locations; (D) collecting, initially, a subset of
a quantity of data needed for reconstruction at each of the
inspection locations; and (E) as the probe moves from inspection
location to inspection location, gradually filling in a data matrix
at a prior inspection location as the probe moves to subsequent
inspection locations.
[0022] Inspection locations may correspond to collection locations
but are not necessarily the same. For example, if only sparse
coverage is required (e.g. for component thickness mapping) then
inspection locations may correspond to some subset of collection
locations.
[0023] The various features of novelty which characterize the
invention are pointed out with particularity in the claims annexed
to and forming a part of this disclosure. For a better
understanding of the invention, its operating advantages and
specific objects attained by its uses, reference is made to the
accompanying drawings and descriptive matter in which a preferred
embodiment of the invention is illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a composite schematic illustration of how an array
probe operating according to the present efficient data collection
method compares with standard data collection;
[0025] FIG. 2 is an illustration of a two-step process specific to
a "pitch-catch" probe arrangement where at each collection
location, in addition to the transmit element firing, the opposing
element from the "catch" probe also transmits a signal and all
elements from the "transmit" probe (save for the one which
originally transmitted) collect the receive signals; and
[0026] FIG. 3 is an illustration of a configuration for a
two-dimensional ultrasonic array, including a representation of
array indices as well as orientation with respect to scan and index
axes.
DESCRIPTION OF THE EMBODIMENTS
[0027] Referring now to the drawings, FIG. 1 illustrates, in the
section identified as "Efficient Data Collection," the present,
novel ultrasound data collection method. Following the "Standard
Data Collection" method, in order to collect all data for the three
probe positions a total of 9 element firings would be needed and 18
waveforms must be collected. According to the present "Efficient
Data Collection" method only 5 element firings and 12 waveforms
need to be collected in order to have all waveform data at all
positions. In order for this particular implementation to be
possible the probe increment must be equal to element pitch. Also,
this particular implementation relies on the reciprocity principle
(i.e. a signal transmitted by element x and received by element y
is in principle the same as a signal transmitted by element y and
received by element x). In the case of pulse-echo operation the
consequence of the reciprocity principle is that the matrix is
symmetrical about its diagonal; i.e. element xy is equal to element
yx. At each probe location only one element is fired and all
elements receive. As a result, a subset of the data needed for
reconstruction at that location is collected. As the probe moves
from position A to B to C, the data matrix at location A is
gradually filled in. While only three firings are shown, as the
probe continues to move the data matrices for locations B and C
will be filled as well. Considering, for example, the data matrix
at location A: as the probe moves, data from locations A, B, and C
are all used to enable reconstruction at that point.
[0028] The advantage in efficiency provided by embodiments of the
present invention increases as the number of elements and positions
increases. For k positions along an inspection line and m elements,
number of firings needed and waveforms to be collected are
expressed below as
Number of firings ( pulse - echo ) = ( k + m - 1 ) , and
##EQU00003## Number of waveforms needed ( pulse - echo ) = ( k m )
+ m ( m - 1 ) 2 . ##EQU00003.2##
So, in the situation in which a 32-element array is used and 100
data points are taken along a scan line, only 3,696 waveforms will
need to be collected and only 131 element firings will be needed.
This compares very favorably to the
(32.times.33/2).times.100=52,800 waveforms that would need to be
collected from 3200 firings in the absence of the presently-claimed
invention, which takes advantage of data redundancy.
[0029] If the probe increment is set to a unit fraction of element
pitch then the procedure outlined in paragraph 20 may still be
applied. In the case that probe increment is equal to element pitch
divided by L, then conceptually L arrays may be created and data
will be collected for each one in turn every L scan increments. In
order to fill all data matrices completely the number k of
inspection locations must be evenly divisible by L. Then, for a
total of k positions the number of firings necessary and number of
waveforms needed are expressed in the equations below as:
Number of firings ( increment is unit fraction of pitch ) = k + L (
m - 1 ) , and ##EQU00004## Number of waveforms ( increment is unit
fraction of pitch ) = ( k m ) + L m ( m - 1 ) 2 , where k > L
for both of the above equations . ##EQU00004.2##
[0030] If the inspection is performed using a pitch-catch
arrangement then a second step is required in order to complete the
subset of data that must be collected at each location. Elements
normally arranged as receivers must be adapted as transmitters as
well, and conversely elements arranged as transmitters must be
arranged as receivers as well. At each collection location, in
addition to the transmit element firing the opposing element from
the "catch" probe must also transmit a signal and all elements from
the "transmit" probe (save for the one which originally
transmitted) must receive the signals. This procedure is
represented in FIG. 2 as a two-step process. In this manner the
sub-array will be filled and collection may proceed as outlined in
paragraph 20. If this arrangement is made then the total number of
firings needed and total number of waveforms needed are expressed
in the equations below as
Number of firings(pitch-catch)=2(k+m-1)-1, and
Number of waveforms collected(pitch-catch)=k(2m-1)+(m-1).sup.2.
[0031] In certain embodiments scan increment is equal to element
pitch. In these embodiments an alternative to moving the probe
along the direction of the array is to make a probe with many
elements and generate a transmit and receive sequence which is
equivalent to moving a smaller probe. While this requires the
construction of a large array, it provides the advantage of
potentially eliminating moving parts and positioning errors.
[0032] Embodiments of the present invention may also be applied in
the context of two-dimensional arrays, for which gains in data
storage and firing efficiency can be even more dramatic. In fact,
without application of the present, novel method to improve
efficiency it is likely that matrix firing would be impractical to
implement for all but the smallest two-dimensional arrays using
computer technology available today. For example, consider the
situation of a 16-element.times.8-element array probe operating in
pulse echo mode. Without implementation of such a technique to
improve efficiency, (16.times.8)=128 firings would be needed at
each probe position in order to obtain the (128.times.129)/2=8256
waveforms. Assuming 1000 one-byte points per waveform and an array
of 100 by 100 probe positions, this leads to a total data storage
size of 82 GB.
[0033] By re-using data collected at different probe positions the
present invention provides a very considerable savings in number of
firings and data collection. Consider a raster scan along both
array directions for a two-dimensional array with n elements along
the scan direction and m elements along the index (or step)
direction. The raster scan includes k collection locations along
the scan direction and l steps. An illustration of this arrangement
is provided in FIG. 3. For the (n.times.m)-element ultrasonic array
operating in pulse-echo mode only m or n firings (whichever is
smaller) are needed and (nm)+(n-1)(m-1) waveforms need to be stored
at each collection location. This corresponds to firing the corner
element (i.e., element (1,1)) and receiving on all elements, then
firing each element along the short edge of the array in turn
(e.g., elements (M,1) for M=2 through m) and, for each firing,
receiving on all elements along the long edge of the array (e.g.,
elements (1,N) where N=2 through n). (Additional waveforms will
need to be recorded in order to fill data matrices near edges of
the inspection grid). In one embodiment the probe will be scanned
beyond the nominal scan boundaries and data will be taken such that
data matrices near the boundaries are filled. The distance the
probe is scanned beyond the scan boundaries is equal to the number
of elements along each respective dimension minus one. Thus, if
there are k scan points along the "n" dimension of the probe and l
scan points along the "m" dimension of the probe, a conservative
estimate of the total number of waveforms needed is shown
below:
Number of waveforms(2D
array).apprxeq.(k+n-1)(l+m-1)[nm+(n-1)(m-1)].
This approximate formula is an overestimate of the total number of
waveforms needed because fewer than [(nm)+(n-1)(m-1)] waveforms
will need to be collected at scan locations near the edges of the
grid in order to provide a full reconstruction over the k by l
grid. However, it is sufficient to demonstrate the advantage of use
of this novel collection method in order to reduce data storage
requirements. Returning to the 16.times.8 array example, this means
that only 8 firings are necessary at each probe position and 233
waveforms need to be stored. For the same 100 by 100 array of probe
positions this leads to total data storage of approximately
(115107233)1000 bytes equals approximately 3 GB which is easily
achievable using the technology currently known in the art.
[0034] In another embodiment of the present invention, as it
pertains to two-dimensional arrays, symmetry is exploited only
along the index direction. This may be done for a variety of
reasons. As examples, if positioning along the index direction
cannot be performed with sufficient precision, or if the index
increment cannot be set equal to element pitch along that
direction, or if the scan is performed along only one direction,
then symmetry cannot be exploited along the index direction. In
this case significant gains can still be made by implementing the
following procedure: at each scan location, all m elements for
which N=1 (i.e. element (M, 1) where M=1 through m) are fired in
turn, and for each firing all received waveforms from all elements
in the array are recorded. (Note that, when firing element(s) (M,
1) where M>1, waveforms at elements (M',1) where M'<M does
not need to be recorded because reciprocity considerations render
it redundant.) At each scan location m firings are thus required
and
[ ( m 2 n ) - m ( m - 1 ) 2 ] ##EQU00005##
waveforms must be recorded. Extra waveforms will need to be
recorded at locations beyond the nominal scan grid in order to
record all waveforms needed to fill all matrices at every scan
location. An estimate of the total number of waveforms needed for a
scan over k by l locations is:
Number of waveforms ( 2 D array , symmetry exploited only along
scan direction ) .apprxeq. ( k + m - 1 ) l [ ( m 2 n ) - m ( m - 1
) 2 ] . ##EQU00006##
This estimate is slightly conservative because it does not account
for the reduced number of waveforms which need to be collected at
locations beyond the nominal range k. Returning to the example of a
16.times.8 array with 100.times.100 scan locations, the total data
which needs to be stored is approximately (115100996)1000 bytes
equals 11.45 GB. This is still a very considerable improvement over
the storage requirement of 82 GB which is required using the
standard collection methodology.
[0035] The present invention provides at least three advantages.
The first is reduction of data storage. This allows more files to
be stored on a single drive and also allows the ability in some
cases to put all scan data into system memory, which would allow
instantaneous access to all scan data. The second is potential for
dramatically increased scan speed. Since less data is being
acquired at each position, data throughput is reduced considerably.
This increase in scan speed can result in reduced inspection costs.
The third advantage is the potential for cleaner data because fewer
transmitter firings results in a longer time interval between
firings, which means that the sound has more time to dissipate.
[0036] Alternatives to the present efficient data collection method
involve collecting the full set of data at every scan location.
This method results in slower scan times, potentially noisier data,
and greatly increased (and in some cases impractical) storage
requirements.
[0037] While a specific embodiment of the invention has been shown
and described in detail to illustrate the application of the
principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles.
* * * * *