Alt-BEAM Archive
Message #12886
To: beam@corp.sgi.com
From: Justin JAF60@student.canterbury.ac.nz
Date: Sat, 01 Apr 2000 16:19:43 +1200
Subject: [alt-beam] Re: Phototrophic Walker
>Hi again, i sent out a mail about this earlier, but nobody replied, so i=
=20
>decided to send another. I've got a schematic of a 'hypothetical' photot=
ropic=20
>bicore on my website, could somebody tell me if at all correct. I'd like=
to=20
>use a bicore setup if at all possible, cause all i have is the 74HCT240 =
chip!=20
I=92ve never build a walker beyond the breadboard stage, and I haven=92t
looked the schematic, but I get the impression that when the circuit
wants to turn, the front motor oscillations will become more one-sided
(eg left leg move forwards lots and back a little bit and forwards lots
and back a little bit). While this would result in effective turning if
it was sustainable, in a bot the legs are going to rotate further and
further from being centred, never come back to being centered, and fall
over.
If this is in fact what happens with your design, or there turns out to
be some other problem, I would suggest that the way to make a
phototropic two-motor walker is to ignore the circuitry for now and
concentrate on finding a physical fixed-leg gait that can be achieved
with two motors and results in turning. Once you know what the physical
motion that you=92re trying to achieve is, then start look at what
circuits you could use to achieve that behaviour from the motors.
I reserve the right for this advice to be poor, misleading, or incorrect
:-)=20
Like I said, I=92ve never built a walker (though I am currently working o=
n
one).
12887 Fri, 31 Mar 2000 22:58:25 -0600 [alt-beam] lookie! a turning 2 motor walker beam@sgiblab.sgi.com SG Hello all, good news!
i have stumbled upon a two motor walker mechanical design that allows the
walker to turn 270 degrees (adjustable) when reverser (direction changer?)
is triggered.
I have to make some pics and I have the capabilities to make video but I am
so excited I thought I'd share it now.
The bot is based on Ian's walker circuit, and the mechanical design is
based on the Horizonal (Chiu style?) front motor.
In a nutshell:
Basically, the reverser cap is shortend down to 10uf, (7 uf might give me a
180 degree turn) and the frame, the design of which honestly is based upon
the motors i was able to get a hold of (simular to bg micro lens motors) is
angled ever so slightly so the horizonal motor is actually pointing down
towards the ground just a bit. (a tad... a smidjin)
the two motors' axis' are almost (but not quite) parellel with each other
but the rear motor's axis is below (just) the front motors axis.
dosn't make sense? yeah i know. pictures are louder than words, so let me
do some wire trimming and i'll have some pics and a vid up maybe by Monday.
I know i shoulda waited till then, but heck, my friends here kinda jus say
"so what." so i had to start crowin somewheres.
thanks for letting me rant.
-Sparky
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