Note: Descriptions are shown in the official language in which they were submitted.
CA 02945247 2016-10-12
US Attorney Docket No. 08.00994.0042
CA Attorney Docket No. 17271-0005
LIGHT EMISSION POWER CONTROL APPARATUS AND METHOD
FIELD
[0001] This disclosure relates to the field of railway track inspection and
assessment systems.
BACKGROUND
[00021 Rail infrastructure owners are motivated to minimize staff exposure to
unsafe
environments and replace the time consuming and subjective process of manual
crosstie (track)
inspection with objective and automated processes. The motivation is driven by
the desire to
improve rail safety in a climate of increasing annual rail traffic volumes and
increasing
regulatory reporting requirements. Objective, repeatable, and accurate track
inventory and
condition assessment also provide owners with the innovative capability of
implementing
comprehensive asset management systems which include owner/region/environment
specific
track component deterioration models. Such rail specific asset management
systems would yield
significant economic benefits in the operation, maintenance and capital
planning of rail
networks. A primary goal of such automated systems is the non-destructive high-
speed
assessment of railway track infrastructure. Track inspection and assessment
systems currently
exist including, for example, Georgetown Rail (GREX) Aurora 3D surface profile
system and
Ensco Rail 2D video automated track inspection systems. Such systems typically
usc coherent
light emitting technology, such as laser radiation, to illuminate regions of
the railway track bed
during assessment operations.
[0003] The effect of variations in surface properties of railroad tracks and
surrounding surfaces
has a significant impact on light levels reflected from these surfaces and
subsequently detected
by 3D sensors. Reflected light levels entering the sensors are not always
optimum due to
variations surface color (light or dark colored surfaces) or texture for
example. Incorrect lighting
levels can cause the 3D track surface profile measured by a 3D sensor to be
distorted or
imperceptible, affecting the measured profile accuracy.
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[0004] In such systems, high power laser light sources may be used. Laser line
projectors may
include high power (Class IV) non-visible infrared laser sources (for example;
a wide fan angle
(75-90 ) laser with a wavelength of 808nm and a power of 10 watts). All Class
IV lasers present
an extreme ocular exposure hazard when used without external eye protection.
Further
.. complicated by the non-visible nature of infrared radiation (deactivating
the natural aversion
reflexes such as protective pupil contraction, blink, or head turn), Class IV
lasers are capable of
causing severe eye damage through direct, or reflected light exposure.
Reflected exposure occurs
when the laser radiation is scattered from highly reflective specular (shiny)
targets such as
polished metal surfaces (for example in the track environment; rail heads,
switches, frogs). In
environments where specular reflections are possible, any potential occurrence
of exposure must
be removed by eliminating ocular access to the beam. Beam access can be
restricted by either
requiring that protective eyewear (appropriately filtered) be worn by all
those with any exposure
potential, or by effectively enclosing the beam.
[0005] For rail testing environments with moving surveys using Class IV
lasers, the top of the
.. rail head presents a nearly ideal continuous omnidirectional specular
reflector. In addition to the
rail head, other flat or otherwise smooth surfaces (plates, switches, frogs,
the materials between
and around the rail head near crossings in urban areas), create conditions
where the Maximum
Permissible Exposure (MPE) limits for ocular damage are exceeded (especially
in situations
where those surfaces are wet). Adding to the danger of reflected laser energy,
the non-divergent
nature of laser sources guarantees that any reflected coherent laser light
will present an ocular
danger for large distances from the reflecting surfaces.
[0006] What is needed, therefore, is a way to control high powered light
emitters used in systems
similar to those described above in real time in order to limit unnecessary
exposure to light
emitted from such light emitters.
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SUMMARY
[0007] A system for inspecting a railway track is disclosed wherein the system
includes a power
source (e.g., a gas powered engine providing electrical power, a generator or
a battery); an
adjustable intensity light emitting apparatus powered by the power source for
emitting light
energy toward a railway track; and a sensor for sensing the emitted light from
the light emitting
apparatus and acquiring three dimensional image data of the railway track to
be stored in a data
storage apparatus. The image data is preferably elevation (or range) and
intensity data gathered
using a 3D sensor. The system also includes at least one processor for
controlling the optical
to power output of the light emitting apparatus, to adjust and compensate
for changes in track bed
color and texture variations and improve the ability to measure track bed
profiles by 3D sensors.
This ability to adjust the optical power output based on track surface
characteristics provides
improved accuracy railway track elevation and intensity measurements over a
much wider range
of real world conditions.
[0008] In one example the track bed surface is predominantly dark colored due,
for example, to
the placement of new wooden ties or localized grease contamination from
lubricating devices,
and the intensity of the light emitting source illuminating the track bed must
be increased to
reduce the number of undetectable reflected light areas in the profile
measured by the 3D
sensors. For typical 3D sensors, such dark areas which cause low intensity
reflections can result
in elevation zero value errors. Elevation zero value errors in 3D elevation
and intensity profiles
negatively impact the ability to generate accurate 3D elevation and intensity
maps of the track
bed surface thereby reducing the accuracy of subsequent inspection and
assessment analysis.
[0009] In a related example the surface of the track bed is light colored due,
for example, to the
placement of concrete ties or localized light colored surface contaminations
from fine soils due
to mud holes, and the intensity of the light emitting source illuminating the
track bed must be
decreased to reduce the number of out-of-range reflected light areas in the
profile measured by
the 3D sensors. For typical 3D sensors, such high intensity reflections from
light colored areas
result in sensor saturation or out-of-range intensity conditions which produce
invalid elevation
measures. High intensity based out-of-range errors in 3D elevation and
intensity profiles
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diminish the ability to generate accurate 3D elevation and intensity maps
thereby reducing the
accuracy of subsequent track bed inspection and assessments.
[0010] To compensate for undesirable light conditions, a system is disclosed
for inspecting a
railway track configured to adjust the intensity of a light emitting apparatus
based on light
reflected from a railway track, the system comprising a power source; a light
emitting apparatus
powered by the power source for emitting light energy toward a railway track;
at least one sensor
for sensing reflected light emitted from the light emitting apparatus; and a
processor in
communication with the at least one sensor wherein the processor includes an
algorithm for
adjusting the power of the light emitting apparatus, the algorithm comprising
the steps of (a)
to calculating one or more intensity histograms based on the reflected
light sensed by the at least
one sensor; and (b) adjusting a light emitter control output value based at
least in part on the
calculated one or more intensity histograms; and a controller in communication
with the
processor wherein the controller is configured to control the light intensity
of the light emitting
apparatus in response to the light emitter control output value.
[00111 In certain embodiments, the algorithm for adjusting the power of the
light emitting
apparatus further comprises the step of calculating one or more aggregate
intensity histograms
for a target zone. In some example embodiments, the target zone further
comprises at least one
surface zone including one or more members selected from the group consisting
of a gage tie
zone, a rail zone, a field tie zone, and a field ballast zone. In some example
embodiments, the
algorithm for adjusting the power of the light emitting apparatus further
comprises the steps of
calculating a median histogram for the target zone and adjusting a light
emitter control output
value based at least in part on the calculated median histogram.
[0012] The algorithm for adjusting the power of the light emitting apparatus
may further
comprise the steps of calculating aggregate zero value error counts for the
target zone and
adjusting a light emitter control output value based at least in part on the
calculated aggregate
zero value error counts. Alternatively or additionally, the algorithm for
adjusting the power of
the light emitting apparatus further comprises the steps of calculating
aggregate out-of-range
error counts for the target zone and adjusting a light emitter control output
value based at least in
part on the calculated aggregate out-of-range error counts.
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[0013] The algorithm for adjusting the power of the light emitting apparatus
may further
comprise the step of determining whether the number of zero value errors are
greater than a zero
value error count number threshold. Additionally or alternatively, the
algorithm for adjusting the
power of the light emitting apparatus further comprises the step of
determining whether the
number of out-of-range errors are greater than a range error count number
threshold.
[0014] A system for inspecting a railway track is disclosed wherein the system
is configured for
disabling or otherwise cutting off power to a light emitting apparatus under
certain conditions.
The system is configured for inspecting a railway track configured to adjust
the intensity of a
light emitting apparatus based on the motion of the system relative to an
adjacent railway track.
The system is mounted to a railway track vehicle and comprises a power source;
a light emitting
apparatus powered by the power source for emitting light energy toward a
railway track; at least
one motion detector for detecting the motion of the system relative to an
adjacent railway track; a
processor in communication with the at least one motion detector wherein the
processor includes
an algorithm for adjusting the power of the light emitting apparatus, the
algorithm comprising
the steps of (a) determining whether the system is moving relative to an
adjacent railway track
based on incoming data from the at least one motion detector, and (b)
adjusting a light emitter
control output value based at least in part on incoming data from the at least
one motion detector;
and a controller in communication with the processor wherein the controller is
configured to
control the light intensity of the light emitting apparatus in response to the
light emitter control
output value.
100151 In one embodiment, the algorithm for adjusting the power of the light
emitting apparatus
further comprises the step of adjusting the light emitter control output value
to a value that
causes the controller to shut off power to the light emitting apparatus if the
system is moving
below a minimum speed relative to an adjacent railway track. In another
embodiment, the
algorithm for adjusting the power of the light emitting apparatus further
comprises the step of
adjusting the light emitter control output value to a value that causes the
controller to provide
power to the light emitting apparatus if the system is moving at or above a
minimum speed
relative to an adjacent railway track.
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[0016] A method of inspecting a railway track bed using a light source with
real time adjustable
light emission is also disclosed, the method comprising the steps of emitting
light from a mobile
inspection system comprising a light source wherein the emitted light is
emitted toward an
adjacent railway track bed; detecting motion of the mobile inspection system
relative to the
adjacent railway track bed; adjusting a light emitter control output value
based on the detected
motion of the mobile inspection system; and controlling the light intensity of
the light emitting
apparatus in response to the adjusted light emitter control output value. In
embodiments, the
detecting step further comprises detecting the speed of the system relative to
the adjacent railway
track bed. The adjusting step may further include adjusting the control output
value to a value
that causes the power to the light emitting apparatus to be shut off if the
detected speed of the
railway track vehicle falls below a minimum speed threshold. Additionally or
alternatively, the
adjusting step may include adjusting the control output value to a value that
causes the power to
the light emitting apparatus to be activated if the detected speed of the
railway track vehicle is
equal to or greater than a minimum speed threshold.
[0017] The controlling step may further include disabling power to the light
emitting apparatus
in response to the control output value and/or activating power to the light
emitting apparatus in
response to the control output value.
100181 The summary provided herein is intended to provide examples of
particular disclosed
embodiments and is not intended to limit the scope of the invention disclosure
in any way.
25
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BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Further features, aspects, and advantages of the present disclosure
will become better
understood by reference to the following detailed description, appended
claims, and
accompanying figures, wherein elements are not to scale so as to more clearly
show the details,
wherein like reference numbers indicate like elements throughout the several
views, and
wherein:
[0020] FIG. 1 shows a graphical relationship between the control port input
versus output power
for a typical light emission source;
[0021] FIG. 2 shows 3D sensor intensity profile for reflected light levels for
normal, light, and
dark surfaces, respectively for the profile of the same arbitrary stepped
elevation object;
[0022] FIG. 3 shows a somewhat schematic diagram of a fixed output light line
projector being
used to illuminate a normal colored object and the resulting typical reflected
normal line
intensity detected by a 3D sensor;
[0023] FIG. 4 shows a somewhat schematic diagram of a fixed output light line
projector being
used to illuminate a dark colored object and the resulting typical reflected
high line intensity
detected by a 3D sensor;
[0024] FIG. 5 shows a somewhat schematic diagram of a fixed output light line
projector being
used to illuminate a light colored object and the resulting typical reflected
low line intensity
detected by a 3D sensor;
[0025] FIG. 6 shows a block diagram of a light emission source power control
system;
[0026] FIG. 7 shows track bed transverse zones defined and used by a light
emission power
control process to characterize profile intensity data based on the location
where the data was
gathered;
[0027] FIG. 8 shows a flow chart illustrating a light emission power control
algorithm used by a
light emission power control process; and
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Date Recue/Date Received 2021-06-22
CA 02945247 2016-10-12
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[0028] FIG. 9 shows a schematic diagram of a light emission source power
control system
configured to activate or deactivate a light emission apparatus under certain
conditions.
[0029] The figures are provided to illustrate concepts of the invention
disclosure and are not
intended to limit the scope of the invention disclosure to the exact
embodiments provided in the
figures.
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DETAILED DESCRIPTION
100301 Various terms used herein are intended to have particular meanings.
Some of these terms
are defined below for the purpose of clarity. The definitions given below are
meant to cover all
forms of the words being defined (e.g., singular, plural, present tense, past
tense). If the
definition of any term below diverges from the commonly understood and/or
dictionary
definition of such term, the definitions below control.
[0031] "Track", "Railway track", "track bed" or "railway track bed" is defined
herein to mean a
section of railway including the rails, ties, components holding the rails to
the ties, and ballast
material.
[0032] "Sample" or "profile" is defined herein to include a discrete
measurement of reflected
light during a specifically defined time period.
[0033] A "processor" is defined herein to include a processing unit including,
for example, one
or more microprocessors, an application-specific instruction-set processor, a
network processor,
a vector processor, a scalar processor, or any combination thereof, or any
other control logic
apparatus now known or later developed that is capable of performing the tasks
described herein,
or any combination thereof.
100341 The phrase "in communication with" means that two or more devices are
in
communication with one another physically (e.g., by wire) or indirectly (e.g.,
by wireless
communication).
10035] "Motion Detector" is broadly defined as anything from a simple motion
detector to a
device configured to detect the speed of a vehicle such as, for example, a
speedometer or a shaft
encoder.
100361 Wide fan-angle line generators used in track inspection and assessment
systems are
typically high power Class IV, non-visible infrared laser sources (nominally
wavelength of
808nm with a maximum power output of 10 watts in this example embodiment).
These laser
devices typically have a power control input port, allowing the direct control
of the emitted laser
optical output power. Based on the control signals applied to the control
port, the radiated laser
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power can be adjusted from 0 to 100 percent of the rated maximum output power.
Adjustments
to this control port are substantially instantaneous. A graphical
representation of a typical laser
control port input versus laser output power is shown in FIG. 1.
100371 In a preferred embodiment, the uniform intensity line generated by a
wide fan-angle light
source is projected onto a surface of a track bed and is reflected and sensed
by one or more
sensors. The intensity detected by the sensors is a complex function of the
characteristics of the
surface illuminated by the light source. Of particular importance are the
surface properties of
texture, uniformity, and color. Changes in surface physical properties result
in changes in
reflected light levels. Light levels deviating substantially from mid-range
negatively impact 3D
elevation measurements. Low light levels result in missing or zero values for
sections of a
measured 3D elevation profile, and excessively high light levels can cause
sensor saturation and
introduce intensity out-of-range errors that result in measured elevation
range errors.
100381 It is not uncommon to have wide variations in the physical surface
characteristics
affecting reflected light levels during track surveys. These variations can be
compensated for by
adjusting the radiated light optical power (intensity) based on the track
surface conditions on a
near real-time basis during survey data collection. To this end, disclosed
herein is a method of
measuring surface elevation of a track bed using at least one 3D sensor,
analyzing measured
elevation and intensity data (for elevation zero value errors, out-of-range
errors, and intensity
distribution) and adjusting light emitter control voltage based on such
analysis to improve
measured 3D elevation data quality.
100391 The effect of variations in surface properties (surface color in this
example) on light 3D
profile line intensity is demonstrated in FIGS. 2 through 5. Dark color
surfaces reflect less
energy (representing undetectable elevations within the measured profiles
which are reported as
elevation "Zero Value Errors") as shown in the dark color surface image 10 in
FIG. 2, and light
color surfaces reflect more light for a given source radiated power
(intensity) as shown in the
light color surface image 12 in HG. 2. A normal or average color surface is
shown as the normal
color surface image 14 in FIG. 2. The effect of surface color on reflected
light levels is
demonstrated for various crosstie colors in FIGS. 3 through 5. These figures
include a light
source 16 (e.g., a laser), a 3D sensor 18, a rail 20 and a tie 22. The light
source 16 casts a light
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beam having a wide fan-angle 24. The 3D sensor 18 has a wide field of view 26
as shown in
FIG. 3, and a 3D profile 28 can be seen where the light strikes the surface of
the tie 22 and rail
20. FIG. 3 shows moderate or normal light conditions resulting in a normal and
desirable 3D
profile line 28 intensity. FIG. 4 shows an example in which a low 3D profile
30 line intensity is
acquired because of the presence of dark colored objects. Finally, FIG. 5
shows a resultant high
3D profile line 32 intensity when light colored objects are encountered.
[0040] FIG. 6 shows a light emitter power control system 34 including an
enclosure 36 that
includes a light source 16 and a 3D sensor 38. A processor 40 is shown for
processing data
collected from the 3D sensor wherein such data is stored in one or more sensor
data storage
to devices 42. A light power controller 44 in communication with the
processor 40 controls the
output optical power of the emitted light based on the analysis of data
compiled by the 3D sensor
38. The light emitter power control system 34 preferably includes a collection
of independent
processes operating concurrently during active survey data collection.
Processes are defined to
interface, control and stream the surface elevation and surface reflection
intensity data for each
applicable 3D sensor. These data streams are segmented into fixed length and
width 3D
elevation and intensity maps as separate data files, where each data file is
preferably defined for
example as 1.6m wide and 30.5m long segments of track for each applicable 3D
sensor.
[0041] A primary light emitter power control process running on the processor
40 monitors the
3D sensor elevation and intensity data streams in real time and preferably
calculates aggregate
31) surface intensity histograms, an elevation Zero Value Error count, and an
Out-of-Range Error
count. The mathematical combination or aggregation of individual scan line
intensity values,
longitudinally in the direction of survey, is an efficient method to produce
representative
intensity measures required for real-time laser power control. To maximize
efficiency and
processing speed, intensity values from the same lateral offset, representing
the same scan
column, are processed in aggregate. The number longitudinal scan line samples
aggregated
together should be preferably selected to be large enough to minimize the
influence of data
outliers (more than 1000 values for example) and small enough to be processed
in real-time
(1000 or less for example). Following fixed column based processing of scan
intensity measures
over a longitudinal interval, a single aggregate measure is produced for each
column. This
method of producing aggregate measures for each scan column is applied
continuously in the
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survey direction during data collection. The aggregated intensity measures are
further processed
to produce histograms for each zone (as shown in FIG. 7, a ballast zone 54, a
field tie end zone
56, a rail zone 58, and a gage zone 60) across the track bed. These zones
defined by transverse
offsets across the track bed are based substantially on sensor location and
crosstie dimensions.
If, in one example, the zones defined in FIG.7 have widths of 600 columns for
gage tie zone 60,
150 columns for rail zone 58, 470 columns for field tie end zone 56, and 316
columns for ballast
zone 54, then the total scan width would be 1536 columns. If in this example,
1000 longitudinal
scans are used to calculate the aggregate intensity measures for each zone,
then the gage tie zone
60 would result in an input matrix of intensity values that is 1000 rows by
600 columns
producing a single aggregate measurement vector of length 600. Similar
calculations for the
remaining zones would produce aggregated intensity vectors of length 150 for
zone 58, length
470 for zone 56, and length 316 for zone 54. A histogram for each of these
aggregate zone
intensity vectors is then calculated and the histograms are then used for
track bed light emitter
power control analysis. The process is repeated continuously and in
substantially real-time
during surveys.
[0042] FIG. 7 shows a segment of one half of the track bed surface with a
width that is defined
by the field of view of a single sensor centered over the rail. The track bed
section shown in
FIG. 7 contains a rail 48, a plurality of cross ties 50, and four separate
transverse light emitter
power control analysis zones as described above. These analysis zones
correspond to the
following: the ballast zone 54, the transverse section of track bed on the
field side of the rail
containing ballast only; the field tie end zone 56, the transverse section of
track bed on the field
side of the rail containing crosstie ends; the rail zone 58, the transverse
section of track bed
containing the rail; and the gage zone 60, the transverse section of track bed
on the gage side of
the rail containing crossties as shown in FIG. 7. The mean, median, maximum,
minimum and
other light intensity statistics, for example, are preferably calculated
continuously for defined
longitudinal intervals (for example, for each 5 meters along the track bed)
for each aggregate
parameter in each transverse zone. A new sample or profile of light intensity
data preferably
occurs about every 2 mm to about every 6 mm in the longitudinal direction
depending on the
speed of the 3D sensor 38.
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[0043] A light emitter power control output value is adjusted if error
conditions are detected
(based on the Elevation Zero Value Error count and Range Error count) which
exceed acceptable
maximum error count thresholds. If a significant number of sensor elevation
errors or out-of-
range intensity errors are detected, the laser control power output level is
adjusted based on the
track bed surface intensity values for zones containing ties. The updated
light emission power
control value is increased if the profile intensity median value is less than
a target intensity value,
and decreased if the intensity median value is greater than the target
intensity value. These steps
are depicted as an algorithm in the flow chart shown in FIG. 8.
[0044] 3D sensor data is gathered in real time and zero value errors are
calculated for each of the
sensors (block 62). Out-of-Range errors are then calculated as shown in block
64. Then, a
determination is made as to whether any of the sensor zero value error counts
are greater than a
predefined zero value error count threshold (block 66). If the maximum number
of zero value
errors for all sensors is below the zero value error count threshold, and the
maximum number of
out-of-range errors for all sensors is less than the range error count
threshold (block 68) then the
system exits without change to the light emitter control output signal as
shown in block 70. If,
however, any sensor zero value error count exceeds the zero value error count
threshold or if any
of the sensor out-of-range error counts exceed the range error count
threshold, the light emitter
power control output signal is adjusted to reduce sensor errors caused by
higher than optimum
radiated light source optical power. In order to calculate the correct laser
control signal
adjustment, intensity histograms are calculated for each of the applicable
sensors (block 72), and
then aggregate intensity histograms are preferably calculated for each of the
light emitter power
control analysis zones including the field ballast zone, the field tie zone,
the rail zone, and the
gage tie zone (block 74). Median histograms arc then calculated (block 76).
Aggregate zero
value error counts are then calculated for each analysis zone (block 78),
followed by aggregate
out-of-range error counts (block 80). Then, light emitter power is adjusted
based at least in part
on the calculated zero error counts, range error counts and intensity
histograms (block 82),
resulting in an update of the Light emitter Output Control signal 84.
[0045] By providing a way to control laser optical output power based on
measurement sensor
feedback during railway track inspections, higher quality and more consistent
3D image data are
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achievable. With higher quality 3D imagery, a more accurate picture of overall
railway structure
is possible.
[0046] Another important issue to consider with the use of high power light
emitting devices is
safety and eye protection for persons in relative close proximity to light
emitting devices. The
various embodiments of the system described herein are preferably mounted on a
railway track
vehicle configured to move and be propelled along a railway track. Railway
track vehicles of
various kinds including trucks configured for travel along railroads are well
known in the art and
are not discussed in detail here.
[0047] In one embodiment, a system 86 for inspecting a railway track is
mounted to a railway
track vehicle. The system 86 is configured to adjust the intensity of a light
emitting apparatus
based on the motion of the system 86 relative to an adjacent railway track.
The system 86, shown
schematically in FIG. 9, includes a light emitting apparatus 16 for emitting
light energy toward a
railway track. The system 86 further includes at least one motion detector 88
for detecting the
speed of the railway track vehicle on which the system 86 is mounted. The
system further
includes a processor 90 in communication with the at least one motion detector
88. The
processor 90 includes an algorithm for adjusting the power of the light
emitting apparatus 16
wherein the algorithm includes the steps of determining whether the system 86
is moving at a
minimum speed relative to an adjacent railway track based on incoming data
from the at least
one motion detector 88, and adjusting a light emitter control output value
based at least in part on
incoming data from the at least one motion detector 88. The system further
includes a controller
92 in communication with the processor 90 wherein the controller 92 is
configured to control the
light intensity of the light emitting apparatus 16 in response to the light
emitter control output
value.
[0048] When the system is moving below a minimum threshold speed, the
processor 90 sends a
control output value to the controller 92 that causes the controller to
disable the light emitting
apparatus 16 so that no light is emitted. The minimum threshold speed can be
set at zero units of
distance per time or another setting such as, for example, 2 miles per hour.
When the system 86
is not moving along a track, the light emitting apparatus 16 is not being used
to help gather data.
Since there is a health risk with exposure to light emitted from the light
emitting apparatus 16,
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the system 86 shuts off the light emitting apparatus 16 while it is not needed
to help gather data.
When the system 86 begins moving again above the minimum threshold speed, the
light emitter
control output value changes to a value that causes the controller 92 to
activate or reactivate the
light emitting apparatus 16. In one embodiment, the motion detector 88 only
detects relative
motion and does not detect speed. If the system 86 is in motion relative to an
adjacent railway
track, the light emitter control output value is set to a setting that causes
the controller 92 to
activate the light emitting apparatus 16. If the system 86 is not in motion
relative to an adjacent
railway track, the light emitter control output value is set to a setting that
causes the controller 92
to deactivate the light emitting apparatus 16.
io [0049] In a preferred embodiment, the motion detector 88 is a shaft
encoder that produces pulses
at a rate that corresponds to the speed at which a shaft rotates. The shaft
encoder is configured to
operate in conjunction with a shaft of the railway track vehicle on which the
system 86 is
mounted. So, when the railway track vehicle is not moving, the shaft encoder
produces zero
pulses. When the railway track vehicle is moving, the shaft encoder provides
information to the
processor 90 including the speed of the system 86 relative to an adjacent
railway track.
[0050] The system 86 described above provides a number of important advantages
including
providing a system for automatically activating and deactivating a high-
powered light emitting
device based on motion of the system relative to an adjacent railway track.
The system 86 allows
for a minimum speed to be set so that a light emitting device is deactivated
when the system
speed falls below the minimum speed, thereby eliminating the eye exposure
hazards associated
with such high powered light emitting devices during times when the system or
associated
components are not actively scanning the adjacent railway track. When the
system resumes
motion and scanning, the system reactivates the light emitting device.
[0051] The foregoing description of preferred embodiments of the present
disclosure has been
presented for purposes of illustration and description. The described
preferred embodiments are
not intended to be exhaustive or to limit the scope of the disclosure to the
precise form(s)
disclosed. Obvious modifications or variations are possible in light of the
above teachings. The
embodiments are chosen and described in an effort to provide the best
illustrations of the
principles of the disclosure and its practical application, and to thereby
enable one of ordinary
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CA 02945247 2016-10-12
US Attorney Docket No. 08.00994.0042
CA Attorney Docket No. 17271-0005
skill in the art to utilize the concepts revealed in the disclosure in various
embodiments and with
various modifications as are suited to the particular use contemplated. All
such modifications and
variations are within the scope of the disclosure as determined by the
appended claims when
interpreted in accordance with the breadth to which they are fairly, legally,
and equitably
entitled.
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