Alt-BEAM Archive
Message #08845
To: beam@sgiblab.sgi.com
From: Dane Gardner dane@foremostspring.com
Date: Wed, 5 Jan 2000 21:07:38 -0500
Subject: Re: Biped Beam Bots
> As far as I've seen...MIT's "tail" comes in contact with the ground from
> time to time, though. This tail would probably do better between the legs
> than up in the air. A step could throw the whole thing off ballance if it
> get's to top heavy. I've seen pot's hooked up to wieghts before. I don't
> think you could get any more simple.
>
> CYA,
>
> Dane
>
>
>
> ----- Original Message -----
> From: "Phillip A. Ryals"
> To:
> Sent: Wednesday, January 05, 2000 10:29 AM
> Subject: RE: Biped Beam Bots
>
>
> > Not to step on toes, but the idea of a tail isn't really new. The MIT
> > leglab comes to mind...
> >
> > If I understood Nathaniel's explanation though, his use of the tail does
> > sound original.
> >
> > Nathaniel, I was wondering... What exactly do you mean by tilt sensors?
> > Are you talking about just normal switches, or some kind of analog
device?
> > I was curious because it seems like if you just use switches, the
> immediate
> > on/off/on would tend to throw the bot into overcorrection.
> >
> > That, and one other thing... At first I though you meant a 'tail' that
> > swung around the bot, but then I pictured it holding the 'tail' up in
the
> > air. (like balancing a yardstick on your finger) Could you clarify?
> >
> > Cheers,
> > phillip
> >
> >
> > -----Original Message-----
> > From: owner-beam@sgiblab.sgi.com [mailto:owner-beam@sgiblab.sgi.com]On
> > Behalf Of Dane Gardner
> > Sent: Tuesday, January 04, 2000 11:23 PM
> > To: beam@sgiblab.sgi.com
> > Subject: Re: Biped Beam Bots
> >
> >
> > The entire notion of a tail is genius. How did you think that one up?
> >
> > CYA,
> >
> > Dane
> >
> >
> >
> > ----- Original Message -----
> > From: "Nathaniel Martin"
> > To:
> > Sent: Tuesday, January 04, 2000 5:48 PM
> > Subject: Re: Biped Beam Bots
> >
> >
> > > Nice bots, Ian and Evaristo.
> > >
> > >
> > > Here's my idea for a Biped BEAM 'Bot ("BBB"). I'll try to build it
after
> I
> > > build a 2 motor 4-legged BEAM bot (A. Miller type.)
> > >
> > > Remember, I'm a newbie at this, so tell me if what I'm thinking is
> > impossible:
> > >
> > >
> > > Basically, I would keep walking and balancing separate.
> > >
> > > The robot would be "chicken legged" with the knees angled back. It
would
> > > have two servos on the hip, one servo on the knee, and an
> > > electro-mechanical clutch on the ankle (I'll get to that later.)
> > >
> > > I would use a few microcores to get a basic walking rhythm:
> > >
> > > 1. Move left leg in air and rotate forwards (loosen ankle clutch)
> > > 2. Straighten left leg (moves foot down) until pressure sensors on the
> > left
> > > foot read that they have touched something.
> > > IF: the leg is completely straight and it hasn't touched anything
> > > (like
> > > with a cliff) then 1: Bend leg again
> > > 2: Move leg left (at hip)
> > > 3: go back to number 2
> > > 3. Lock ankle clutch (the clutch allows the foot to rotate to work
with
> > > rough surfaces)
> > > 4. Bend knee while rotating leg back and straighting right leg (moves
> the
> > > body of the BBB forward.)
> > >
> > > Repeat for right leg.
> > >
> > > Now this would walk, but it would fall down. Here's how it would
> balance:
> > >
> > > I would have a "tail" to balance it. I put tail in quotes because it
can
> > be
> > > in front of the bot or in back, so it isn't exactly like a real tail.
> > >
> > > The tail would be on top of the bot. Basically it would be a fairly
long
> > > rod (compared with the BBB) with a fairly heavy (compared to the BBB)
> > > weight on the end.
> > >
> > > I would have 4 (or more) tilt switches on the BBB.
> > >
> > > I would have a very simple circuit: If a tilt switch registers a tilt,
> it
> > > moves the tail to the opposite direction of the tilt to reposition the
> > > center of gravity.
> > >
> > > The tail would have 2 DOF so that it can go anywhere above the 'bot.
> > >
> > >
> > > Did I explain this well?
> > >
> > > Do you guys think this would work?
> > >
> > >
> > > -Nathaniel Martin
> > > nat@lumiere.net
> >
> >
>
>
>
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