| The Automated Shuttle Carrier (AShC)
Concept
As a smaller version of the Automated Straddle Carrier, the Automated
Shuttle Carrier is a concept designed to operate alongside Rail
Mounted Gantries (RMGs) in a state of the art, Automated Container
Terminal.
Unlike the Straddle Carrier, the Automated Shuttle Carrier will
not be used extensively for stacking containers. Lower in height
and faster over the ground, the Automated Shuttle Carrier is designed
to quickly and efficiently transfer containers around the Terminal.
By combining those advantages from the Automated Shuttle Carrier
with the advantages of Automated Rail Mounted Gantries, both Terminal
logistics and stacking capabilities will be improved.
The Automated RMGs will make very efficient use of ground space,
and automation will allow for continual, inexpensive movement
of containers around the stack to suit all ongoing demands.
Systems
The same ASC system design is used for the Automated Shuttle Carrier,
and the Hi-tech Navigational systems will allow free ranging movement,
suitable for use in any Terminal worldwide.
The same Traffic Management Systems will control the movement
of Automated Shuttle Carriers and also the RMGs, acting as the
first level of collision avoidance between them, and effecting
a highly productive operation.
The AShC systems will Interface with standard Terminal Operations
systems, facilitating the introduction of the AShC either as a
replacement for less efficient equipment, or even as a complete,
new operation.
But Automatic Guided Vehicles (AGVs) are already used with Automated
RMGs to transfer containers between stacks and ship to shore cranes,
so why is automation of the Shuttle Carrier so significant?
The AGV and the Automated Shuttle Carrier both offer similar
reductions in manning costs, but operationally they are very different.
Logistics and Productivity - AGVs
As AGVs do not have their own lifting mechanism, they cannot operate
independently when exchanging containers, and so productivity
is often lost.
The logistics chain relies on Resource Management Systems effecting
simultaneous arrival of AGVs and RMGs at container exchange points.
If this is not achieved, and often it is not, one machine will
have to wait for the other, and for that period will be non productive.
Simultaneous arrival at the exchange point requires the travel
time for each piece of equipment to be exactly the same. Of course
the Traffic Management System could slow down either the AGV or
the RMG to achieve this, but reduced speed nevertheless means
reduced productivity.
The same problem arises at the interface between ship to shore
cranes and AGVs. The ship to shore crane will rely on the AGV
always being under the crane and ready to accept a container being
discharged. When the ship to shore crane is loading, the AGV often
has to wait it's turn until the crane is ready to remove the container
from the AGV before the AGV can continue to collect another container
for loading.
To compensate for the loss of productivity, the AGV fleet size
is usually greater than the fleet of an independent and more productive
type of equipment.
Logistics and Productivity - Automated Shuttle Carriers
The Automated Shuttle Carrier is a fully independent piece of
equipment, able to exchange boxes without relying on other equipment,
and offers significant operational advantages over the AGV in
both productivity and logistics.
Neither the RMG nor the ship to shore crane operation is interrupted
from awaiting the arrival of the Shuttle Carrier, and similarly
the Shuttle does not rely on the arrival of the RMG or crane to
continue it's work.
The free ranging flexibility of the Automated Shuttle Carrier
will allow Traffic Management Systems to minimise congestion,
through almost an unlimited choice of routes.
AGV travel is normally controlled over a specific route, using
underground or other fixed sensors to manage the Traffic Routing.
This, combined with the greater number of AGVs, does little to
manage congestion.
Buffers
The 'buffer' concept is an effective operational tactic. It is
something that allows for the continual operation of the Terminal
even when the unexpected may occur. A 'buffer' or reserve quantity
of boxes in the RMG exchange area, for example, allows the crane
operation to continue for some time should there be a failure
of the RMG and transfer to the shuttle exchange is halted.
The independence of the Automated Shuttle Carrier will allow
for extensive use of such a concept.
In the AGV operation however, the buffer concept simply cannot
be operated in this fashion. As a non-independent link in the
logistics chain, the only solution is to create the 'buffer' capacity
actually on the AGVs, reducing equipment productivity, and then
only by increasing the AGV fleet and cost.
Twin lifting (two containers lifted simultaneously)
The AGV is able to transfer two twenty-foot containers at the
same time either to the ship to shore crane or the RMG, ready
for twin lift crane or RMG operation. This has always been an
advantage over the conventional straddle carrier operation, but
the shuttle/RMG concept design again matches this.
The use of Automated RMGs alongside Automated Shuttle Carriers
allows for precise pre-positioning of two compatible twenty-foot
containers, ready for collection with twin lift AShC spreaders
at the exchange point.
The automated RMGs will consolidate suitable pre-planned exports
ready for twin lift transfer to Automated Shuttle Carriers, for
twin lift shuttle transfer from RMG exchange to ship to shore
cranes, and 'twin lift' ship loading - and of course the reverse
for discharge operations.
Automation
The drive towards full automation continues and the development
of systems by Patrick Technology heralds a major milestone in
Container Terminal operational design.
The Automated Shuttle Carrier and the Automated Straddle Carrier
have been designed specifically to allow for ease of introduction
and operation anywhere worldwide.
Position Detection System (PDS)
A major ongoing issue confronting container handling operations
is the tracking of containers within the storage area.
Inefficiencies in this operation lead to significant time delays
locating containers for eventual customer delivery. Conventional
management of this process depends on manual entry or confirmation
of container positions by control staff or equipment operators.
Most container stevedoring operations experience significant position
recording error rates, resulting in costly interruptions to ship
load cycles or truck turnaround delays.
Patrick Technology & Systems has developed a Differential
Global Position Systems (GPS) based Position Detection System,
(PDS). By using state of the art GPS equipment, the system can
accurately track all container movements by providing the position
of container handling equipment as containers are handled.
All container movements are controlled by the Patrick Equipment
Control System. Each time a carrier picks up or sets down a container
the system senses the twist-lock activation and calculates a position
utilising the DGPS sensor. This high performance GPS receiver
calculates real time, positions to an accuracy of between 10 to
30 cm, while in motion around the yard. The position generated
by the GPS receiver is passed to an onboard micro-controller,
which collects vehicle status information, and controls transmission
of the information back to the central computer. This data is
transmitted using radio data. The central computer converts the
position to local co-ordinates and passes the information to the
control system (which generated the original movement request).
The terminal control system carries out post processing to evaluate
the quality and the validity of the position returned. Over 99.5%
of positions are correct and positions that are suspect are identified
and flagged for later checking.
The vehicle-mounted unit comprises of the PTS Processor,
a GPS receiver and antennae, and a radio data modem.
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Communicates with the vehicles PLC or control
processor |
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Receives continuous differential correction
information and passes this to the on board GPS receiver receives
continuous DGPS readings |
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Receives continuous DGPS readings |
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Checks the validity of position solutions |
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Provides watch-dog functions to the on-board
systems |
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Interfaces to the central message handler and
display manager via wireless data modems |
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Sends raw position and status information on
twist-lock activation to the central message handler and period
position information to the central display manager. |
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The NovAtel GPS receiver provides kinematic position resolution.
The receiver uses differential correction information to calculate
locations down to the sub-meter capability required for container
position resolution. A specialised GPS antenna incorporating
magnetic choke rings are utilised to mitigate 'close in' multi-path
affects and to improve antennae performance. |
The central messaging console controls the passing of
information between the host system, the differential reference
receiver and the vehicle mounted unit. Information provided to
the host includes:
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straddle identification |
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container location |
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position quality |
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container size |
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date and time |
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carries out systems integrity and provides monitoring facilities
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translation of Cartesian 3 dimensional co-ordinates to local
survey co-ordinates in which the yard map is stored |
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provides facilities for remote diagnostics and software
down-load capabilities for the vehicle mounted hardware. |
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The host interface handles the messaging between the PDS
and the terminal control system. It uses the yard map information
to convert the raw position information to yard slot numbers.
The interface evaluates the quality of the position data by rationalising
the data received with yard configuration and movement request
information.
The radio data network utilises spread spectrum radio modem
technology to transfer differential position and systems data
to and from the straddle carrier.
Summary
The system has been in successful operation at the company's Port
Botany and East Swanson Dock sites since 1998. Reliable container
positioning is essential for the elimination of straddle to crane
pooling and the introduction of expert grounding systems. The
system greatly assists electronic control of the shipload operation
by eliminating interruptions caused by lost containers. The introduction
of PDS within Patrick terminals has played an important role in
the major labor and productivity reforms achieved by Patrick Terminals
over the past 2 years.
The positioning technology has now been adapted for providing
container positions under the quay crane as part of Patrick's
advanced optimisation system. The technology can be easily transferred
to other container handling equipment such as rubber tyred or
rail mounted gantries.
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