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[DPRG] Skid(s) or Castor?

Subject: [DPRG] Skid(s) or Castor?
From: David Peterson robologist at yahoo.com
Date: Tue Oct 16 23:44:57 CDT 2001

Robosnail had a roll on deoderant ball for a caster, though
it didn't roll much in use initially. Next a castor was
added, but that definately added it's own "personality" of
swinging the robot away from a true track. Lately, Scooter
had front and rear cabinet knobs that worked pretty good for
support and didn't change it's commanded wheel direction at
all, but would tend to get hung up on minor ripples in a
surface. They were a cheap $1.50 Home Depot plastic that did
show some scuffing, so I'm considering going to a rear only,
metal knob of some sort. Oh, Stingray has a sort of roller
that acts more as a skid, but actually helps the robot track
fairly straight. It is mounted to not turn, but I can see it
getting moved in a turn and causing the robot to have a
distinct curve to its motion. None of these robots have
odometry (yet) but I can see that a skid would introduce
less than a standard caster in errors. Cool factor? The
plastic knobs aren't really that great, but I think a nice
chrome one could look pretty good. The chrome ones will
probably go for about $3 or $4 each, no skid would probably
survive asphalt well, but on most contest floors should be
just fine. Ease of manufacture? Drill a hole, screw them on,
maybe with a rubber washer for cushioning.
David P

----- Original Message -----
>From: "Eric Yundt" <eric at facetcorp.com>
To: "Dallas Personal Robotics Group" <dprglist at dprg.org>
Sent: Tuesday, October 16, 2001 9:37 PM
Subject: [DPRG] Skid(s) or Castor?

> I've had a leisurely debate echoing in my head of late
about the
> merits of a castor tail-dragger wheel versus a skid or
> on the back of a small-to-middlin' 2-wheeled roller --
kind of
> like a fire-fighting size chariot with 4" wheels.
>         |----- 10" ----|               |----- 10" ----|
>                 _---_                          _---_
>         =======/=====\==               =======/=====\==
>         |      |  o  |        vs.      |      |  o  |
>         =======\=====/==               =======\=====/==
>        ()       `---'                 _/       `---'
> Anyone have skid/castor experience (pro or con) they'd
care to share?
> Favorable traits I'm looking for are:
> ease of manufacturing (will be making many)
> robustness in typical hobby Robot environment (huh?!?)
> cool factor
> cost of manufacturing
> minimum introduction of odometry error
> (???)
> Por su atencion, gracias...
> --
> Eric
> _______________________________________________
> DPRGlist mailing list
> DPRGlist at dprg.org
> http://nimon.ncc.com/mailman/listinfo/dprglist

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