Alt-BEAM Archive

Message #08826



To: beam@sgiblab.sgi.com
From: Nathaniel Martin nat@lumiere.net
Date: Tue, 4 Jan 2000 18:48:35 -0700
Subject: [alt-beam] 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



8827 Wed, 5 Jan 2000 10:38:26 +0530 (IST) [alt-beam] No Subject alt-beam@egroups.com "N.VEERENDRANATH" <98ec425@vikram.svrec.ernet.in>
Hi!!!
I am new to your group.
Has anyone done a complete evaluation and simulation of a four legged
"Walker" ?
Does any one know how to represent a motor in evaluation software such as
Pspice?
Which software do you suggest for doing such evaluation?


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BF-4,NARMAD BHAVAN,
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