Newsgroups: comp.robotics
Path: brunix!sgiblab!sgigate.sgi.com!olivea!decwrl!decwrl!netcomsv!netcom.com!pplante
From: pplante@netcom.com (P. Plantec)
Subject: Re: BUILDING TACTILE SENSORS
Message-ID: <pplanteCKCLJt.35z@netcom.com>
Organization: NETCOM On-line Communication Services (408 241-9760 guest)
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References: <khD9Kqu00iV6EAtJ52@andrew.cmu.edu>
Date: Fri, 28 Jan 1994 16:23:52 GMT
Lines: 69


HI,  I had good luck with a piece of conductive foam from a pc board 
shipping box and some sheet copper glued on either side. You can dip the 
whole thing in that goop they use to insulate screwdrivers... thin it out 
for a thinner coat.  It's nonliniar, but certainly can tell your fingers when 
they have hold of something.

Samuel Giles Miller 
(sm7z+@andrew.cmu.edu) wrote:
: Excerpts from netnews.comp.robotics: 18-Jan-94 Building Tactile Sensors
: by Manfred Huber@cs.umass.e 
: > 
: >In order to receive more feedback from our robot hand we want to 
: >build an inexpensive, low resolution (only a small number of 
: >"taxels") pressure sensitive fingertip sensor which should provide 
: >information about the contact force applied to the finger. 
: >Since this sensor has to cover the whole surface of the fingertip,
: >it has to be formable to tailor it to the spherical regions. It
: >also has to be sensitive enough to avoid the moving of objects
: >before contact can be detected.


: Manfred,

: I'll just supply a little bit of info off the top of my head and if any
: of it seems to be what you (or anyone else) is looking for I can go find
: out correct spellings addresses etc.

: Ercon Inc.: This small company in Ma. makes conductive rubber and
: conductive inks.  You need to build some sort of semi-rigid circuit
: board with inter-digitated fingers to apply to one side of the rubber. 
: The idea is that the rubber actually has a rough surface that under
: minimal load comes in contact with your circuit only at the peaks of the
: micro-bumps.  As you press harder more rubber comes in contact with the
: circuit.  They can make rubber with all sorts of conductive properties. 
: The samples I experimented with had only a limited range where they were
: usefull.  Very cheap....try it.  Ask them to make samples "very bumpy"
: for better results than I got.  Nice people

: Interlink: This company makes array sensors that have been used in many
: robotic fingers.  This is probably your best bet.  They use some magic
: FSR polymer.  If you happen to be unfortunate enough to destroy one of
: these little things ($$$$ouch$$$$) you can use one side of it as your
: circuit board for the conductive rubber.

: Bonneville Scientific: I have never seen these things work.  But they
: claim to have some fantastic array sensor system that uses a little
: ultrasonic emmiter/dector stuck to some compressable stuff.  The measure
: TOF of pulse as it bounces off of other side of compressable stuff. 
: They claim it can be made thin enough for a skin and they have pictures
: of it being used on a robot finger picking up a washer (which can be
: recognized on their output graphic).  Not recommended.

: Emed Systems: Makes some sort of system that uses capacitive sensors.  I
: have not tested these things.  You have to buy a complete system with
: electronics etc.  They have some distributor in America but they want
: you to buy a system to stick in your shoe to measure foot preassure. 
: They do have individual sensors of finger tip size but I don't think
: they have arrays that small.  Difficult to deal with.

: Enjoy,

: Sam

-- 
************************************************************************
Peter Plantec                                     DreamScape Prods      
Beverly Hills, CA                                 Movies in the Mind
pplante@netcom.com                                Gargleing at the
                                                  fountain of Knowledge
