Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!ihnp4.ucsd.edu!galaxy.ucr.edu!library.ucla.edu!csulb.edu!csus.edu!netcom.com!nagle
From: nagle@netcom.com (John Nagle)
Subject: Re: nitinol underwater?
Message-ID: <nagleCoHvuM.6At@netcom.com>
Keywords: nitinol
Organization: NETCOM On-line Communication Services (408 241-9760 guest)
References: <2osgb1$bmn@birdie-blue.cis.pitt.edu>
Date: Tue, 19 Apr 1994 07:08:46 GMT
Lines: 20

filip@alpha.smi.med.pitt.edu (Filip M Gieszczykiewicz) writes:
>	Greetings. Has anyone tried to use nitinol wires as active 
>	elements in underwater robots? If the robot is tethered, power
>	is not a problem and due to the excellent cooling provided by
>	water (especially when moving :-) would permit decent cycle
>	times. And the winning factor for hobbyists like me is that it
>	makes possible build robots that are inherenly water-proof :-)

      That would be a good application.  The big problem with this stuff
is that you get a contraction quickly when you apply power, but it takes
time for wire in air to cool, so it takes a few seconds in air for the
stuff to relax.  In water, or in a fast-moving air stream, this drops
to a fraction of a second.  So the stuff should be much more effective
in water.  In air, it's more of a curiosity than a useful actuator.

      The other big problem is that you only get a few percent 
contraction.  So you need some kind of mechanical leverage to get any
significant travel.

					John Nagle
