EE-May10-P28.PASS:EE-May10-P28.PASS.qxd 12/05/2010 10:27 Page 28
Feature Test & Measurement
Saving money for a cool customer
Supplier of automated logistics solutions, TGW Ibérica, are using devices from Leuze Electronic to provide
position measurement and data transmission within the harsh operating conditions of a new storage warehouse
Laser distance measurement
T
GW is a
supplier of
automated logistics solutions for
warehousing and, in Spain, TGW
Ibérica has installed a nine lane, automatic, high bay warehouse with 6,600
pallet locations for storing food. Despite
inhospitable ambient temperatures as
low as -30°C, the warehouse relies on
Leuze Electronic’s products to help
position the storage and retrieval units,
optically transmit data and thereby,
monitor safe pallet positioning.
The 20m high warehouse has a floor
space of 40,000m2 and is divided into
three temperature zones. The first
zone holds 3,400 storage locations
which are kept at normal room temperature. The second zone (the cooling
zone), is kept at 0°C and holds 1,600
pallets, as does the third zone (the
deep freezing area), which has a temperature of -30°C.
All of these locations are served by
dynamic, high bay stacker cranes and,
for these to operate faultlessly in these
extremely variable climatic conditions,
they must be equipped with a high performance and reliable sensor system.
The cranes’ transportation paths are
measured and positioned by two AMS
200 laser distance measuring devices
from Leuze. One is used to control the
driving movement, the other is used to
control the lifting movement.
To communicate between the
stacker cranes and their base station,
data is transmitted optically by
Leuze’s DDLS 200 optical data transceivers which operate with total
immunity from the AMS 200 positioned alongside. The sensors monitoring the positioning of the cargo
throughout the warehouse are Leuze’s
46B series opto-electronic sensors.
28
The AMS200 (Absolute Measurement
Systems), are mounted in X and Y orientations at the same height as the
running gear. They offer several interface options which aid ease of use
and provide additional convenience,
for example, by internally calculating
the absolute position of the high bay
crane and its lifting unit. The speed of
this calculation of position is vital in
enabling the high bay crane to travel
between locations at speed, and
achieve TGW’s objective of offering a
highly dynamic system.
Calibrated positions are reproduced across an operating range of
up to 200m, and an absolute accuracy
of ±2mm is achieved. An additional
feature is that the unit can also use
the change of position against time to
internally calculate velocity.
Because of the velocity feature
offered on the AMS200, TGW Ibérica
was able to reduce by 30% the complexity of mechanical velocity control mechanisms or buffers, which slow down the
cranes from full speed. Traverse paths
for the cranes are divided into four different distance sectors, with each sector
configured with a separate velocity. The
AMS monitors these parameters
autonomously, reporting to control if
the calibrated velocity is exceeded, and
this velocity control fulfils the requirement for a second independent measurement system, which is necessary for
implementing this buffer reduction.
To ensure maximum system availability, the AMS 200 issues early warning messages, for example when its
optics are becoming soiled, or the laser
diode loses power, enabling preventative maintenance.
The AMS200s are available with
optional integrated heating of the optics
which enable them to reliably work in
the deep freeze zone.
laser red light to provide total immunity
from each other.
The system consists of a pair of
devices which communicate bi-directionally, with each device operating as
both a transmitter and receiver unit
using different frequencies. The DDLS
200 systems have an operating range of
up to 500m and is a totally transparent
system. This transparency, means that
Profibus masters do not need to be
configured, saving commissioning
time and cost.
The option of internal heating is
also available on the DDLS 200 units
and was again used by TGW Ibérica
in the deep freezing area, to ensure
trouble-free operation.
Above: TGW Ibérica
has installed a nine
lane, automatic,
high bay
warehouse with
6,600 pallet
locations for
storing food
Left: AMS 200
devices are used in
the warehouse to
provide position
measurement
Below: the
AMS200s are
available with
optional integrated
heating of the
optics which enable
them to reliably
work in the
deep freeze zone
Optical data transmission
For communication between the
stacker cranes and their base station,
TGW Ibérica used Leuze’s DDLS 200
optical data transceivers. This system
offers the benefit of high speed data
transmission without the wear issues
of fixed wiring, plus the promise of
being free from interference.
The DDLS 200 transceivers use invisible infrared light, enabling them to be
placed alongside the AMS 200 optical
distance measurement units which use
Leuze Electronic
www.leuze.com
T: 01480 408 500
Enter 221
MAY 2010 Electrical
Engineering