Alt-BEAM Archive
Message #08328
To: beam@sgiblab.sgi.com
From: Richard Weait crs0274@inforamp.net
Date: Fri, 17 Dec 1999 19:46:31 -0500
Subject: [alt-beam] Re: Bipedal walker
At 03:44 PM 12/17/98 -0700, Ian wrote:
>I'm looking for any suggestions and ideas on the design and actually how I'm
>going to get this thing to walk. I am sort of leaning towards a BS2 for
>control and adding BEAM in for some stuff. Not sure what yet. I've already
>done some walking around trying to simulate the limitations in movement when
>no ones around (they would think I was weird walking around all funny) and
>it seems like it will work. Anyway, I'm looking forward to hearing your
>ideas.
Hey Ian,
Great graphic / design! Wow. And only 13k, too.
Have a look at the first issue of _The Robotics Practitioner_
(it's defunct now, turned into _Robotics Digest_) It had
a construction article with a bipedal walker. I have pictures
of a bipedal walker (from Robotix '96, Glasgow) that looked
a bit like yours, but adds a large controlled counter weight
above the waist. I should scan that for you.
As for suggestions, hmmm. Nice ambitious project. You'll
have mechanical challenges and control challenges. This
project is one that I've dreamed of doing, so here are some
thoughts / comments / musings in stream of consciousness style:
Think about closing the feedback loop, right from the start.
Count on adding sensors for each degree of freedom. Perhaps analog
feedback, but end of travel sensors at a bare minimum.
You'll get some great ideas from the RC model people for the
mechanical problems.
Don't forget that there are bigger, stronger servos that might
do a better job for the joints under more stress.
Which joint is under the most stress? The 'stepping' ankle
has to support the rest of the 'bot. How much force does it
have to exert to move the body? (the right way)
How about a hinge for toes? Do you need the extra contact?
You'll want 'double ball bearing' servos for their extra
strength.
To use the servos as structural members you'll have to shave
every last bit of weight from the 'bot.
On board power or a tether?
On board control or a tether?
Great project; good luck.
Cheers,
Richard.
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