Subject:
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RE: Navigation using landmarks (Was: Re: lasers and RCX)
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 9 Jul 2002 14:58:35 GMT
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Original-From:
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Rob Limbaugh <rlimbaugh@NOMORESPAMgreenfieldgroup.com>
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Viewed:
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635 times
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A Killough platform may have 3 motors, but it operates in a X-Y coordinate
plane, not X-Y-Z.
The camera is looking for pattern shifts horizontally or vertically, not
radially within it's field of vision.
As long as the axis of the spin is not passing through the field of vision of
the optic sensor, bearings can probably be calculated without too much trouble.
Rethinking the clearance issue... perhaps a Lego magnifying glass could help.
The focal points seem to be around an inch from the lense (or so).
-----Original Message-----
From: Steve Baker [mailto:sjbaker1@airmail.net]
Sent: Tuesday, July 09, 2002 6:08 AM
To: Mike Payson
Cc: Rob Limbaugh; lego-robotics@crynwr.com
Subject: Re: Navigation using landmarks (Was: Re: lasers and RCX)
Mike Payson wrote:
> Just use the bottom half of the mouse, trimmed as much as possible, as a
> skid plate. It will need to be mounted to allow vertical movement, but
> it should work alright. This wouldn't solve the spin issue, but the
> clearance shouldn't be a problem. A nice side benefit is that this
> simplifies construction since you don't need to worry about mounting the
> optics, etc..
Yes - I was thinking of some kind of spring-loaded arm pressing the mouse's
underside against the ground.
> At 02:31 PM 6/30/02 -0400, Rob Limbaugh wrote:
>
> > I'm certain that the optics need to be insanely close to the surface they
> > are monitoring, causing a clearance problem.
> >
> > If such a device was hacked, would placing it in the center of a
> > synchro or
> > Killough platform prove useless in a spin?
For a Killough platform, you have a fundamental problem. That type of
drive has three degrees of freedom (well - it *ought* to have only two -
but it won't in practice). Since the mouse camera delivers only two
(translational) degrees of freedom, it fundamentally can't measure all
three axes (X-direction motion, Y-direction motion and rotation).
So, you need TWO mouse-cams - one on each side of the platform. That should
allow you to measure translation in any direction - and by comparing the
outputs of two cameras, you can deduce the rotation.
----------------------------- Steve Baker -------------------------------
Mail : <sjbaker1@airmail.net> WorkMail: <sjbaker@link.com>
URLs : http://www.sjbaker.org
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Message has 1 Reply:
 | | Re: Navigation using landmarks (Was: Re: lasers and RCX)
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| (...) When I said "three degrees of freedom" - I didn't mean "X-Y-Z", I mean't X, Y and Rotation-about-Z. Whilst (in theory) a Killough platform moves in X and Y only - they do rotate a little in practice. (...) From reading the specifications for (...) (22 years ago, 10-Jul-02, to lugnet.robotics)
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