Newsgroups: comp.robotics
From: Leon@lfheller.demon.co.uk (Leon Heller)
Path: cantaloupe.srv.cs.cmu.edu!das-news.harvard.edu!news2.near.net!MathWorks.Com!europa.eng.gtefsd.com!howland.reston.ans.net!swrinde!pipex!demon!lfheller.demon.co.uk!Leon
Subject: Re: Bend Sensors
References: <35bp7f$rbd@balsam.unca.edu>
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Date: Sat, 17 Sep 1994 06:16:03 +0000
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In article <35bp7f$rbd@balsam.unca.edu> schuh@phys.unca.edu "Paul Schuh" writes:

> Has anyone had any success using fiber-optic bend sensors with
> the Miniboard and/or the 6.270 Microcontroller?
> 
> I believe I read somewhere that you can make fiber-optic bendsensors
> by putting nicks on one side of a fiber optic strand. The more the 
> strand bends, the less light is transmitted  through the fiberoptic
> cable. With a light source at one end, and a photo-resistor at the other
> end, it should work as well as the resistance bend sensors.
> 
> The only problem I can see, is that you have to have a receiver at one
> end, and a transmitter at the other end. I figure that this arrangement
> could be used for position sensing on joints. (Elbows).
> 
> Has anyone worked with this? How effective are they? 
> Are there any other robotic applications/arrangements that I may have
> missed? 
> 
> Later,
> Paul

This technique is used quite successfully in the Dataglove, for detecting
finger flexion in virtual reality systems. We had a couple of Datagloves
where I used to work, and they were quite reliable, although we did have
a bit of trouble with the LEDs/sensors coming away from the end of the
fibre optic cable. Another technique that works quite well is a flexible
tube filled with mercury - the resistance changes as the tube is stretched.
I've seen this used for medical/psychological investigations.

Leon
-- 
Leon Heller
Email: leon@lfheller.demon.co.uk
Phone: +44 (0734) 266679
