Newsgroups: comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!europa.chnt.gtegsc.com!news.sprintlink.net!noc.netcom.net!netcom.com!nagle
From: nagle@netcom.com (John Nagle)
Subject: Re: I need help on a school project
Message-ID: <nagleDB68F6.6sw@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
References: <3t9ims$4ae@news.acns.nwu.edu>
Date: Tue, 4 Jul 1995 03:01:54 GMT
Lines: 27
Sender: nagle@netcom12.netcom.com

bdr289@lulu.acns.nwu.edu (Bernard David Reger) writes:
>I am working on a project at school to design a model of a 
>rodent leg.  I am designing small actuators for the project,
>but there are other matters of concern.  The first of which
>is a sensor.  I need something to sense the rotational 
>displacement of the knee and hip joints.  To give an example
>of the size of the leg, the links will be approximately 3 
>inches long, 1/4 inch thick, and 3/8 inch wide.  The shaft 
>connecting the links and the knee and hip will  be 1/8 inch
>in diameter.  Does any body know about a rotational sensor
>or potentiometer that will take a 1/8 inch shaft and has an
>OD of around 1/2 inch (or a little bigger)?

     That's easy.  There are lots of pots in that size.  Look in
the Digi-Key, Mouser, or Newark catalog.  Yes, the pot will wear
out eventually, but in a research application that probably isn't an
issue.

>My second problem is force sensors.  I need to be able to 
>detect the amount of tension on one of the tendons on the
>leg.  

     For that you need a silicon strain gauge.  Look in Sensors
magazine for ads.  Output from those things is large enough that
an ordinary op-amp can amplify the output signal.

					John Nagle
