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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to tracking and monitoring the intermodal
movement status of mobile assets such as cargo containers.
Mobile asset management is a major concern in various transportation
industries such as trucking, railroad and rental cars. In the trucking
industry, the asset manager has to keep track of the status and location
of each tractor and trailer in a fleet. The asset manager should also know
whether each asset is in service (i.e., being transported by a tractor or
other means) or out of service (i.e., not being transported by a tractor
or any other transportation means). The asset manager should have similar
information with respect to whether each tractor in the fleet is hauling a
trailer or is not, and thus available for service. The asset manager
should also be able to monitor the progress of each tractor and trailer
according to plan for scheduling purposes.
Systems for tracking and monitoring mobile assets for fleet management are
generally known. These systems typically include various sensors and
communication units. Trucking companies usually install the sensors and
communication units on the mobile units, e.g., the tractor or cargo
trailers. The sensor determines the status and location, checks for proper
operating conditions and any misuse, and monitors the progress of each
tractor and coupled trailer for scheduling and security purposes.
In the transportation industry, it is also common for a trailer to be moved
by railroad cars, known as piggybacking. When this happens, there is no
tractor hauling the trailer, and thus no driver. As a result, there is a
lack of security that the driver normally provides when the tractor is
hauling the trailer. In addition, since the tractor equipped with tracking
and monitoring system devices is not coupled to the trailer, the owner of
the trailer loses visibility of the trailer's location and status while
the trailer is in transit on railroad cars. Although some railroads
provide status messages to the owners of trailers, this is not always
available or reliable.
SUMMARY OF THE INVENTION
There is a need to monitor equipment and shipments when intermodal move is
in progress, i.e., in transit by rail. In addition, there is a need for
frequent location reports of the trailers during such a transit for more
efficient asset management.
The present invention is a system for tracking and monitoring the
intermodal status of cargo trailers. The system of the present invention
uses various asset tracking and monitoring sensors on a trailer, including
a location determining sensor and a wheel movement sensor. The present
invention determines the intermodal status of the trailer with a high
level of reliability. In addition, the system of the present invention can
be incorporated with existing complete cargo tracking systems to provide
the intermodal status information with other monitoring and reporting
features.
The system includes a sensor for providing data relating to the movement of
the trailer and a wheel monitoring unit for monitoring the status of the
trailer wheels. Wireless radio communication equipment transmits the
trailer movement and wheel information data to a central station. A
communications system, such as a cellular telephone system or paging
system, is used to provide the wireless data links required between the
trailer and central station. The central station receives the trailer
information data and inputs the data to a processor. The processor
determines the intermodal movement status using the trailer movement and
wheel rotation data.
More specifically, the processor receives location or velocity information
from the location sensor in combination with wheel rotation information,
in particular whether there is rotation of the wheels or not. For example,
if the location sensor indicates that the trailer is moving, but the wheel
monitoring unit indicates that the wheels are not rotating, then the
processor determines that an intermodal move is in progress. In contrast,
if the location sensor indicates that the trailer is moving and the wheel
monitoring unit indicates that the wheels are rotating, the processor
determines that an intermodal move is not in progress. In addition, since
an intermodal move is not in progress, the processor can deduce that a
tractor is coupled to the trailer and moving the trailer.
A Global Positioning System (GPS) unit is used to provide data relating to
the location and/or velocity of the trailer. If successive location
reports are available, then position changes in successive location
reports may be used rather than using GPS velocity data.
Signal information indicative of the wheel rotation status can be provided
by anti-lock braking systems that are standard on trailers. Alternatively,
an independent wheel rotation sensor is used to provide wheel rotation
status.
In accordance with the invention, appropriate filters are applied to the
GPS movement data to assure that the trailer movement and wheel status
information is accurate. As a result, intermodal status errors caused by a
small change in trail movement and wheel rotation status are eliminated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of a system for providing intermodal movement status of
cargo trailers according to the invention.
FIG. 2 is a block diagram showing in further detail the system for
providing intermodal movement status as shown in FIG. 1.
FIG. 3A is a block diagram of a cargo trailer including the processor shown
in as FIG. 2.
FIG. 3B is a block diagram of a cargo trailer using an anti-lock braking
system and a global positioning system unit according to the invention.
FIG. 4 is a flow chart of a method which may be performed in accordance
with the invention.
FIG. 5 is a flow chart of the operations performed by the processor to
determine the intermodal movement status of the trailer as shown in FIGS.
1-3.
The foregoing and other objects, features and advantages of the invention
will be apparent from the following more particular description of
preferred embodiments of the invention, as illustrated in the accompanying
drawings in which like reference characters refer to the same parts
throughout the different views. The drawings are not necessarily to scale,
emphasis instead being placed upon illustrating the principles of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, FIG. 1 is a high level diagram of a system
10 for providing intermodal movement status of cargo trailers according to
the invention. The system 10 includes trailers 160, railroad cars 140,
tractors 150, a central station 130, and one or more GPS satellites 100.
The system 10 makes use of a two-way communication system to permit the
transmission of data to and from a radio subscriber unit 260 located on a
cargo trailer 160 to a central hub station 130.
More specifically, the two-way communication system includes one or more
communication satellites 110, satellite links 180, base stations 120, and
base station links 170. The trailers 160 may transmit data signals 170 to
the central station 130 via the base stations 120. The trailers 160 also
communicate with the central station 130 via satellites 110 or a
combination of satellites 110 and base stations 120.
Such a communication system may preferably be implemented according to U.S.
Pat. No. 5,734,963 issued to Fitzgerald et al. and assigned to Terion,
Inc., the assignee of the present application, which application is hereby
incorporated by reference in its entirety. It has been suggested that this
system can be used to track the location of shipping containers carried on
ocean going vessels, as described in U.S. Pat. No. 5,995,804 issued to
Rootsey et al., which application is also incorporated by reference herein
in its entirety.
Other types of two-way communications systems, such as cellular telephone
systems or two-way paging systems may be used to provide the wireless data
links required between the trailers 160 and the central station 130.
In FIG. 1, some of the trailers 160 are on railroad cars 140 and the other
trailers 160 are hauled by tractors 150. Although it is not illustrated in
FIG. 1, it is understood that there exist parked trailers 160 that are not
in service and thus not in transit.
FIG. 2 is a block diagram showing in further detail the system 10 for
providing intermodal movement status as shown in FIG. 1. The trailer 160-2
includes a sensor 240-2 and a monitoring unit 250-2 both connected to a
transmitter 230-2. The location sensor 240-2 provides data relating to the
movement of the trailer 160. In particular, the location sensor 240-2,
such as a GPS unit, provides position and velocity data. One or more GPS
satellites 100 provides highly accurate navigation signals 190 which can
be used to determine trailer location and velocity when the signals 190
are acquired by the GPS unit. The location sensor 240-2 is connected to
the transmitter 230 to transmit the trailer movement data to the central
station 130.
The transmitter 230-2 receives the trailer movement and wheel status data
from the location sensor 240-2 and the monitoring unit 250-2. Then, the
transmitter 230-2 transmits signals 210-1 to the central station 130.
The trailers 160-1 and 160-2 further include subscriber unit 260-1 and
260-2 that are connected to various sensors on the trailers160-1 and
160-2, to receive data indicating the status of the trailer and forwarding
the trailer information data to the transmitters 230-1 and 230-2. The
trailer information data provided by various senors include
loaded/unloaded status, trailer door activity, and mileage.
The monitoring unit 250 monitors the status of one or more wheels 105. In
particular, the monitoring unit 250 detects whether there is rotation of
the wheels or not. The monitoring unit 250 is also connected to the
transmitter 230 to transmit the wheel rotation data to the central station
130. An independent wheel rotation sensor may be used to detect rotation
of the wheels 105.
The central station 130 receives the trailer information data signals 220
from the transmitter 230 and inputs the trailer data to a processor 200.
The central station has a communication link to users, such as asset
managers, to provide the intermodal status of each trailer in the fleet.
The processor 200 determines the intermodal status of the trailers 160
using the trailer movement and wheel information. For example, if the
location sensor 240 indicates that the trailer 160 is moving, but the
wheels 105 are not rotating, then the system 10 determines that an
intermodal move is in progress. Appropriate filters should preferably be
applied to the GPS movement data to assure that the trailer movement and
wheel status data is accurate. Furthermore, location reports from
different sensors may be used rather than velocity data to provide the
trailer movement data.
FIG. 3A is a block diagram of the cargo trailer 160-4 including the
processor 200. The cargo trailer 160-4 further includes the processor 200
connected to the subscriber unit 200 to receive the trailer movement and
wheel status data and determine the intermodal status of the trailer
160-4. So, the intermodal status of the trailer 160-4 is determined by the
processor at the trailer 160-4 and sends the intermodal status data to the
transmitter 230-4 for transmitting to the central station 130.
FIG. 3B is a block diagram of the cargo trailer 160-5 using the anti-lock
braking system 310 to detect rotation of the wheels. Besides an
independent wheel sensor, the existing anti-lock braking system 310, which
is becoming standard on trailers, can be used to detect rotation of the
wheels 105. The anti-lock braking systems 310 include inductive wheel
rotation speed senor system to control the anti-lock braking mechanism.
Such a wheel rotation speed sensor used in anti-lock braking systems
provides the wheel rotation status of the trailer 160-5.
The invention can also be implemented as a sequence of process steps as
shown in FIG. 4. The steps may be carried out by the hardware components
shown in FIGS. 1-3.
After an initial process step, a step 405 is performed where at least one
of the wheels is monitored by the wheel monitoring unit 250. Control then
passes to step 410.
In this step 410, the location sensor 240 provides the trailer movement
data to the transmitter 230 and control passes to step 420.
In step 420, the trailer movement data and wheel status information is
transmitted to the central station 130.
Control then proceeds to step 430, the central station 130 receives the
trailer movement and wheel status data. Control then passes to step 440.
In step 440, the intermodal status of the trailer 160 is determined.
Although not shown, it is understood that step 440 can be performed where
the intermodal status is determined at the trailer 160 and then proceed to
step 420 where the intermodal status is transmitted to the central station
130. So that in step 430, the central station receives the intermodal
status data.
FIG. 5 is a flow chart of the operations performed by a processor 200 to
determine the intermodal movement status of the trailer as shown in FIG.
4.
As described above, in step 430, the central station receives the trailer
movement and wheel status data and control passes to step 500.
In this step 500, if movement of the trailer is detected then control
passes to step 520. If no movement is detected then control returns to
step 430.
In step 520, the computer processor 200 checks rotation of the wheels.
Control passes to step 530.
In step 520, if the wheels have rotated then control passes to step 550. If
the wheels have not rotated then control passes to step 540.
In step 540, it is determined that the intermodal move is in progress.
In step 550, it is determined that the intermodal move is not in progress
and the tractor 150 is hauling the trailer 160.
While this invention has been particularly shown and described with
references to preferred embodiments thereof, it will be understood by
those skilled in the art that various changes in form and details may be
made therein without departing from the scope of the invention encompassed
by the appended claims.
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