Alt-BEAM Archive
Message #03185
To: BEAM Mailing List beam@corp.sgi.com
From: "Paul B. Webster." pwebster@clinipath.com.au
Date: Tue, 11 May 1999 18:12:24 +1000
Subject: [alt-beam] Re: Incapable robots-Give 'em feet.
Dennison wrote:
> Think about it, our bot's are more or less built from insect designs,
> and as a result work great. But there are no insects the size of our
> walkers. Insect locomotion stops being a very effective method of
> locomotion when you get to squirrel size. We of course run into the
> time old problem of volume being a cubic function, and lets face it,
> legs don't exaclty 'drag' well in the grass.
Come now. Insects don't drag their legs in the grass, they *step*
over things. The problem is that your so-called "walkers" aren't
walkers at all, they're "shufflers" akin to a person who has had a
stroke!
Put real legs on the thing, with independent drives to each joint and
two axes of freedom at the hip and drive each joint with an independent
processor like all *real* insects have. *Then* you'll see walking.
Size? Watch a few stick insects or mantis. They have no problems.
Or those giant spiders.
Something else (two things actually) most insects have: Wrists and
*claws*! With algortithms for extraction from crevices. Using these,
they "walk" over walls and ceilings.
But please don't whinge about problems with your "insect design".
> To this I have a few suggestions for building more capable robots.
> Make them larger.
You've just contradicted yourself.
> With this increased size they will have greater weight (A necessity
> for nagivating grass and stuff).
No. Insects negotiate grass. You can crush it if you like, it's
faster but takes (wastes) more energy. Fine if you are *much* bigger,
but you *can* simply climb over it instead.
> Give them Paws. All our robots are these things balanced on the ends
> of wire. Thats no good. These things need some feet. With feet they
> wouldn't get so bogged down in Grass or sand. With feet they are
> better balanced.
Feet are used for some balance in bipeds (which have big feet!). They
are not otherwise *necessary* for balance but they *need* ankles.
Tripod stance is adequate. I agree on one aspect - large feet *are*
used to supporte *large* animals on soft surfaces. Many others however
still have quite small feet.
> The robot can stand on top of more stuff. (kinda like snow shoes) and
> the legs won't get caught so much in every little nook and cranny.
True enough if you go to a real *big* thing, say a large dog or
bigger.
--
Cheers,
Paul B.
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