U.S. patent application number 12/391442 was filed with the patent office on 2010-08-26 for method and systems for end of train force reporting.
This patent application is currently assigned to QUANTUM ENGINEERING, INC.. Invention is credited to James Brady, Mark Edward Kane.
Application Number | 20100213321 12/391442 |
Document ID | / |
Family ID | 42630118 |
Filed Date | 2010-08-26 |
United States Patent
Application |
20100213321 |
Kind Code |
A1 |
Kane; Mark Edward ; et
al. |
August 26, 2010 |
METHOD AND SYSTEMS FOR END OF TRAIN FORCE REPORTING
Abstract
An EOT unit detects an excessive end of train force using an
accelerometer and reports the excessive force. The report may be
made to a device located off the train, to an event recorder in the
EOT unit, and/or to another device located on the train such as a
head of train unit and/or an event recorder located outside the EOT
unit. The accelerometer may be a singe, dual, or tri-axial
accelerometer. The message may be sent in response to the detection
of the excessive acceleration or may be part of a periodically
transmitted message from the EOT unit to a HOT unit. A HOT unit is
configured to receive a message indicating an excessive EOT
acceleration and display an indication of the excessive
acceleration to the operator and/or record the message in an event
recorder and/or report the excessive acceleration to a device
located off the train.
Inventors: |
Kane; Mark Edward; (Orange
Park, FL) ; Brady; James; (Orange Park, FL) |
Correspondence
Address: |
DLA PIPER LLP (US);ATTN: PATENT GROUP
P.O. Box 2758
Reston
VA
20195
US
|
Assignee: |
QUANTUM ENGINEERING, INC.
Orange Park
FL
|
Family ID: |
42630118 |
Appl. No.: |
12/391442 |
Filed: |
February 24, 2009 |
Current U.S.
Class: |
246/167R ;
246/122R |
Current CPC
Class: |
B61L 15/0027 20130101;
B61L 15/0054 20130101; B61L 2205/04 20130101; B61L 25/025 20130101;
B61L 15/0081 20130101; B61L 27/0094 20130101 |
Class at
Publication: |
246/167.R ;
246/122.R |
International
Class: |
B61L 15/00 20060101
B61L015/00; B61L 25/00 20060101 B61L025/00 |
Claims
1. An end of train unit suitable for use on a train, the end of
train unit comprising: a processor connected to a housing; a first
coupling connected to the housing, the first coupling being
configured to engage a train coupling; an end of train marker light
connected to the housing and configured to be controlled by the
processor; a pressure transducer connected to the processor and in
fluid communication with a second coupling connectable to an air
brake pipe of a train; an accelerometer connected to the processor;
and a first transmitter connected to the processor; wherein the
processor is configured to perform the steps of receiving an
acceleration from the accelerometer; performing a comparison of the
acceleration to a threshold; determining that the acceleration
exceeds the threshold; and transmitting a message via the first
transmitter in response to the acceleration exceeding the
threshold.
2. The end of train unit of claim 1, wherein the message includes
an identifier of the end of train unit and wherein the first
transmitter is a wireless transmitter configured to transmit the
message wirelessly to a head of train device.
3. The end of train unit of claim 1, wherein the message includes
an identifier of the end of train unit and an address of a device
located off of the train, and the first transmitter is a wireless
transmitter configured to transmit the message wirelessly.
4. The end of train unit of claim 1, further comprising: an event
recorder connected to the processor; wherein the first transmitter
transmits the message to the event recorder.
5. The end of train unit of claim 1, wherein the message includes a
time corresponding to the acceleration.
6. The end of train unit of claim 1 further comprising: a
positioning system connected to the processor; wherein the message
includes a position corresponding to the acceleration.
7. The end of train unit of claim 1, wherein the threshold is at
least 0.25 g.
8. The end of train unit of claim 1, wherein the message includes a
magnitude of the acceleration.
9. The end of train unit of claim 1, wherein the message includes
an indication that an acceleration in excess of the threshold has
been detected.
10. The end of train unit of claim 1, wherein the acceleration is
an instantaneous acceleration.
11. The end of train unit of claim 1, wherein the acceleration is a
filtered acceleration.
12. The end of train unit of claim 1, wherein the comparison is an
absolute value comparison.
13. The end of train unit of claim 1, wherein the accelerometer is
a triaxial accelerometer.
14. The end of train unit of claim 13, wherein the message
indicates an orientation of the acceleration.
15. The end of train unit of claim 1, wherein the message includes
a magnitude for acceleration in each axis of the triaxial
accelerometer.
16. An end of train unit comprising: a processor connected to a
housing; a first coupling connected to the housing, the first
coupling being configured to engage a train coupling; an end of
train marker light connected to the housing and configured to be
controlled by the processor; a pressure transducer connected to the
processor and in fluid communication with a second coupling
connectable to an air brake pipe of a train; an accelerometer
connected to the processor; and a first transmitter connected to
the processor; wherein the processor is configured to perform the
steps of receiving an acceleration from the accelerometer;
performing a comparison of the acceleration to a threshold;
determining that the acceleration exceeds the threshold; and
transmitting a message including a magnitude of the acceleration
via the first transmitter.
17. A head of train device comprising: a processor; a wireless
receiver connected to the processor; and a display connected to the
processor; wherein the processor is configured to perform the steps
of receiving a message from an end of train unit, the message
indicating that an excessive end of train acceleration has been
detected; and reporting the excessive end of train force.
18. The head of train device of claim 17, wherein the processor is
configured to display an indication that the excessive end of train
force acceleration has been detected on the display.
19. The head of train device of claim 17, further comprising: an
interface to an event recorder, the interface being connected to
the processor; wherein the processor is further configured to
record the message on the event recorder.
20. The head of train device of claim 19, wherein the processor is
further configured to perform the step of: taking a corrective
action if an acknowledgment of the display of the excessive end of
train acceleration is not received from an operator.
21. The head of train device of claim 20, wherein the corrective
action comprises activating the train's brakes.
22. The head of train device of claim 17, wherein the processor is
further configured to perform the step of: comparing the
acceleration to a higher threshold; and taking corrective action if
the acceleration exceeds the higher threshold.
23. The end of train device of claim 22, wherein the corrective
action comprises activating the train's brakes.
Description
FIELD
[0001] The invention relates generally to railroad end of train
telemetry, and more particularly to the reporting of end of train
forces.
BACKGROUND
[0002] Within the railroad industry, end of train (EOT) units
(sometimes also referred to as end of train devices) are typically
attached at the rear of the last car on a train, often to the
unused coupling on the end of the last car opposite the head of the
train. These EOT devices were originally designed to perform some
of the functions previously performed by train personnel located in
the caboose, thereby allowing trains to operate without a caboose
and with a reduced number of human operators.
[0003] Modern EOT units can perform a number of functions, some
required by FRA (Federal Railroad Administration) regulations and
some not. EOT units monitor air pressure in the air brake pipe and
transmit this information to a head of the train (HOT) device
located near the front of the train. EOT units also often include
an end-of-train marker light to alert trailing trains on the same
track of the presence of the end of the train. Two-way EOT units
(now required by FRA regulation in the U.S.) can accept a command
from the HOT to open a valve to release pressure in the air brake
pipe so that the train's air brakes activate to stop the train in
an emergency situation. Some EOT units include GPS receivers that
are used to transmit location information pertaining to the end of
the train to HOT equipment as discussed in U.S. Pat. No. 6,081,769.
EOT units typically communicate with the HOT using radio-based
communications. This is because there is no hard-wired electrical
connection between the head of the train and the end of the train
on some trains, especially freight trains.
[0004] Some EOT units include motion detectors that are used to
inform the HOT as to whether, and in some cases in which direction,
a train is moving. In some EOT units, an accelerometer is used as
the motion detector. Motion detection is reported by only a single
bit (i.e., the single bit indicates only motion or lack thereof
without any indication of speed or direction) under AAR Standard
S-5701 for "End-of-Train Communications." The indication of train
movement or lack thereof from the motion detector, together with an
indication of the head of train movement, may be used by train
personnel and/or computerized on-board train control systems to
determine whether or not a train separation has occurred. However,
such a determination is not very reliable given the single bit used
to report motion pursuant to AAR Standard S-5701 because movement
in opposite directions, and movement at significantly different
speeds in the same direction, cannot be determined.
[0005] A somewhat more capable device is described in U.S. Pat. No.
6,087,950, which describes a motion detector that can be attached
to an end of train unit. The motion detector includes a single axis
accelerometer. The motion detector is configured to report a motion
state that can be moving or non-moving and a motion direction that
can be forward or reverse.
[0006] More recently, EOT units that can communicate their
positions to devices located off of the train, such as those
described in U.S. Pat. No. 7,096,096 and in U.S. Pat. Pub. No.
2007/0170314 (the entire contents of both hereby being incorporated
by reference herein), have become known in the art. These
communications allow personnel responsible for such EOT units to
locate them. Such communications can occur both when the EOT units
are mounted on a train and when they are not mounted on any
train.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] A more complete appreciation of the invention and many of
the attendant features and advantages thereof will be readily
obtained as the same become better understood by reference to the
following detailed description when considered in connection with
the accompanying drawings, wherein:
[0008] FIG. 1 is a system for reporting excessive EOT force
according to one embodiment of the invention.
[0009] FIGS. 2a and 2b are perspective and front views,
respectively, of an EOT unit according to one embodiment of the
invention.
[0010] FIG. 3 is a block diagram of the EOT unit of FIGS. 2a and
2b.
[0011] FIG. 4 is a flow chart illustrating a location reporting
subroutine performed by the end of train unit of FIG. 3.
[0012] FIG. 5 is a front view of a head of train device according
to one embodiment of the invention.
[0013] FIG. 6 is a block diagram of the head of train device of
FIG. 5.
[0014] FIG. 7 is a flow chart illustrating processing performed by
the head of train device of FIG. 5.
DETAILED DESCRIPTION
[0015] The present invention will be discussed with reference to
preferred embodiments of end of train units. Specific details, such
as message formats and various reporting methods, are set forth in
order to provide a thorough understanding of the present invention.
The preferred embodiments discussed herein should not be understood
to limit the invention. Furthermore, for ease of understanding,
certain method steps are delineated as separate steps; however,
these steps should not be construed as necessarily distinct nor
order dependent in their performance.
[0016] Excessive forces exerted on trains can damage both equipment
(train and track) and cargo being carried on the train. Excessive
forces applied to a train tends to become magnified at the end of
the train. Such excessive forces can result from various causes. An
operator can cause excessive forces at the end of the train by
accelerating too rapidly, which will cause a car at the end of the
train to jerk in the direction of track once the slack between cars
is taken up as the locomotive(s) at the head of the train
accelerate. An inexperienced operator, or even an experienced
operator who is operating a very long train, may not realize the
forces being exerted on an end of the train due to his/her actions.
Another potential cause of excessive forces at the end of the train
can result from excessively "wavy" tracks that cause cars to sway
rapidly from side to side as the cars travel along the tracks.
These forces occur mainly along an axis perpendicular to the track.
Still another potential cause of excessive forces at an end of a
train are poor track joints, which may occur at grade crossings,
bridges, or the like but which may also occur anywhere along a
track. These forces tend to occur primarily along an axis that is
vertically oriented with respect to the track. Excessive forces at
the end of the train can also be caused in other ways.
[0017] Because of the different possible causes for excessive
forces at the end of the train, different actions are performed in
different embodiments discussed herein. The first step is to detect
the occurrence of an excessive force. This step may be performed
using an accelerometer located in an end of train unit (it being
understood that an accelerometer measures acceleration, which is
proportional to force). In preferred embodiments, the accelerometer
is a tri-axial accelerometer with the axes oriented such that a
first axis is along a direction of the track, a second axis is
along a direction perpendicular to the track and a third axis is
along a direction vertical to the track. This arrangement is
advantageous in that it provides the ability to determine a
direction along with an acceleration has occurred, which may be
indicative of the cause of the acceleration (e.g., a sudden
vertical acceleration may result from a problem with the track
whereas a sudden acceleration in a direction of a track may result
from an operator accelerating a train from a stopped position too
rapidly). In other embodiments, a single or dual axis accelerometer
is used. Such embodiments may employ one or more accelerometers
along one of the three axes discussed above, or may orient the
accelerometer such that it is sensitive to accelerations in more
than one axis as discussed in U.S. Pat. No. 6,087,950. Embodiments
utilizing a single accelerometer can be less expensive than
embodiments employing multiple accelerometers or multiple axis
accelerometers.
[0018] The accelerometer(s) may be periodically polled in real time
to detect forces greater than a threshold. Alternatively, a
triggering circuit such as a one-shot may be used to generate an
interrupt when the accelerometer measures a force greater than the
threshold. The accelerations reported by the accelerometers are
typically "instantaneous" accelerations, and these instantaneous
accelerations are used directly in some embodiments. In other
embodiments, a plurality of instantaneous accelerations are
filtered (e.g., moving window average filtering, Kalman filtering,
etc.).
[0019] Various embodiments employ different thresholds. In some
embodiments, the threshold may be fixed. In such embodiments, the
threshold may be set to an acceleration based on a safety factor
and maximum force for which a typical car coupling can withstand
divided by a maximum car weight. A typical freight car coupling in
use in the U.S. can withstand a force of about 350,000 pounds, and
a current maximum expected car weight in the U.S. freight railroad
industry is 268,000 pounds (this represents the weight of the car
plus a maximum cargo). In some embodiments, the acceleration
threshold based on these values and a safety factor is chosen as 1
g. The threshold is preferably 0.25 g or greater to ensure that
accelerations associated with normal movement of the train are not
reported as excessive. In yet other embodiments, the threshold is
set dynamically. The threshold may be set dynamically based on a
particular cargo being carried on the train, particular equipment
(e.g., couplings, types of cars) used on the train, or any other
factor which may affect a desirable maximum EOT force.
[0020] Once an excessive force has been detected, the detection
must be communicated. The communication may occur immediately or
soon after the detection has been made, and/or the detection may be
recorded and communicated later. In some embodiments, the
occurrence of the excessive force is communicated to a head of
train device for display to an operator immediately or soon after
the detection occurs (such display being different from the manner
in which an indication of movement of the train is normally
displayed to the operator). The message and/or display may include
a simple indication that an acceleration greater than the threshold
has been observed, or may include the actual (preferably
instantaneous) acceleration (or accelerations in multiple axis
accelerometer embodiments) measured by the accelerometer. In such
embodiments, the head of train device relays the message to a
central office, either in addition to or instead of displaying the
message. In other embodiments, the EOT device may transmit the
message directly to a central data collection site. For example,
EOTs equipped for long range communication with a central site
(e.g., via a cellular modem that communicates with a cellular base
station) are disclosed in U.S. Pat. Pub. No. 2007/0170314. As
disclosed in that publication, the EOT may periodically transmit a
message including the EOT location.
[0021] In some embodiments, the message further includes
information (e.g., an amount of excessive force or an indication
that an excessive force has been detected together with a location
and/or time at which the excessive force was detected). In yet
other embodiments, the EOT device includes an event recorder which
records information pertaining to the excessive force. The data
from the EOT device is accessed later and appropriate action (e.g.,
informing the operator of the excessive force if the operator was
the cause, repairing the section of track causing the excessive
force) is taken. In still other embodiments, an excessive force
detection message sent from the EOT to the HOT is recorded in an
event recorder included in the HOT device and/or forwarded from the
HOT device to the train's main event recorder. Still other methods
for communicating the detection of an excessive force are
possible.
[0022] An exemplary embodiment of an EOT force reporting system
will now be discussed. This embodiment will include multiple EOT
force reporting methods as discussed above. It should be understood
that other embodiments employ less than all of, or alternatives to,
the reporting methods discussed in connection with this
embodiment.
[0023] FIG. 1 is a block diagram of a system 10 for measuring and
reporting EOT forces. The system includes an EOT unit 100
configured for wireless communications with an HOT device 300. The
HOT device 300 is connected to an event recorder 301. The EOT unit
100, the HOT device 300 and the event recorder 301 are all located
onboard a train. The HOT device 300 is configured for wireless
communications with a central office 303. The EOT unit 100 is also
configured for wireless communications with and EOT Tracking
Facility 302.
[0024] FIGS. 2a and 2b illustrate an embodiment of the EOT unit
100. The EOT unit 100 includes a housing 110 in which the internal
components of the EOT unit 100 (discussed in further detail below)
are located. A handle 111 is attached to the housing 110 to
facilitate the installation and removal of the EOT unit 100 from a
train car. Also attached to the housing is a connector 120 for
connecting the EOT unit 100 to an air brake hose 10 which is in
fluid communication with the train's air brake pipe (not shown in
FIG. 2a or 2b). Also attached to the housing 110 is a coupler 130
which couples the EOT unit 100 to a train car coupling. The EOT
unit 100 also includes a marker light 140 attached to the housing
110. Three antennas are also attached to the housing 110: a first
antenna 150 for communicating with the HOT, a second antenna 160
for communicating with a cellular base station network, and a third
antenna 170 for receiving messages from GPS satellites.
[0025] A block diagram 30 of the EOT unit 100 of FIG. 1 is
illustrated in FIG. 3. The EOT unit 100 is controlled by a
processor 210. The processor 210 receives power from a power
subsystem 220 which includes an air-powered electrical generator
221 connected to the air brake pipe 10, a rectifier 222, a voltage
regulator 223 and one or more batteries 224. Details concerning the
power subsystem 220 are discussed in greater detail in
corresponding U.S. Pat. No. 7,096,096.
[0026] The processor 210 is connected to control an EOT marker
light 140 (although a direct connection is illustrated in FIG. 2,
those of skill in the art will understand that the processor 210
may supply the control of power to the EOT marker light 140 via a
relay or similar device) in accordance with applicable FRA
regulations. Also connected to the processor 210 is a tilt sensor
230. The processor 210 uses the tilt sensor 230, among other
things, to determine when the EOT unit 100 has been placed in a
horizontal position so that the processor 210 can take the EOT unit
to a low power state to conserve battery power.
[0027] Also connected to the processor 210 is an air pressure
transducer 240, which is in fluid communication with the air brake
pipe 10 and is configured to detect the pressure in the air brake
pipe 10. The processor 210 reads the pressure in the air brake pipe
10 reported by the transducer 240 and periodically transmits this
and other information to the HOT using the HOT transceiver 250.
Under AAR Standard S-5701, the report occurs once every 55-65
seconds in the absence of significant pressure changes. The format
of an exemplary report is set forth below:
TABLE-US-00001 TABLE 1 FRA Message Guidelines - Standard S-5701
Basic Bit sync 69 bits Block Frame sync 11 bits Chaining bits 2
bits Device battery condition 2 bits Message type identifier 3 bits
Unit address code 17 bits Rear brake pipe status and pressure 7
bits Discretionary information 11 bits* Motion detection 1 bit
Marker light battery condition 1 bit Marker light status 1 bit
Basic block BCH code 18 bits Trailing bit 1 bit Total Length 144
bits Optional Bit sync 69 bits Block(s) Frame sync 11 bits Chaining
bits 2 bits Block format indicator bit 1 bit Optional block data
bits 42 bits Optional block BCH code 18 bits Trailing bit 1 bit
Total length 144 bits *For two-way systems, see paragraph 3.0.
In embodiments in which excessive EOT forces are reported to the
HOT device 300, the occurrence and/or measurement(s) (e.g.,
magnitudes) of excessive accelerations can be included in the
"optional block data bits" portion of the message described above
or may be sent in a separate message.
[0028] An emergency solenoid 280 is also connected to the processor
210 and the air brake pipe 10. When the processor 210 receives an
emergency braking command from the HOT via the HOT transceiver 250,
the processor 210 controls the solenoid 280 to open, causing a loss
of pressure in the air brake pipe 10 and activation of the train's
brakes. In some embodiments, another solenoid (not shown in FIG. 2)
is also connected to the processor 210 and between the air brake
pipe 10 and the air powered generator 221. This solenoid is used to
perform certain tests required by the FRA.
[0029] An accelerometer 290 is also connected to the processor 210.
As discussed above, the accelerometer may be a single axis, dual
axis or three axis accelerometer in various embodiments. Those of
skill in the art will recognize that the signals from some
accelerometers may be in analog form and that an analog-to-digital
(A/D) converter (not shown in FIG. 3) may be used to convert the
analog sensor signal to digital form if the processor 210 does not
include an integral A/D converter. The accelerometer 290 preferably
measures instantaneous acceleration. The processor 210 is
configured to filter the instantaneous acceleration reported from
the accelerometer in some embodiments; in other embodiments, no
filtering is used. In embodiments in which filtering of the
instantaneous accelerations measured by the accelerometer is
employed, care must be taken in choosing the filtering parameters
such that sensitivity to accelerations of short temporal duration
(such as those that may occur when an end of train is first forced
into motion from a stopped state by a locomotive) are not missed.
Some embodiments employ a moving window average filter with a
window size of the three most recent readings, with readings being
taken every 10 milliseconds.
[0030] Also connected to the processor 210 is an event recorder
295. The event recorder 295 records data pertinent to the EOT unit
100, such as the content and time of transmission of various
messages sent and received by the EOT unit 100. As discussed above,
the occurrence of excessive acceleration events are also recorded
for later retrieval in some embodiments. The data recorded for such
events can include the date, time, and location of the train at the
time of the event as reported by the positioning system 270 plus
other circumstances surrounding the event.
[0031] The processor 210 is further connected to a positioning
system 270, which is a GPS receiver in preferred embodiments but
may also be an INS (intertial navigation system), LORAN device, or
any other positioning system. The positioning system 270 supplies
the processor 210 with reports on the position of the EOT unit
100.
[0032] The processor 210 is also connected to a cellular modem 260.
The processor 210 uses the cellular modem to send reports including
an identifier of the EOT unit 100 and location (and preferably
time) information obtained from the positioning system 270 to an
EOT tracking station at periodic intervals. The processor 210 also
receives "page" messages (messages requesting the EOT unit to
report its current location) and "disable" messages (messages
instructing the EOT unit to enter an non-operational state) via the
cellular modem 260. In addition to reporting EOT location to the
EOT tracking facility 302, the cellular modem 260 may also report
excessive accelerations detected by the accelerometer 290. This
reporting is in addition to (or, in some embodiments, in lieu of,
the reporting accomplished via recording at the EOT event recorder
295, the display at the HOT device 300, and/or the recording at the
event recorder 301).
[0033] During normal operation, the processor 210 controls the EOT
marker light 140, communicates air brake pipe pressure information
to the HOT, activates the emergency solenoid 280 in response to
commands from the HOT, communicates train position to the EOT
tracking facility 302 and performs other functions that will not be
discussed further herein to avoid obscuring this disclosure.
[0034] In addition to the operations discussed above, the processor
210 monitors the accelerometer 290 in order to detect excessive
accelerations. A flowchart 400 of the operations performed by the
processor 210 is shown in FIG. 4. The processor reads the
accelerometer 290 at step 402 and uses the value read (which is an
instantaneous acceleration in this embodiment) to calculate a
filtered acceleration value at step 404. In some embodiments, the
filtering algorithm is a moving window filter with a width of three
accelerations values. The processor 210 then compares the filtered
acceleration to a threshold at step 406. The threshold may be a
fixed value, or may be set by an operator of the train on which the
EOT unit 100 is mounted and communicated by messages received from
the HOT device, or may be communicated to the EOT unit 100 via a
message received on the cellular modem 260 from the EOT Tracking
Facility 302. Others ways of setting the threshold are also
possible. The comparison of step 210 may be an absolute value
comparison (i.e., the absolute value of the acceleration is
compared to a threshold) or may be a signed value comparison. An
absolute value comparison is preferable in some circumstances
(e.g., in connection with an accelerometer measuring vertical
acceleration for the purpose of detecting track defects) whereas a
signed value comparison is preferable in others (e.g., in
connection with an accelerometer measuring acceleration in the
direction of the track for the purpose of detecting accelerations
caused by an operator incorrectly starting movement of a
train).
[0035] If the filtered acceleration is below the threshold, no
reporting is necessary and the processor 210 delays a period of
time (100 ms in some embodiments) at step 408 before repeating step
402. If the filtered acceleration exceeds the threshold at step
406, the processor 210 records the filtered acceleration in the EOT
event recorder 295 at step 410. Next, the processor 210 reports the
filtered acceleration to the EOT Tracking Facility 302 via the
cellular modem 260 at step 412. The processor 210 then reports the
filtered acceleration to the HOT device 300 at step 414. The
processor then delays for a brief period at step 408 before
repeating steps 402 and following.
[0036] The HOT device 300 of FIG. 1 is shown in more detail in FIG.
5. As discussed above, the HOT device is typically (but not
necessarily) mounted in a locomotive at the head of the train. In
North America, the HOT device 300 communicates with the EOT unit
100 using a short range 2-watt digital radio transceiver over
certain frequencies assigned by the FCC in the U.S. Additional
details concerning HOT device/EOT unit communications can be found
in U.S. patent application Ser. No. 11/929,605, the contents of
which are hereby incorporated by reference herein. Shown in FIG. 5
is an EOT emergency switch 342 for use by an operator in initiating
an emergency braking operation. A display 350 indicates the brake
pressure measured by the EOT unit 100, and a second display 351 is
used for displaying various messages including a message indicating
that an excessive EOT force/acceleration has been detected can be
displayed to the operator. A keypad 340 is available to the
operator for entering data such as the serial number of the EOT
unit 100 with which the HOT device 300 is to communicate. Various
indicators 330, some of which are combined with push buttons are
available for use by the operator as described further in the
above-mentioned application. One of the indicators 330 indicates to
the operator when the train is in motion.
[0037] A block diagram of the HOT device 300 is shown in FIG. 6.
The HOT device includes a processor 320 which is connected to a
memory (the memory is shown onboard the processor 320 in FIG. 6,
but those of skill in the art will recognize that one or more
external memories, such as ROM, RAM, etc. may also be used). The
processor 320 is connected (via an interface not shown in FIG. 6)
to a train event recorder 301. An EOT transceiver 330 is also
connected to the processor 320 for communications with an EOT unit
100. A speed sensor input port 360 connects the processor 320 to a
speed sensor 470. A GPS receiver 480 is also connected to the
processor 320 in some embodiments (this is particularly useful in
the event that the EOT unit 100 does not include its own GPS
receiver; in this case, the GPS position from the GPS receiver 480
can be used to determine and report the location of the train upon
the receipt of an excessive EOT force message from the EOT unit 100
and an approximate EOT location can be calculated with knowledge of
a length of the train).
[0038] FIG. 7 is a flowchart 600 illustrating operations performed
by the HOT device 300 in some embodiments of the invention. Less
than all of the reporting steps illustrated in FIG. 6 may be
performed in various alternative embodiments. The flowchart of FIG.
7 is suitable for implementation as a subroutine called upon
receipt of a message from the EOT unit 100. The EOT message is read
at step 402. The processor 320 determines the type of message at
step 404. If the EOT message is a message other than an excessive
force message, other processing (which shall not be discussed in
detail herein to avoid obscuring the invention) is performed at
step 406.
[0039] If the message from the EOT does indicate that an excessive
EOT force has been detected by the EOT unit 100 at step 404, a
message is displayed at the HOT display 351 at step 408. In those
embodiments in which the excessive force message from the EOT only
indicates that an excessive EOT force has been detected, the
message in the display 351 may simply indicate "EXCS EOT ACC DET."
In those embodiments in which the detected EOT force is reported in
the message from the EOT, the HOT may display a message such as
"EOT ACC XXG DET," where XX represents the EOT acceleration
(filtered or unfiltered) reported by the EOT unit 100. In those
embodiments utilizing a triaxial accelerometer, the message shown
to the operator in display 351 may also include an X, Y, or Z to
indicate the axis on which the excessive EOT acceleration occurred.
In some embodiments, the processor 320 may take corrective action,
such as requiring the operator to acknowledge the excessive
acceleration (e.g., by pushing one of the indicator buttons 330 or
keys 340) or forcing an emergency braking operation in the event
that no acknowledgement from the operator is received. Such
corrective action may occur only when the EOT acceleration exceeds
a second, higher threshold and/or only after a certain number of
excessive accelerations have been detected in some period of time
in some embodiments. In yet other embodiments, the processor 320
requires an operator acknowledgement if a first threshold is
exceeded and initiates an emergency braking operation if the second
threshold is exceeded.
[0040] It should be noted that, in some embodiments, the
accelerometer may be used to both a) determine whether the train is
in motion, and b) detect excessive EOT acceleration. In such
embodiments, a first threshold is used for the former and a second,
higher threshold is used for the latter. Such embodiment may also
employ a still higher third threshold that can be used to include
an indication in a message to a head of train device that the
train's brakes should be activated (alternatively, the third
threshold can be implemented in the HOT device).
[0041] Next, the processor 320 records the occurrence of the
excessive EOT force at the event recorder 301 at step 410 and
transmits a message to a central office (e.g., a dispatcher) at
step 412. The next EOT message is then processed at step 402.
Alternatively, in embodiments in which the excessive force
indication is in a message with the format of Table 1, the rest of
the message is processed at step 406.
[0042] Those of skill in the art will recognize that various
modifications to the EOT unit 100 are possible. For example, it is
possible to operate the EOT unit 100 solely with battery power
rather than using batteries in conjunction with an air powered
generator. Cellular modem 260 may be replaced with any type of
wireless communication system. Various other modifications to the
components of the EOT unit 100 are also possible.
[0043] Furthermore, the purpose of the Abstract is to enable the
U.S. Patent and Trademark Office and the public generally, and
especially the scientists, engineers and practitioners in the art
who are not familiar with patent or legal terms or phraseology, to
determine quickly from a cursory inspection the nature and essence
of the technical disclosure of the application. The Abstract is not
intended to be limiting as to the scope of the present invention in
any way.
[0044] While the invention has been described with respect to
certain specific embodiments, it will be appreciated that many
modifications and changes may be made by those skilled in the art
without departing from the spirit of the invention. It is intended
therefore, by the appended claims to cover all such modifications
and changes as fall within the true spirit and scope of the
invention.
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