[tt] [NSG] Meeting Announcement 10/2

[Eugen Leitl]

----- Forwarded message from Fred Hapgood <hapgood at pobox.com> -----

From: Fred Hapgood <hapgood at pobox.com>
Date: Mon, 01 Oct 2007 12:26:23 -0400
To: nsg at marshome.org
Subject: [NSG] Meeting Announcement  10/2
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Reply-To: Nanotechnology Study Group <nsg at marshome.org>




Meeting notice: The 071002 meeting will be held at 7:30 P.M. at the
Royal East (782 Main St., Cambridge), a block down from the corner of
Main St. and Mass Ave.  If you're new and can't recognize us, ask the
manager. He'll probably know where we are. More details below.

Suggested topic:  Prostheses for machines

Thirty years ago I wrote a story about a research team working on hands
for robots. Even then it was understood that the lack of general-purpose
gripping manipulators, peripherals that could pick up objects with a
wide range of shapes, weights, and orientations, and move those objects
through all six degrees of freedom, excluded machines from a long list
of useful applications. It was and is very hard to imagine a practical
construction robot, or a housework robot, or an assisted living robot,
that does not have the equivalent of fingers and thumbs. Many of the
machines that we have now, like dishwashers or robot vacuum cleaners or
welding machines or lathes, would be immensely more useful if they had
hands (and not just two, either).

The major problem is not mechanics.  Hands are first and foremost data
gathering devices, instruments that acquire the several species of
information (pressure, temperature, texture, pain) required to figure
out the handled object's properties.  Building hands for machines is
all about sensors.

An obvious first attempt was to copy the biological solution, and that
was the path being explored by the team I wrote about.  However, the
natural somatic system is pixel- oriented, like vision. (Sometimes blind
people say they can "see" with their skin.)  Pixels work great if you
can afford thousands of sensor points per square inch, but this is not
where the technology is, which means that the R&D costs of imitating the
biological model would be immense. Another issue is that the sensing
machinery in our skin is located right on the working surface, exposed
to constant physical abuse and contamination.  Our bodies deal with this
by repairing their sensors continuously and in place, which is a nice
trick but nothing close to what we can do at the moment.

So most efforts to build hands have explored other sensing
technologies. One class of these efforts involve optical sensors.
Unfortunately optics don't tell you much about weight, which is a very
important piece of data for a hand to know, are highly vulnerable to
noise (small variations in lighting), and are likely to be occluded by
movements of the hand anyway. So this approach has gone approximately
nowhere as well.

Recently interest has begun to grow in a technology called electric
field proximity sensing, or EFPS.  EFPS relies on the fact that if you
move an electric field close to an object that is at least slightly
conductive (or vice versa) the shape and strength of the field change.
EFPS is almost entirely nonbiological (with the interesting exception of
electric fish), but it has the immense advantage of being both well-
understood and widely used (automobile safety bag deployment systems use
it to sense where humans are sitting).  It is practically an off- the-
shelf technology and requires very little hardware, making it more
attractive than the alternatives demonstrated by evolution. The field
generators are inside the fingers, protected from physical insult.

The way it works is that first an object is acquired and categorized
from a distance, probably by vision.  The manipulator is moved into a
position where it can cup the object or at least a protruding edge of it
with its fingers (without at this point touching it; the technique is
sometimes called "pre-touch"). Each finger both creates its own field
and senses changes in the fields generated by the other fingers.  The
manipulator rotates its hand around the object to be picked up, with
each finger monitoring changes in the field over three dimensions.

This process generates data about both the shape and the approximate
density of the object (the denser the object, the larger the distortions
imposed on the field).  Once enough information has been gathered the
fingers configure themselves properly, close around the object, lift it
up, and carry it through  the desired path.

EFPS has some limitations, primarily that it cannot see electrically
neutral materials (which include some plastics and paper), but adding
conductivity to objects as needed would be trivial.  If the software
issues can be addressed -- not a small matter but probably not a show-
stopper -- machines might be about to get hands.

When one considers the difference that the evolution of the opposable
thumb has made to our phyla, we seem justified in expecting something
interesting.



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In twenty years half the population of Europe will have visited the
moon.

                                -- Jules Verne, 1865

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Announcement Archive: http://www.pobox.com/~fhapgood/nsgpage.html.

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Legend:

"NSG" expands to Nanotechnology Study Group.  The Group meets on the
first and third Tuesdays of each month at the above address, which
refers to a restaurant located in Cambridge, Massachusetts.

The NSG mailing list carries announcements of these meetings and little
else. If you wish to subscribe to this list (perhaps having received a
sample via a forward) send the string 'subscribe nsg'  to
majordomo at polymathy.org.  Unsubs follow the same model.

Comments, petitions, and suggestions re list management to:
nsg at pobox.com. www.pobox.com/~fhapgood   www.pobox.com/~fhapgood



www.pobox.com/~fhapgood
www.BostonScienceAndEngineeringLectures.com

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----- End forwarded message -----
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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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