U.S. patent application number 09/866207 was filed with the patent office on 2001-11-15 for systems and methods for monitoring and controlling tractor/trailer vehicle systems.
This patent application is currently assigned to Vehicle Enhancement Systems, Inc.. Invention is credited to Lesesky, Alan, Weant, Bobby Ray.
Application Number | 20010040408 09/866207 |
Document ID | / |
Family ID | 25524045 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040408 |
Kind Code |
A1 |
Lesesky, Alan ; et
al. |
November 15, 2001 |
Systems and methods for monitoring and controlling tractor/trailer
vehicle systems
Abstract
A status of one or more subsystems positioned on one or more
trailers is communicated to a tractor electrically and mechanically
connected to the trailer. The status may be automatically supplied
by the subsystem or may be requested either by the operator of the
tractor/trailer combination or automatically by another subsystem
on either the tractor or the trailer. A spread spectrum data
communications signal representing the status of a respective
subsystem is superposed on the power bus. The status of the
respective subsystem can then be determined from the spread
spectrum data communications signal. Preferably, the status of the
subsystem is indicated to an operator positioned on the tractor. A
command for controlling a subsystem on a trailer can also be
communicated from the tractor to the trailer over the power bus. A
spread spectrum data communications signal representing the command
is produced on the power bus, and the subsystem is controlled based
on the spread spectrum data communications signal. Preferably, the
command is received from an operator positioned in the tractor.
Inventors: |
Lesesky, Alan; (Charlotte,
NC) ; Weant, Bobby Ray; (Rock Hill, SC) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Vehicle Enhancement Systems,
Inc.
|
Family ID: |
25524045 |
Appl. No.: |
09/866207 |
Filed: |
May 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09866207 |
May 26, 2001 |
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09333183 |
Jun 14, 1999 |
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6254201 |
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09333183 |
Jun 14, 1999 |
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08976391 |
Nov 21, 1997 |
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6127939 |
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08976391 |
Nov 21, 1997 |
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08554907 |
Nov 9, 1995 |
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08976391 |
Nov 21, 1997 |
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PCT/US96/01658 |
Oct 14, 1996 |
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Current U.S.
Class: |
303/122.02 |
Current CPC
Class: |
B60T 8/1708 20130101;
B60T 13/66 20130101; B60T 7/20 20130101; B60T 8/885 20130101; B60T
2270/406 20130101; B60R 16/0315 20130101; B60T 13/662 20130101;
B60R 2016/0322 20130101; B60T 8/323 20130101 |
Class at
Publication: |
303/122.02 |
International
Class: |
B60T 008/88 |
Claims
That which is claimed is:
1. A vehicle comprising: a tractor including a tractor cab for
housing a tractor/trailer operator; a trailer mechanically and
electrically connected to said tractor, said trailer including an
antilock braking system and an antilock braking system interface
responsive to said antilock braking system which produces a data
signal representing a status of said antilock braking system; a
power bus which distributes electrical power to said antilock
braking system; power line carrier communicating means responsive
to said antilock braking system interface for producing a data
communications signal on said power bus from said data signal,
wherein said power line carrier communicating means comprises
spread spectrum signal producing means, responsive to the antilock
braking system, for producing a spread spectrum data communications
signal on said power bus from said data signal; and status
determining means responsive to said power bus for determining the
status of said antilock braking system from said data
communications signal, wherein said status determining means
comprises means for determining the status of the antilock braking
system from said spread spectrum data communications signal.
2. A vehicle according to claim 1, wherein said spread spectrum
signal producing means comprises: a modulator responsive to said
antilock braking system which produces said spread spectrum data
communications signal from said data signal, said spread spectrum
data communications signal being distributed over a predetermined
spectrum of frequencies; and electrical coupling means for
electrically coupling said modulator to said power bus so that said
spread spectrum data communications signal is superposed on said
power bus.
3. A vehicle according to claim 1, wherein said status determining
means further comprises: spread spectrum signal receiving means,
responsive to the power bus, for receiving said spread spectrum
data communications signal; and means, responsive to said spread
spectrum signal receiving means, for determining the status of the
antilock braking system from the received spread spectrum data
communications signal.
4. A vehicle according to claim 1, wherein said status determining
means further comprises an indicator which indicates the status of
said antilock braking system to a tractor/trailer operator in said
tractor cab.
5. A vehicle according to claim 1, wherein the power bus comprises:
a first plurality of conductors, positioned in the trailer; a
second plurality of conductors, positioned in the trailer; and a
connector which electrically connects the first plurality of
conductors and the second plurality of conductors; and wherein said
status determining means is electrically connected to a conductor
of said second plurality of conductors.
6. A vehicle according to claim 5, wherein the power bus further
comprises a first capacitor disposed between at least two of said
first plurality of conductors and a second capacitor disposed
between at least two of said second plurality of conductors, and
wherein the spread spectrum signal producing means is electrically
connected to one of the capacitively coupled conductors of said
first plurality of conductors such that the spread spectrum data
communications signal is transmitted via each of the capacitively
coupled conductors.
7. A vehicle according to claim 5, wherein said connector comprises
a standardized SAE J560 connector.
8. A vehicle according to claim 1 further comprising: a warning
indicator which indicates the status of said antilock braking
system, said warning indicator being responsive to said antilock
braking system interface; and a trailer warning indicator package,
said power line carrier communicating means and said warning
indicator being integrated in said trailer warning indicator
package, said trailer warning indicator package further including
means for mounting said trailer warning indicator package on the
trailer so that said warning indicator is viewable by a
tractor/trailer operator positioned within said tractor cab.
9. A vehicle according to claim 1, wherein said tractor includes a
cab having an instrument console positioned therein, and wherein
said status determining means further comprises a display mounted
on said instrument console which indicates the status of the
antilock braking system to an operator positioned in the
tractor.
10. A vehicle according to claim 1, further comprising: a tractor
communications module housing which houses said status determining
means; and means for mounting said tractor communications module
housing to said tractor.
11. A vehicle according to claim 1, further comprising: a trailer
communications module housing which houses said power line carrier
communicating means; and means for mounting said trailer
communications module housing to said trailer.
12. A communications system for a trailer for communicating a
status of a subsystem positioned on the trailer, the system
comprising: a power bus which supplies electrical power to the
trailer; spread spectrum signal producing means, responsive to a
status signal from the subsystem and positioned on the trailer, for
producing a spread spectrum data communications signal representing
the status of the subsystem on the power bus, wherein said spread
spectrum signal producing means comprises means for producing said
spread spectrum data communications signal from the status signal;
and status determining means, remotely positioned relative to the
trailer and responsive to the power bus, for determining the status
of the subsystem from the spread spectrum data communications
signal, wherein said status determining means comprises: spread
spectrum signal receiving means, responsive to the power bus, for
receiving said spread spectrum data communications signal; and
means, responsive to said spread spectrum signal receiving means,
for determining the status of the subsystem from the received
spread spectrum data communications signal.
13. A communications system according to claim 12, wherein the
power bus comprises: a first plurality of conductors, positioned in
the trailer; a second plurality of conductors, positioned in a
trailer; and a connector which electrically connects the first
plurality of conductors and the second plurality of conductors; and
wherein said status determining means is electrically connected to
a conductor of said second plurality of conductors.
14. A communications system according to claim 13, wherein the
power bus further comprises a first capacitor disposed between at
least two of said first plurality of conductors and a second
capacitor disposed between at least two of said second plurality of
conductors, and wherein the spread spectrum signal producing means
is electrically connected to one of the capacitively coupled
conductors of said first plurality of conductors such that the
spread spectrum data communications signal is transmitted via each
of the capacitively coupled conductors.
15. A communications system according to claim 13, wherein said
connector comprises a SAE J560 seven-pin connector.
16. A communications system according to claim 12, wherein said
status determining means comprises an indicator which indicates the
status of the subsystem to an operator remote from the trailer.
17. A communications system according to claim 12, further
comprising: a tractor communications module housing which houses
said status determining means; and means for mounting said tractor
communications module housing to a tractor.
18. A communications system according to claim 12, further
comprising: a trailer communications module housing which houses
said spread spectrum signal producing means; and means for mounting
said trailer communications module to said trailer.
19. A communications system for connecting to a combination of a
tractor and a trailer mechanically and electrically connected to
the tractor to communicate a command from the tractor to a
subsystem positioned on the trailer, the system comprising: a power
bus which supplies electrical power to the combination of the
tractor and the trailer; spread spectrum signal producing means,
positioned on the tractor, for producing a spread spectrum data
communications signal representing the command on said power bus,
wherein said spread spectrum signal producing means comprises means
for producing said spread spectrum data communications signal from
the command; and controlling means, positioned on the trailer, for
controlling the subsystem based on the spread spectrum data
communications signal, wherein said controlling means comprises:
spread spectrum signal receiving means, positioned on the trailer
and responsive to said power bus, for receiving said spread
spectrum data communications signal; and means for controlling the
subsystem from the received spread spectrum data communications
signal.
20. A communications system according to claim 19, wherein the
power bus comprises: a first plurality of conductors, positioned in
the trailer; a second plurality of conductors, positioned in the
tractor; and a connector which electrically connects the first
plurality of conductors and the second plurality of conductors; and
wherein said spread spectrum signal producing means is electrically
connected to a conductor of said second plurality of conductors;
and wherein said spread spectrum signal receiving means is
electrically connected to a conductor of said first plurality of
conductors.
21. A communications system according to claim 20, wherein said
power bus supplies electrical power to a plurality of electrical
loads within the tractor, and wherein said spread spectrum signal
producing means is electrically connected to a conductor of said
second plurality of conductors at a point nearer said connector
than the respective points at which the plurality of electrical
loads are electrically connected to said power bus.
22. A communications system according to claim 21 further
comprising a capacitor disposed between said spread spectrum signal
producing means and the respective conductor of said second
plurality of conductors to couple the spread spectrum data
communications signal to the respective conductor of said second
plurality of conductors.
23. A communications system according to claim 20, wherein said
connector comprises a SAE J560 seven-pin connector.
24. A communications system according to claim 19, further
comprising operator input means for receiving a command from an
operator positioned on the tractor, and wherein said spread
spectrum signal producing means comprises means for producing a
spread spectrum data communications signal representing the
conveyed command.
25. A communications system according to claim 19, further
comprising: a tractor communications module housing which houses
said spread spectrum signal producing means; and means for mounting
said tractor communications module housing to said tractor.
26. A communications system according to claim 19, further
comprising: a trailer communications module housing which houses
said controlling means; and means for mounting said trailer
communications module housing to said trailer.
27. A communications system for a trailer for communicating a
status of a first subsystem positioned on the trailer, the system
comprising: a power bus which supplies electrical power to the
trailer, wherein said power bus supplies power to the first
subsystem and each of a plurality of second subsystems; spread
spectrum signal producing means, responsive to the first subsystem,
for producing a spread spectrum data communications signal
representing the status of the subsystem on the power bus; spread
spectrum blocking means, associated with respective ones of said
second subsystems, for protecting the spread spectrum data
communications signal placed on said power bus by said spread
spectrum signal producing means from attenuation by the second
subsystems; and status determining means, positioned remote from
the trailer and responsive to the power bus, for determining the
status of the subsystem from the spread spectrum data
communications signal.
28. A communications system according to claim 27, wherein said
spread spectrum blocking means comprises a plurality of inductive
elements associated with respective ones of the second
subsystems.
29. A communications system according to claim 27, wherein said
spread spectrum blocking means comprises a plurality of ferrite
beads associated with respective ones of the second subsystems.
30. A communications system according to claim 27, wherein the
subsystem produces a status signal representing the status of the
subsystem, wherein said spread spectrum signal producing means
comprises means for producing said spread spectrum data
communications signal from the status signal, and wherein said
status determining means comprises: spread spectrum signal
receiving means, responsive to the power bus, for receiving said
spread spectrum data communications signal; and means, responsive
to said spread spectrum signal receiving means, for determining the
status of the subsystem from the received spread spectrum data
communications signal.
31. A communications system according to claim 27, wherein the
power bus comprises: a first plurality of conductors, positioned in
the trailer; a second plurality of conductors, positioned in a
tractor; and a connector which electrically connects the first
plurality of conductors and the second plurality of conductors; and
wherein said spread spectrum signal producing means is electrically
connected to a conductor of said first plurality of conductors; and
wherein said status determining means is electrically connected to
a conductor of said second plurality of conductors.
32. A communications system according to claim 31, wherein the
power bus further comprises a first capacitor disposed between at
least two of said first plurality of conductors and a second
capacitor disposed between at least two of said second plurality of
conductors, and wherein the spread spectrum signal producing means
is electrically connected to one of the capacitively coupled
conductors of said first plurality of conductors such that the
spread spectrum data communications signal is transmitted via each
of the capacitively coupled conductors.
33. A communications system according to claim 31, wherein said
connector comprises a SAE J560 seven-pin connector.
34. A communications system for at least one trailer, for
communicating a respective status of a plurality of subsystems
positioned on the at least one trailer, wherein the plurality of
subsystems positioned on the at least one trailer communicate
according to at least two different protocols, and wherein the
communications system comprises: a power bus which supplies
electrical power to the at least one trailer; spread spectrum
signal producing means, responsive to the plurality of subsystems
and positioned on the trailer, for producing spread spectrum data
communications signals representing the status of the plurality of
subsystems on the power bus, wherein said spread spectrum signal
producing means comprises; a plurality of protocol specific
transmitters associated with respective ones of said subsystems,
wherein each protocol specific transmitter receives signals having
a predetermined protocol and converts the signals to a standardized
format; and means for producing spread spectrum data communications
signals representative of the status of respective ones of the
subsystems based upon the signals having the standardized format
provided by the protocol specific transmitters; and status
determining means, responsive to the power bus, for determining the
status of respective ones of the plurality of subsystems from the
spread spectrum data communications signals.
35. A communications system according to claim 34, wherein the
plurality of subsystems include a refrigeration system that
communicates according to RS-232 protocol and an antilock braking
system that communicates according to J-1708 protocol, and wherein
said plurality of protocol specific transmitters comprise an RS-232
transceiver and an RS-485 transceiver for converting RS-232 signals
and J-1708 signals, respectively, to a standardized format.
36. A communications system according to claim 34, wherein said
means for producing spread spectrum data communications signals
comprises a spread spectrum transceiver that includes means for
determining the state of the spread spectrum transceiver such that
signals transmitted by the spread spectrum transceiver are not also
received and processed by the spread spectrum transceiver.
37. A communications system according to claim 34 further
comprising a selection input for selecting at least one protocol
specific transmitter to receive signals having a predetermined
protocol and to convert the signals to the standardized format.
38. A communications system according to claim 34, wherein said
status determining means comprises: spread spectrum signal
receiving means, responsive to the power bus, for receiving said
spread spectrum data communications signal; and means, responsive
to said spread spectrum signal receiving means, for determining the
status of the antilock braking system from the received spread
spectrum data communications signal.
39. A communications system according to claim 34, wherein the
power bus comprises: a first plurality of conductors, positioned in
the trailer; a second plurality of conductors, positioned in a
tractor; and a connector which electrically connects the first
plurality of conductors and the second plurality of conductors; and
wherein said spread spectrum signal producing means is electrically
connected to a conductor of said first plurality of conductors; and
wherein said spread spectrum signal receiving means is electrically
connected to a conductor of said second plurality of
conductors.
40. A communications system according to claim 39, wherein the
power bus further comprises a first capacitor disposed between at
least two of said first plurality of conductors and a second
capacitor disposed between at least two of said second plurality of
conductors, and wherein the spread spectrum signal producing means
is electrically connected to one of the capacitively coupled
conductors of said first plurality of conductors such that the
spread spectrum data communications signal is transmitted via each
of the capacitively coupled conductors.
41. A communications system for at least one trailer, for
communicating a respective status of a plurality of subsystems
positioned on the at least one trailer, the system comprising: a
power bus which supplies electrical power to the at least one
trailer; spread spectrum signal producing means, responsive to the
subsystems and positioned on the at least one trailer, for
producing spread spectrum data communications signals representing
the respective status of the subsystems on the power bus, wherein
said spread spectrum signal producing means comprises a plurality
of spread spectrum transmitters responsive to respective ones of
the subsystems for producing spread spectrum communications signals
representing the status of the respective subsystem, and wherein
said spread spectrum signal producing means comprises
self-diagnostic means associated with at least one of said
transmitter and for halting further transmission by the respective
spread spectrum transmitter to the communications system if said
self-diagnostic means determines that the respective spread
spectrum transmitter is being provided with inaccurate signals such
that the remainder of the communications system will continue to
operate; and status determining means, responsive to the power bus,
for determining the status of respective ones of the plurality of
subsystems from the spread spectrum data communications
signals.
42. A communications system according to claim 41, wherein said
status determining means comprises: spread spectrum signal
receiving means, responsive to the power bus, for receiving said
spread spectrum data communications signal; and means, responsive
to said spread spectrum signal receiving means, for determining the
status of respective ones of the subsystems from the received
spread spectrum data communications signal.
43. A communications system according to claim 41, wherein the
power bus comprises: a first plurality of conductors, positioned in
the trailer; a second plurality of conductors, positioned in a
tractor; and a connector which electrically connects the first
plurality of conductors and the second plurality of conductors; and
wherein said spread spectrum signal producing means is electrically
connected to a conductor of said first plurality of conductors; and
wherein said status determining means is electrically connected to
a conductor of said second plurality of conductors.
44. A communications system according to claim 43, wherein the
power bus further comprises a first capacitor disposed between at
least two of said first plurality of conductors and a second
capacitor disposed between at least two of said second plurality of
conductors, and wherein the spread spectrum signal producing means
is electrically connected to one of the capacitively coupled
conductors of said first plurality of conductors such that the
spread spectrum data communications signal is transmitted via each
of the capacitively coupled conductors.
45. A method of monitoring a subsystem positioned on a trailer that
produces a data signal representing a status of the subsystem and a
power bus which distributes electrical power to the trailer and a
tractor connected thereto, the method comprising the steps of:
producing a data communications signal from the data signal;
communicating said data communications signal over the power bus,
wherein said step of communicating comprises the steps of:
modulating the data communications signal to produce a spread
spectrum data communications signal; and superposing the spread
spectrum data communications signal on the power bus, at the
trailer; and determining the status of the subsystem from the
communicated data communications signal, wherein said step of
determining comprises the steps of: receiving the superposed spread
spectrum data communications signal; and determining the status of
the subsystem from the received spread spectrum data communications
signal.
46. A method according to claim 45, wherein the step of determining
comprises the step of indicating said status of the subsystem to a
tractor/trailer operator positioned within a cab of a tractor
connected to the trailer.
47. A method according to claim 46, wherein said step of
determining the status of the subsystem comprises: producing a
data-modulated digital carrier signal including a plurality of
transitions from the received data communications signal; and
detecting the status of the subsystem from the transitions of said
data-modulated digital carrier signal occurring during a
predetermined time interval.
48. A method of communicating a command from a tractor to a
subsystem positioned on a trailer electrically and mechanically
connected to the tractor, the tractor and trailer combination
including a power bus which supplies electrical power to the
tractor and the trailer, the method comprising the steps of:
producing a data communications signal representing the command on
the power bus, wherein said step of producing comprises the steps
of: modulating the data communications signal to produce a spread
spectrum data communications signal; and superposing the spread
spectrum data communications signal on the power bus, at the
tractor; receiving the superposed spread spectrum data
communications signal, at the trailer; and controlling the
subsystem based on the spread spectrum data communications
signal.
49. A method according to claim 48, wherein said step of
communicating is preceded by the step of receiving a command from
an operator positioned in the tractor.
50. A method according to claim 48, wherein said step of
controlling the subsystem comprises the step of producing a command
signal from the spread spectrum data communications signal.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
Pat. application Ser. No. 08/554,907, filed Nov. 9, 1995, and of
International patent application Ser. No. PCT/US96/1658, filed Oct.
14, 1996, the contents of both of which are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to data communications with
a trailer and, more specifically, to data communications systems
and methods for monitoring and controlling subsystems on a
trailer.
BACKGROUND OF THE INVENTION
[0003] The trucking industry has for many years used
tractor/trailer combinations to transport cargo over the roadways
to intended destinations. As shown in FIG. 1, tractor 10 and
trailer 20 are mechanically coupled together so that the tractor
can pull the trailer with its cargo in an efficient and cost
effective manner. Various links between the tractor and the trailer
provide vehicle subsystems with power and/or control signals to
operate. Hydraulic, pneumatic, electrical and other subsystems on
the tractor/trailer combination have associated electrical
conductors and pneumatic lines running therebetween so these
subsystems can operate. With respect to electrical subsystems, a
tractor/trailer combination typically includes a tractor 10 and
trailer 20 and a power bus 30 electrically connected to one or more
batteries 32, which are typically charged by an alternator 34
mechanically driven by a tractor engine 15. Thus, electrical power
is distributed from tractor 10 to subsystems in trailer 20.
[0004] The trucking industry has historically lagged behind other
industries with respect to technological innovation, but recently
has been incorporating more and more sophisticated electronic
subsystems in both tractors and trailers. For example, regulatory
changes arising from safety concerns have led to the incorporation
of trailer antilock braking systems (ABS), frequently
microprocessor-controlled, in trailers in order to minimize the
risk of trailer skids and jackknifing. New trailers are being
constructed with ABS, while older trailers are being retrofitted to
incorporate ABS. These systems may include, for example, actuators
and transducers operatively connected to the trailer wheels and
braking hardware, controlled by electronic circuits located
elsewhere on the trailer and tractor. As shown in FIG. 1, an
antilock braking system 100, as well as other subsystems,
conventionally receives electrical power from power bus 30.
[0005] Antilock braking systems may produce data signals which
indicate various conditions of the ABS. These data signals may
include, for example, a failure warning signal which is asserted if
an ABS microprocessor detects a failure within itself or other
components of the ABS. In some applications, a data signal may
drive a light-emitting diode (LED) or other indicator.
Conventionally, the tractor/trailer operator has no external
indication of the state of the ABS. Even those systems having an
external indicator may not allow a tractor/trailer operator to
inspect the state of the ABS while positioned in the tractor cab
with the tractor/trailer combination in operation. The operator
typically may have to park the vehicle, exit the cab, and inspect
an ABS indicator on the trailer, if present, in order to monitor
the state of the ABS. Thus, it may be difficult for the operator to
monitor the state of the ABS system while the vehicle is
moving.
[0006] It may be possible to wire data signals from an ABS to a
tractor using a dedicated signal path such as a twisted wire pair
passed from the trailer to the tractor. A seven-pin connector has
been widely used by the trucking industry to convey electrical
power for lighting and equipment operation between a tractor and a
trailer. As shown in FIG. 2, the connector 40 includes two
disengageable connector portions 50 and 60 to permit the tractor
and trailer combination to be disconnected. An example of such a
seven-pin connector is illustrated in U.S. Pat. No. 4,969,839 to
Nilsson, the entire disclosure of which is specifically
incorporated herein by reference. These seven-pin connectors are
well known and have been specified by the Society of Automotive
Engineering (SAE) according to the standard number "SAE J560", the
teachings of which are also incorporated herein by reference.
[0007] Each of the sockets 54 in the standard seven-pin connector
(SAE J560) is an electrical conductor carried by the plug portion
50 of the connector and which is adapted to mate with a
corresponding electrical pin 63, also an electrical conductor, in
the receptacle portion 60 of the connector to thereby provide an
electrical signal between the tractor and the trailer. The pins and
corresponding sockets generally are assigned to specific electrical
subsystems, for example, power,. ground, turn signals, brake
lights, clearance lamps, emergency flashers, and other devices
requiring electrical signals.
[0008] Until recently, the seventh pin on the connector has been an
"auxiliary" pin which could be used for specific electrical
purposes or applications on individual tractor/trailer
combinations. Pursuant to Federal Motor Vehicle Safety Standard No.
121, however, the National Highway Traffic Safety Administration
has mandated that the antilock braking systems of all trailers on
the road after Mar. 1, 1998 must not only be powered by the power
line that drives the brake lights, but also by a second power line
that is connected to the tractor by means of the seventh pin, i.e.,
the former auxiliary pin. As a result, all seven pins of the
connector will soon be dedicated to a particular purpose.
[0009] Although pins and sockets of the seven-pin connector may be
used to convey an ABS status signal to a tractor, the generally
limited circuit capacity afforded by the standardized connector
would be reduced even further. The standard seven-pin connector
simply may not provide the circuit capacity needed to convey to a
tractor an increased number of data signals from various systems
located on trailers, including additional ABS systems which may be
present when a tractor is connected to multiple trailers.
Connectors with greater capacity could be employed, but the
seven-pin connector (SAE J560) is an industry standard for
tractor/trailers. Alternative communications techniques such as
fiber optic links or radio communication through free space may
bypass the bottleneck of limited channel capacity in the standard
connectors used to connect tractors and trailers, but may require
the installation of complex and expensive electronic components.
These components, often referred to as "black boxes," may be
vulnerable to theft and vandalism when placed on trailers which
often are under the control of multiple operators and left in
unsecured areas.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing, it is therefore an object of the
present invention to provide systems and methods for data
communications in a tractor and/or a trailer.
[0011] It is another object of the present invention to provide
data communications systems and methods which utilize existing
wiring on tractors and trailers.
[0012] It is another object of the present invention to provide
data communications systems and methods that are also compatible
with standardized connectors widely used in the trucking
industry.
[0013] It is another object of the present invention to provide
data communications systems which are less sensitive to the
interference and noise frequently present in tractor and trailer
electrical systems.
[0014] It is another object of the present invention to provide
systems and methods for monitoring a warning system of a
tractor/trailer combination.
[0015] It is another object of the present invention to provide
systems and methods for monitoring an antilock braking system of a
tractor/trailer combination by a tractor/trailer operator
positioned in a cab of a tractor.
[0016] It is another object of the present invention to provide
systems and methods for monitoring an antilock braking system which
allow a trailer equipped with elements of an antilock braking
system monitoring system to be used with a tractor which is not
equipped with complementary elements while still providing an
indication of a status of the antilock braking system to a
tractor/trailer operator positioned within the tractor cab.
[0017] It is another object of the present invention to provide
systems for monitoring an antilock braking system in a
tractor/trailer combination using components packaged to be
inconspicuous and less vulnerable to theft and vandalism.
[0018] It is another object of the present invention to reliably
communicate with a number of subsystems positioned on one or more
trailers.
[0019] These and other objects, features and advantages of the
present invention are provided according to one embodiment by
systems and methods for communicating antilock braking signals to a
status indicator via the power bus which distributes power to the
antilock braking system. Thus, a vehicle according to the
embodiment includes a tractor connected to a trailer having an
antilock braking system and an antilock braking system interface
which produces a data signal, typically representing the status of
the antilock braking system. The vehicle also has an ABS reporting
system that receives the data signal and includes power line
carrier communicating means, responsive to the antilock braking
system, that produces a data communications signal representing the
status of the antilock braking system over the power bus. The
vehicle of this embodiment also includes status determining means
for determining the status of the antilock braking system from the
data communications signal. The status determining means preferably
includes an indicator which indicates the determined status to a
tractor/trailer operator positioned within the cab of the
tractor.
[0020] The present invention provides for remote monitoring an
antilock braking system by a tractor/trailer operator. Thus, the
present invention allows a tractor/trailer operator to monitor an
antilock braking system while the operator is positioned in the
tractor cab and the tractor/trailer combination is in motion. The
present invention also provides for monitoring of the status of an
antilock braking system without requiring extensive rewiring of the
tractor or the trailer. Furthermore, the present invention provides
for monitoring of an antilock braking system using existing power
wiring and connectors.
[0021] According to one embodiment, the power line carrier
communicating means may include a waveform generator, preferably an
oscillator, which produces a power line carrier signal having a
predetermined carrier frequency. A modulator is responsive to the
waveform generator and the antilock braking system and produces the
data communications signal from the power line carrier signal and
the data signal. Coupling means couples the modulator to the power
bus and superposes the data communications signal on the power
bus.
[0022] The status determining means may include power line carrier
receiving means that is responsive to the power bus and receives
the data communications signal. Processing means is responsive to
the power line carrier receiving means and produces a
data-modulated digital carrier signal from the received data
communications signal. Detecting means detects a status of the
antilock braking system from a count of the transitions of the
data-modulated digital carrier signal occurring during a
predetermined time interval. The status determining means may also
include an indicator for indicating the determined status to a
tractor/trailer operator positioned within a cab of the tractor,
thus informing the operator of the condition of the antilock
braking system while the tractor/trailer combination is in
operation. The indicator may be in the form of lights, gauges,
images on a CRT screen, audible annunciators and the like, as would
be readily understood by those skilled in the art.
[0023] The power bus may include a plurality of tractor power lines
and trailer power lines electrically connected by a connector. The
connector may include an industry-standard SAE J560 connector. Thus
the present invention provides for monitoring of an antilock
braking system using existing wiring and connectors.
[0024] According to one advantageous embodiment, the power bus also
includes a first capacitor disposed between at least two of the
tractor power lines and a second capacitor disposed between at
least two of the trailer power lines. By placing the data
communications signal on one of the capacitively coupled power
lines, the data communications signal is transmitted via each of
the capacitively coupled conductors. As a result, the
communications system of this embodiment provides redundancy.
[0025] In another aspect of the present invention, the power line
carrier communicating means may be integrated with a warning
indicator in a trailer warning indicator package. The warning
indicator is responsive to the antilock braking system interface
and indicates a status of the antilock braking system from the data
signal. The trailer warning indicator package includes means for
mounting the trailer warning indicator package so that it is
positioned on the trailer and is viewable by a tractor/trailer
operator positioned within the tractor cab. Thus, a trailer which
incorporates the power line carrier communicating means of an
antilock braking system according to the present invention may be
used with a tractor which is not equipped with the complementary
status determining means, while still providing a way to indicate a
status of the trailer antilock braking system to a tractor/trailer
operator positioned within the tractor cab. The trailer warning
indicator package preferably has a standard form factor, such as
that of the standard running lights commonly used on trailers,
thereby providing components of an antilock braking system
monitoring system which are inconspicuous and less susceptible to
vandalism and theft.
[0026] According to another aspect of the present invention, a
communications system for communicating the status of a subsystem
positioned on a trailer to a tractor is provided that includes a
power bus which supplies electrical power to the combination of the
tractor and the trailer, and spread spectrum signal producing
means, responsive to the subsystem and positioned on the trailer,
for producing a spread spectrum data communications signal
representing the status of the subsystem on the power bus. For
example, the subsystem may produce a status signal representing a
status of the subsystem, and the spread spectrum signal producing
means may include means for producing the spread spectrum data
communications signal from the status signal. Status determining
means, positioned on the tractor, is responsive to the power bus
for determining the status of the subsystem from the spread
spectrum data communications signal. The status determining means
may include spread spectrum signal receiving means, positioned on
the tractor and responsive to the power bus, for receiving the
spread spectrum data communications signal, and means, positioned
on the tractor and responsive to the spread spectrum signal
receiving means, for determining the status of the subsystem from
the received spread spectrum data communications signal. The status
determining means also preferably includes an indicator, such as an
alphanumeric display, an a LED display, or an audio annunciator,
which indicates a status of the subsystem to an operator positioned
in the tractor.
[0027] According to another aspect, a communications system is
provided for permitting a tractor and a trailer mechanically and
electrically connected to the tractor to communicate a command from
the tractor to a subsystem positioned on the trailer. According to
this embodiment, the communications system includes a power bus
which supplies electrical power to the combination of the tractor
and the trailer, spread spectrum signal producing means, positioned
on the tractor, for producing a spread spectrum data communications
signal representing the command on the power bus, and controlling
means, positioned on the trailer, for controlling the subsystem
based on the spread spectrum data communications signal. The
controlling means preferably includes spread spectrum signal
receiving means, positioned on the trailer and responsive to the
power bus, for receiving the spread spectrum data communications
signal, and means for controlling the subsystem from the received
spread spectrum data communications signal. The system also
preferably includes operator input means for receiving a command
from an operator positioned on the tractor, such as via a switch
mounted on an instrument cluster in the tractor.
[0028] Thus, the communications system of the present invention can
provide commands to the various subsystems on the trailer. These
commands may be provided by the operator of the tractor/trailer
combination or may be automatically generated, such as according to
a predetermined schedule or in response to a particular event.
Among other things, the command may request that one or more
subsystems provide status or other data. In addition to responding
to commands, the subsystems themselves may initiate communications,
such as with other subsystems in the trailer or tractor, if so
desired.
[0029] According to the present invention, a communications module
designed to be mounted to a trailer can communicate via a power bus
and includes a status signal input and a command signal output. The
communications module includes spread spectrum signal producing
means, responsive to the status signal input, for producing a
spread spectrum data communications signal from a status signal
provided at the status signal input. The spread spectrum signal
producing means is coupled to the power bus such that the spread
spectrum data communications signal is superposed on the power bus.
The communications module also includes spread spectrum signal
receiving means for receiving a spread spectrum communications
signal superposed on the power bus and for producing a command
signal at the command signal output from the received spread
spectrum communications signal. The communications module also
preferably includes a communications module housing which houses
the spread spectrum signal receiving means and the spread spectrum
signal producing means. Typically, the communications module
housing is mounted to the trailer.
[0030] Likewise, one embodiment of the present invention also
provides a communications module designed to be mounted within the
tractor that communicates via the power bus and which includes a
command input. The communications module of this embodiment also
includes spread spectrum signal producing means, responsive to the
command input, for producing a spread spectrum data communications
signal from a command provided at the command input. The spread
spectrum signal producing means is coupled to the power bus such
that the spread spectrum data communications signal is superposed
on the power bus. The communications module also includes spread
spectrum receiving means for receiving a spread spectrum data
communications signal superposed on the power bus that typically
represents the status of a respective subsystem. The communications
module also preferably includes status determining means,
responsive to the spread spectrum receiving means, for determining
the status of the subsystem from the received spread spectrum data
communications signal. In this regard, the status determining means
preferably includes an indicator which indicates the status of the
subsystem. The communications module also preferably includes
operator input means for receiving a command from an operator, such
as via a switch. The communications module also preferably includes
a communications module housing which houses the spread spectrum
signal producing means, the spread spectrum signal receiving means,
the indicator and the operator input means, and means for mounting
the communications module on the tractor such that the indictor is
viewable by and the operator input means is accessible to an
operator positioned in the tractor.
[0031] The power bus may oftentimes supply power to a number of
subsystems on one or more trailers. According to one particularly
advantageous embodiment, the communications system is designed to
communicate or otherwise broadcast the respective status of each of
the plurality of subsystems positioned on at least one trailer to
the tractor even though the subsystems communicate according to at
least two different protocols. For example, the subsystems can
include an antilock braking system that communicates according to a
J-1708 protocol and a refrigeration unit that communicates
according to an RS-232 protocol. According to this embodiment, the
spread spectrum signal producing means preferably includes a
plurality of protocol specific transmitters associated with
respective ones of the subsystems. Each protocol specific
transmitter receives signals from the respective subsystem that
have a predetermined protocol and converts the signals to a
standardized format. For example, the protocol specific
transmitters can include an RS-485 transceiver associated with an
antilock braking system for receiving J-1708 signals and an RS-232
transceiver associated with a refrigeration unit for receiving
RS-232 signals. The spread spectrum signal producing means of this
embodiment also preferably includes means for producing spread
spectrum data communications signals representative of the status
of respective ones of the subsystems based upon the standardized
signals that are provided by the protocol specific transmitters.
Based upon the spread spectrum data communications signals, the
status determining means of the communications system of this
embodiment can determine the status of respective ones of the
subsystems.
[0032] In one embodiment, the protocol specific transmitters are
protocol specific transceivers. As such, the protocol specific
transceivers preferably include means for determining the state of
the respective transceiver such that signals transmitted by the
protocol specific transceiver are not also received and processed
by the protocol specific transceiver.
[0033] According to another embodiment of the communications system
that communicates the respective status of each of a plurality of
subsystems positioned on at least one trailer to the tractor, the
spread spectrum signal producing means includes a plurality of
spread spectrum transmitters responsive to respective ones of the
subsystems for producing spread spectrum communications signals
representing the status of the respective subsystems. The spread
spectrum signal producing means of this embodiment preferably
includes self-diagnostic means for monitoring the signals provided
to the spread spectrum transmitter by the protocol specific
transmitters and for halting further transmission by the spread
spectrum signal producing means to the communications system if the
self-diagnostic means determines that the signals provided to the
spread spectrum transmitters are inaccurate or otherwise includes
errors. As a result, the remainder of the communications system can
continue to operate as designed without being corrupted by
inaccurate signals.
[0034] In order to permit the communications system of the present
invention to effectively broadcast a spread spectrum data
communications signal representing the status of a first subsystem
on the power bus, the communications system of one advantageous
embodiment further includes spread spectrum blocking means
associated with respective ones of the other subsystems. The spread
spectrum blocking means protect the spread spectrum data
communications signal placed on the power bus by the spread
spectrum signal producing means from attenuation by the other
subsystems. In one embodiment, the spread spectrum blocking means
includes a plurality of inductive elements associated with
respective ones of the other subsystems. Alternatively, the spread
spectrum blocking means can include a plurality of ferrite beads
associated with respective ones of the other subsystems. In either
embodiment, the spread spectrum blocking means is designed to
prevent or at least significantly reduce the filtering or other
attenuation of the spread spectrum data communications signals by
the other subsystems electrically connected to the power bus. As
such, the status determining means of the communications system can
receive and process a spread spectrum data communications signal
without concern that the spread spectrum data communications signal
has been significantly attenuated or otherwise distorted by the
other subsystems.
[0035] The power bus also typically supplies electrical power to a
plurality of electrical loads within the tractor. In order to
prevent attenuation or other distortion of the spread spectrum data
communications signals by the plurality of other electrical loads
within the tractor, the spread spectrum signal producing means is
preferably electrically connected to a conductor of the tractor
power lines at a point nearer the connector than the respective
points at which the plurality of electrical loads are electrically
connected to the power bus. More particularly, the communications
system of this embodiment can include a capacitor disposed between
the spread spectrum signal producing means and the respective
tractor power line to couple the spread spectrum data
communications signal to the respective tractor power line.
[0036] Monitoring methods according to the present invention are
used for monitoring a subsystem, such as an antilock braking
system, of a tractor/trailer combination. These methods include the
following steps: a data signal, such as a status signal, is
provided by the subsystem; a data communications signal is produced
from the data signal; the data communications signal is
communicated over a power bus; and the status of the subsystem,
such as the antilock braking system, is determined from the data
communications signal. The step of communicating may include steps
of modulating the data signal with a signal having either a
predetermined carrier frequency or a predetermined spectrum of
carrier frequencies to produce the data communications signal and
superposing the data communications signal on the power bus. The
step of determining may include the step of indicating the
determined status of the antilock braking system to a
tractor/trailer operator positioned within a cab of the
tractor.
[0037] A method for determining the status of an antilock braking
system from a data communications signal representing the status of
the antilock braking system is also provided by the present
invention. The method includes the steps of: receiving a data
communications signal representing one status of a subsystem, such
as the antilock braking system; producing a data-modulated digital
carrier signal from the received data communications signal; and
detecting a status of the subsystem, such as the antilock braking
system, from a count of transitions of the data-modulated digital
carrier signal occurring during a predetermined time interval.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Some of the objects and advantages of the present invention
having been stated, others will be more fully understood from the
detailed description that follows and by reference to the
accompanying drawings in which:
[0039] FIG. 1 is a schematic diagram illustrating a combination
tractor/trailer as in the prior art;
[0040] FIG. 2 is an isometric exploded view illustrating a prior
art SAE J560 connector;
[0041] FIG. 3 is a schematic diagram illustrating an antilock
braking system monitoring system according to an embodiment of the
warning system of the present invention;
[0042] FIG. 4 is a block diagram illustrating power line carrier
communicating means according to the present invention;
[0043] FIG. 5 is a block diagram illustrating status determining
means according to the present invention;
[0044] FIG. 6 is an electrical schematic diagram illustrating an
electrical circuit for communicating a data communications signal
over a power bus according to the present invention;
[0045] FIG. 7 is an electrical schematic diagram illustrating an
electrical circuit for determining a status of an antilock braking
signal from a data communications signal received from a power bus
according to an embodiment of a warning system of the present
invention;
[0046] FIGS. 8A-B are software block diagrams illustrating
operations used in determining a status of an antilock braking
system from transitions of a data communications signal according
to the present invention;
[0047] FIG. 9A is a schematic diagram illustrating a
tractor/trailer combination with an antilock braking system
monitoring system according to an embodiment of a warning system of
the present invention;
[0048] FIG. 9B is a perspective drawing illustrating an instrument
cluster of a tractor including an indicator according to the
present invention;
[0049] FIG. 10 is a schematic diagram illustrating a
tractor/trailer combination with a warning indicator according to
the present invention;
[0050] FIG. 11 is a schematic diagram illustrating an intelligent
warning indicator according to the present invention;
[0051] FIG. 12 is a schematic diagram illustrating a tractor
connected to multiple trailers including an antilock braking system
monitoring system according to an embodiment of a warning system of
the present invention;
[0052] FIG. 13 is a block diagram illustrating an embodiment of a
communications system according to the present invention;
[0053] FIG. 14 is a block diagram illustrating another embodiment
of a communications system according to the present invention;
[0054] FIG. 15 is a block diagram illustrating yet another
embodiment of a communications system according to the present
invention;
[0055] FIG. 16 illustrates embodiments of a tractor communications
module and a trailer communications module according to the present
invention;
[0056] FIG. 17 is a block diagram illustrating an embodiment of a
trailer communications module according to the present
invention;
[0057] FIG. 18 is a block diagram illustrating an embodiment of a
tractor communications module according to the present
invention;
[0058] FIG. 19 illustrates an embodiment of the visual indicator
provided by a tractor communications module according to one
embodiment of the present invention;
[0059] FIG. 20 is a block diagram illustrating the communication
between a plurality of nodes and the power line that is provided by
the trailer communications module of one embodiment of the present
invention;
[0060] FIG. 21 is a block diagram illustrating a power bus that
provides electrical power to a number of subsystems that are each
associated with a spread spectrum blocking device;
[0061] FIG. 22 is a block diagram illustrating a tractor
communications module according to one embodiment of the present
invention that bypasses a number of other loads that are
electrically connected to the power bus and which superposes the
spread spectrum communications data signal on the power bus at a
point near the connector; and
[0062] FIG. 23 is a schematic drawing illustrating the capacitive
coupling of several of the conductors or power lines that are
interconnected by a conventional seven-pin connector.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0063] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which a
preferred embodiment of the invention is shown. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein; rather,
this embodiment is provided so that this disclosure will be
thorough and complete and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0064] The communications system of the present invention will be
hereinafter described in conjunction with communications between a
tractor 10 and a trailer 20 and, in particular, with communications
involving an antilock braking system on the trailer. However, the
communications system of the present invention can be employed with
other subsystems on a tractor and/or a trailer if so desired. In
addition, the communications system of the present invention can
provide communications with the various electrical subsystems of a
trailer in instances in which the trailer is not mechanically and
electrically coupled to a tractor, such as instances in which the
trailer is primarily serving as a container. For example, the
communications system of the present invention can provide
communications with the various subsystems on the trailer in
instances in which the trailer is being carried aboard a railcar, a
ship or the like, without departing from the spirit and scope of
the present invention.
[0065] FIG. 3 illustrates an antilock braking system monitoring
system according to the present invention. The antilock braking
system 100 receives electrical power 35 from the power bus 30. An
antilock braking system interfaces 110, responsive to the antilock
braking system 100, produces a data signal 105 representing a
status of antilock braking system 100. Data signal 105 may be a
binary signal representing an either/or condition of the antilock
braking system 100 such as failed/operational, active/standby, and
the like. As many antilock braking systems employ
microprocessor-based controllers, the antilock braking system
interface may be located within the antilock braking system 100 and
the data signal 105 may be a digital signal produced by the
antilock braking system controller. It will be understood by those
skilled in the art that various forms of antilock braking system
interface 110 may be used with the present invention, such as
relays or switches electrically connected to control signals of
antilock braking system 100, transducers mechanically or
electrically connected to components of antilock braking system
100, and the like. The data signal 105 may be digital as described
above, or may be an AC or DC analog signal, the amplitude,
frequency and other parameters of which may provide
information.
[0066] The power line carrier communicating means 320 is responsive
to antilock braking system interface 110 and produces the data
communications signal 325 superposed on power bus 30. As
illustrated in FIG. 4, the power line carrier communicating means
320 preferably includes a modulator 410 which modulates a carrier
signal 425, produced by a waveform generator 420 which may be an
oscillator, with data signal 105. Electrical coupling means 430
couples the modulator 410 to the power bus 30, superposing the data
communications signal 325, in the form of a data-modulated carrier
signal, on the power bus 30.
[0067] Power line carrier techniques for superposing a modulated
carrier signal on a power bus and receiving the superposed signal
from the power bus are known for other applications. It will be
understood by those skilled in the art that the modulator 410 may
perform amplitude modulation, frequency modulation, phase
modulation and other modulation functions. It will also be
understood that the electrical coupling means 430 may utilize
inductive coupling, capacitive coupling, a combination of inductive
and capacitive coupling, and other methods to superpose the data
communications signal 325 on the power bus 30. It will be
understood by those skilled in the art that superposing refers to
any linear or nonlinear combination of signals in transmission
media such as wires, busbars, and the like.
[0068] FIG. 6 is an electrical schematic diagram of an exemplary
embodiment according to the present invention, illustrating an
electrical circuit which performs functions of the power line
carrier communicating means 320. For example, an LM555 timer IC U1
preferably produces a carrier signal having a predetermined
frequency such as approximately 125 kHz at a carrier signal output
node CARRIER when the voltage at an input node ABS, where the data
signal 105 is input, is above a predetermined level, preferably
approximately 12 volts. The signal at the carrier signal output
node CARRIER drives the base of transistor Q1. This induces a
sinusoidal current between terminals 5,6 of a transformer T1 which
is capacitively coupled through a capacitor C7 to a power bus 30
present at a power bus output node BAT. Thus, modulation of the
carrier signal at the carrier signal output node CARRIER by the
data signal 105 at the input node ABS is effected, producing the
data communications signal 325 superposed on the power bus 30.
[0069] It will be understood by those skilled in the art that the
power line carrier communicating means 320 may be implemented using
various circuits and techniques. For example, the power line
carrier communicating means 320 may perform signal processing on
the data signal 105 or combine the data signal 105 with other
signals in an encoded data stream which is used to modulate a
carrier signal and superposed on the power bus 30. The waveform
generator 420 may be integrated into the antilock braking system
100 or another electronic system present on the tractor or trailer.
The ABS system 100 may also be a pressure monitoring system, a
temperature monitoring system, or other subsystem so that the
status of the system is indicated or warned to others such as an
operator positioned in the cab of a tractor. In the embodiment
illustrated in FIG. 6 the data signal 105 present at the input node
ABS corresponds to a voltage supplied by the antilock braking
system interface 110, but it will be understood that the data
signal 105 may be coupled into modulator 420 in various other ways,
such as optical and magnetic coupling.
[0070] It will be understood by those skilled in the art that power
line carrier communicating means 320 may be centralized or
distributed. It will also be understood that power line carrier
communicating means 320 may include other means for processing data
signal 105, such as signal processing or coding functions
implemented using special purpose hardware or a combination of
special purpose hardware and general purpose hardware running
software. Preferably, the power line carrier communicating means
320, however, includes means for communicating data, which may
include a modulator, over a predetermined spectrum of frequencies
such as illustrated by the spread spectrum technology embodied in
the integrated circuits and components (i.e., Intellon SSC PLCEFN,
XCR38149PRO2, QHCK-9409 integrated circuit or CEBus-compliant
communications modules according to EIA RS-232 and ISA bus module
standards) of the Intellon Spread Spectrum Carrier of the Intellon
Corporation of Ocala, Fla. which are hereby incorporated herein in
its entirety by reference. As described in detail below, a spectrum
(e.g., 100-400 KHz) of frequencies for data communications allows
the signal to be communicated in a manner over the power line which
significantly reduces the interference or suppression of the
received signal by other electromechanical systems in the tractor
such as the alternator.
[0071] An antilock braking system monitoring system according to
the present invention may also include a warning indicator 1000 as
shown in FIGS. 10 and 11. The warning indicator 1000 preferably is
packaged with power line carrier transmitter means 320 in a trailer
warning indicator package 1100, producing an "intelligent warning
indicator" as illustrated in FIG. 11. The trailer warning indicator
package 1100 is positioned on trailer 20 so that the warning
indicator 1000 is visible to a tractor/trailer operator 1020
positioned within a tractor cab 1010, as shown in FIG. 10, thus
providing a way to indicate a status of the antilock braking system
100 to a tractor/trailer operator even if the tractor 10 is not
equipped with status determining means 330. For example, the
trailer warning indicator package 1100 can include means, such as a
mounting flange with holes drilled therein, for mounting the
indicator package to the trailer. Preferably, the warning indicator
1000 is powered by the data signal 105, but it will be understood
by those skilled in the art that the warning indicator 1000 may be
directly actuated by the data signal 105 or indirectly actuated by
such devices as relays, lamp drivers and the like. The trailer
warning indicator package 1100 also preferably has an inconspicuous
standard form factor, such as that used for the running lights
commonly used on trailers, to thereby reduce the risk of vandalism
or theft.
[0072] Referring again to FIG. 3, status determining means 330
determines a status 335 of antilock braking system 100 from the
data communications signal 325 superposed on the power bus 30 by
the power line carrier communicating means 320. As shown in FIG. 5,
the status determining means 330 preferably includes power line
carrier receiving means 510 for receiving the data communications
signal 325 from the power bus 30, processing means 520 for
producing a data-modulated digital carrier signal 525 from the
received data communications signal 325, and detecting means 530
for detecting a status 535 of the antilock braking system 100 from
transitions of data-modulated digital carrier signal 525. It will
be understood by those skilled in the art that the status
determining means 330, processing means 520 and detecting means 530
may be centralized or distributed. The status determining means
330, processing means 520 and detecting means 530 may also be
implemented using special purpose hardware or a combination of
special purpose hardware and general purpose hardware running
software.
[0073] FIG. 7 is an electrical schematic diagram of an exemplary
embodiment according to the present invention, illustrating an
electrical circuit which performs functions of status determining
means 330. Data communications signal 325, here an
amplitude-modulated signal produced by a power line carrier
communicating circuit of the type shown in FIG. 5, is received by
the power line carrier receiving means as illustrated by the
resonant tank circuit including capacitors C5 and C6 and inductor
L1 from power bus 30 present at a power bus input node VPWRIN. The
received signal is capacitively coupled through capacitor C7 into
multistage level-changing and shaping circuits including
transistors Q5-Q8. As will be understood by those skilled in the
art, these circuits produce a first data-modulated digital carrier
signal at a first digital carrier signal output node LOGIC with the
same carrier frequency as the received data communications signal
325.
[0074] In the illustrated embodiment, the first data-modulated
digital carrier signal at the first digital carrier signal output
node LOGIC is then divided in counter IC U2 to produce a second
data-modulated digital carrier signal at a second digital carrier
signal output node PIN which has a carrier frequency {fraction
(1/128)}th of the first data-modulated digital carrier signal at
the second node LOGIC. The second data-modulated digital carrier
signal is then input into a programmable controller IC U3 having
operating software which counts transitions of the second
data-modulated digital carrier signal, illuminating an external
light-emitting diode (LED) LED if the number of transitions
occurring in the second data-modulated digital carrier signal
occurring during a predetermined time interval is above a
predetermined threshold, indicating a state of data signal 325.
[0075] FIGS. 8A-B illustrate exemplary operations for the
programmable controller chip U3 of FIG. 7. A pair of software
counters control a main routine 800 and a sampling routine 850. One
of the software counters is a first software hit count which counts
the number of times a transition is detected in the second
data-modulated signal at the second digital carrier signal output
node PIN, while the other software counter is a loop count which
keeps track of the number of times the second data-modulated signal
is sampled during the sampling routine 850.
[0076] The main routine 800 determines if the external
light-emitting diode LED is already in an "on" state 801. If it is,
the sampling routine 850 is called, shown in FIG. 8B. The two
software counts are initialized 851 and the external counter IC U2
is cleared 852. The sampling routine waits to see if a transition
occurs in the second data-modulated digital carrier signal at the
second digital carrier signal output node PIN during a
predetermined time interval, preferably within 823 to 1280
milliseconds from the time the external counter IC U2 is cleared.
If a transition occurs during the predetermined time interval, a
software hit count is incremented 854. If not, the software loop
count is incremented 855. If the loop count is less than a
predetermined number 856, preferably 500, the routine returns to
clear the external counter IC 852. If not, the sampling routine is
exited 857.
[0077] Returning to FIG. 8A, if the program returns to the main
routine 800 from the sampling routine 850 and the software hit
count is less than a predetermined number, preferably 50, the main
program recalls the sampling program 804. The sampling routine is
called three times. After the final iteration 807, if the returned
software hit count is less than a predetermined number, preferably
50, the diode LED is turned off before returning to the main
program 800. If the diode LED is off entering the main 800, the
main routine calls the sampling program once 809. If the returned
software hit count is greater than a predetermined number,
preferably 400, then the diode LED is turned off.
[0078] Techniques for demodulating a modulated carrier signal are
known in other applications. It will be understood by those skilled
in the art that the exemplary operations of FIGS. 8A and 8B provide
sufficient hysteresis in the detection of the transitions of a
modulated digital carrier signal to provide noise-resistant
demodulation of the data-modulated signal 325. It will also be
understood that other means of demodulating data-modulated digital
carrier signal 325 may be used with the present invention.
[0079] FIG. 9A illustrates an aspect of the present invention,
showing status determining means 330 located in tractor 10. Power
bus 30 is shown including a plurality of trailer power lines 910
connected to a plurality of tractor power lines 915 by a connector
920. Connector 920 preferably is an industry standard seven-pin SAE
J560 connector as illustrated in FIG. 2. As shown in FIG. 9B,
status determining means may include an indicator 950, here shown
as a visual indicator 960 mounted on a tractor instrument cluster
970. As will be understood by those skilled in the art that
indicator 950 may include other devices to indicate status of an
antilock braking system to an operator of a tractor/trailer
combination, including visual displays such as CRT's and lights,
and audible annunciators. As will be also understood by those
skilled in the art, status determining means 330 may be positioned
elsewhere, including on the trailer.
[0080] FIG. 12 illustrates another aspect of the present invention,
showing a tractor 10 connected to multiple trailers 20. Trailers 20
may each include an antilock braking system 100 and an antilock
braking system interface 110 producing a data signal 105. Each data
signal 105 may be used to produce a data communications signal 325
which is superposed on the power bus 30. Status determining means
330 determines statuses of antilock braking systems 100 from the
data communications signals 325. It will be understood by those
skilled in the art that although data communications signals 325
may each have a unique predetermined carrier frequency allowing
them to be separately received, power line carrier communicating
means 320 and status determining means 330 may utilize, for
example, time-multiplexing, code-multiplexing or other signal
processing techniques to allow data communications signals 325 to
have the same carrier frequency.
[0081] FIGS. 3-5 illustrate operations for monitoring an antilock
braking system of a tractor/trailer operation according to the
present invention. A data communications signal 325 is produced in
power line carrier communicating means 320 from a data signal 105
representing a status of an antilock braking system 100 produced by
an antilock braking system interface 110. The data communications
signal 325 is superposed on a power bus 30 by power line carrier
communicating means 320. A status 335 of the antilock braking
system 100 is determined from the data communications signal
325.
[0082] The data communications signal 325 may be produced by
modulating a carrier signal 425 having a predetermined carrier
frequency by the data signal 105. The data communications signal
may be superposed on power bus 30 by electrical coupling means 430,
as illustrated by FIG. 4. The data communications signal 325 may be
received by power line carrier receiving means 510, as shown in
FIG. 5. The received data modulated carrier signal may be processed
by processing means 520 to produce a data-modulated digital carrier
signal 525. A status 535 of the antilock braking system 100 is
detected from a count of transitions of the data-modulated digital
signal 525 occurring during a predetermined time interval.
[0083] It has been found, according to the present invention, that
spread spectrum technology, not generally used in tractor/trailer
power line communications, is particularly suitable for the
electrical environment of tractor/trailer systems. The energy of a
spread spectrum data communications signal is spread across a broad
range of frequencies such that even if one component is subject to
coherent interference, the signal can still be reliably recovered.
As the signal energy is widely distributed across a relatively wide
spectrum, spread spectrum data communications systems tend to
interfere less with coherent receivers such as radios. In contrast,
the conventional modulation techniques utilized in some power line
carrier systems is generally susceptible to interference from
coherent electrical signals, such as those generated on the power
bus of the tractor/trailer by switching transients from an
alternator. In addition, because of the coherent nature of
conventionally modulated signals, conventionally modulated signals
may interfere with systems such as citizens', band (CB) radios,
stereo systems, and navigation systems.
[0084] As illustrated in FIG. 13, one advantageous embodiment of
the communications system 1300 for a tractor/trailer combination
according to the present invention includes bidirectional
communicating means 1305 for communicating a first spread spectrum
data communications signal 1341 representing the status of a first
subsystem from a trailer 20 to a tractor 10 and for communicating a
second spread spectrum data communications signal 1311 representing
a command from the tractor 10 to a second subsystem on the trailer
20. As described above, the spread spectrum data communications
signals 1311, 1341 are superposed on the power bus 30 that extends
through the tractor and the trailer. As shown in FIG. 13, first
spread spectrum signal producing means 1340, positioned on a
trailer 20 and responsive to the first subsystem, produces the
first spread spectrum data communications signal 1341 on the power
bus 30. First spread spectrum signal receiving means 1320,
positioned on the tractor 10 and responsive to the power bus 30,
receives the first spread spectrum data communications signal 1341.
Second spread spectrum signal producing means 1310, positioned on
the tractor 10 and electrically coupled to the power bus 30,
produces the second spread spectrum data communications signal
1311. Second spread spectrum signal receiving means 1320,
positioned on the trailer 20 and responsive to the power bus 30,
receives the second spread spectrum data communications signal
1311.
[0085] FIG. 14 illustrates another embodiment of a communications
system 1400 of the present invention for communicating the status
of a subsystem 100, e.g., an antilock braking system, a trailer
refrigeration system, a door sensor and the like. Spread spectrum
signal producing means 1430, positioned on a trailer 20, produces a
spread spectrum data communications signal 1431 on a power bus 30
that represents the status of the subsystem 100. Preferably, the
spread spectrum data communications signal 1431 is produced from a
status signal 101 produced by the subsystem 100 in the manner
described above. Status determining means 1410, positioned on a
tractor 10 and responsive to the power bus 30, determines the
status 1411 of the subsystem 100 from the spread spectrum data
communications signal 1431. Preferably, status determining means
1410 includes spread spectrum signal receiving means 1420, such as
a spread spectrum transceiver as described below, for receiving the
spread spectrum data communications signal 1431. Although the
status signal 101 may be produced by the subsystem 100 in response
to a command as described below, the subsystems themselves may
initiate communications, such as with other subsystems in the
trailer or tractor, if so desired.
[0086] FIG. 15 illustrates yet another embodiment of a
communications system 1500 of the present invention for
communicating a command from a tractor 10 to a subsystem 100, e.g.,
an antilock braking system, a trailer lighting system, and the
like, in a trailer 20. Spread spectrum signal producing means 1510
produces a spread spectrum data communications signal 1511
representing the command, on a power bus 30. Controlling means 1520
controls the subsystem 100 based on the spread spectrum data
communications signal 1511. Preferably, the controlling means 1520
includes spread spectrum signal receiving means 1522 for receiving
the spread spectrum data communications signal 1511.
[0087] As illustrated in FIG. 16, the various means illustrated in
FIGS. 14 and 15 may be included in a tractor communications module
1610 and a trailer communications module 1630, each of which are
connected to the power bus 30. The trailer communications module
includes a communications module housing 1635, which houses the
module components, and means 1632 for mounting the housing 1435 to
a trailer, such as a mounting flange with holes drilled therein.
The trailer communications module 1630 also preferably includes
means 1640 for electrically connecting the module to the power bus
30, a status signal input 1651, and a command signal output 1652,
here illustrated as pigtail connections, although those skilled in
the art will understand that other devices may be employed for the
connecting means 1640, the input 1651 and the output 1652, such as
connectors.
[0088] Likewise, the tractor communications module 1610 preferably
includes a communications module housing 1615 which houses the
module components, and means 1518 for mounting the module 1610 to a
tractor, such as a mounting flange with mounting holes drilled
therethrough. The tractor communications module 1610 also
preferably includes an indicator, such as an alphanumeric display
1612 and LED displays 1616 which indicate the status to an
operator, operator input means, such as a membrane switch 1614
positioned on the module 1610, for receiving a command from an
operator, as well as means 1620, such as a pigtail connection, for
electrically connecting the module 1610 to the power bus 1620.
Although the command may originate with the operator, the
communications system of the present invention can be designed to
transmit commands to the various electrical subsystems on the
trailer that are generated automatically, such as according to a
predetermined schedule or in response to a particular event. Among
other things, the command may request that one or more subsystems
provide status or other data.
[0089] Although not illustrated, one or both of the trailer
communications module 1630 and the tractor communications module
1610 can include one or more lights, such as LEDs, for providing a
visible indication of the status and current operations of the
module. For example, the modules can include a green LED that is
illuminated when the module is receiving power and is operating
properly. In addition, the modules can include red and yellow LEDs
which are illuminated or flash when the module is transmitting and
receiving spread spectrum data communications signals,
respectively. Further, the modules can include addition LEDs to
indicate the protocol of the data being communicated, as described
below.
[0090] A preferred embodiment of a trailer communications module
1630 includes the spread spectrum signal producing means 1430 of
FIG. 14, and the controlling means 1520 of FIG. 15, implemented as
shown in FIG. 17 using a microcontroller 1720 connected to input
and output buffer circuits 1730, 1740 and a spread spectrum
transceiver 1710, preferably a CEBus compliant transceiver such as
the above-mentioned CEBus-compliant devices produced by the
Intellon Corporation. In particular, these devices employ spread
spectrum techniques and contention-resolving/collis- ion detecting
data transfer protocols to improve data communications, as
described in U.S. Pat. No. 5,090,024 to Vander Mey et al. These
devices are designed to interface with a microcontroller or similar
data processor via a parallel or serial data interface, producing
spread spectrum data packets from data received from the processor
over the interface and converting spread spectrum data packets into
conventional digital signals which are conveyed to the data
processor over the data interface.
[0091] In a preferred embodiment of a tractor communications module
1630, the status determining means 1420 of FIG. 14 and the spread
spectrum signal producing means 1510 of FIG. 15 are similarly
implemented using a microcontroller 1720 and a spread spectrum
transceiver 1710, as illustrated in FIG. 18. In the tractor
communications module 1630, however, the microcontroller 1720
interfaces with operator input means 1614 and an indicator 1612, to
receive commands from an operator and to indicate status to the
operator. The use of microcontrollers to control displays and
receive inputs from input devices is well-known to those skilled in
the art, and need not be discussed in detail herein.
[0092] As illustrated in FIG. 19, the tractor communications module
1610 may be mounted on the instrument cluster 970 of a tractor,
such that the indicators 1612, 1614 are viewable by an operator
positioned in the tractor 10, and the operator input means 1514 is
accessible to the operator.
[0093] As shown schematically in FIG. 20, the power bus 30
oftentimes supplies power to a number of subsystems 100 on one or
more trailers 20. According to one particularly advantageous
embodiment, the communications system 2000 is designed to
communicate or otherwise broadcast the respective status of each of
the plurality of subsystems 100 via the power bus 30. Moreover, the
communications system 2000 of this advantageous embodiment is
designed to communicate the respective status of each of the
plurality of subsystems 100 even through the subsystems communicate
according to at least two different protocols. For example, the
subsystems 100 can include an antilock braking system that
communicates according to a J-1708 protocol and a refrigeration
unit that communicates according to an RS-232 protocol.
[0094] According to this embodiment, the trailer communications
module 2020 and, more particularly, the spread spectrum signal
producing means preferably includes a plurality of protocol
specific transmitters 2010 associated with respective ones of the
subsystems 100. As shown in FIG. 20, each subsystem generally
includes a protocol specific transmitter 2010 that converts the
digital signals otherwise provided by the subsystem to signals
having a predetermined protocol for transmission to the trailer
communications module 2020. For example, the protocol specific
transmitters 2010 can include an RS-485 transceiver associated with
each antilock braking system for converting digital signals to
J-1708 signals for transmission to the trailer communications
module 2020. In addition, the protocol specific transmitters can
include an RS-232 transceiver associated with a refrigeration unit
for converting digital signals to RS-232 signals for transmission
to the trailer communications module 2020. The conversion of the
digital signals to another specific signal protocol, such as J-1708
and RS-232, prior to transmission of the signals to the trailer
communications module 2020 is particularly important since signal
protocols, such as J-1708 and RS-232, provide more robust signal
transmission capabilities and reduce the deleterious impact of
noise on the signals than otherwise provided by the transmission of
signals having conventional TTL logic levels. Although J-1708 and
RS-232 signal protocols are described herein, the protocol specific
transmitters can be designed to receive and process signals
formatted according to any desired protocol. For example, the
protocol specific transmitter can be designed to receive and
process signals formatted according to a J1850, J1939, RS 170 or
ISO protocol, if so desired.
[0095] As also shown in FIG. 20, the trailer communications module
2020 also includes protocol specific transceivers 2015 for
receiving the signals from the subsystems 100 and reconverting the
signals to digital signals having TTL logic levels, for example.
The trailer communications module 2020 of FIG. 20 includes protocol
specific transceivers 2015 that communicate with multiple
subsystems 100, all of which communicate according to the same
protocol, i.e., subsystems 1, 2 and 3 of FIG. 20. However, the
trailer communications module 2020 can include a dedicated protocol
specific transceiver 2015 for each subsystem, if so desired.
[0096] The spread spectrum signal producing means of this
embodiment also preferably includes means for producing spread
spectrum data communications signals representative of the status
of respective ones of the subsystems 100 based upon the signals
provided by the subsystems via the protocol specific transceivers
2010, 2015. As shown in FIG. 20 and as described above, the means
for producing spread spectrum data communications signals typically
includes a spread spectrum transceiver 2030 for converting the
digital signals provided by protocol specific transceivers 2015 to
spread spectrum data communications signals for transmission via
the power line 30, and vice versa. Based upon the spread spectrum
data communications signals transmitted via the power line 30, the
status determining means of the communications system 2000 of this
embodiment can determine the status of respective ones of the
plurality of subsystems, i.e., the status of the antilock braking
system and the status of the refrigeration unit. As described
above, the status determining means as well as any associated
indicator or warning system is typically included in the tractor
communications module mounted in the cab of the tractor 10.
[0097] The protocol specific transceivers 2010, 2015 preferably
employ conventional collision avoidance and collision detection
techniques in order to minimize collisions between signals intended
for the spread spectrum transceiver 2030. The protocol specific
transceivers 2010, 2015 also preferably employ conventional
techniques from recovering from any such collisions that are
detected such that the communications system 2000 of this
embodiment of the present invention will continue to function
properly. As known to those skilled in the art, conventional
collision avoidance techniques involve assigning different
priorities and, correspondingly, different waiting times to each of
the protocol specific transceivers 2010, 2015, while conventional
collision recovery techniques involve one or more retransmissions
of the signal following various waiting periods. However, the
communications system 2000 and, more particularly, the protocol
specific transceivers 2010, 2015 can include other collision
avoidance and collision recovery techniques known to those skilled
in the art without departing from the spirit and scope of the
present invention.
[0098] In addition to broadcasting spread spectrum data
communications signals from the subsystems 100 to the status
determining means, the communications system 2000 of this
embodiment can also receive signals, such as commands (or other
data) requesting particular types of data including the status of a
particular subsystem, that are broadcast via the power bus 30.
Although only a single trailer communications module 2020 is
illustrated in FIG. 20 as being attached to the power line 30, each
trailer typically includes one or more trailer communications
modules 2020 (also referred to as a bridge). Thus, the
communications system 2000 of a tractor/trailer combination that
includes multiple trailers 20 will preferably include multiple
trailer communications modules 2020, one of which is positioned on
each trailer and each of which may communicate with a number of
subsystems 100 within the respective trailer 20. As such, commands
or data broadcast via the power bus 30 will be received by the
spread spectrum transceiver 2030 of each respective trailer
communications module 2020. The spread spectrum transceivers 2030
will convert the spread spectrum data communications signal that
represents the command or data to a digital signal for presentation
to the protocol specific transceivers 2015 of the trailer
communications module 2020. Typically, the digital signal that is
presented to the protocol specific transceivers 2015 of the trailer
communications module 2015 includes an address or destination
identifying the specific subsystem to which the command or data is
directed as well as the address of the source or origin of the
command or data. Alternatively, the command or data could be
proceeded by a message broadcast via the power bus 30 that the
ensuing command is intended for only one particular subsystem 100
or one particular class of subsystems, such as the antilock braking
systems on each of the trailers 20. The message that identifies the
subsystem to which the ensuing command or data is directed may be
interpreted by the protocol specific transceivers 2015 themselves
or by a microprocessor 2040 associated with the spread spectrum
transceiver 2030 and the protocol specific transceivers as shown in
FIG. 20.
[0099] Alternatively, each trailer communications module 2000 can
include a selection input that can be used to select either the
particular subsystem 100 or class of subsystems with which
communication will be established. For example, the select line of
the trailer communications module 2000 of the illustrated
embodiment may be used to select either those subsystems that
communicate according to J-1708 protocol, i.e., subsystems 1, 2 and
3, or the subsystems that communicate according to RS-232 protocol,
i.e., subsystem 4. The select line may be hardwired during system
installation if the trailer communications module 2020 will be
communicating with either a particular subsystem or a particular
class of subsystem. As such, a universal trailer communications
module 2020 or bridge that has the capability for communicating
with a wide variety of subsystems may be installed and subsequently
configured to optimize communications with the subsystems of
interest.
[0100] In embodiments of the communications system 2000 of the
present invention that include a spread spectrum transceiver 2030
that both receives and transmits signals, the spread spectrum
transceiver 2030 preferably includes means 2050 for determining the
state of the transceiver. In particular, the spread spectrum
transceiver preferably includes a state register or an associated
microprocessor 2040 which continuously identifies the state of the
spread spectrum transceiver 2030, i.e., either receiving or
transmitting. As such, the signals transmitted by the spread
spectrum transceiver 2030 will not be received and processed by the
spread spectrum transceiver but will, instead, be recognized as
having been transmitted by the spread spectrum transceiver, thereby
avoiding erroneous signal reception and transmission by the spread
spectrum transceiver 2030.
[0101] As described above, the communications system 2000 and, more
particularly, the spread spectrum signal producing means of one
embodiment includes a plurality of spread spectrum transmitters
2030, typically spread spectrum transceivers, responsive to one or
more subsystems 100 for producing spread spectrum data
communications signals representative of the status of the
respective subsystems. In this embodiment, the spread spectrum
signal producing means preferably includes self-diagnostic means
2060 associated with at least one of the spread spectrum
transmitters 2030 for monitoring the signals provided to the
respective spread spectrum transmitter and for halting further
transmission from the respective spread spectrum transmitter to the
remainder of the communications system 2000 if the self-diagnostic
means determines that the signals provided to the respective spread
spectrum transmitter are indicative of a malfunctioning or
otherwise defective subsystem 100 or protocol specific transceiver
2010, 2015. As a result, the remainder of the communications system
2000, including the remainder of the spread spectrum transmitters
2030, can continue to operate in an otherwise normal fashion.
[0102] Although the spread spectrum transceiver 2030 can include
the self diagnostic means 2060, the trailer communications module
2020 of the illustrated embodiment includes a microprocessor 2040
that includes the self-diagnostic means. The self-diagnostic means
is typically embodied by a combination of hardware and software
which cooperate to monitor the standardized signals provided to the
spread spectrum transceiver 2030 by the associated signal protocol
transmitters 2015. Although a variety of techniques can be utilized
to determine if the signals provided to the spread spectrum
transceiver 2030 are inaccurate, the self-diagnostic means 2060 of
one embodiment analyzes the signals to determine: (1) if the data
is nonsensical, and/or (2) if the check sum as well as any address
data associated with the signals are incorrect. For example, the
self-diagnostic means 2060 may determine that the signals provided
to the spread spectrum transceiver 2030 are inaccurate if the
signal remains at the same signal level for an extended time
period. More specifically, if the signals provided to the spread
spectrum transceiver 2030 remain high for 20 or more bit times, the
self-diagnostic means 2060 may determine that a subsystem 100 or a
protocol specific transceiver 2010, 2015 is malfunctioning or is
otherwise defective. As a result, the self-diagnostic means 2060
will generally prohibit the spread spectrum transceiver 2030 from
producing spread spectrum data communications signals for broadcast
via the power bus 30. Instead, the spread spectrum transceiver 2030
would either be inactivated or would transmit a message via the
power bus 30 to the operator that some type of error has occurred.
Thereafter, the self-diagnostic means 2060 can periodically
reexamine the signals provided to the spread spectrum transceiver
2030 to determine if the signals now appear to be proper, in which
case the spread spectrum transceiver could again be activated.
[0103] In order to permit the communications system 2000 of the
present invention to effectively broadcast a spread spectrum data
communications signal representing the status of a first subsystem
on the power bus 30, the communications system of one advantageous
embodiment further includes spread spectrum blocking means 2070
associated with respective one of the other subsystems 100, as
shown in FIG. 21. The spread spectrum blocking means 2070 protect
the spread spectrum data communications signals placed on the power
bus 30 by the spread spectrum signal producing means from
attenuation by the other subsystems 100. Typically, the spread
spectrum blocking means 2070 is disposed between each subsystem 100
and the power bus 30 as shown in FIG. 21.
[0104] In one embodiment, the spread spectrum blocking means 2070
include a plurality of inductive elements associated with
respective ones of the subsystems 100. Alternatively, the spread
spectrum blocking means 2070 can include a plurality of ferrite
beads associated with respective ones of the subsystems 100. In any
event, the spread spectrum blocking means 2070 is designed to
prevent or at least significantly reduce the filtering or other
attenuation of the spread spectrum data communication signals that
would otherwise be performed the other subsystems 100 electrically
connected to the power bus that are specifically designed in some
instances to filter out high frequency signals including at least
some spread spectrum signals. As such, the status determining means
of the communications system 2000 can receive and process a spread
spectrum data communications signal without concern that the spread
spectrum data communications signal has been significantly
attenuated or otherwise distorted by the other subsystems 100.
[0105] The power bus 30 also typically supplies electrical power to
a plurality of electrical loads 2080 within the tractor 10, as
shown in FIG. 22. In order to prevent attenuation or other
distortion of the spread spectrum data communications signals by
the plurality of other electrical loads 2080 within the tractor 10,
the spread spectrum signal producing means of the tractor
communications module 2090, including the spread spectrum
transceiver 2030, is preferably electrically connected to the
tractor power line at a point nearer the connector 2100 than the
respective points at which the plurality of electrical loads 2080
are electrically connected to the tractor power line. More
particularly, the communications system 2110 of this embodiment can
include a capacitor 2120 disposed between the spread spectrum
signal producing means and the respective tractor power line to
couple the spread spectrum data communications signals to the
respective tractor power line with little, if any, distortion or
attenuation arising as a result of the other electrical loads 2080
within the tractor 20 that are electrically connected to the power
bus 30.
[0106] As shown in FIG. 22, the tractor communications module 2090
can also include a load dump circuit 2130 for protecting the spread
spectrum transceiver 2120 from voltage spikes or other excessive
voltages. In addition, the tractor communications module 2090 can
include a regulator 2190, such as a +5V regulator, for providing a
regulated voltage to the spread spectrum transceiver 2120 and any
associated circuitry, such as microprocessor 2150.
[0107] According to one advantageous embodiment, the power bus 30
also includes a first capacitor 2160 disposed between at least two
of the trailer power lines, i.e., the first plurality of
conductors, and a second capacitor 2170 disposed between at least
two of the corresponding tractor power lines, i.e, corresponding
ones of the second plurality of conductors. Since the spread
spectrum signal producing means of this embodiment including the
respective spread spectrum transceivers 2180, are electrically
connected to one of the capacitively coupled power lines as shown
in FIG. 23, the spread spectrum data communications signals are
transmitted via each of the capacitively coupled power lines. As a
result, the communications system of this embodiment provides
redundancy if one of the power lines should fail or have some other
problem.
[0108] Thus, the communications system of the present invention
preferably utilizes spread spectrum data communications signals in
order to reduce interference and other distortion with other
electrical devices within the tractor/trailer combination. In
addition, the communications systems described above further
optimize the transmission and reception of spread spectrum data
communications signals to permit reliable communication with a wide
variety of subsystems 100 that may transmit and receive signals
according to different signal protocols. In addition, the
communications systems of the above-described embodiments are
specifically designed to minimize the deleterious impact of other
subsystems or electrical loads that are electrically connected to
the power bus 30 and to provide self-monitoring to identify
inaccurate signals prior to the broadcast of those signals via the
power bus, thereby avoiding corruption of the power bus with
inaccurate signals.
[0109] In the drawings and specification, there have been disclosed
typical preferred embodiments of the invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for purposes of limitation, the
scope of the invention being set forth in the following claims.
* * * * *