⎪
Materials handling and logistics
⎪
Mechanical Technology — August 2013
19
management
The distance of each scan point is calculated and used to create a 3D visualization of the stockpile.
This scan sequence revealed that someone accidentally dumped 19 t of
material on the wrong stockpile.
accurate and reliable, with an accuracy
of 98% or better,” she believes.
At the data centre, all of the bound-
aries, bin sidewalls, or obstructions are
removed to leave only the 3D profile of
the stockpile itself. The system actually
knows the distances between the scan-
ner and the surface of the stockpile,
so to determine the real profile from
the ground up, an initially determined
‘empty stockpile’ profile needs to be
established. By subtracting the ‘empty
distances’ from the scanned ones, the
height for each point on the cloud is
established, which enables accurate
volumes to be calculated. “And if you
give us a density, we can give you a
mass, too,” adds Nilsen.
The measured profile is then made
available to clients as an image on a
secure ABB-managed website. “This
can be accessed 24/7 from anywhere
in the world. It gives a 3D visualisation
of the stockpile, a volume measurement
and, if the density is known, a total mass
calculation,” she reveals.
The measurement system consists
of a control box linked to between one
and four laser scanners. A 3G network
card is embedded into the control box.
“All we need from the plant is a mains
supply. If 3G coverage is a problem,
we can also link to the plant’s local
network and ABB also takes care of all
3G-network connectivity issues. The
client, no matter where they are, need
not worry about service providers or
data contracts.
Addressing difficulties in establish-
ing a zero level for a pile or storage
bin, Nilsen says that the easiest way
is simply to do a scan before material
arrives. “This is not always possible,
though. If a silo or storage vessel has
been built, then we can use the blue-
prints or designs. On an open site, we
can use photographs to determine the
ground level, and if all else fails, we can
initially use estimates and then, over
time, we can improve the accuracy of
the initial estimate from scans taken at
almost zero volume,” she explains.
Once set up and initialised, scanning
is fully automatic, based only on the
scanning time and frequency chosen
by the stockpile operators. “If you tell
us the time, we will do the scan. The
laser scans across
the stockpile in
140 concentric
c i r c l e s , t a ke s
3 678 level points
and a single scan
takes roughly 45
minutes. We can
increase this to
25 000 points,
b u t w e h a v e
discovered that
this doesn’t add
significantly to
measurement ac-
curacy, but takes
much longer” she says.
The optimal scan times will be
determined by the client. “We recom-
mend times of least movement,” Nilsen
advises, “you don’t want to be scanning
while stock is being added or removed,”
she explains.
Exemplifying the importance of vi-
sualisation, Nilsen shows a sequence
of scans that reveals how the stockpile
volume is moving. “Between these
two scans, someone has accidentally
dumped 19 t of material on the wrong
stockpile. This was picked up because
of visualisation. The scan does not just
produce a number, you can see exactly
where material has been added. You
can easily track the filling and emptying
sequence over time.”
ABB offers several service levels to
customers wishing to use its VM3D
system. “Included in the purchase of any
system is one free scan, every month for
a three year period,” announces Nilsen.
“This is at no extra cost and is ideal for
the monthly stocktake. It can be sched-
uled on any day and at any time and
the scan will take place automatically,
at exactly the same time every month.
The results will be available within 24
hours, but we are flexible and if results
are needed immediately, this can be
accommodated,” she says.
For more regular scans, customers
can buy one of several data packages.
“Many operators prefer the daily scan
package, where we scan every morning.
We also offer a weekly package and an
on demand package, where the client
buys 10 additional scans, for example,
for use at any time over a two year pe-
riod. All we need is 24 hours notice,”
Nilsen advises.
“This is an extremely convenient
solution. We install the system, receive
and process the data. All operators need
to do is to download the results. Also,
for financial management purposes, we
are an independent third party. We don’t
have any vested interests and we won’t
be tempted to manipulate the results.
“The VM3D laser scanning system
and service is the most cost-effective,
convenient, accurate and reliable auto-
mated stockpile management solution
on the market,” Nilsen concludes.
q
