Alt-BEAM Archive
Message #10672
To: beam@sgiblab.sgi.com
From: BUDSCOTT@aol.com
Date: Tue, 22 Feb 2000 16:22:46 EST
Subject: [alt-beam] Walker Legs
I'm currently on the assembly stage of a walker, i'm still lookin to see what
to use as a frame, and i believe i have what i want for legs. now, i plan on
angling the first motor 40-45 degrees or less, and the back, of course, with
the shaft perpendicular to the ground. the question is how should one go
about attaching legs to the motor shaft, the shaft on my motors (MPJA one's
that do work!!!) are 1/8 of an inch in diameter, any insight? also, what's
good for frame materials? Thanks a ton!
-Spencer
10673 Tue, 22 Feb 2000 16:22:38 -0500 [alt-beam] Re: BEAM: Tendency toward miniaturization beam@sgiblab.sgi.com "Sathe Dilip"
Timothy Flytch wrote:
>
> Bruce,
> I like your points on scaling ... I can also see a deferent possible
> future, or at least a faction... That is shoe box sized robots... small
> enough to stay out of your way but big enough to do real yard work... to
> walk over grass you need a bot that can take 3-5 inch steps and be big
> enough to be able to pick up a leaf and do something with it... Tall enough
> to reach the tops of the grass with enough span so as to be stable so that
> as it cuts, the cuts are all at the same relative height... Big enough to
> sweep the kitchen but small enough to fit under the counters where it seeks
> refuge when you enter...
I once posted the following link about such a bot. It happens to be
self sufficient & does useful yard work. Size is about right where you
want it. Check it out.
http://news.bbc.co.uk/hi/english/sci/tech/newsid_503000/503149.stm
Dilip
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10674 Tue, 22 Feb 2000 15:20:44 -0600 [alt-beam] Re: Steering an Aquabot and giving it a purpose. alt-beam@egroups.com Ben A Micklin Yes, with one main drive unit in the center, and two on the side. If the
'bot is very long an tall, the sidedriver motors would need to be fairly
powerful to compensate for the speed lost by making it larger, and much
harder too control and keep up. ALSO, how would it go up? An SE placed on
the bottom that makes the APV surface would also be good, so you don't
have to dive all the way down to get him.
Does anybody have any advice for ubilding a Cartesian water diver? I
found a neat canister and prop that would go good together.
I also have a spare SE I am building.
~ben~
On Tue, 22 Feb 2000 12:57:48 EST Ld5253@aol.com writes:
> How about designing the aquabot with a motor on either side, with no
> rudder.
>
>
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10675 Tue, 22 Feb 2000 15:16:39 -0600 [alt-beam] Re: Steering an Aquabot and giving it a purpose. alt-beam@egroups.com Ben A Micklin True.
~ben~
On Tue, 22 Feb 2000 13:04:54 -0500 "Sathe Dilip"
writes:
>
>
> JVernonM@aol.com wrote:
> >
> SNIP
> > I like it! Only one problem though. Temperature. If you make these
> things
> > slightly positively buoyant at a given temperature, they will sink
> like a
> > rock at colder temps. Water density changes at different
> temperatures. This
>
> I think it should be the other way around wrt temperature. Density
> of
> water increases with falling temperature until it reaches 4 degrees
> Centigrade. At this point the water is densest. Below 4 degree C,
> the
> density decreases again. So the bot should become more buoyant with
> increase in temperature if you disregard the little zone between 0
> to 4
> degree C.
>
> Dilip
> ----------------------------------------------------------------------
> The early bird may get the worm, but the second mouse gets the
> cheese.
> ----------------------------------------------------------------------
>
>
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10676 Tue, 22 Feb 2000 16:31:06 EST [alt-beam] Re: Steering an Aquabot and giving it a purpose. beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 2/22/00 12:58:56 PM Eastern Standard Time, Ld5253@aol.com
writes:
> How about designing the Aquabot with a motor on either side, with no rudder.
That will work too. But to get a popper kind of movement, you need more
ooommmpphhh on each side, but not to much. The only way to do this is
limiting resistors to keep the bot from dumping the whole cap into one motor.
Bob Shannon did this on Vore-n-more. A similar circuit should work on an
Aquabot.
See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870
10677 Tue, 22 Feb 2000 16:33:14 EST [alt-beam] Re: Steering an Aquabot and giving it a purpose. beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 2/22/00 1:05:47 PM Eastern Standard Time,
sathe_dilip@bah.com writes:
> So the bot should become more buoyant with
> increase in temperature if you disregard the little zone between 0 to 4
> degree C.
Yep, I got mixed up in the heat of the moment. Sorry. I've done the
experiments a thousand times with various objects, you'd think I'd get it
right :).
See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870
10678 Tue, 22 Feb 2000 13:36:16 -0800 [alt-beam] Re: Walker problems beam@sgiblab.sgi.com Bernard Nazari On H-gates, Bruce wrote:
>That's the route Sparky took with his Lotus. The common configuration is
>good for 100 mA (200 if you push it), and by substituting some
>transistors you can push it up to 800 mA easily (cost you about 25 cents
>more per bridge).
I think I'm going to do this method. Bruce, do you know how to make one
that handles the higher 800 mA?
On feedback, Ben wrote:
>Sounds like you need a 0.1 uF cap across the power leads of the chip.
>This should stop the saturation.
Ben, thanks for the advice, I'm on my way to the store! :-)
On servo mechanics, Ben wrote:
>This problem sounds like the servos are at the limits of their travel.
>Once you gibve the bot legs, the servos should 'auto center', providing
>you don't stack too many chips. Try centering the servos and seeing what
>happens.
Actually, I opened the servos, took out the guts, filed away the stops, and
took out the guts of the potentiometer. (I think I committed some sort of
crime in R.C. circles!) I'll tell you how things go with the .1 uF caps.
Take care and thanks guys!!
Bernie
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