Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: Remote Control System for Locomotives
FIELD OF THE INVENTION
The present invention relates to an electronic
system for remotely controlling locomotives in a train.
The system is particularly suitable for use in transfer
assignments as well as switching yard assignments.
BACKGROUND OF THE INVENTION
Economic constraints have led railway companies to
develop portable units allowing a ground-based operator
to remotely control a locomotive in a switching yard.
The module is essentially a transmitter communicating
with a trail controller on the locomotive by way of a
radio link. Typically, the operator carries this module
and can perform duties such as coupling, and uncoupling
cars while remaining in control of the locomotive
movement at all times. This allows for placing the point
of control at the point of movement thereby potentially
enhancing safety, accuracy and efficiency.
Remote locomotive controllers currently used in the
industry are relatively simple devices that enable the
operator to manually regulate the throttle and brake in
order to accelerate, decelerate and/or maintain a desired
speed. The operator is required to judge the speed of
the locomotive and modulate the throttle and/or brake
levers to control the movement of the locomotive.
Therefore, the operator must possess a good understanding
of the track dynamics, the braking characteristics of the
train, etc. to remotely operate the locomotive in a safe
manner.
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In several situations where locomotives and trains are
used, there are both forward and backward movements of the
train. In certain circumstances, the locomotive is pulling
the train. In instances where the train is going in the
opposite direction, the locomotive is pushing the train. In
these situations, the remote locomotive controllers also
enable the operator to manually regulate the direction of
movement of the locomotive. Regulations define a limited
distance during which the locomotive may push the train
given that, during the time that the locomotive is pushing
the train, there is no conductor at the front end of the
train. A common solution to this problem is to have a
caboose at the other end of the train where another
conductor stands and observes where the train is going.
Such a solution requires a duplication of the amount of
personnel that is required to operate a train, thereby
incurring additional costs in the form of an extra crew
person. However, these extra crewmembers are required for
security purposes.
Accordingly, there exists a need in the industry to
provide a system for remotely controlling a locomotive
that alleviates at least some of the problems associated
with prior art devices.
SUMMARY OF THE INVENTION
In accordance with a broad aspect, the present
invention provides a system of controller modules
allowing to remotely control a train having a first
locomotive and a second locomotive separated from one
another by at least one car. The system of controller
modules comprises a first controller module associated to
the first locomotive and a second controller module
associated to the second locomotive. One of the
controller modules has a lead operational status and the
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other of the controller modules has a trail operational
status. The controller module having the lead
operational status includes an input for receiving a
master control signal for signaling the train to move in
a desired direction. The controller module having the
lead operational status also includes an output to
release in response to the master control signal a first
local command signal operative to cause displacement of
the locomotive associated with the controller module
l0 having the lead operational status. The controller
module having the trail operational status includes an
output. The controller module having a lead operational
status is further operative to transmit to the controller
module having a trail operational status a local control
signal derived from the master control signal. The
controller module having the trail operational status is
responsive to the local control signal to generate a
second command signal operative to cause displacement of
the locomotive associated to the controller module having
a trail operational status. The movement of the
locomotive associated with the controller module having
the lead operational status and the movement of the
locomotive associated with the controller module having
the trail operational status being such as to cause
displacement of the train in the desired direction.
In a specific example of implementation, the first
controller module is operative to acquire either one of a
lead operational status and a trail operational status
and the second controller module is operative to acquire
either one of a lead operational status and a trail
operational status. When one of said controller modules
acquires the lead operational status the other of the
controller modules acquires the trail operational status.
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In a specific non-limiting example of
implementation, the master control signal is an RF (a
radio frequency) signal issued from a remote module. The
master control signal carries information about the
direction in which the train is to move and also
information about the desired throttle and/or speed of
the train.
l0 The controller module having the lead operational
status includes at the input a receiver unit that senses
the master control signal, demodulates the master control
signal to extract the information relating to the
direction of movement and throttle, brake and/or speed of
the train and passes this information to a processing
unit. The processing unit generates the first local
command signal that conveys a throttle setting
information and a brake setting information. The first
local command signal is applied to the locomotive
associated to the controller module having the lead
operational status such as to set the throttle at the
desired setting and the brake at the desired setting in
order to achieve the desired speed in the desired
direction.
The processing unit also generates throttle setting
information and brake setting information for the
locomotive associated with the controller module having
the trail operational status. Typically, the throttle
setting information for the second locomotive is such as
to produce a displacement of the locomotive associated to
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the controller module having the trail operational status
having the same velocity and direction as the
displacement of the locomotive associated with the
controller module having the lead operational status. As
5 for the brake setting information, it is essentially
identical to the brake setting information for the first
locomotive.
Alternatively, other control strategies may be
implemented. For instance, differences are introduced
between the throttle setting information and the brake
setting information computed for the locomotive
associated to the controller module having the lead
operational status and the throttle setting information
and the brake setting information computed for the
locomotive associated to the controller module having the
trail operational status. This may be desirable to
better control the movement of the train and reduce train
action for example. A specific example is a situation
where the track dynamics, train length and/or weight may
be such that a totally synchronized movement between the
two locomotives is not desired.
The controller module having the lead operational
status sends to the controller module having the trail
operational status over an RF link, a local control
signal that contains the throttle setting information and
the brake setting information for the locomotive
associated to the controller module having the trail
operational status. The controller module having the
trail operational status includes an input coupled to the
receiver unit to establish the RF link with the
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controller module having the lead operational status.
The receiver unit demodulates the local control signal
and passes the extracted information to a processing unit
that generates the second command signal for application
to the locomotive associated with the controller module
having the trail operational status such as to set the
throttle and the brake of that locomotive.
It will be noted that under this specific non-
limiting example of implementation, the receiver unit of
the controller module having the lead operational status
is used to communicate with the remote module (for
receiving the master control signal) and also to
establish the RF link with the controller module having
the trail operational status. Accordingly, the receiver
unit can communicate over at least two (and possibly
more) separate communication links.
In the specific non-limiting example of
implementation described above, the controller modules
are operative to switch roles, in other words the lead
operational status can be transferred from the first
controller module to the second controller module. This
is desirable in circumstances where the direction of
movement of the train is changed. In particular, an
advantageous practice is to assign the lead operational
status to the locomotive that is pulling the train.
Accordingly, when the controller module that currently
holds the lead operational status receives a master
control signal which indicates to relinquish its lead
operational status, the controller module that currently
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holds the lead operational status relinquishes the lead
operational status to the other controller module and
acquires the trail operational status. The exchange of
status is effected by an exchange of commands over the RF
link between the two controller modules.
In a specific example, when the first controller module
has the lead operational status and the second controller
module has the trail operational status, the first
controller module is operative to relinquish the lead
operational status and acquire the trail operational
status. Similarly, the second controller module is
operative to relinquish the trail operational status and
to acquire the lead operational status. When the second
controller module acquires the lead operational status
and when the first controller module acquires the trail
operational status, the second controller module is
operative to receive the master control signal and is
operative to transmit to the first controller module a
local control signal derived from the master control
signal.
In accordance with another broad aspect, the invention
provides a system for remotely controlling a train having
a first locomotive and a second locomotive separated from
one another by at least one car. The system comprises a
first controller module associated to the first
locomotive, a second controller module associated to the
second locomotive and a remote control module. Each of
the modules has a machine readable storage medium for
storage of an identifier, the identifier allowing to
uniquely distinguish the modules from one another. Each
module is operative to transmit messages to another one
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of the modules over a non-proximity communication link.
A message sent by any one of the modules over the non-
proximity communication link is sensed by each of the
other modules. Each message includes an address portion
for holding the identifier of the module to which the
message is directed. Each message may also include an
identifier associated to the module from which the
message was sent. The remote control module and the
first controller module are operative to establish a
first proximity data exchange transaction. During the
first proximity data exchange transaction, the remote
control module acquires and stores in the machine
readable storage medium of the remote control module the
identifier of the first controller module. Similarly,
the first controller module acquires and stores in the
machine readable storage medium of the first controller
module the identifier of the remote control module. The
first proximity data exchange transaction excludes the
second controller module.
The remote control module and the second controller
module are operative to establish a second proximity data
exchange transaction. During the second proximity data
exchange transaction, the remote control module acquires
and stores in the machine readable storage medium of the
remote control module the identifier of the second
controller module. Similarly, the second controller
module acquires and stores in the machine readable
storage medium of the second controller module the
identifier of the remote control module and the
identifier of the first controller module. The second
proximity data exchange transaction excludes the first
controller module.
The first controller module and the second controller
module are operative to establish a third data exchange
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transaction over the non-proximity communication link
such that the first controller module acquires and stores
in the machine readable storage medium of the first
controller module the identifier of the second controller
module.
In a specific example of implementation, the first
controller module is operative to acquire either one of a
lead operational status and a trail operational status
l0 and the second controller module is operative to acquire
either one of a lead operational status and a trail
operational status. When one of said controller modules
acquires the lead operational status, the other of the
controller modules acquires the trail operational status.
The remote control module generates a master control
signal for signaling the train to move in a desired
direction. The controller module having the lead
operational status includes an input for receiving the
master control signal and an output to generate in
response to the master control signal a first local
command signal operative to cause displacement of the
locomotive with which it is associated. The controller
module having the lead operational status is further
operative to transmit to the controller module having the
trail operational status a local control signal derived
from the master control signal. The controller module
having the trail operational status has an output and it
is responsive to the local control signal to generate a
second command signal operative to cause displacement of
the second locomotive such as to cause displacement of
the train in the desired direction.
In a specific example of implementation, the non-
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proximity communication link is a radio frequency (RF)
link, the first and second proximity data exchange
transactions are effected over respective infra red (IR)
links. Alternatively, first and second proximity data
5 exchange transactions are effected over links selected
from the set consisting of an infra red link, a coaxial
cable link, a wire link and an optical cable link.
For the purposes of this specification, the
10 expression "proximity data exchange transaction" is used
to designate a transaction over a communication link
where the participants of the transaction receive the
messages that are transmitted over the communication
link. Examples of such communication links include an
infra red link, a coaxial cable link, a wire link and an
optical cable link.
For the purposes of this specification, the
expression "non-proximity communication link" is used to
designate a transaction over a communication link where
components other that the participants of the transaction
receive the messages that are transmitted over the
communication link. Examples of such communication links
include radio frequency links.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a very general illustration of a train that
includes two locomotives separated by two cars;
Figure 2 is a functional block diagram of a controller
module of the remote control system for a locomotive in
accordance with a non-limiting example of implementation
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of the present invention;
Figure 3 is a functional block diagram of the remote
control module of the remote control system for a
locomotive in accordance with a non-limiting example of
implementation of the present invention;
Figure 4 is a block diagram of the processing unit of the
controller module illustrated in figure 2;
Figures 5a and 5b depict flowcharts illustrating the
operation of the remote control system for a locomotive
according to a non-limiting example of implementation of
the present invention;
Figures 6a, 6b, 6c and 6d depict functional block
diagrams of a system for remotely controlling a train in
accordance with an alternative aspect of the invention.
DETAILED DESCRIPTION
Figure 1 illustrates schematically a train
configuration of the type that could be used
advantageously in connection with an embodiment of the
invention. The train configuration includes from left to
right a first locomotive 10, a first car 12, a second car
14 and a second locomotive 16. For the purposes of the
present invention a number of variations of the train
configuration shown in figure 1 can be considered. For
example it is not essential that the locomotives 10, 16
be located at the respective ends of the train.
Possibilities where the ends of the train are formed by
cars instead of locomotives are within the ambit of this
invention. Also, it is not essential that the
locomotives 10, 16 be separated by two cars. It can be
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envisaged to place between the locomotives 10, 16 more or
less than two cars without departing from the spirit of
the invention.
Under one possible form of implementation, the
present invention provides a novel remote control system
for the train configuration illustrated in figure 1. The
remote control system includes three main components
namely a remote control module and two controller
modules. The remote control module is the device with
which the operator conveys commands to the train. In a
specific example of implementation, the remote control
module includes a transmitter unit operative to send
signals. Alternatively, the remote control module
includes a transceiver unit operative to send and receive
signals. The controller modules are mounted in the
respective locomotives 10, 16 and they interface with
existing throttle/brake actuators and other controls and
sensors on the locomotive such as to control the
locomotive in response to commands issued by the remote
control module.
The physical layout of the remote control module is
not illustrated in the drawings because it can greatly
vary without departing from the spirit of the invention.
The remote control module can be in the form of a
portable module comprising a housing that encloses the
electronic circuitry and a battery supplying electrical
power to operate the remote control module. A plurality
of manually operable levers and switches project outside
the housing and are provided to dial-in train speed,
brake and other possible settings. For additional
specific information on this topic and for general
information on remote locomotive control systems the
reader is invited to consult the U.S. patents 5,511,749
and 5,685,507 granted to CANAC International Inc. and the
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U.S. patent 4,582,280 assigned to the Harris Corp. The
contents of these documents are incorporated herein by
reference. Alternatively, the remote control module can
be in the form of a console fixed in either one of the
locomotives 10, 16.
Figure 3 provides a functional block diagram of the
remote control module that is designated by the reference
numeral 24. The remote control module 24 includes three
l0 main units or blocks namely, the operator control panel
30, a processing unit 28 and a communication unit 26. As
briefly mentioned above, the operator control panel 30
encompasses the various manually operable levers and
switches designed to be selectively actuated by the
operator in order to dial-in train speed, throttle, brake
and other possible settings. The operator control panel
30 generates electrical signals that are directed to the
processing unit 28. The structure of the processing unit
28 will be described in greater detail later in this
specification. For the moment, suffice it to say that
the processing unit 28 receives the raw electrical
signals from the operator control panel 30 and generates
a digital train status word that reflects the desired
functional status of the train. In other words, the
digital train status expresses in what direction the
train should be moving, at what speed, whether the
headlights on the locomotive should be on, whether the
horn should be activated, etc. Optionally, the digital
train status may express what throttle/brake should be
applied instead of or in addition to a desired speed
indicator. The digital train status word is part of a
packet of bits arranged according to a certain format.
Various possible formats can be considered without
departing from the spirit of the invention. In one
specific example, the format includes a header portion, a
user data portion and an error detection/correction
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portion. The header portion includes an address that
uniquely identifies the controller module to whom the
packet is destined. The user data portion includes the
digital train status word data. Finally the error
detection/correction portion includes data allowing to
detect and possibly correct transmission errors.
Optionally, the error detection/correction includes a
data element indicative of the address of the sender.
Examples of error detection/correction strategies include
l0 data parity, cyclic redundancy check (CRC), check sum,
among other possibilities.
The packet of bits generated by the processing unit
28 is passed to the communication unit 26 that includes a
transmitter unit. The transmitter unit handles outgoing
signals. Optionally, the communication unit 26 includes
a receiver unit handling incoming signals. The
transmitter unit modulates the packet to produce an RF
signal. Frequency shift keying (FSK) is a suitable
modulation technique. The RF signal transmitted by the
remote control module 24 forms a master control signal.
The RF master control signal issued by the remote
control module 24 is received by a controller module 18
illustrated in figure 2. The remote control system
includes two controller modules 18, one mounted on each
locomotive 10, 16. Under the example of implementation
described here the controller modules 18 are identical,
accordingly, only one will be described with the
understanding that the structure and operation of the
other controller module 18 are identical.
The controller module 18 includes a communication
unit 20 that in general is very similar to the
communication unit 26 described earlier. In particular,
the communication unit 20 includes a transmitter unit and
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a receiver unit. The controller module 18 also includes
a processing unit 22 that is linked to the communication
unit 20. The function of the receiver unit of the
communication unit 20 is to demodulate the RF master
5 control signal and to extract header information and the
train status word data that are passed to the processing
unit 22. The structure of the processing unit 22 is
illustrated in figure 4. Generally stated, the
processing unit 22 is a computing device including a
10 central processing unit (CPU) 34 that is connected
through a data bus with a memory 36. Typically, the
memory 36 will comprise a non-volatile portion designed
to retain data without loss even when the electrical
power is discontinued. The memory 36 also includes a
15 random access memory portion divided into two segments
one for holding the instructions of the program element
that are executed by the CPU 34 and another one for
holding data on which the program element executed by the
CPU 34 operates. The processing unit 22 also includes an
input/output (I/O) interface 32 of a conventional
construction that allows the processing unit 22 to
exchange signals with the external world.
It should be noted that the structure of the
processing unit 28 is very similar to the structure of
the processing unit 22 as described in connection with
figure 4.
The controller module 18 includes an input/output 23
that is used for exchanging signals with the locomotive
in which the controller module 18 is installed. In
particular, the input/output 23 is the port through which
the controller module 18 issues a local command signal to
cause the locomotive to move in a certain direction and
at a certain speed. More specifically, the local command
signal includes a throttle setting information, direction
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of travel, brake setting information etc. Also, the
controller module 18 receives through the input/output 23
signals from sensors in the locomotive that provide real-
time information on the actual speed, direction of
movement and alarms. The processing unit 22 receives the
signals from the locomotive and interprets them by using
a suitable algorithm in order to adjust the local command
signal such as to maintain the direction of travel and
speed or throttle/brake setting specified in the master
l0 control signal from the remote control module 24. The
person skilled in the art will readily appreciate that
the controller module 18 may include additional
input/output ports for receiving a master control signal
without detracting from the spirit of the invention.
Most locomotive manufacturers will install on the
diesel/electric engine as original equipment a series of
actuators that control the fuel injection, power contacts
and brakes among others, hence the tractive power that
the locomotive develops. This feature permits coupling
several locomotives under the control of one driver. By
electrically and pneumatically interconnecting the
actuators of all the locomotives, the throttle commands
the driver issues in the cab of the lead engine are
duplicated in all the trail locomotives. The locomotive
remote control system in accordance with the invention
makes use of the existing throttle/brake actuators in
order to control power. This feature is described in
greater detail in the U.S. patent 5,685,507 mentioned
earlier in this specification.
The operation of the remote control system will now
be described in greater detail with reference to the
flowcharts appearing in figures 5a and 5b. The process
starts at step 38 in figure 5a. As described earlier,
the operator sets the various controls on the control
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panel 30 as desired and the remote control module 24
issues the master control signal. As discussed earlier,
the master control signal includes an address portion
that uniquely identifies the controller module 18 to whom
the master control signal is destined. In a specific
example, the various controller modules are assigned
respective addresses that are hardwired and that cannot
be easily changed. This avoids a situation where two
controller modules may be assigned by mistake the same
l0 address which may create a hazardous condition if both
controller modules come within the communication range of
the remote control module 24. It is to be noted however
that other methods of assigning addresses may be used
such as storing the address on a programmable memory
(ROM, PROM, EPROM and so on) without detracting from the
spirit of the invention.
At step 40, the controller module 18 receives the
master control signal. Assume for the sake of this
example that the controller module 18 to whom the master
control signal is addressed is installed in the
locomotive 10. Note that the controller module 18 that
is installed in the locomotive 16 will also receive the
signal, however it will ignore it since the address
portion in the signal will not match the local address.
The controller module 18 in the locomotive 10 processes
the master control signal and extracts the instructions
contained therein.
At step 46, the controller module 18 sends a signal
to the remote control module acknowledging reception of
the master control signal. Optionally, the remote
control module may, upon reception of the acknowledgment
signal visually indicate to the operator that the
controller module 18 in the locomotive 10 has confirmed
reception of the command. It is to be noted that step 46
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is essentially a method of confirming the reception of an
instruction and may be omitted without detracting from
the spirit of the invention.
At step 48, in a second form of implementation where
the master control signal includes a desired speed, the
processing unit 22 will compute appropriate throttle and
brake settings and generate a local command signal that,
as described earlier, includes a throttle setting
information and brake setting information among others.
The local command signal is issued through the
input/output 23 and applied to the locomotive controls as
briefly described earlier.
At step 48, in a second form of implementation where
the master control signal includes a throttle and brake
setting, the processing unit 22 will generate a local
command signal that, as described earlier, includes a
throttle setting information and a brake setting
information among others. The local command signal is
issued through the input/output 23 and applied to the
locomotive controls as briefly described earlier.
The processing unit 22 will also derive a throttle
setting information and a brake setting information for
the other locomotive (locomotive 16). In a specific
example of implementation, the brake settings for both
locomotives 10, 16 are identical. The throttle settings
for the locomotives 10, 16 are also essentially
identical. Alternatively, the processing unit 22 can
compute the throttle settings and brake settings for the
locomotives 10, 16 such as to introduce delays in
application of the commands between the locomotives 10,
16 or any other differences.
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At step 50, the processing unit 22 inserts the
throttle setting information and the brake setting
information for the locomotive 16 into a packet and
transmits this packet over an RF link between the two
controller modules 18. The RF link is established
between the communication units 20 of the controller
modules 18. It is preferred that the inter controller
module communication be effected over a different
communication channel than the communication between a
l0 controller module 18 and the remote control module 24.
Each channel may be assigned a different frequency band.
Alternatively, the same frequency band can be used but
the channels are multiplexed by using a time division
multiplexing and code division multiplexing, among
others. Yet another possibility is to use a single
communication channel, and provide in each data packet
sent a flag that indicates whether the packet is for
inter controller module communication or for
communication between a controller module 18 and the
remote control module 24. Yet another possibility is to
use a single communication channel, and provide in each
data packet sent an address that indicates to whom the
packet is directed.
At step 50, the controller module 18 in the
locomotive 10 sends to the controller module 18 in the
locomotive 16 the local control signal. The data packet
in the local control signal includes in the header
portion the address of the controller module 18 in the
locomotive 16 to ensure that this command will not be
received by any other entity. At step 54 the controller
module 18 in the locomotive 16 receives the local control
signal. The controller module 18 in the locomotive 16
acts as a trail and simply implements the throttle
setting and the brake setting (among other possible
settings) computed by the controller module 18 in the
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locomotive 10. The implementation is materialized by the
generation of the local command signal that is applied to
the controls of the locomotive 16.
5 As a result of the above-described process, the
train is caused to move in the desired direction and the
desired throttle/brake setting is applied. If any change
is necessary, the operator alters the settings at the
remote control module 24 and the above-described process
l0 is repeated.
As a variant, a master control signal is transmitted
from the remote control module to the lead controller
module at every control cycle. If a master control
15 signal is not received within a certain number of control
cycles, the lead controller module assumes that an error
has occurred and the train is stopped. The control cycle
is typically several times per second but may vary
depending on the train on which the system is mounted.
In another example of a typical interaction, the
remote control module 24 generates a master control
signal indicative of a switch in the lead operational
status. This interaction is depicted in figure 5b. At
step 58, the controller module having the lead
operational status receives the master control signal
indicative of a switch in the lead operational status.
At step 60, the controller module 18 in the locomotive 10
having the lead operational status relinquishes the lead
operational status to the controller module 18 in the
locomotive 16 having the trail operational status. The
status of a controller module 18, whether lead or trail
can be identified by the value of a flag in the memory 36
of the processing unit 22. For instance, if the flag is
set this means that the controller module 18 holds the
lead operational status. Otherwise, the controller
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module holds the trail operational status. A status
switch is effected by exchanging messages between the
controller modules 18 over the RF link. In particular,
as indicated at step 60, the controller module 18 in the
locomotive 10 generates and sends over the RF link a
command to the controller module 18 in the locomotive 16
to set its status flag (acquire lead operational status).
At step 62 the controller module 18 in the locomotive 16
sends an acknowledgment to the controller module 18 in
the locomotive 10 that confirms the acquisition of the
lead operational status. At this point, the controller
module 18 in the locomotive 10 clears its status flag
such as to acquire the trail operational status.
Optionally, at step 64 the controller module 18 in
the locomotive 16 sends a control message to the remote
control module 24 to indicate that it has acquired the
lead operational status. In response to this control
message the remote control module 24 will replace in a
register implemented in the processing unit 28 the
address of the controller module 18 in the locomotive 10
by the address of the controller module 18 in the
locomotive 16. Accordingly, any further communication
originating from the remote control module 24 will be
directed to the controller module 18 in the locomotive
16. Alternatively, the address of the controller module
18 in the locomotive 10 may be replaced by the address of
the controller module 18 in the locomotive 16 prior to
the remote control module sending the master control
signal indicative of a status switch. In this
alternative example, step 64 may be omitted.
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As a variant, the remote control module 24 initiates
a switch in the lead operational status by redirecting
the transmission of the master control signal from the
current lead controller module to the current trail
controller module. This interaction is depicted in
figure 5c. At step 102, the controller module having the
trail operational status receives the master control
signal. At step 104, the current trail controller module
sends a message over the RF link to the current lead
controller module indicative of a switch in lead
operational status. A step 106, the current lead
controller module, no longer receiving message from the
remote control module and receiving the message sent at
step 104, relinquishes the lead operational status and
acquires the trail operational status. At step 108, the
original trail controller module acquires the lead
operational status. Preferably, during the status switch
process, the train on which are mounted the first
controller module and the second controller module is
stationary.
As described above, the controller modules 18 and
the remote control module 24 communicate with one another
through radio frequency links by placing in a header
portion of messages data elements indicative of
addresses. These addresses, also referred to as
identifiers, allow to uniquely identify each of the
components of the communication system. The address of a
component is communicated to the other component during
an initialization phase. The system initialization will
now be described with reference to figures 6a, 6b, 6c and
6d.
The locomotive control system considered in this
CA 02313918 2000-07-14
23
specific example is a remote control system that
comprises three components, namely: a remote control
module 604, a first controller module 600, and a second
controller module 602. In figure 6a, the components are
shown prior to any address exchange. Each component is
associated to a respective address and stores this
address in a memory location. For instance, the first
controller module 600 is associated to ID#l, the second
controller module 602 to ID #2 and the remote control
module 604 to ID REMOTE. ID#l, ID#2 and ID REMOTE are
alphanumeric strings allowing to distinguish the various
components.
In figure 6b, the remote control module 604
establishes a first proximity data exchange transaction
with the first controller module 600 allowing the first
controller module 600 to received the address of the remote
control module 604 (ID REMOTE) and for the remote control
module 604 to receive the address of the first controller
2o module 600 (ID #1). At the end of the transaction, the
remote control module 604 and the first controller module
600 store ID REMOTE and ID#1. In a specific example of
implementation, the first proximity data exchange
transaction is effected over an infrared (IR) link.
Alternative, the first proximity data exchange transaction
is effected over a link selected from the set consisting of
an infra red link, a coaxial cable link, a wire link and an
optical cable link.
In figure 6c, the remote control module 604
establishes a second proximity data exchange transaction
CA 02313918 2000-07-14
24
with the second controller module 602 allowing the second
controller module to receive the address of the remote
control module 604 (ID REMOTE), the address of the first
controller module 600 (ID#1) and for the remote control
module 604 to received the address of the second controller
module 602(ID #2). At the end of the transaction, the
remote control module 604 and the second controller module
602 store ID REMOTE, ID#1 and ID#2. In a specific example
of implementation, the second proximity data exchange
transaction is effected over an infrared (IR) link.
Alternatively, the second proximity data exchange
transaction is effected over a link selected from the set
consisting of an infra red link, a coaxial cable link, a
wire link and an optical cable link.
In figure 6d, the second controller module 602
establishes a non-proximity communication link with the
first controller module 600 allowing the first controller
module 600 to received the address of the second
controller module 602 (ID#2). At the end of the
transaction, all components store ID REMOTE, ID#1 and
ID#2. In a specific example of implementation, the non-
proximity communication link is a radio frequency (RF)
link.
Each component 600, 602, 604 stores the addresses of
the other component in a memory unit for use when
transmitting messages. Once each component has the address
of the other components in the remote control system, the
remote control module 604 communicates over an RF channel
with either the first controller module or the second
controller module to assign the lead operational status.
CA 02313918 2000-07-14
Once the lead operational status has been assigned, the
controller module having the lead operational status
communicates over a RF channel with the other controller
module to assign to it a trail operational status.
5
The functional elements of the process described
earlier are implemented in software that is in the form
of program elements executed in the processing units 22,
28 in the controller modules 18 and in the remote control
10 module 24.
Although various embodiments have been illustrated,
this was for the purpose of describing, but not limiting,
the invention. Various modifications will become
15 apparent to those skilled in the art and are within the
scope of this invention, which is defined more
particularly by the attached claims.
