U.S. patent application number 17/143564 was filed with the patent office on 2021-07-08 for methods and systems for virtual trip stops in train networks.
The applicant listed for this patent is Metrom Rail, LLC. Invention is credited to Richard C. Carlson, Kurt A. Gunther.
Application Number | 20210206407 17/143564 |
Document ID | / |
Family ID | 1000005347472 |
Filed Date | 2021-07-08 |
United States Patent
Application |
20210206407 |
Kind Code |
A1 |
Carlson; Richard C. ; et
al. |
July 8, 2021 |
METHODS AND SYSTEMS FOR VIRTUAL TRIP STOPS IN TRAIN NETWORKS
Abstract
Systems and methods are provided for virtual trip stops in train
networks. The rail network includes one or more wayside control
units configured for deployment on or near tracks in the rail
network, with each wayside control unit coupled or attached to a
train signal, and the train-based control unit is configured to
communicate with any wayside control unit that comes within
communication range of the train-based control unit, determine
based on processing of communicated signals with at least one
wayside control unit one or both of operation information relating
to one or both of the at least one wayside control unit and the
train and state information relating to a state of train signal,
and generate based on the operation information and the state
information, control information configured for use in controlling
one or more functions of the train in conjunction with operation in
the rail network.
Inventors: |
Carlson; Richard C.;
(Manchester-by-the-sea, MA) ; Gunther; Kurt A.;
(Woodstock, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Metrom Rail, LLC |
Crystal Lake |
IL |
US |
|
|
Family ID: |
1000005347472 |
Appl. No.: |
17/143564 |
Filed: |
January 7, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62958114 |
Jan 7, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B61L 15/0027 20130101;
B61L 27/0038 20130101 |
International
Class: |
B61L 27/00 20060101
B61L027/00; B61L 15/00 20060101 B61L015/00 |
Claims
1. A system for train control, comprising: a train-based control
unit configured for deployment on a train operating within a rail
network, the train-based control unit comprising: one or more
transceivers configured for transmitting and/or receiving wireless
signals; and one or more circuits configured to: process signals
and data, and perform based, at least in part, on the processing of
signals one or more functions relating to operations of the
train-based control unit; wherein: the rail network comprises one
or more wayside control units configured for deployment on or near
tracks in the rail network; each wayside control unit is coupled or
attached to a train signal; and the train-based control unit is
configured to: communicate with any wayside control unit that comes
within communication range of the train-based control unit;
determine based on processing of communicated signals with at least
one wayside control unit: operation information relating to one or
both of the at least one wayside control unit and the train; and
state information relating to a state of train signal; and generate
based on the operation information and the state information,
control information configured for use in controlling one or more
functions of the train in conjunction with operation in the rail
network.
2. The system of claim 1, wherein the operation information
comprises ranging information, and wherein the train-based control
unit is configured to determine range to at least one wayside
control unit.
3. The system of claim 2, wherein the train-based control unit is
configured to determine approximate range to each wayside control
unit within communication range of the train-based control
unit.
4. The system of claim 2, wherein the train-based control unit is
configured to: identify at least one nearest wayside control unit;
and obtain, based on processing of received signals, precision
range measurements to the at least one nearest wayside control
unit.
5. The system of claim 2, wherein the train-based control unit is
configured to repeat obtaining range measurements after a time
delay.
6. The system of claim 1, wherein the operation information
comprises one or more of direction, speed, and location, wherein
the train-based control unit is configured to determine at least
one of direction of movement of the train, speed of the train,
location of the train, and operating track based, at least in part,
on processing of received signals from at least one wayside control
unit.
7. The system of claim 6, wherein the train-based control unit is
configured to determine at least one of the direction of movement
of the train, the speed of the train, the location of the train,
and the operating track based on range measurement to at least one
wayside control unit.
8. The system of claim 1, wherein the train-based control unit is
configured to select a nearest virtual trip stop based on
identifying of a train signal, wherein the train signal is
determined based on a corresponding wayside control unit.
9. The system of claim 8, wherein the train-based control unit is
configured to determine a safe braking distance for the virtual
trip stop based on speed of the train.
10. The system of claim 1, wherein the state information comprises
an indication of whether the state of train signal is restrictive,
permissive, or not confirmed, and wherein the train-based control
unit is configured to: select a virtual trip stop based on
identifying a particular wayside control unit; and generate or
adjust the control information based on the indication.
11. The system of claim 10, wherein the one or more functions of
the train comprise braking, and wherein the train-based control
unit is configured to generate a safe braking command based on a
determination that the state of train signal is restrictive or is
not confirmed.
12. The system of claim 1, wherein the train-based control unit is
configured to communicate with at least one wayside control unit
that comes within communication range of the train-based control
unit using ultra-wideband (UWB) signals.
13. A system for train control, comprising: a wayside control unit
configured for deployment on or near tracks in a rail network, the
wayside control unit comprising: one or more transceivers
configured for transmitting and/or receiving wireless signals; and
one or more circuits configured to: process signals and data, and
perform based, at least in part, on the processing of signals one
or more functions relating to operations of the wayside control
unit; wherein: the wayside control unit is coupled or attached to
the train signal; and the wayside control unit is configured to:
communicate with any train-based control unit that comes within
communication range of the wayside control unit.
14. The system of claim 13, wherein the wayside control unit is
configured to communicate with at least one train-based control
unit that comes within communication range of the wayside control
unit using ultra-wideband (UWB) signals.
Description
CLAIM OF PRIORITY
[0001] This patent application makes reference to, claims priority
to, and claims benefit from U.S. Provisional Patent Application No.
62/958,114, filed on Jan. 7, 2020. The above identified
applications is incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to control solutions for use
in train systems. More specifically, various implementations of the
present disclosure relate to methods and systems for facilitating
and implementing virtual trip stops in train networks.
BACKGROUND
[0003] Various issues may exist with conventional train control
solutions. In this regard, conventional systems and methods, if any
existed, for facilitating and/or managing trip stops in railway
systems, may be costly (e.g., to install and maintain),
inefficient, and/or ineffective.
[0004] Further limitations and disadvantages of conventional and
traditional approaches will become apparent to one of skill in the
art, through comparison of such approaches with some aspects of
various example methods and systems as set forth in the remainder
of this disclosure with reference to the drawings.
BRIEF SUMMARY
[0005] System and methods are provided for virtual trip stops in
train networks, substantially as shown in and/or described in
connection with at least one of the figures, as set forth more
completely in the claims.
[0006] These and other advantages, aspects and novel features of
the present disclosure, as well as details of an illustrated
embodiment thereof, will be more fully understood from the
following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 illustrates an example virtual trip stop system, in
accordance with the present disclosure.
[0008] FIG. 2 illustrates an example deployment of virtual trip
stop system in a rail network, in accordance with the present
disclosure.
[0009] FIG. 3 illustrates an example home signal incorporating
virtual trip stop related components, in accordance with the
present disclosure.
[0010] FIG. 4 illustrates example use scenarios comparing
conventional trip stop and virtual trip stop in a rail network.
[0011] FIG. 5 illustrates an example implementation of a home
signal with fail-safe sensing, in accordance with the present
disclosure.
[0012] FIG. 6 illustrates a flowchart of an example process for
enforcing rail vehicle adherence to a home signal using a virtual
trip stop, in accordance with the present disclosure.
DETAILED DESCRIPTION
[0013] As utilized herein the terms "circuits" and "circuitry"
refer to physical electronic components (e.g., hardware), and any
software and/or firmware ("code") that may configure the hardware,
be executed by the hardware, and or otherwise be associated with
the hardware. As used herein, for example, a particular processor
and memory (e.g., a volatile or non-volatile memory device, a
general computer-readable medium, etc.) may comprise a first
"circuit" when executing a first one or more lines of code and may
comprise a second "circuit" when executing a second one or more
lines of code. Additionally, a circuit may comprise analog and/or
digital circuitry. Such circuitry may, for example, operate on
analog and/or digital signals. It should be understood that a
circuit may be in a single device or chip, on a single motherboard,
in a single chassis, in a plurality of enclosures at a single
geographical location, in a plurality of enclosures distributed
over a plurality of geographical locations, etc. Similarly, the
term "module" may, for example, refer to physical electronic
components (e.g., hardware) and any software and/or firmware
("code") that may configure the hardware, be executed by the
hardware, and or otherwise be associated with the hardware.
[0014] As utilized herein, circuitry or module is "operable" to
perform a function whenever the circuitry or module comprises the
necessary hardware and code (if any is necessary) to perform the
function, regardless of whether performance of the function is
disabled or not enabled (e.g., by a user-configurable setting,
factory trim, etc.).
[0015] As utilized herein, "and/or" means any one or more of the
items in the list joined by "and/or". As an example, "x and/or y"
means any element of the three-element set {(x), (y), (x, y)}. In
other words, "x and/or y" means "one or both of x and y." As
another example, "x, y, and/or z" means any element of the
seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y,
z)}. In other words, "x, y and/or z" means "one or more of x, y,
and z." As utilized herein, the term "exemplary" means serving as a
non-limiting example, instance, or illustration. As utilized
herein, the terms "for example" and "e.g." set off lists of one or
more non-limiting examples, instances, or illustrations.
[0016] As utilized herein, "train" refers to any vehicle, car or
the like that operates on train racks. This may include vehicles,
cars or the like that operating individually (e.g., as single
vehicle) or within a group (e.g., one of cars in a multi-car
railway train). Further, as utilized herein a train may include
powered vehicles, cars or the like (e.g., incorporating power means
for driving the car or the vehicle, autonomously and/or based on
power provided to the car or the vehicle from external sources)
and/or non-powered cars or vehicles.
[0017] The present disclosure is directed to control solutions for
use in train systems. In particular, various implementations in
accordance with the present disclosure are directed to providing
virtual trip stops. In this regard, with virtual trip stops a train
may, for example, be automatically stopped if the train violates a
control signal without requiring track-mounted mechanical
infrastructure. Transit systems may utilize, for example,
Communication Based Train Control (CBTC) technology to bolster
operational safety and improve throughput on busy train lines.
While expensive to deploy, CBTC allows transit authorities to
maximize the volume of passengers which may be transported without
compromising safety and avoiding the great expense of adding
additional track. The cost of adding additional track is
significant, particularly in the United States, and especially so
in heavily populated areas.
[0018] A "true CBTC system" depends exclusively upon the automated
system to maintain safe train separation. CBTC systems provide
contingency features to allow safe movement of trains in the event
normal CBTC system operation fails. The throughput using the
contingency system, however, is usually much lower than is achieved
during normal CBTC operation. For busy transit systems that operate
at or near full capacity during "rush hour" periods, the
contingency system is too disruptive to normal passenger flow. As a
result, many transit authorities choose to retain certain elements
of legacy "fixed block signaling" train protection systems when
they implement CBTC. They do this primarily to provide backup
(supplemental) train protection systems in the event that the
complex CBTC systems on the train, the wayside, or in the entire
CBTC system malfunction. These supplemental systems are often
referred to as "secondary train protection".
[0019] Malfunctions and failures in CBTC operation are a particular
issue during the "cutover" process when the CBTC system is first
activated. An effective secondary train protection system is
particularly important during cutover to avoid deterioration in the
transit system throughput. Since the cutover process may extend for
multiple months, even years, an effective secondary protection
system can become particularly important.
[0020] However, not all aspects of fixed block signaling systems
are retained, however, due to the significant expense associated
with maintenance and repair of those signaling systems. Usually
many of the track segments (blocks) are consolidated in single,
large blocks to minimize the residual equipment upkeep cost. One
portion of legacy fixed block signaling that is often left entirely
intact with CBTC implementations are "home signals" and the
associated "trip stops" (sometimes called a "train stop",
"tripcock", or "tripper").
[0021] A home signal is a wayside signal placed at the transition
point of a route (such as at a track switch) or at the entrance to
a block in order to regulate the movement of trains into that route
or block. If a block is already occupied with a train, the home
signal will display at stop indication to trains approaching the
entrances to that block. This is intended to prevent train
collisions, such as by enforcing train separation. The signal by
itself, however, is unable to prevent train entry if the operator
fails to respond to the stop signal. This fault condition is why
trip stops are associated with home signals.
[0022] A trip stop (or train stop) is a train protection device
that may trigger the emergency brake on a train, resulting in an
automatic stop of a train if the train attempts to pass a
restrictive (stop) signal which indicates the train must not
proceed passed the signal. If the signal indicates a stop condition
for the approaching track, the trip stop mechanically activates a
brake-tripping arm upward. When a properly equipped train attempts
to pass the trip stop in the activated condition, the raised arm on
the trip stop contacts a hanging paddle on the train. That paddle
is an activation valve for the emergency braking system on the
train and causes the train to quickly stop, thus preventing entry
into the zone protected by the home signal.
[0023] The combination of a home signal and the associated trip
stop provide an automatic protection system as a backup in the
event the CBTC system fails. This fallback protection prevents
trains from moving through improperly aligned switches into areas
where trains may collide. During normal CBTC operation, the trip
stop arm is commanded to move to the "down" position to allow the
train to pass. In effect, a properly operating CBTC system
overrides the home signal/trip stop combination.
[0024] Trip stops were first introduced over one hundred years ago.
A trip stop is a relatively complex mechanical system with moving
parts. Trip stops are expensive to install and to maintain. In
addition, trip stops are track-mounted, which complicates track
maintenance and repairs, increasing the cost and duration of
disruption to track operation during service.
[0025] An additional disadvantage of the trip stop is that it must
be positioned well in advance of the desired stopping point. This
location in advance of the home signal is required to account for
the maximum necessary emergency braking distance of the train to
ensure the train will stop prior to entering the restricted area.
If the train is traveling faster than the assumed maximum speed
used for determining this distance, the trip stop will not prevent
the train from entering the restricted area, possibly resulting in
a collision. The CTA collision with the end-of-track bumping post
at O'Hare airport on Mar. 24, 2014 is an example of how a trip stop
may fail to safely stop a train it is traveling faster than the
assumed maximum travel speed at that location.
[0026] Therefore, less costly and/or less complex alternatives to
the trip stop may be desirable. In particular, for fallback
protection in CBTC implementations, use of virtual trip stops may
be a desirable option. In this regard, use of virtual trip stops
reduces installation and maintenance costs, while also addressing
weaknesses in conventional (legacy) solutions, as it improves
system performance compared to conventional (legacy) trip stops as
exemplified by the CTA accident noted above. This may be done, for
example, by use of wireless communications. In this regard, in
recent years, ultra-wideband (UWB) wireless precision ranging
technology has been proposed and demonstrated at various transit
agencies as a means of determining train position and/or train
separation from other objects on a continuous basis. Several United
States patents and patent applications describe various aspects
and/or uses of this technology, including, e.g., U.S. Pat. Nos.
8,812,227; 9,043,131; 9,731,738; 10,778,363; and U.S. patent
application Ser. Nos. 16/055,905; 16/290,576; 16/447,631;
16/118,941; and Ser. No. 16/521,269. Such UWB systems may be
deployed to supplement CBTC implementations, providing improved
train location technology, as well as providing a virtual trip stop
capability.
[0027] Accordingly, in various implementations in accordance with
the present disclosure, virtual trip stop may incorporate use of
UWB technology to enhance operation. For example, virtual trip stop
may incorporate UWB wireless ranging transducers mounted on each
end face of the trains and at the approaches to each home signal
location. The home signals may be retained, but the track-mounted
physical trip stop mechanism may be eliminated, as the function
typically performed by the physical trip stop may be performed
"virtually", such as by triggering the brakes in the train based on
the wireless communications.
[0028] FIG. 1 illustrates an example virtual trip stop system, in
accordance with the present disclosure. In this regard, FIG. 1
shows a block diagram of an example virtual trip stop system 10
which may be used to provide secondary protection by providing
enforcement of restrictive home signal aspect indications.
[0029] The virtual trip stop system 10 is composed of two distinct
elements. The track-side (wayside) portion comprises existing
trackside home signal 20 which has been modified to support remote
sensing of the signal aspects. The wayside portion also comprises
vital (failsafe) signal aspect sensing circuitry and a vital
processor 30, which controls the UWB transceiver and antenna
combination 40. Each of these components may comprise suitable
hardware (comprising, e.g., circuitry and/or other types of
hardware), software, or any combination thereof configured for
supporting virtual trip stop related operations or functions as
described herein.
[0030] The UWB transceiver and antenna 40 may communicate
wirelessly with train-borne UWB transceiver and antenna 50, which
in turn interfaced with the train-borne vital controller 60. The
virtual trip stop vital controller 60 may directly interface with
the train emergency braking system 80. In an alternative
implementation, the emergency brake triggering by the virtual trip
stop may be accomplished via the interface with the CBTC controller
70 on the train. Each of these components may comprise suitable
hardware (comprising, e.g., circuitry and/or other types of
hardware), software, or any combination thereof configured for
supporting virtual trip stop related operations or functions as
described herein.
[0031] A virtual trip stop installation at a home signal along the
rail wayside may comprise the following components: UWB transceiver
and antenna (with associated UWB processing), and a tower or
structure to elevate the UWB antenna to an appropriate height for
optimal performance, a redundant (fail-safe) home signal aspect
sensing interface, a vital processor to create the appropriate
status messages for UWB transmission, and a power converter to
allow the system to be supplied by a convenient power source
available at the home signal. The power source may be 115 VAC
mains, or low-voltage DC signaling power, or one of other power
variations found in transit systems.
[0032] The virtual trip stop controller on the train receives the
home signal indication, which may be included with UWB range
results, or from data-only UWB transactions. If the indication is
not permissive (either restrictive or missing), the UWB-based vital
controller will determine when it is appropriate to trigger the
train emergency brakes in order to enforce the home signal.
[0033] The virtual trip stop controller performs UWB ranging
operations to the home signal's associated UWB transducer and
determines the distance to the home signal. This may consist of a
calculation which includes the offset distance between the UWB
transducer and the track transition point by which the train must
stop, plus safety factors specified by the agency. The offset
distance may be necessary when the UWB transceiver is installed on
a structure which is separated from the home signal.
[0034] This UWB-ranging distance to the home signal is continuously
updated (usually more than once per second), and this distance
measurement is conveyed to the appropriate automatic train
protection (ATP) controller on the train. The ATP function may be
provided by a system on the train which is completely independent
of the CBTC system (e.g., the train-borne vital controller 60 of
FIG. 1), or it may be performed by a portion of the CBTC system
installed on the train. Thus, when the CBTC system fails, there
still may be an independent portion that remains operational due to
redundancy, and that portion may retain functionality during
secondary train protection operation. Whichever processor performs
the ATP function, it determines the maximum safe braking distance
required for that location given the speed of the train and the
train's operating condition.
[0035] The UWB range measurement system may also be used to detect
the speed of the train, such as by calculating the
"delta-separation" between the train UWB transducer and the home
signal UWB transducer. Delta separation may be determined by making
at least two separate measurements of the distance with a known
time interval between the measurements. For example, if the first
UWB distance measurement is 450.05 ft, the second measurement is
403.09 ft, and precisely one second elapsed between the distance
measurements, it may be determined that the train is approaching
the home signal at .about.32.0 mph ((450.05 ft-403.09 ft)/(1
s)=46.96 ft/s or .about.32.0 mph).
[0036] If a permissive signal condition is not received from this
particular home signal location (either a restrictive signal
condition is received, or the signal state is missing from
communications), the ATP processor will execute an emergency brake
activation if the train operator fails to slow the train properly
in advance of the home signal. The emergency brake will be
triggered far enough in advance in order to assure that in worst
case conditions, the emergency brake will be capable of stopping
the train prior to passing the home signal. This is called the
"safe braking distance."
[0037] Some transit agencies have significant safety margins such
that even the virtual train stop will stop the train short of the
home signal. If the operator desires to move forward to reach the
home signal (to improve throughput), the virtual trip stop remains
operational and will still enforce a train stop before the passes
the home signal at the slower approach speed. However, the train
may be stopped much closer to the home signal. This system behavior
may be contrasted with legacy mechanical trip stop based solutions,
where the train may have already passed the trip stop actuating arm
on the first stop, so no further protection against violating the
home signal may be provided.
[0038] In various implementations, the sensing of the home signal
aspect indication may be performed in a non-intrusive fashion, such
as by using inductive current sensing of the current flowing to the
home signal indicating lamp(s) as described in more detail
below.
[0039] FIG. 2 illustrates an example deployment of virtual trip
stop system in a rail network, in accordance with the present
disclosure. In this regard, FIG. 2 shows an overhead view of a rail
vehicle on a rail line equipped with a virtual trip stop system. In
particular, FIG. 2 illustrates a typical installation of both the
physical trip stop and the virtual trip stop.
[0040] Train 100 was traveling left-to-right at a relatively low
speed along track 110. The home signal 120 was showing a
restrictive signal aspect which caused the trip stop arm 140,
located in advance of the home signal, to be extended upward. The
corresponding "sensing" arm on the passing train 100 contacted the
trip stop arm and triggered the train emergency braking system. The
train stopped a short time distance beyond the trip stop arm
140.
[0041] Referring to FIG. 2, with the proposed virtual trip stop,
the trip stop arm 140 and its associated motor and mechanism
(hidden by the train) would be eliminated, replaced by the virtual
trip stop UWB antenna and the associated electronics 130. UWB range
measurements and data communication are achieved between the
virtual trip stop and the train via UWB transceiver and antenna
assemblies 150 which are installed at each end of the train 100. In
this regard, each of the UWB transceiver and antenna assemblies 150
may be similar to the train-borne UWB transceiver and antenna 50 of
FIG. 1. The determination of which transceiver is used may be done
in various ways. For example, in some implementations this may be
done based on networking between the transceivers (e.g., UWB
transceiver and antenna assemblies 150) on each end of the train.
The train-borne vital controller 60 may determine the direction of
movement, such as based on "delta-separation" measurement and/or by
utilizing other/available sources (e.g., the train's wheel sensor
inputs or other means), to determine which transceiver 150 is on
the forward moving end of the train. The identified transceiver is
used for virtual trip stop operation.
[0042] FIG. 3 illustrates an example home signal incorporating
virtual trip stop related components, in accordance with the
present disclosure. In this regard, FIG. 3 shows an example home
signal 120 with associated conventional physical trip stop
components as well as virtual trip stop components.
[0043] In particular, FIG. 3 illustrates a wayside installation of
trip stop components, both of the legacy physical trip stop and the
virtual trip stop. For the purposes of illustration, the physical
trip stop is shown immediately adjacent to the home signal. In many
installations, the home signal and the trip stop mechanism and trip
arm are separated by considerable distance.
[0044] The home signal 120 is installed alongside the tracks 110.
The physical trip stop consists of two parts. The trip stop motor
and actuating mechanism 160 is located between the tracks. A
rotating shaft extends from the actuating mechanism 160 to the trip
stop arm 140. When the home signal indication is green
(unrestrictive), the trip stop arm 140 is rotated downward so that
the corresponding emergency brake tripping arm of passing trains
will not contact the trip stop. When the home signal 120 is showing
a red indication (restrictive), the trip stop actuating motor 160
rotates the trip stop arm 140 upward such that any passing train
equipped with the emergency brake tripping arm will have the
emergency brakes triggered.
[0045] Also shown in FIG. 3 for comparison purposes is the virtual
trip stop components. Nonetheless, it should be noted that both the
physical trip stop components 140 and 160, and the virtual trip
stop components 130 and 170 may not normally be in place
simultaneously. An upward extension 170 from the home signal 120
provides mechanical support, power supply wiring, and home signal
sensing conductors to the virtual trip stop UWB transceiver,
antenna, and control electronics 130. The upward extension 170
places the UWB antenna high (e.g., roughly 8 to 10 ft) above the
track level. Positioning the antenna at such height may aid in
ensuring proper and/or optimal operation of the UWB ranging
system.
[0046] The virtual trip stop UWB ranging transducers allow precise
measurement of the distance between the train and the home signal.
When a home signal is in a permissive state (indicating that an
approaching train may pass), the associated UWB transducer will
transmit a permissive signal indication using a vital (fail-safe)
protocol to approaching trains. When a home signal is in a
restrictive state (indicating that an approaching train must stop),
the associated UWB transducer will transmit a restrictive
indication using a vital (fail-safe) protocol to approaching
trains.
[0047] Because UWB radios used in virtual trip stops may sense an
approaching train many hundreds of feet away, the virtual trip stop
(e.g., the associated UWB transducer) may be located near or on the
home signal, unlike the legacy physical trip stop actuating motor
and stop arm which must be located hundreds of feet prior to the
home signal. By co-locating the virtual trip stop at the home
signal, the installation cost of the system is reduced because
signal communication cabling along the track to the remote trip
stop location is not required. Costs are reduced even further
because there is no track modification necessary to install the
physical activation mechanism. Plus, with the elimination of the
mechanism that must operate hundreds of times per day, the
maintenance burden is also significantly lower.
[0048] Alternatively, the virtual trip stop may be placed wherever
convenient and effective along the wayside at a location where a
passing train may successfully make continuous range measurements
to the UWB transducer at the distances necessary to allow the train
emergency brake to stop the train prior to passing the home
signal.
[0049] The distinct advantage of the UWB virtual trip stop over the
legacy physical trip stop is that it provides an adaptive
application point for the emergency brake prior to the home signal.
The faster the train, the further back the emergency brake will be
applied to ensure that the train stops prior to the home
signal.
[0050] In contrast, to ensure safety, the physical trip stop must
be placed at the maximum required emergency braking distance prior
to the home signal. This distance must correspond to the maximum
emergency brake stopping distance required at the highest
achievable train speed. This lack of adaptability in the legacy
physical trip stop system may have significant disadvantages as
described in the following scenario.
[0051] For example, at 10 mph, the train's emergency brake may stop
the train in 40 ft or less; at 20 mph, the maximum stopping
distance may be 120 ft; at 30 mph, the maximum stopping distance
may be 250 ft; at 40 mph, the maximum stopping distance may be 430
ft; and at 50 mph, the maximum stopping distance may be 700 ft. If
the maximum achievable speed of the train is 50 mph, to provide
complete protection, the physical trip stop must be placed 700 ft
in advance of the home signal in order to ensure that the train may
be stopped prior to the track section protected by the home
signal.
[0052] FIG. 4 illustrates example use scenarios comparing
conventional trip stop and virtual trip stop in a rail network. In
this regard, FIG. 4 shows an overhead view of two scenarios over
the same section of track where a conventional trip stop has
brought a train to a stop. In particular, the top view shows the
result when a train was traveling at the maximum allowable track
speed, whereas the bottom view shows the result when train was
traveling at a much lower speed.
[0053] For example, the use scenario shown in the top drawing of
FIG. 4 illustrates the result of a train stop caused by physical
trip stop where the train was travelling at the maximum speed. The
train 100 was traveling left to right on track 110. The home signal
120 was indicating a restrictive aspect, which means the train must
stop prior to passing the home signal 120. In response to the
restrictive signal, the trip stop motor 160 has raised the trip
stop arm assembly 140.
[0054] When the train 100 passed the trip stop arm 140, the train
emergency brake was triggered. As a result of the train's high
speed, it required a significant distance to stop the train and the
train ended up a small distance d.sub.1 180 short of the home
signal 120. The train stopped short of the home signal because the
trip stop was located according to the worst case maximum emergency
braking distance at the highest speed, while the train stopped in a
shorter distance according to the nominal emergency braking
distance at that speed.
[0055] In contrast, in the scenario where a train is approaching
the same restrictive (red) home signal at 10 mph. The bottom
drawing in FIG. 4 illustrates the result. The trip stop arm will
extend any time the home signal aspect indication is restrictive
and cause the passing train to apply emergency braking and stop at
least 660 ft prior to the home signal. The trip stop is installed
700 ft in advance of the home signal, and the train stops in no
more than 40 ft at 10 mph, so 700-40=660 for the distance d.sub.2
190, well short of the home signal 120. This situation is
inconvenient, counterproductive, possibly dangerous, and
potentially unsafe.
[0056] This situation is inconvenient, because the train has been
stopped far in advance of the home signal instead of properly just
before the home signal, as well as inefficient, as stopping and
starting the train wastes energy. If the train in the next block,
which caused the restrictive home signal, moves out of the block
protected by the home signal within the next 40 seconds, stopping
the train was unnecessary. The approaching train could have
continued moving at 10 mph towards the home signal and the home
signal would have changed to a permissive indication prior to the
train reaching the home signal stopping point.
[0057] This situation is counterproductive because the train will
now take considerably more time to enter the block protected by the
home signal once the signal becomes permissive. This will slow down
throughput in the system. In addition, since the train stopped well
before the home signal, the rear of the train may block entrance of
a following train into a station, or into another protected block,
cascading additional delays further back through the system. This
is particularly problematic during "rush hour" when transit
capacity is often strained even without additional delays
associated with premature braking due to trip stops.
[0058] This situation is possibly dangerous because an unnecessary
emergency braking event has been triggered. The train still had
plenty of distance to stop before the home signal, so the emergency
brake application may not have been necessary. Emergency braking
may result in passenger injuries due to the aggressive braking rate
employed.
[0059] This situation which resulted in stopping the train in
advance of the home signal may also degrade safety. When the train
is stopped so far back from the home signal, the train operator may
feel pressured to advance the train to the home signal. This may be
the result of the knowledge that the prematurely stopped train is
impacting rush hour throughput. The operator may hastily reset the
emergency brake and advance. Now, however, there is no longer a
trip stop between the train and the home signal to enforce a train
stop prior to entering the next block of track. If the train is
short, and/or the train was moving at a sufficient speed when
stopped by the trip stop, such that there are no remaining brake
actuators on the train which will contact the trip stop arm, there
is no remaining mechanism to automatically prevent the train from
entering the unauthorized block of track beyond the home signal. If
the operator is inattentive or is distracted again, and fails to
appropriately stop the train prior to the home signal, the train
may enter an unauthorized block of track.
[0060] The classic solution to address the issue of the fixed brake
application point of the trip stop and the associated issues
described above is to add more trip stops, and/or add advance
(approach) home signals with associated trip stops, and/or timed
trip stops that will actuate train brakes only if the train is
traveling above a defined speed. Each of these measures add
significantly more installation and maintenance costs, further
exacerbating the issue of the cost of trip stops in an already
costly CBTC environment. The virtual trip stop may also be used to
provide or support other functionalities, such as enforcing speed
limits--e.g., on the approach to a home signal, to ensure that the
maximum stopping distance is within the capability of the virtual
trip stop system.
[0061] Because of the infinitely adjustable trigger point feature
of the virtual trip stop, the complications described above with
physical trip stops are eliminated. The virtual strip stop system
automatically compensates for train speed when determining the
point where emergency brake application is required. With a virtual
trip stop, both of the aforementioned operating scenarios (a high
speed and low speed approach to a restrictive home signal) would
result in the train stopping as shown in the scenario shown in the
top drawing of FIG. 4, where the train stops a small distance
d.sub.1 180 short of the home signal 120. Only with the legacy
physical trip stop installation would the bottom drawing scenario
occur, with the train stopping at distance d.sub.2 190, well short
of the home signal 120. Note also that in a virtual trip stop
installation, trip stop arm 140 and actuating mechanism 160 would
be eliminated.
[0062] A virtual trip stop installation onto a train may comprise
the following components: UWB transceiver and antenna (with
associated UWB processing), a vital processor to determine if the
emergency brake should be initiated in response to UWB data, an
interface to the train emergency brake system, an interface to the
CBTC vehicle on-board controller (VOBC), and a connection to
low-voltage power from the train. Some installations may also
comprise a user display or an interface to an existing display in
the cab of the train to convey status and health indications to the
operator. The status and indication functions may be handled by the
CBTC system.
[0063] FIG. 5 illustrates an example implementation of a home
signal with fail-safe sensing, in accordance with the present
disclosure. In this regard, shown in FIG. 5 is an electrical
schematic of an example home signal aspect fail-safe sensing
configuration in accordance with at least one embodiment of the
present technology. In particular, FIG. 5 illustrates one such
implementation of home signal aspect sensing. Such a current sensor
520 may consist of multiple turns of magnet wire wrapped on an
appropriate toroidal magnetic core (such as a ferrite core) in the
case of AC-powered home signals.
[0064] In the event the home signal is DC-powered, the current
sensor may consist of a Hall effect sensor placed in the gap of a
cut toroidal tape-wound high permeability core (such as a
nickel-iron core). Such a non-contacting current sensing system
allows the sensing electronics to be completely isolated from the
home signal circuit. Safety standards may require as much as 3,000
VAC of galvanic isolation.
[0065] For fail-safe detection of the home signal aspect, dual
current sensors may be employed on each conductor, as shown in FIG.
5, where there are two independent current sensors 520 on each
signal aspect conductor. The conductor 530 for signal lamp 510
passes through two current sensors 520, providing redundant
sensing.
[0066] This current sensor redundancy allows for one sensor to fail
while the other sensor will still detect the signal state.
Additional safety in sensing may be achieved by sensing each home
signal aspect conductor, such that a restrictive state is
determined any time anything other than a single permissive aspect
is lit. Fault conditions such as no aspect and improper multiple
aspects may be treated as a restrictive indication for safety
reasons.
[0067] Fault handling of the signal aspect sensing shown in FIG. 5
is handled in the UWB transceiver, antenna, and control electronics
130. Each current sensor is connected to the vital current sensor
and processor 40, which senses if current is flowing in the
corresponding signal lamp, indicating that the lamp is lit. Each
independent current sensor input is processed in a fail-safe
fashion by the vital processor 40, and the results of the
determination is sent to the remote train requesting range
measurements and status updates via the UWB transceiver 30.
[0068] Precision UWB range measurements are used by the virtual
trip stop train-borne controller to determine the range and closing
speed to the home signal, and those range measurements may also
include data which identifies the signal aspect displayed by the
associated home signal. There is another function of the UWB range
measurements which is often required to allow determination of
which home signal controls the movement of the host train.
[0069] When there is more than one operating track, the train-borne
controller must determine the track upon which the train is
traveling. This is necessary to select the appropriate home signal,
and not the home signal which controls train flow on the opposite
track or other tracks adjacent to the one upon which the train is
operating.
[0070] In order to make this operating track determination, it may
be necessary to locate more than one UWB transceiver with the
virtual trip stop for each home signal. Multiple UWB transceivers
at known locations (stored in a non-volatile memory track map in
the train-borne virtual trip stop controller) allow the processor
to determine the operating track using geometric analysis of range
results. The additional UWB transceivers may be located prior to
the home signal in order to allow and/or confirm operating track
determination well in advance of the associated home signal.
[0071] The additional UWB transceivers for operating track
determination also allow detection of failures of individual UWB
transceivers. For example, if one or two UWB transceivers located
prior to the home signal are responsive, but the expected home
signal UWB transceiver is not responsive, a fault may be flagged
and logged for service. This condition may also cause the virtual
trip stop to enter a fail-safe condition of assuming a restrictive
signal indication on the home signal. The virtual trip stop
controller may make this association of UWB transceivers via the
on-board track map stored in the controller. The track
determination technique and track map technology is described in
U.S. Pat. No. 10,778,363. Virtual trip stop operational integrity
may also be assured during normal CBTC operation by having the CBTC
VOBC confirm that it is receiving proper status messages from the
virtual trip stop train-borne processor. The CBTC system may know
the location, and the distance to an upcoming home signal. The VOBC
can verify that the virtual trip stop system is detecting the home
signal status and distance to home signal when the train reaches a
threshold where the UWB radios should be capable of ranging and
data communications.
[0072] FIG. 6 illustrates a flowchart of an example process for
enforcing rail vehicle adherence to a home signal using a virtual
trip stop, in accordance with the present disclosure. In this
regard, shown in FIG. 6 is a flow diagram 600 of an example process
for enforcing rail vehicle adherence to a home signal using a
virtual trip stop.
[0073] In particular, the flow diagram 600 depicts a method for
implementing virtual trip stop to enforce home signal restrictions.
The method may be performable using the structures and functions
described herein. The steps illustrated in the flow diagram 600 may
be performable at least in part by one or more processors, such as
the processor(s) depicted in FIG. 1, which comprise the trackside
vital processor 30, the train-borne vital processor 60, and the
CBTC vehicle-on-board controller 70.
[0074] At the start of the process, upon power up of the virtual
trip stop controller located on a train, the proximity to any
wayside virtual trip stop systems is not known, and as such the
controller reverts to a "location unknown" condition. Hence, at
step 605 the train-borne controller transmits an UWB "all units
respond" request. At step 610, all properly equipped and configured
virtual trip stop UWB radios located close enough to successfully
receive the transmission respond via UWB with their unique ID.
[0075] At step 615, the train-borne controller inspects the
messages and rapidly determines the approximate range to each
responding UWB radio using the data from each transmitted response.
The train-borne controller then executes, at step 620, precision
range measurements to several of the closest responding radios, and
then, at step 625, repeats the range measurements after a precise
time delay. The resulting data may allow the train-borne controller
to determine, at step 630, the direction of movement, the speed of
the train to each UWB responder, and the operating track. The
train-borne controller then selects, at step 635, the next virtual
trip stop ahead (e.g., nearest virtual trip stop for the operating
track), the signal indication of the associated home signal, and
the closing velocity to the next virtual trip stop. If there was
not a sufficient quantity of UWB responders to determine all of
these values, partial data may still be helpful, and the
train-borne controller will continue to attempt range measurements
to the appropriate targets and may add additional targets based
upon data in the stored track map.
[0076] At step 640, the computed distance to the next home single
may be adjusted by a programmed offset value if the home signal and
the associated UWB transceiver are not co-located. The offset value
may be obtained from the programmed track map, or may be included
in the data sent by the home signal UWB transceiver.
[0077] At step 645, once the speed of the train is determined, the
safe braking distance may be computed by the train-borne
controller. At step 650, train train-borne controller periodically
updates range and home signal indication with nearest virtual trip
stop. At step 655, a comparison of the current distance to the home
signal and the safe braking distance coupled with the home signal
aspect indication will determine when and if it is necessary to
enforce a stop by triggering the emergency brake. For example, if
the home signal indication is restrictive, or if signal state is
not confirmed, and safe braking distance is violated, the train
emergency brake is commanded.
[0078] At step 660, once the home signal/virtual trip stop is
passed, the train-borne controller may consult the stored track map
to determine the next home signal and may begin ranging attempts
with the next home signal. At step 665, if there is no response
from the next home signal, the train-borne controller may return
the location state to "unknown", and begin the acquisition process
just described back into operation.
[0079] Furthermore, in some implementations the steps illustrated
in the flow diagram 600 may be performed in a different order, or
some steps may be omitted, such as according to design and/or
preferences. The steps illustrated in the flow diagram 600, or a
portion thereof, may be performable by software, hardware, and/or
firmware. The steps illustrated in the flow diagram 600, or portion
thereof, may also be expressible through a set of instruction
stored on one or more computer-readable storage devices, such as
RAM, ROM, EEPROM, flash memory, other non-volatile electronic
memory, optical disk, magnetic disk, solid state drive, magnetic
tape, and/or the like.
[0080] An example system for train control, in accordance with the
present disclosure, comprises a train-based control unit configured
for deployment on a train operating within a rail network, with the
train-based control unit comprising one or more transceivers
configured for transmitting and/or receiving wireless signals, and
one or more circuits configured to: process signals and data, and
perform based, at least in part, on the processing of signals one
or more functions relating to operations of the train-based control
unit. The rail network comprises one or more wayside control units
configured for deployment on or near tracks in the rail network,
with each wayside control unit coupled or attached to a train
signal (e.g., home signal), and the train-based control unit
configured to communicate with any wayside control unit that comes
within communication range of the train-based control unit, to
determine based on processing of communicated signals with at least
one wayside control unit one or both of operation information and
state information, and to generate based on the operation
information and the state information, control information
configured for use in controlling one or more functions of the
train in conjunction with operation in the rail network. The
operation information relate to one or both of the at least one
wayside control unit and the train. The state information relate to
a state of train signal.
[0081] In an example implementation, the operation information
comprises ranging information, and wherein the train-based control
unit is configured to determine range to at least one wayside
control unit.
[0082] In an example implementation, the train-based control unit
is configured to determine approximate range to each wayside
control unit within communication range of the train-based control
unit.
[0083] In an example implementation, the train-based control unit
is configured to: identify at least one nearest wayside control
unit, and obtain, based on processing of received signals,
precision range measurements to the at least one nearest wayside
control unit.
[0084] In an example implementation, the train-based control unit
is configured to repeat obtaining range measurements after a time
delay.
[0085] The system of claim 1, wherein the operation information
comprises one or more of direction, speed, and location, wherein
the train-based control unit is configured to determine at least
one of direction of movement of the train, speed of the train,
location of the train, and operating track based, at least in part,
on processing of received signals from at least one wayside control
unit.
[0086] In an example implementation, the train-based control unit
is configured to determine at least one of the direction of
movement of the train, the speed of the train, the location of the
train, and the operating track based on range measurement to at
least one wayside control unit.
[0087] In an example implementation, the train-based control unit
is configured to select a nearest virtual trip stop based on
identifying of a train signal (e.g., home signal), wherein the
train signal is determined based on a corresponding wayside control
unit.
[0088] In an example implementation, the train-based control unit
is configured to determine a safe braking distance for the virtual
trip stop based on speed of the train.
[0089] In an example implementation, the state information
comprises an indication of whether the state of train signal is
restrictive, permissive, or not confirmed, and wherein the
train-based control unit is configured to: select a virtual trip
stop based on identifying a particular wayside control unit, and
generate or adjust the control information based on the
indication.
[0090] In an example implementation, the one or more functions of
the train comprise braking, and wherein the train-based control
unit is configured to generate a safe braking command based on a
determination that the state of train signal is restrictive or is
not confirmed.
[0091] In an example implementation, the train-based control unit
is configured to communicate with at least one wayside control unit
that comes within communication range of the train-based control
unit using ultra-wideband (UWB) signals.
[0092] An example system for train control, in accordance with the
present disclosure, comprises a wayside control unit configured for
deployment on or near tracks in a rail network, with the wayside
control unit comprising one or more transceivers configured for
transmitting and/or receiving wireless signals, and one or more
circuits configured to process signals and data, and perform based,
at least in part, on the processing of signals one or more
functions relating to operations of the wayside control unit. The
wayside control unit is coupled or attached to the train signal,
and the wayside control unit is configured to communicate with any
train-based control unit that comes within communication range of
the wayside control unit.
[0093] In an example implementation, the wayside control unit is
configured to communicate with at least one train-based control
unit that comes within communication range of the wayside control
unit using ultra-wideband (UWB) signals.
[0094] Aspects of the techniques described herein may be
implemented in digital electronic circuitry, computer software,
firmware, or hardware, including the structures disclosed herein
and their structural equivalents, or in various combinations.
Aspects of the techniques described herein may be implemented using
a non-transitory computer readable medium and/or storage medium,
and/or a non-transitory machine readable medium and/or storage
medium, having stored thereon, a machine code and/or a computer
program having at least one code section executable by a machine
and/or a computer, thereby causing the machine and/or computer to
perform the processes as described herein.
[0095] Each of the computer programs may have, for example, one or
more sets of program instructions residing on or encoded in the
non-transitory computer-readable storage medium for execution by,
or to control the operation of, one or more processors of the
machine or the computer. Alternatively or in addition, the
instructions may be encoded on an artificially-generated propagated
signal, for example, a machine-generated electrical, optical, or
electromagnetic signal that may be generated to encode information
for transmission to a suitable receiver apparatus for execution by
one or more processors.
[0096] A non-transitory computer-readable medium may be, or be
included in, a non-transitory computer-readable storage device, a
non-transitory computer-readable storage substrate, a random or
serial access memory array or device, various combinations thereof.
Moreover, while a non-transitory computer-readable medium may or
may not be a propagated signal, a non-transitory computer-readable
medium may be a source or destination of program instructions
encoded in an artificially-generated propagated signal. The
non-transitory computer-readable medium may also be, or be included
in, one or more separate physical components or media (for example,
CDs, disks, or other storage devices).
[0097] Certain techniques described in this specification may be
implemented as operations performed by one or more processors on
data stored on one or more computer-readable mediums or received
from other sources. The term "processor" may encompass various
kinds of apparatuses, devices, or machines for processing data,
including by way of example a central processing unit, a
microprocessor, a microcontroller, a digital-signal processor,
programmable processor, a computer, a system on a chip, or various
combinations thereof. The processor may include special purpose
logic circuitry, for example, a field programmable gate array or an
application-specific integrated circuit.
[0098] Program instructions (for example, a program, software,
software application, script, or code) may be written in various
programming languages, including compiled or interpreted languages,
declarative or procedural languages, and may be deployed in various
forms, for example as a stand-alone program or as a module,
component, subroutine, object, or other unit suitable for use in a
computing environment. Program instructions may correspond to a
file in a file system. Program instructions may be stored in a
portion of a file that holds other programs or data (for example,
one or more scripts stored in a markup language document), in a
dedicated file or in multiple coordinated files (for example, files
that store one or more modules, sub-programs, or portions of code).
Program instructions may be deployed to be executed on one or more
processors located at one site or distributed across multiple sites
connected by a network.
[0099] The present technology has now been described in such full,
clear, concise and exact terms as to enable any person skilled in
the art to which it pertains, to practice the same. It is to be
understood that the foregoing describes preferred embodiments and
examples of the present technology and that modifications may be
made therein without departing from the spirit or scope of the
invention as set forth in the claims. Moreover, it is also
understood that the embodiments shown in the drawings, if any, and
as described above are merely for illustrative purposes and not
intended to limit the scope of the invention. As used in this
description, the singular forms "a," "an," and "the" include plural
reference such as "more than one" unless the context clearly
dictates otherwise. Where the term "comprising" appears, it is
contemplated that the terms "consisting essentially of" or
"consisting of" could be used in its place to describe certain
embodiments of the present technology. Further, all references
cited herein are incorporated in their entireties.
[0100] Accordingly, various embodiments in accordance with the
present invention may be realized in hardware, software, or a
combination of hardware and software. The present invention may be
realized in a centralized fashion in at least one computing system,
or in a distributed fashion where different elements are spread
across several interconnected computing systems. Any kind of
computing system or other apparatus adapted for carrying out the
methods described herein is suited. A typical combination of
hardware and software may be a general-purpose computing system
with a program or other code that, when being loaded and executed,
controls the computing system such that it carries out the methods
described herein. Another typical implementation may comprise an
application specific integrated circuit or chip.
[0101] Various embodiments in accordance with the present invention
may also be embedded in a computer program product, which comprises
all the features enabling the implementation of the methods
described herein, and which when loaded in a computer system is
able to carry out these methods. Computer program in the present
context means any expression, in any language, code or notation, of
a set of instructions intended to cause a system having an
information processing capability to perform a particular function
either directly or after either or both of the following: a)
conversion to another language, code or notation; b) reproduction
in a different material form.
[0102] While the present invention has been described with
reference to certain embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the scope of the present
invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the present
invention without departing from its scope. Therefore, it is
intended that the present invention not be limited to the
particular embodiment disclosed, but that the present invention
will include all embodiments falling within the scope of the
appended claims.
* * * * *