SYSTEM AND METHOD FOR CONTROLLING A VEHICLE
BACKGROUND OF THE INVENTION
Field
[001] Embodiments of the invention relate to vehicles, e.g., rail vehicles. Other
embodiments relate to methods and systems for controlling rail vehicles or other
vehicles.
Discussion of art
[002] Especially when various on-board systems are integrated with a vehicle
braking system for conjointly operating the vehicle, the vehicle may be operated
according to a "worst case" assumption of braking capability. For example, in the
case of a locomotive or other rail vehicle, the rail vehicle may be operated according
to the assumption that only fifty percent of mechanical braking capability (e.g., air
brakes) is available and with no dynamic brake capability. Making such assumptions
may result in the rail vehicle being slowed earlier than necessary, which results in a
loss of average speed over a full duration of a trip/mission. Additionally, this may
result in delay and loss of route capacity, considering that other vehicles also operate
of the same route. Furthermore, the actual braking capability may actually be less
than what is assumed, due to discrepancies between actual capabilities and assumed
capabilities, brake system failures during a trip, environmental conditions, etc.
[003] One approach currently utilized to assess braking capability of a rail
vehicle is to check the air brakes prior to departure to ensure that air pressure is
present. This approach, however, does not provide for a true determination of braking
capability or effectiveness. This is because checking for air pressure does not convey
any information about how much braking force would be applied in actually using the
brakes during motoring, e.g., actual braking pads or shoes may not function properly,
thus not being able to apply a full breaking force to wheels of the rail vehicle, even
though a positive air pressure reading is obtained.
[004] It may be desirable to have a vehicle control system, taking into account
braking system capability, that differs from those vehicle control systems that are
currently available.
BRIEF DESCRIPTION OF THE INVENTION
[005] Embodiments of the present invention relate to systems and methods for
vehicle control that determine a braking capability of a vehicle and control the vehicle
based on the determined braking capability.
[006] In one embodiment, a method for vehicle control comprises determining a
braking capability of a braking system of a vehicle, and modifying application of at
least one mission parameter by a control system of the vehicle based on the
determined braking capability. (Mission parameter refers to a quantity or factor,
relating to the vehicle or a mission of the vehicle, which is used by a control system as
a basis for controlling the vehicle. Modifying application of the mission parameter
may include modifying the parameter and applying the modified parameter the same
as the parameter before modification, and/or applying the parameter in a different way
than the parameter would have been applied previously.)
[007] In another embodiment, a method for vehicle control comprises activating
a braking system of a vehicle to apply a braking force on the vehicle. Concurrently, a
level of tractive effort of the vehicle is applied sufficient to overcome the braking
force. The method further comprises determining a braking capability of the vehicle
based on the level of tractive effort, and controlling the vehicle based on the
determined braking capability.
[008] In another embodiment, a method for vehicle control comprises
autonomously determining when a vehicle is moving along a route having a grade
during a mission. (The grade may be a zero degree grade, a downhill grade, or an
uphill grade; autonomously means by a machine, e.g., automatically.) The method
further comprises applying the braking system of the vehicle while on the grade to test
a capability of the braking system. The method further comprises modifying
application (e.g., enforcement) of a mission parameter by the vehicle based on a result
from the test.
[009] Another embodiment relates to a system for a vehicle. The system
comprises a braking capability module configured to determine a braking capability
of a braking system of the vehicle. The system further comprises a control module
operably coupled with the braking capability module and configured to modify
application of a mission parameter by the control module based on the determined
braking capability.
[010] Another embodiment of a system for a vehicle comprises a location
module configured to identify when a vehicle is moving along a route having a grade
during a mission. The system further comprises a braking capability module
configured to command applying a braking system of the vehicle while on the grade
to test a capability of the braking system. The system further comprises a control
module configured to modify application of a mission parameter by the control
module based on a result from the test.
[Oi l ] In embodiments, the vehicle in question is a locomotive, other single rail
vehicle, a train, or another type of rail vehicle consist (e.g., a group of mining ore
carts).
BRIEF DESCRIPTION OF THE DRAWINGS
[012] Embodiments of the invention may be best understood by reference to the
following description taken in conjunction with the accompanying drawing figures
wherein:
[013] FIG. 1 is a flowchart illustrating a method for vehicle control, according to
an embodiment of the invention;
[014] FIG. 2 is a schematic diagram of a vehicle consist, according to an
embodiment of the invention;
[015] FIG. 3 is a flowchart illustrating a method for vehicle control, according to
another embodiment of the invention;
[016] FIG. 4 is a schematic diagram of a vehicle consist, according to another
embodiment of the invention;
[017] FIG. 5 is a velocity versus time profile showing two braking profiles;
[018] FIG. 6 is a velocity versus time profile showing modification of a default
safety threshold to a maximum allowed speed profile;
[019] FIG. 7 is a flowchart of a method for vehicle control, according to another
embodiment of the invention;
[020] FIG. 8 is a flowchart of a method for vehicle control, according to another
embodiment of the invention;
[021] FIG. 9 is a schematic diagram of a vehicle control system, according to
another embodiment of the invention;
[022] FIG. 10 is a flowchart of a method for vehicle control, according to
another embodiment of the invention; and
[023] FIG. 11 is a schematic diagram of a vehicle control system, according to
another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[024] Reference will be made below in detail to exemplary embodiments of the
invention, examples of which are illustrated in the accompanying drawings.
Wherever possible, the same reference numerals used throughout the drawings refer
to the same or like parts; however, the existence of the same or like parts in multiple
embodiments does not mean every embodiment of the invention necessarily includes
such parts. Exemplary embodiments of the invention solve problems in the art by
controlling a vehicle based on a determined condition of a braking system of the
vehicle. Additionally, embodiments of the invention can be implemented in
numerous ways, including as a system (including a computer processing system), a
method (including a computerized method), an apparatus, a computer readable
medium, a computer program product, or a data structure tangibly fixed in a computer
readable memory. Several embodiments of the invention are discussed below.
[025] Although embodiments are described herein in reference to locomotives
and other rail vehicles, the invention is not limited as such, and is applicable to other
types of vehicles. For example, exemplary embodiments of the invention may be
used in other vehicles, such as, but not limited to, other off-highway vehicles, over
road transportation systems, etc. Additionally, unless specifically referred to as a
single or individual vehicle, the term vehicle includes vehicle consists, "consist"
referring to a group of vehicles mechanically linked to travel together along a route.
[026] With reference to FIGS. 1 and 2, an embodiment of the invention relates to
a method 10 for controlling a vehicle 12 (in this case a consist including a first unit 14
and a second unit 16) based on a determined braking capability of a braking system
18 of the vehicle. Certain vehicles (e.g., rail vehicles) may include more than one
braking mechanism or sub-system (e.g., an air brake sub-system, a dynamic braking
sub-system, and/or a braking system utilized when operating in a distributed power
configuration). Thus, the use of the term "braking system" may relate to an individual
braking mechanism or sub-system in a vehicle or vehicle consist, or plural braking
mechanisms or sub-systems collectively. The method 10 comprises determining a
braking capability of the braking system 18 of the vehicle 12, at step 20, and
modifying application (e.g., enforcement) of at least one mission parameter 22 by a
control system 24 of the vehicle based on the determined braking capability, at step
26. As noted above, the mission parameter 22 comprises a quantity or factor, relating
to the vehicle or a mission of the vehicle, which is used by the control system 24 as a
basis for controlling the vehicle. Examples of mission parameters include maximum
allowed speeds of a vehicle, safety thresholds relative to maximum allowed speeds,
designated braking profiles for a vehicle (e.g., which specify how a vehicle is to be
braked in certain designated situations), factors that are used by an energy
management system to create a trip or mission plan for a vehicle, and the like.
Modifying application of the mission parameter may include modifying the parameter
and applying the modified parameter the same as the parameter before modification,
and/or applying the parameter in a different way than the parameter would have been
applied previously.
[027] The braking capability may be determined in different manners. With
reference to FIGS. 2 and 3, in one embodiment, the step 20 of determining the braking
capability comprises a step 28 of activating the braking system 18 of the vehicle to
apply a braking force "B" on the vehicle. Activating the braking system 18 may
comprise fully activating all braking mechanisms/sub -systems on the vehicle or
vehicle consist, or fully activating one braking mechanism or sub-system, or fully
activating all those braking mechanisms/sub-systems that can controlled automatically
and/or that can be controlled with reasonably certainty about how the braking system
will affect deceleration of a vehicle when moving and/or that are configured for use in
slowing the vehicle while it is moving. (For example, a manual or other parking
brake of an automobile or other vehicle would typically not be activated for assessing
braking capability, since it is unpredictable in regards to how it would slow a vehicle,
and is neither configured nor intended for slowing a vehicle while it is moving.) In
one embodiment, the vehicle is a rail vehicle, and the step of determining the braking
capability comprises determining a combined braking capability of air brake and
dynamic brake portions of the braking system of the rail vehicle, or only the braking
capability of the air brake portion. The step 20 of determining the braking capability
further comprises, at step 30, concurrently applying a level of tractive effort "TE" of
the vehicle sufficient to overcome the braking force. (B and TE are directionally
shown in FIG. 2 with the assumption that the vehicle is configured to move from left
to right.) The braking capability is determined based on the level of tractive effort.
[028] To elaborate, braking capability is a level of force available to be applied
by the braking system 18 for slowing the vehicle. Tractive effort is the pulling or
pushing force exerted by a vehicle to move a load (itself and other mass, if any). At
the point where the tractive effort overcomes the braking force, this means that the
tractive effort is equal to, or just slightly higher than, the braking force. Thus, a
measure of tractive effort at this point is indicative of braking capability. As should
be appreciated, tractive effort does not necessarily refer to the maximum possible
tractive effort of a vehicle (which is a function of vehicle configuration), but rather to
the level of tractive effort currently being expended by the vehicle. It is assumed that
the maximum possible tractive effort is greater than the maximum braking capability
of the braking system. Tractive effort may be measured using force sensors (e.g., in a
rail vehicle, drawbar or coupling strain sensors), and/or by leveraging information
available to the vehicle traction system. For example, in the case of a diesel electric
locomotive (engine runs an alternator for generating electricity to power traction
motors), tractive effort may be derived based on the throttle level or other control
inputs, which map to the energy demanded of the traction system and the tractive
effort, and/or on a per-axle basis based on the torque produced by each motor
(determinable based on the electrical signals being applied to the motor and/or on
sensor outputs of motor operation) and knowledge of wheel diameter and gear ratio
(of gears between the motor and axle).
[029] In embodiments of the vehicle control method, the braking system is
activated (as at step 28) when the vehicle is stopped, and the level of tractive effort is
gauged (as part of step 30) by identifying when the vehicle starts to move despite the
braking force, for determining the braking capability. One example of activating the
braking system when the vehicle is stopped is to do so at or before a time of departure
of the vehicle. In other embodiments, the braking system is activated when the
vehicle is moving. This may be done at times when braking is not needed to slow the
vehicle for vehicle control purposes as part of its mission, or when the braking is
needed to slow the vehicle for vehicle control purposes. The tractive effort of the
vehicle is increased to maintain speed despite the braking, and the braking capability
is determined based on the difference between the increased tractive effort and the
level of tractive effort before braking (before the tractive effort was increased).
[030] As noted above, embodiments of a control method include a step of
modifying application of at least one mission parameter 22 by a control system 24 of
the vehicle based on the determined braking capability. As further noted, modifying
application of the mission parameter may include modifying the parameter and
applying the modified parameter the same as the parameter before modification,
and/or applying the parameter in a different way than the parameter would have been
applied previously. As one example, the control system 24 may comprise an energy
management system. One such energy management system is described in U.S.
Patent Publication No. 2007/0219680, dated September 20, 2007, incorporated by
reference herein in its entirety. The energy management system creates a trip or
mission plan for automatically controlling a vehicle along a route or for coaching an
operator to control the vehicle along the route, based on mission parameters that may
include information about the vehicle, information about the route of the vehicle,
information about business objects of the mission (start point, end point, businessbased
time constraints, goal of mission plan), and/or physics or other models of how
the vehicle operates. The goal of such mission plans may be to save fuel (versus
controlling the vehicle in some other manner than the mission plan), or to arrive at a
designated stop point at a given time (e.g., as fast as possible). The energy
management system may be configured, as part of the physics or other models of
vehicle operation, to create a mission plan based on an assumed braking capability of
the vehicle. According to one aspect of the invention, instead of generating a trip or
mission plan based on an assumed braking capability, the energy management system
would receive information of the determined braking capability of the vehicle (i.e., an
indication of actually how effective the braking system is in operation of the vehicle)
and generate the trip or mission plan based on the determined braking capability.
Thus, the mission parameter would be a vehicle braking information used by the
energy management system to generate trip or mission plans, and the step of
modifying application of the vehicle braking information would comprise using the
determined braking capability instead of an assumed or default braking capability to
generate the mission plan. Put another way, the step of modifying application of the
at least one mission parameter may comprise modifying a mission plan that is
generated on board the vehicle for controlling the vehicle during a mission of the
vehicle.
[031] As another example, the step of modifying application of the at least one
mission parameter based on the determined braking capability may comprise
modifying a designated speed and/or time of the mission, as part of a mission or trip
plan or otherwise. For example, if the vehicle is designated to travel at a first speed
under the default of an assumed braking capability, then according to aspects of the
invention, it may be the case that the vehicle is instead designated to travel at a second
speed, which is higher than the first speed, based on the determined (actual) braking
capability. Higher speeds may be allowable because it is known, according to the
determined braking capability, that the vehicle can be stopped according to designated
criteria, e.g., within a designated minimum stopping distance, notwithstanding the
higher speed.
[032] As another example, with reference to FIG. 4, the control system 24 may
comprise a positive train control or other vehicle safety system 32. The vehicle safety
system 32 is configured to automatically control the vehicle 12, such as initiating
braking of the vehicle, responsive to receiving a signal 34 from off-board the vehicle.
(The signal would be generated off board for purposes of braking the vehicle for
safety reasons, such as the vehicle violating a signal, the vehicle exceeding a
designated speed limit, or to account for the unplanned movement of other vehicles,
e.g., an unscheduled stop of another vehicle ahead of the vehicle.) The vehicle safety
system may control braking of the vehicle according to a braking profile, which may
specify an end target speed (e.g., relatively slow speed, or stop), a target location for
stop, how soon the vehicle must commence braking, and/or how steep of a
deceleration rate is allowed. Typically, such braking profiles are relatively
conservative, meaning the vehicle must commence braking well ahead of a target stop
location and/or brake very gradually. According to an aspect of the invention,
however, instead of following a default braking profile, the vehicle safety system
would receive information of the determined braking capability of the vehicle, and
brake the vehicle based on the determined braking capability (while still meeting any
set/"hard" constraints). This might allow the vehicle to be braked later than it would
have been braked based on the default braking profile, or at a steeper deceleration rate
(i.e., braked harder), thus providing time for the safety situation to possibly be
resolved without having to slow the vehicle, while still allowing the vehicle to be
actually braked to meet the set/hard safety constraints if the safety situation is not
resolved. Thus, the mission parameter would be a default braking profile used by the
vehicle safety system to brake the vehicle under certain designated conditions, and the
step of modifying application of the braking profile would comprise modifying the
default braking profile, for use in braking the vehicle, based on the determined
braking capability (i.e., using a modified braking profile instead of a default braking
profile). The modified braking profile might be configured for a less conservative
braking strategy (e.g., steeper deceleration rates, and/or commencing braking later)
relative to the default braking profile. One example is shown in FIG. 5, which
illustrates a relatively more conservative default braking profile 36 for braking to a
stop point "P," versus a relatively less conservative modified braking profile 38.
[033] In another embodiment of a control method, with reference to FIG. 6, the
vehicle 12 is controlled according to a speed profile 40 that specifies one or more
maximum allowed speeds 42 of the vehicle as a function of location and/or time.
(The method illustrated in FIG. 6 is one example of modifying application of a speed
enforcement parameter, in this case a safety threshold below a maximum allowed
speed profile.) The mission parameter comprises a designated speed 44 of the vehicle
(speed to which a vehicle is controlled); the designated speed 44 is less than the
maximum allowed speed 42 for a current location and/or time of the vehicle by at
least a safety threshold 46. In other words, the speed profile sets maximum allowed
speeds, but the vehicle is controlled to a speed that is below the maximum allowed
speed, for a given location and/or time, to provide a safety margin (the safety
threshold 46) to reduce the likelihood of the vehicle exceeding the maximum allowed
speed. According to the method, the designated speed 44 is modified, based on the
determined braking capability, to a vehicle speed 48 within the safety threshold.
Thus, due to having knowledge of the braking capability, the vehicle is controlled to a
speed, for a given location and/or time, that is at or below the maximum allowed
speed but above the safety threshold speed 46. (In other words, the magnitude of the
safety threshold 46 is reduced based on the determined braking capability.)
[034] In another embodiment of the control method, the braking capability is r e
determined, and application of the at least one mission parameter is modified based on
the re-determined braking capability, when (or whenever) vehicle weight or another
vehicle characteristic changes. This is because a change in a vehicle characteristic
may have an effect on braking capability, e.g., lower weight generally means it is
easier to slow the vehicle. For example, with reference to FIGS. 2 and 7, the method
further comprises a step 50 of receiving information 52 indicative of a characteristic
of the vehicle having changed. Responsive to receiving the information, the method
comprises, at step 54, re-determining the braking capability of the braking system of
the vehicle, and, as step 56, modifying application of the at least one mission
parameter by the control system of the vehicle based on the re-determined braking
capability. Characteristics for initiating re-determination of the braking capability
may include, but are not limited to, weight of the vehicle (in the case of a train, such
as if a rail car has been removed at an intermediate stop during a mission), a
mechanical issue is experienced with the vehicle, etc. Any of the approaches
discussed herein may be initiated or otherwise used responsive to a vehicle
characteristic changing.
[035] In embodiments, determining the braking capability additionally or
alternatively comprises determining a stopping distance of the vehicle 12. The
stopping distance may then be used as a basis for controlling the vehicle, e.g., braking
is commenced at or before the vehicle is the stopping distance away from a designated
stop point. A simplified model for determining stopping distance is stopping distance
= (0.5MV )/f, where M is the mass of the vehicle, V is the velocity of the vehicle, and
f is the available braking force, e.g., determined as described herein.
[036] The method of FIG. 3 may be applied outside the context of modifying
application of a mission parameter. For example, with reference to FIG. 8, another
embodiment of a vehicle control method 58 comprises a step 60 of activating a
braking system of a vehicle to apply a braking force on the vehicle. The method
further comprises a step 62 of concurrently applying a level of tractive effort of the
vehicle sufficient to overcome the braking force, and a step 64 of determining a
braking capability of the vehicle based on the level of tractive effort. The method
further comprises a step 66 of controlling the vehicle based on the determined braking
capability. (Other portions of the present description are applicable to the method of
FIG. 8. For example, the braking system may be activated when the vehicle is
stopped, and the level of tractive effort may be gauged by identifying when the
vehicle starts to move despite the braking force.)
[037] With reference to FIG. 9, another embodiment relates to a system 68 for a
vehicle. The system comprises a braking capability module 70 configured to
determine a braking capability of a braking system of the vehicle. The system
additionally comprises a control module 72 operably coupled with the braking
capability module and configured to modify application of a mission parameter by the
control module based on the determined braking capability. One or both of the
braking capability module 70 and/or the control module 72 may be implemented as
part of the control system 24. Additionally, one or both of the braking capability
module 70 and/or the control module 72 may be further configured to carry out one or
more of the other methods described herein.
[038] In another embodiment, with reference to FIG. 10, a method for vehicle
control 74 comprises a step 76 of autonomously determining when a vehicle is
moving along a route having a grade during a mission. (The grade may be a zero
degree grade, a downhill grade, or an uphill grade; autonomously means by a
machine, e.g., automatically.) The method further comprises, at step 78, applying the
braking system of the vehicle while on the grade to test a capability of the braking
system. The brakes may be applied additionally, separately, or independently of any
applications of the braking system for traction/movement control purposes. The
method further comprises, at step 80, modifying enforcement or other application of a
mission parameter by the vehicle based on a result from the test. (The enforcement or
application of the mission parameter may be modified as described herein in regards
to other embodiments.)
[039] In another embodiment of the method of FIG. 10, the braking system is
applied to exceed an amount of braking applied by a control system of the vehicle for
purposes of controlling the vehicle to traverse the grade. Thus, while the vehicle is
traversing the grade, the control system may apply brakes for traction/movement
control purposes, i.e., to slow the vehicle in order to safely traverse the grade.
According to the method, during this time, the brakes are applied more than needed
for the traction/movement control purposes, in order to test the braking capability of
the braking system. In another aspect, the braking system is applied when the vehicle
is traversing the grade, but at a time when the brakes are not being applied for
traction/movement control purposes.
[040] In another embodiment of the method of FIG. 10, the step of determining
when the vehicle is moving along the route comprises autonomously determining
when the vehicle is moving along a downhill grade of the route. The braking system
is applied while the vehicle is on the downhill grade to test the capability of the
braking system. It is possible to determine when the vehicle is traversing the
downhill grade by correlating a current location of the vehicle (e.g., determined via
GPS) with a route database that provides information of characteristics of the route of
the vehicle. (Such route databases are used in many rail applications for energy
management system calculations.)
[041] In another embodiment of the method of FIG. 10, the braking system is
applied to an extent and/or for a duration sufficient to test the capability of the braking
system but not to significantly slow down the vehicle versus a speed of the vehicle
before the braking system was applied. This may be accomplished by testing the
braking system on a downhill grade when the vehicle is not being braked for traction
control/movement purposes. That is, the braking may be matched to (or applied less
than) the accelerating force exerted on the vehicle by gravity on the downhill. Thus,
as the vehicle accelerates due to gravity, the brakes are applied for testing, slowing the
vehicle, but with the net effect being no significant reduction in speed. According to
one aspect, a significant speed reduction is more than 5%. In another aspect, a
significant speed reduction is more than 2%. In another aspect, a significant speed
reduction is more than 1%. (That is, for testing the braking on a downhill grade, the
speed is reduced by no more than 5%, or 2%, or 1%.) The exact level allowed may
depend on the characteristics of the train, the speed range of the train (e.g., higher
speeds allow for a greater percentage decrease, since the train is still going relatively
fast), and/or what is desired, from a business, train operation, and/or energy
management perspective, for a given implementation. For example, a business
decision may be made that testing takes priority over speed reductions, allowing,
therefore, for a 5% max reduction, for example. As another example, an energy
management system may dictate that the speed be reduced by no more than 1%, for
example, to avoid excess fuel usage versus controlling the train according to a trip or
mission plan but without the brake testing.
[042] In another embodiment of the method of FIG. 10, a duration of applying
the braking system to test the capability of the braking system is determined based on
a slope of the downward grade. For example, for a steeper slope, it may be possible
to brake the train harder, for determining braking capability, but for a shorter duration,
versus braking the train on a less steep slope.
[043] FIG. 11 shows an embodiment of a system 82 for a vehicle. The system
comprises a location module 84 configured to identify when a vehicle is moving
along a route having a grade during a mission. The system additionally comprises a
braking capability module 86 configured to command applying a braking system of
the vehicle while on the grade to test a capability of the braking system. The system
additionally comprises a control module 88 configured to modify application of a
mission parameter by the control module based on a result from the test. The location
module 84 may include, or have access to, a GPS module or other geographic position
determination device 90 and/or a route database 92. Alternatively, travel on a grade
may be determined using a tilt sensor or the like.
[044] The system 82 may be further configured to carry out one or more other
methods as described herein. For example, the location module may be configured to
identify when the vehicle is moving along a downhill grade of the route, and the
braking capability module may be configured to command applying the braking
system of the vehicle while on the downhill grade.
[045] The methods of FIGS. 1 and 10, and related systems, may determine
braking capability in ways other than as described in FIG. 3. For example, braking
capability may be determined by fully or otherwise applying the braking system, or
sub-systems of interest, and calculating the braking capability based on a change in
vehicle speed over a given distance, as a function of vehicle mass. A simplified
model is braking force = 0.5M(V1 2-V22)/d, where M is vehicle mass, VI is a starting
velocity of the vehicle, V2 is an ending velocity of the vehicle, and d is the distance
traveled while slowing down from VI to V2 (as determined, for example, using GPS
or wayside markers).
[046] As noted, determining the braking capability of the braking system of the
vehicle may involve determining the overall braking capability (e.g., braking during
movement capability, not factoring in parking brakes or the like), or the braking
capability of one or more sub-systems of the braking system. For example,
determining the braking capability may comprise determining the braking capability
of each braking sub-system of a vehicle at a time of departure of the vehicle.
Determining the braking capability of each braking system of the vehicle may
comprise determining the braking capability at a time each braking system of the
vehicle is applied as needed during a mission. Alternatively, it may comprise testing
the braking capability of the vehicle at a time braking of the vehicle is not required.
The testing may be carried out using a very brief application of at least one braking
sub-system, where the test is so brief so as not to significantly slow the vehicle. The
test may be done at a location where gravity experienced by the rail vehicle, such as
traveling downhill, may further minimize any reduction in speed during the test.
[047] Modifying enforcement or other application of a mission parameter by the
vehicle based on the determined braking capability may comprise modifying a speed
enforcement element (such as, but not limited to, a speed enforcement algorithm), an
element that creates, on board the vehicle, a modified mission plan as the vehicle is
motoring, and/or an element that enforces a desired mission speed and time of
mission. Modifying enforcement or other application may also comprise using
airbrake application timing to include locomotive consist/distributed power (DP)
position wherein braking is different, since braking is applied from both ends of the
rail vehicle as opposed to just one end of the rail vehicle.
[048] As used herein, the term "module" includes a hardware and/or software
system that operates to perform one or more functions. For example, a module may
include a computer processor, controller, or other logic-based device that performs
operations based on instructions stored on a tangible and non-transitory computer
readable storage medium, such as a computer memory. Alternatively or additionally,
a module may include a hard-wired device that performs operations based on hard
wired logic of the device. The module(s) shown in the attached figures may represent
the hardware that operates based on software or hardwired instructions, the software
that directs hardware to perform the operations, or a combination thereof.
[049] The exemplary methods described herein may be implemented as sets of
instructions stored on non-transient electronically readable media, for execution by a
processor (the processor accesses the media and instructions, and performs control
functions based on the contents of the instructions). Each element set forth in the
flowcharts of the drawings may be implemented as a software module specific to
performing the function of the element.
[050] An apparatus, such as a data processing system, including a CPU,
memory, I/O, program storage, a connecting bus, and other appropriate components,
could be programmed or otherwise designed to facilitate the practice of exemplary
embodiments of the method of the invention. Such a system would include
appropriate program means (sets of instructions) for executing the method of the
invention. Also, an article of manufacture, such as a pre-recorded disk, computer
readable media, or other similar computer program product, for use with a data
processing system, could include a storage medium and program means (sets of
instructions) recorded thereon for directing the data processing system to facilitate the
practice of the method of the invention. Such apparatus and articles of manufacture
also fall within the spirit and scope of the invention.
[051] Broadly speaking, a technical effect is to determine a condition of the
braking system of a rail vehicle or other vehicle and to use the condition as a basis for
controlling movement of the vehicle along a route. Exemplary embodiments of the
invention may be described in the general context of computer-executable
instructions, such as program modules, being executed by a device, such as, but not
limited to, a computer, designed to accept data, perform prescribed mathematical
and/or logical operations usually at high speed, where results of such operations may
or may not be displayed. Generally, program modules include routines, programs,
objects, components, data structures, etc., that perform particular tasks or implement
particular abstract data types. For example, the software programs that underlie
exemplary embodiments of the invention can be coded in different programming
languages, for use with different devices, or platforms. It will be appreciated,
however, that the principles that underlie exemplary embodiments of the invention
can be implemented with other types of computer software technologies as well.
[052] Moreover, embodiments of the invention may be practiced with other
computer system configurations, multiprocessor systems, microprocessor-based or
programmable consumer electronics, minicomputers, mainframe computers, and the
like. Exemplary embodiments of the invention may also be practiced in distributed
computing environments where tasks are performed by processing devices located at
different locations on board of a vehicle, that are linked through at least one
communications network. In a distributed computing environment, program modules
may be located in both local and remote computer storage media including memory
storage devices.
[053] It is to be understood that the above description is intended to be
illustrative, and not restrictive. For example, the above-described embodiments
(and/or aspects thereof) may be used in combination with each other. In addition,
many modifications may be made to adapt a particular situation or material to the
teachings of the inventive subject matter without departing from its scope. While the
dimensions and types of materials described herein are intended to define the
parameters of the inventive subject matter, they are by no means limiting and are
exemplary embodiments. Many other embodiments will be apparent to one of
ordinary skill in the art upon reviewing the above description. The scope of the
inventive subject matter should, therefore, be determined with reference to the
appended claims, along with the full scope of equivalents to which such claims are
entitled. In the appended claims, the terms "including" and "in which" are used as the
plain-English equivalents of the respective terms "comprising" and "wherein."
Moreover, in the following claims, the terms "first," "second," and "third," etc. are
used merely as labels, and are not intended to impose numerical requirements on their
objects.
[054] This written description uses examples to disclose several embodiments of
the inventive subject matter, including the best mode, and also to enable one of
ordinary skill in the art to practice the embodiments of inventive subject matter,
including making and using any devices or systems and performing any incorporated
methods. The patentable scope of the inventive subject matter is defined by the
claims, and may include other examples that occur to one of ordinary skill in the art.
Such other examples are intended to be within the scope of the claims if they have
structural elements that do not differ from the literal language of the claims, or if they
include equivalent structural elements with insubstantial differences from the literal
languages of the claims.
[055] The foregoing description of certain embodiments of the present inventive
subject matter will be better understood when read in conjunction with the appended
drawings. To the extent that the figures illustrate diagrams of the functional blocks of
various embodiments, the functional blocks are not necessarily indicative of the
division between hardware circuitry. Thus, for example, one or more of the
functional blocks (for example, controllers or memories) may be implemented in a
single piece of hardware (for example, a general purpose signal processor,
microcontroller, random access memory, hard disk, and the like). Similarly, the
programs may be standalone programs, may be incorporated as subroutines in an
operating system, may be functions in an installed software package, and the like.
The various embodiments are not limited to the arrangements and instrumentality
shown in the drawings.
[056] As used herein, an element or step recited in the singular and proceeded
with the word "a" or "an" should be understood as not excluding plural of said
elements or steps, unless such exclusion is explicitly stated. Furthermore, references
to "one embodiment" of the present invention are not intended to be interpreted as
excluding the existence of additional embodiments that also incorporate the recited
features. Moreover, unless explicitly stated to the contrary, embodiments
"comprising," "comprises," "including," "includes," "having," or "has" an element or
a plurality of elements having a particular property may include additional such
elements not having that property.
WHAT IS CLAIMED IS:
1. A method for vehicle control comprising:
determining a braking capability of a braking system of a vehicle; and
modifying application of at least one mission parameter by a control system of
the vehicle based on the determined braking capability.
2. The method of claim 1, wherein the step of determining the braking capability
comprises:
activating the braking system of the vehicle to apply a braking force on the
vehicle; and
concurrently applying a level of tractive effort of the vehicle sufficient to
overcome the braking force, wherein the braking capability is determined based on
the level of tractive effort.
3. The method of claim 2, wherein the braking system is activated when the
vehicle is stopped, and the level of tractive effort is gauged by identifying when the
vehicle starts to move despite the braking force.
4. The method of claim 2, wherein:
the control system comprises a vehicle safety system configured to control
braking of the vehicle responsive to receiving a signal from off board the vehicle;
the mission parameter comprises a default braking profile of the vehicle safety
system; and
the default braking profile is modified to a modified braking profile based on
the determined braking capability, wherein the modified braking profile is less
conservative than the default braking profile.
5. The method of claim 2, wherein:
the vehicle is controlled according to a speed profile that specifies one or more
maximum allowed speeds of the vehicle as a function of location and/or time;
the mission parameter comprises a designated speed of the vehicle, the
designated speed being less than the maximum allowed speed for a current location
and/or time of the vehicle by at least a safety threshold; and
the designated speed is modified, based on the determined braking capability,
to a vehicle speed within the safety threshold.
6. The method of claim 1, wherein:
the control system comprises a vehicle safety system configured to control
braking of the vehicle responsive to receiving a signal from off board the vehicle;
the mission parameter comprises a default braking profile of the vehicle safety
system; and
the default braking profile is modified to a modified braking profile based on
the determined braking capability, wherein the modified braking profile is less
conservative than the default braking profile.
7. The method of claim 1, wherein:
the vehicle is controlled according to a speed profile that specifies one or more
maximum allowed speeds of the vehicle as a function of location and/or time;
the mission parameter comprises a designated speed of the vehicle, the
designated speed being less than the maximum allowed speed for a current location
and/or time of the vehicle by at least a safety threshold; and
the designated speed is modified, based on the determined braking capability,
to a vehicle speed within the safety threshold.
8. The method of claim 1, further comprising:
receiving information indicative of a characteristic of the vehicle having
changed; and
responsive to receiving the information:
re-determining the braking capability of the braking system of the
vehicle; and
modifying application of the at least one mission parameter by the
control system of the vehicle based on the re-determined braking capability.
9. The method of claim 1, wherein the vehicle is a rail vehicle, and the step of
determining the braking capability comprises determining a combined braking
capability of air brake and dynamic brake portions of the braking system of the rail
vehicle.
10. The method of claim 1, wherein the braking capability is determined at or
before a time of departure of the vehicle.
11. The method of claim 1, wherein the braking capability is determined at a time
the braking system of the vehicle is applied as needed during a mission.
12. The method of claim 1, wherein the step of determining the braking capability
comprises activating the braking system of the vehicle to apply a braking force on the
vehicle at a time when braking of the vehicle is not required for purposes of slowing
the vehicle.
13. The method of claim 1, wherein modifying application of the at least one
mission parameter comprises modifying a speed enforcement parameter, modifying a
mission plan that is generated on board the vehicle for controlling the vehicle during a
mission of the vehicle, and/or modifying a designated speed and/or time of the
mission.
14. The method of claim 1, wherein determining the braking capability comprises
determining a stopping distance of the vehicle.
15. A method for vehicle control comprising:
activating a braking system of a vehicle to apply a braking force on the
vehicle;
concurrently applying a level of tractive effort of the vehicle sufficient to
overcome the braking force;
determining a braking capability of the vehicle based on the level of tractive
effort; and
controlling the vehicle based on the determined braking capability.
16. The method of claim 15, wherein the braking system is activated when the
vehicle is stopped, and the level of tractive effort is gauged by identifying when the
vehicle starts to move despite the braking force.
17. A method for vehicle control comprising:
autonomously determining when a vehicle is moving along a route having a
grade during a mission;
applying the braking system of the vehicle while on the grade to test a
capability of the braking system; and
modifying application of a mission parameter by the vehicle based on a result
from the test.
18. The method of claim 17, wherein applying the braking system comprises
exceeding an amount of braking applied by a control system of the vehicle for
purposes of controlling the vehicle to traverse the grade.
19. The method of claim 17, wherein:
the step of determining when the vehicle is moving along the route comprises
autonomously determining when the vehicle is moving along a downhill grade of the
route; and
the braking system is applied while the vehicle is on the downhill grade to test
the capability of the braking system.
20. The method of claim 19, wherein the braking system is applied to an extent
and/or for a duration sufficient to test the capability of the braking system but not to
significantly slow down the vehicle versus a speed of the vehicle before the braking
system was applied.
2 1. The method of claim 19, wherein a duration of applying the braking system to
test the capability of the braking system is determined based on a slope of the
downward grade.
22. A system for a vehicle, comprising:
a braking capability module configured to determine a braking capability of a
braking system of the vehicle; and
a control module operably coupled with the braking capability module and
configured to modify application of a mission parameter by the control module based
on the determined braking capability.
23. A system for a vehicle, comprising:
a location module configured to identify when a vehicle is moving along a
route having a grade during a mission;
a braking capability module configured to command applying a braking
system of the vehicle while on the grade to test a capability of the braking system; and
a control module configured to modify application of a mission parameter by
the control module based on a result from the test.
24. The system of claim 23, wherein:
the location module is configured to identify when the vehicle is moving along
a downhill grade of the route; and
the braking capability module is configured to command applying the braking
system of the vehicle while on the downhill grade.