Home' MHD Supply Chain Solutions : MHD Spt-Oct 2014 Contents T
he Automated Warehouse Solutions (AWS)
cross-belt sorter is said to incorporate
many of the latest innovations, together
with programming and controls to provide a
reliable, high-capacity and flexible system.
The new cross-belt sorters feature
contactless induction motors to drive the
cars and wireless infrared communications to
transmit on-the-fly instructions, reducing wear
and maintenance requirements.
Each ‘smart car’ is equipped with a central
processing unit that is programmed to perform
a myriad of dynamic functions such as belt
acceleration, turn rate, distance and timing
in a multitude of combinations as dictated by
circumstances. Among the many features and
options are automatic induction, full tracking,
weigh-in-motion and dynamic deployment.
Each cross belt car is equipped with a pro-
grammable microprocessor making each
carrier a smart carrier. There may be one or
two DC motors, depending on the product
weight requirement that power the cross-belt
used to deploy the product. The micropro-
cessor controls the speed of the motor and is
independently programmable. For example,
the motor characteristics at the loading that
are used to pull the items from the loader onto
each car are programmed differently than the
motor at the chute sections where the product
The sorter frames on all AWS tilt tray and
cross belt sorters are built from extruded
aluminium to precise specifications. The frame
construction incorporates in-built channels for
compressed air, wire cabling and continuous
sensor and guard / bracket positioning.
This uniform model allows for configuration
flexibility, modular construction, and rapid
installation and expansion.
All the carriers travel on a solid stainless steel
base track mounted within the aluminium frame.
Product is identified utilising an omni-directional
laser scanner or a state-of-the-art vision system
with a depth-of-focus as needed or specified.
A process for manually entering product codes
is also available to identify unlabelled product
The cross-belt sorter is driven by sets of induction
motors. Each cross-belt car is mounted on a
captured set of durable long-life urethane wheels,
configured to a wishbone pivot design, travelling
on a solid steel track within the aluminium frame.
The result is a quiet and highly reliable drive
mechanism with no moving drive parts.
The sorter can be fitted with several auto-induc-
tion units to automatically load the items onto
the passing carriers. Carriers that are moving
quickly are impossible to reliably load by hand.
Items are placed on a series of metered
belts that automatically stage the package, then
release it onto the passing carriers. The system
controls help ensure that the item is released at
the appropriate time for proper placement and
to coordinate all the loaders to fill the carriers.
Safeguards are in place to prevent loading of
two or more items to the same carrier.
Theory of operation
The automatic induction units consist of a
three-stage induction metering mechanism that
contains sensors along the travel path; this unit
is controlled by the AWS’ node controller. An
operator (when manually loaded), or conveyor
(when automatically loaded), delivers the
package onto the first stage / buffering unit.
Sensors then detect a package on the unit
and if the second buffering unit is empty, the
node controller will send a signal to move the
package directly to the second stage.
If the second-stage buffering unit has a
package on it, the first package will remain on
the first stage until the second stage deploys
its package. The second buffering unit receives
packages from the first unit and sensors, con-
trolled by the node controller along the unit,
trigger the controls to move the package to the
end of the second buffering unit.
When an empty carrier moves into position,
the AW node controller sends another signal
to the second belt at the precisely correct time
to deploy the package onto the merge belts,
where the package is merged onto a cross-belt
carrier. The cross-belt on each carrier moves in
sync with the merge belts to carry the product
across the cross-belt car. Cars are assigned on
a first available basis and are not restricted to a
Communication between the node controller
and the cross-belt carriers at load area
The AWS node controller, utilising encoder pulses,
tracks the exact position of each cross-belt carrier.
The node controller communicates instructions
to each empty carrier via noise-immune IR
MHD SUPPLY CHAIN SOLUTIONS — SEPTEMBER / OCTOBER 2014
64 MATERIALS HANDLING AND MANAGEMENT
MHD Sep-Oct 2014 56-69.indd 64
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