US2015285927A1PendingUtilityA1
System and method for detecting rock fall
Assignee: WEIR JONES ENGINEERING CONSULTANTS LTDPriority: Jun 17, 2008Filed: Apr 10, 2015Published: Oct 8, 2015
Est. expiryJun 17, 2028(~1.9 yrs left)· nominal 20-yr term from priority
G01N 29/44G01V 1/001B61L 23/041B61K 9/08
43
PatentIndex Score
0
Cited by
0
References
0
Claims
Abstract
Aspects of the invention provide systems and methods for using ballast sensors to detect rock fall events in a vicinity of railway tracks or similar roadways or tracks. The ballast sensors are spaced apart from the tracks. Particular embodiments permit the use of signals from the ballast sensors to discriminate rock fall events from other types of events and to detect the hypocenter of a rock fall event.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A system for detection of rock fall in a vicinity of a section of railway track, the system comprising:
a plurality of ballast sensors spaced apart along the track section, each ballast sensor located in a ballast proximate to the track section but spaced apart from rails and ties associated with the track section and each ballast sensor sensitive to acoustic energy and configured to generate a corresponding ballast sensor signal in response to detecting acoustic energy; a signal processing unit operatively connected to receive the ballast sensor signals from the plurality of ballast sensors, the signal processing unit configured to detect rock fall events in a vicinity of the track section based, at least in part, on the ballast sensor signals.
2 . A system according to claim 1 wherein the signal processing unit is configured to detect a plurality of different types of events comprising rock fall events, train events wherein a train travels over the track section and highrail vehicle events wherein a highrail vehicle travels over the track section and wherein the signal processing unit is configured to discriminate rock fall events from train events or highrail vehicle events.
3 . A system according to claim 2 wherein the signal processing unit is configured to detect an event for a particular one of the ballast sensors based, at least in part, on its corresponding ballast sensor signal.
4 . A system according to claim 3 wherein the signal processing unit is configured to detect a start of the event and an associated time t start , for the particular one of the ballast sensors, when a STA/LTA parameter associated with the corresponding ballast sensor signal is greater than a start trigger threshold (thresh_start).
5 . A system according to claim wherein the signal processing unit is configured to detect an end of the event and an associated time t end , for the particular one of the ballast sensors, when the STA/LTA parameter associated with the corresponding ballast sensor signal is less than an end trigger threshold (thresh_end).
6 . A system according to claim 4 wherein the signal processing unit is configured to determine the STA/LTA parameter for the corresponding ballast sensor signal according to one of:
(
i
)
(
STA
LTA
)
n
=
∑
i
=
(
n
-
(
a
-
1
)
)
i
=
n
x
i
a
∑
i
=
(
n
-
(
b
-
1
)
)
i
=
n
x
i
b
where
b
>
a
>
0
and
n
≥
a
,
b
where: x i represents a value of an i th sample of the corresponding ballast sensor signal, n is an index of a current sample x n , a is an STA duration constant, b is an LTA duration constant and
(
STA
LTA
)
n
is the STA/LTA parameter; and
(
ii
)
(
STA
LTA
)
mod
,
n
=
∑
i
=
(
n
-
(
a
-
1
)
)
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=
n
x
i
a
c
where
n
>
a
>
0
where: x i represents a value of an i th sample of the corresponding ballast sensor signal, n is an index of a current sample x n , a is an STA duration constant, c is an experimentally determined constant that is representative of an LTA during event free times and
(
STA
LTA
)
mod
,
n
is the STA/LTA parameter.
7 . A system according to claim 3 wherein the signal processing unit is configured to detect a start of the event and an associated time t start , for the particular one of the ballast sensors, when an energy parameter associated with the corresponding ballast sensor signal is greater than a start trigger threshold (E_thresh_start), the energy parameter comprising a windowed average of a squared amplitude of the corresponding ballast sensor signal.
8 . A system according to claim 7 wherein the signal processing unit is configured to detect an end of the event and an associated time t end , for the particular one of the ballast sensors, when the energy parameter associated with the corresponding ballast sensor signal is less than an end trigger threshold (E_thresh_end).
9 . A system according to claim 7 wherein the signal processing unit is configured to determine the energy parameter for the corresponding ballast sensor signal according to:
E
n
=
∑
i
=
n
-
(
d
-
1
)
n
(
x
i
)
2
d
where: x i represents a value of an i th sample of the corresponding ballast sensor signal, n is an index of a current sample x n , d is a window duration constant and E n is the energy parameter.
10 . A system according to claim 3 wherein the signal processing unit is configured to determine a duration t dur associated with the event for the particular one of the ballast sensors based, at least in part, on its corresponding ballast sensor signal.
11 . A system according to claim 10 wherein the signal processing unit is configured to compare the event duration t dur with one or more duration criteria and to determine on the basis of this comparison that the event is not a rock fall event.
12 . A system according to claim 11 wherein the signal processing unit is configured to determine that the event is a train event or a highrail vehicle event based at least in part on the comparison of the event duration t dur with the one or more duration criteria.
13 . A system according to claim 12 wherein the signal processing unit is configured to determine, for the particular one of the ballast sensors, a PPV parameter which represents a magnitude of a sample of the corresponding ballast sensor signal with the largest absolute value during the event and wherein the signal processing unit is configured to compare the PPV parameter with one or more magnitude criteria and to determine on the basis of this comparison whether the event is a train event or a highrail vehicle event.
14 . A system according to claim 3 wherein the signal processing unit is configured to determine a spectral power distribution associated with the event for the particular one of the ballast sensors based, at least in part, on its corresponding ballast sensor signal.
15 . A system according to claim 14 wherein the signal processing unit is configured to compare the spectral power distribution with one or more spectral criteria and to determine on the basis of this comparison that the event is not a rock fall event.
16 . A system according to claim 15 wherein the one or more spectral criteria comprise a frequency threshold (thresh_freq) and the signal processing unit is configured to determine that the event is a train event or a highrail vehicle event when the spectral power distribution comprises more than a particular percentage of its power at frequencies above the frequency threshold (thresh_freq).
17 . A system according to claim 16 wherein the signal processing unit is configured to determine, for the particular one of the ballast sensors, a PPV parameter which represents a magnitude of a sample of the corresponding ballast sensor signal with the largest absolute value during the event and the signal processing unit is configured to compare the PPV parameter with one or more magnitude criteria and to determine on the basis of this comparison whether the event is a train event or a highrail vehicle event.
18 . A system according to claim 3 comprising one or more rail sensors, each rail sensor operatively contacting the rails or the ties associated with the track section and each rail sensor sensitive to acoustic energy and configured to generate a corresponding rail sensor signal in response to detecting acoustic energy and wherein the signal processing unit is operatively connected to receive the rail sensor signal.
19 . A system according to claim 18 wherein the signal processing unit is configured to determine a rail sensor spectral power distribution associated with the event for a particular one of the rail sensors based, at least in part, on its corresponding rail sensor signal and configured to compare the rail sensor spectral power distribution with one or more spectral criteria and to determine on the basis of this comparison that the event is not a rock fall event.
20 . A system according to claim 3 wherein the signal processing unit is configured to determine a PPV parameter associated with the event for the particular one of the ballast sensors and its corresponding ballast sensor signal, the PPV parameter representing a magnitude of a sample of the corresponding ballast sensor signal with the largest absolute value during the event.Join the waitlist — get patent alerts
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