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DPRG: Diffrent terrains for navigation

Subject: DPRG: Diffrent terrains for navigation
From: robert.posey robert.posey at worldnet.att.net
Date: Thu Aug 19 08:40:29 CDT 1999

- ----- Original Message -----
>From: Matt Minnis <mminnis at prefres.com>
To: <dprglist at dprg.org>
Sent: Wednesday, August 18, 1999 10:13 AM
Subject: DPRG: Diffrent terrains for navigation

> I was wondering how the rest of you handle wheel slippage and other errors
> on diffrent terrains.
> Like if I am on carpet it turns vastly diffrent than on linoleum, which is
> also diffrent than on hardwood flooring.
> On each diffrent surface, I turn a diffrent amount for the same # of
> encoder clicks.
I pretty sure that there is not a clean way to slove this problem.  I have
read a
whole lot of literature and no one claims to have a very good solution.
The research
robots all seem to use multiple sensors of different types to maintain their
The only solution that works over long duration operation seems to be
positional fixes
based on some type of reference point.  The reference points can be DGPS, RF
fixed location passive tags etc.  None of these are really available in the
contest, since its
in doors, and RF beacons are expensive and should violate the rules.  For
other uses there
are several simple ways to encode reference points.  If you want I can send
you some references.

I am designing a tracked based robot that needs to operate for hopefully
days without support, and
one of the concepts I am considering for improving dead reconing(tracked
robots tend to have more
Slipagge problems) is to add a spring loaded reconning wheel.  This wheel
would be designed to
turn freely and to achieve maximum accuracy.  If I can figure out how to
correct for all all the
cases where the tracking wheel spins the long way around in a turn, I think
the concept of a
tracking wheel will greatly improve my tracked vehilce's dead reconning

(Robert Posey)

> Do any of the rest of you have this problem?
> Thanks,
> Matt Minnis
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