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From: kilian@cray.com (Alan Kilian)
Subject: Please describe Whiskers' object sensing system
Message-ID: <1993Feb1.101027.18098@hemlock.cray.com>
Lines: 36
Nntp-Posting-Host: gopher
Organization: Cray Research, Inc.
Date: 1 Feb 93 10:10:27 CST


Don,
  Could you please describe how whiskers manages to get such good performance
  from it's infrared object detection circuit.

  You say :
  "Four visible light obstacle sensors, one on each side and two in the front,
   can see over one foot away.'

  The _Minimalist_ book also gets about a foot from it's detectors.

  Whenever I use infrared to do reflective object detection it works crappy.

  I have tried straight IR LED and a phototransistor/opamp and a modulated
  IR LED and a Sharp IR demodulator things (From Radio Shack) Even if I run the
  LED at 120 Milliamps 50% duty cycle I only get about 4 inches for a real
  object (My hand) And even then I am not willing to use up 480 mAmps even at
  50% duty cycle just to run my object detection system.

  1) How do you do it.
     a) Modulated or not?
     b) LED or laser?
     c) How much current?
     d) Transistor or diode detector?

  2) Can you give us a circuit diagram and physical layout diagram?

  This could really boost your standing with this group. As well as allowing
  you to promote Whiskers at the same time. What could be better?

                          -Alan Kilian

-- 
 -Alan Kilian           kilian@cray.com 612.683.5499 (Work) 612.721.3990 (Home)
 "It is a little hard to tell the difference between a machine that doesn't
  work and a machine that doesn't exist." -Martin Walker quoting someone else
