On Thu, 28 Jul 2005 03:32:25 +1000, Michael Ahgizew wrote:
If you're looking for a commercial solution, check out NorthStar from
Evolution robotics. (www.evolution.com) It uses an IR transmitter on the
ceiling or wall and a receiver on the robot to localize fairly well.
(1-4cm according to their specs) They also have vSlam as part of their
ERSP package, which works using an inexpensive web cam, but the ERSP
software is pretty expensive unless you're an educational user.
I've also looked at Carmen, a free software toolkit from CMU.
(http://www-2.cs.cmu.edu/~carmen/) It sounds like that will do
localization reasonably well, but right now I believe it depends on a
laser range finder to work properly. It looks like player/stage
(http://playerstage.sourceforge.net /) implements a basic Monte-Carlo based
localization scheme in their amcl driver which could be used with sonar
data, but you'd probably not get great results without some additional
work there because of the noise and error rate in typical sonar systems.
Odometry works pretty well by it's self as long as you're on a flat,
smooth surface, until you have to turn. :)
Last I heard was magnetic tape stuck to the floor in such a way that it
would not wear due to being stepped on or rolled on. This allowed the robots
to measure to within fractions of an inch exactly where they were at any
given time, and could divert into rooms or racks, then rejoin the mag
tape... But this was years ago at the IBM facility in Boulder, Colorado.
This is still a pretty common approach. The big warehouse robots at the
coca-cola bottling facility hereabouts use this same strategy, w/
permanent magnets (not tape) embedded in the warehouse floor itself at
regular intervals. Not very interesting computationlly, but highly
reliable -- which is important with machines this large, capable of
doing a great deal of damage to people and property if they run astray.
(Replies: cleanse my address of the Mark of the Beast!)
The latest and greatest in warehouse automation can be seen at Ralph's in
the Los Angeles distribution center. Everything comes in by truck... rail is
non responsive, non competitive and with an attitude. Trucks are unloaded
and the pallets put into bins with a bill of material for all items. Then,
across the street, is another warehouse where pallets are transported as
required and put into slots, again bar code date on all items. But the
clever thing here, is that they use humans to rush from box to box to fill
each store's order and actually do it according to the shelf height level of
the store. For example, Banana Crunch cereal is always at the top of the
shelf, so when a carton of this stuff is taken from the major carton, it is
loaded on the top shelf of the loading cart. When the individual store
receive their restocking order, the stockers need only reach across with
their loads. And so it goes. These individual humans scoot about the
warehouse as though on roller blades and even faster. They are compensated
by the number of orders filled during their shift. And no robotic system has
yet come close to beating them except for the interface robotic ASCARA
(automated Storage and Retrieval system) which deals with pallet sized BOMs
and not details.
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