Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!unixhub!shelby!csli!cphoenix
From: cphoenix@csli.Stanford.EDU (Chris Phoenix)
Newsgroups: comp.robotics
Subject: Re: ideas for inclination sensors
Message-ID: <15845@csli.Stanford.EDU>
Date: 16 Oct 90 05:29:10 GMT
References: <3717@media-lab.MEDIA.MIT.EDU>
Reply-To: cphoenix@csli.stanford.edu (Chris Phoenix)
Organization: Center for the Study of Language and Information, Stanford U.
Lines: 25

In article <3717@media-lab.MEDIA.MIT.EDU> fredm@media-lab.MEDIA.MIT.EDU (Fred Martin) writes:
>robots must do is climb an inclinated plane.  Thus, I'm soliciting
>all of you robot hackers for ideas on inclination sensors.

Use a free-swinging pendulum with a white bob, and beam infra-red rangefinders
at it.  I don't know how precise you want to get, but if you just want to
know level/not level and which way to turn to point up a hill, this should 
work with as few as 3 IR transmitter/receiver pairs.  You might want to 
feed the receiver outputs pairwise into comparators (op amps?) and then send 
those outputs into thresholders (D-A converters?)  (So I'm not an EE.) 
You might also try mounting one transmitter on the pendulum, and receivers 
around it.

This will give you some data.  I have no idea if it will be enough.  My 
experience with IR is that it has lousy range, about 12-16" with our set-up
(not a problem here) and was rather non-linear over most of its range (I
don't know if it's a problem).  Our set-up used the output to drive a 
voltage-controlled oscillator, then counted the time it took to get N 
ticks off the oscillator.  Good luck...

-- 
War is a little naked kid running along a road and screaming because the 
napalm hurts so bad. War is young men in body bags -- theirs and ours. And 
the dying doesn't necessarily have anything to do with baseball, apple pie 
and the Grand Old Flag.  -- Mike Royko