Alt-BEAM Archive
Message #12928
To: beam@sgiblab.sgi.com
From: SkavenArmy@cs.com
Date: Sun, 2 Apr 2000 01:43:04 EST
Subject: [alt-beam] Re: Ideas................. was --- Biped
i dont know...it works great from what i understand......and it never wears
oout(just repace the ky...weve got lots of this around my
house(married).....it works great..a little embarrasing to buy (specially if
you enjoy its performance under high heat situations(sounds like moto oil ,
doesnt it?) and want one that has a good vscosity ,))))))
jay z
12929 Sat, 01 Apr 2000 22:48:06 -0800 [alt-beam] Re: Biped beam@sgiblab.sgi.com Bruce Robinson BUDSCOTT@aol.com wrote:
>
> Somebody was talking about lowering the center of gravity,
> that would be the best shot to make a stable walker. ...
> ... What i was thinking was to put the motors in the feet,
> and use a belt drive system to turn the knees, that might
> clear out the bulkyness.
We had a rather lengthy discussion on bipeds a while back. The low
centre of gravity turns out not to be a great advantage for a biped.
In order to walk, a biped has to shift its centre of gravity over its
centre of support (i.e., the planted foot). The lower you make the
centre of gravity, the greater the angle you have to tilt it through in
order to move it over the foot. This also means you have to LIFT the
centre of gravity as it moves through that large angle.
On the other hand, if you keep the centre of gravity high, you only have
to move it through a small angle, and the lifting motion is negligible.
Another principle of walking is that you want to keep the momentum small
in the limbs -- otherwise a swinging foot could be enough to make the
robot fall over! In mammals, the muscles that control the gross (and
powerful) movements of the feet are all in ther lower leg; the muscles
that control the lower leg are all in the upper thigh; the muscles that
control the hips are in the body. This means the smallest muscle mass is
in the part of the leg that is moving fastest.
In a robot, this would mean keeping the motors high rather than low.
All this seems counter-intuitive, but it's good physics.
Bruce
12930 Sat, 01 Apr 2000 21:09:46 -0800 [alt-beam] Re: FRED tutorial alt-beam@egroups.com David Simmons He's used the 1381, the FLED, and the FRED, most on bots and all on the
breadboard. Plus he has plans for several more of each. Next we are
looking at some type of vibration bot, and another Pvore.
Regards,
Dave
Ben Hitchcock wrote:
>
> If he hasn't made a 1381 bot then I recommend making one, rather than
> limiting yourself to one circuit.
>
> After all, isnt experimentation the best part of this hobby?
>
> I've been thinking about spring suspension as well - perhaps you could let
> the group know how your robot performs?
>
> Ben
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