Newsgroups: comp.robotics
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From: nagle@netcom.com (John Nagle)
Subject: Re: Very-short-range finder
Message-ID: <nagleC7D3GD.HB5@netcom.com>
Organization: NETCOM On-line Communication Services (408 241-9760 guest)
References: <May19.175549.78132@yuma.ACNS.ColoState.EDU>
Date: Fri, 21 May 1993 05:33:48 GMT
Lines: 14

jv844072@longs.LANCE.ColoState.Edu (josh vanriper) writes:
>I am looking for a sensor that can detect the presence of 
>plastic parts acurate within 1/4 inch resolution (in essence,
>a range finder or proximity sensor that will work in a range of
>0-1 inch).  

       Relative IR sensors are good for this.  These consist of one
emitter and two detectors, with one detector closer to the target than
the other.  Distance is computed from the ratio of the two detector 
outputs, and is thus independent of reflectance.  This was used in a
robot hand built at Stanford about a decade ago, and I expect commercial
versions are available.  Try "Sensors" magazine.

					John Nagle
