Alt-BEAM Archive

Message #07174



To: beam@sgiblab.sgi.com
From: JVernonM@aol.com
Date: Sat, 30 Oct 1999 14:25:23 EDT
Subject: [alt-beam] Re: aquabot


In a message dated 10/30/99 6:57:46 AM Eastern Daylight Time,
gpowell@engr.uvic.ca writes:

Hi Greg,
Aquabots aye? You know I love 'em.
> I recently came upon a page with a vertically diving bot. I really liked
the
> idea. The person proposed to put it in a long glass tube filled with water
> in his living room as a piece of work to admire. I liked that idea too :).

That would be Bram. That was the first working Aquabot that I ever saw as
well.

> propose to build one and I propose to build one in an inverted test tube.
> The solar panel (perhaps some of the very small 0.5 volt, 3mA cells in
> series) will be in the top where it will charge under a lamp or sunshine at
> the surface of the water level. The cap will be below it with a solar
> engine, probably a 1381 type and the pager motor will have a shaft
extending
> out the bottom test tube plug with a propeller. I intend to use metal
> washers of equal diameter to the test tube to achieve just above neutral
> bouancy. I want to make it in as small a test tube possible so that I can
> put it in a large graduated cylinder on my desk as an active ornament.

OK, here's some things to keep in mind. Make the beast slightly more buoyant
than you think you need. I have found that over time the Aquabots become
slightly heavier when constantly submerged in water. This is not water
encroachment into the bot or motor. I think it has something to do with a
clear slime coat that covers everything over time. Not algae, but a bacteria
colony that fish need to stay healthy. Also, while testing and tweaking
buoyancy, maintain a constant temperature in the tank. Once you have set
buoyancy at a certain temperature the bot will sink or float at lower or
higher temps due to changes in water density. I would advise against pager
motors and the photodiode solar cells. Pagers have no torque and stall easily
in water. Also, the tiny cells have very low current allowing even less
power. I use Walkman motors with larger solar cells and they work great.
Attach your prop to the drive shaft in a very sturdy manner. In the
configuration you describe, when the bot fires, the prop could pull right of
the shaft because it is pulling the bot down instead of pushing it. Take a
look at my tutorial on water tight drive assembles. It may help you with your
drive system. Friction is a real problem here, especially with a pager motor.
Use a high capacitance. The key to getting a good dive is power. Configure
your bot so that floats are on top and weights are on the bottom. This lowers
the center of gravity making the beasty right itself solar cell side up no
matter how it flips or turns (in your case the test tube will have an air
pocket at the top anyway). Put a small cowling or enclosure around the prop
to help direct and strengthen thrust. Place a small packet of desiccant
inside of the electronics housing. This isn't for leaks, which are disastrous
in any case, but rather for condensation. The water contained in the air
inside of your enclosed bot will condense into liquid when you place the bot
in water. Kinda like the water that condenses on the outside of a cold drink.
The desiccant will absorb this helping to keep your electronics dry and
corrosion free. Good luck, and I hope to see your work soon.

PS. It's good to see the word Aquabot being accepted (I'm glad I thought of
it), the old word, Aquavore, just didn't quite cut it.

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



7175 Sat, 30 Oct 1999 11:25:34 PDT [alt-beam] Re: Time Capsules beam@sgiblab.sgi.com "Timothy Flytcher" >I have a 20 year old small electric DC motor and it still works

> > what about the magnets in the motors??? would the motors still run after
>...
> > say 30 years???

yes I too have some that old... but how efficient are they? I also have some
that completely died after just a year or so (new still in package) I know
my r/c friends magnetize there competition motors on a regular bases... I
have seen gains of 10%-30% by dissembly of the motor and remagnetizing the
magnets and demagnetizing the armature.

Timothy...

______________________________________________________



7176 Sat, 30 Oct 1999 11:30:33 PDT [alt-beam] Re: Micro Motors, Skitters, and BeetleBots beam@sgiblab.sgi.com "Jim Cook" >Like we spoke about many months ago.
>Yes, I a pretty annoyed with e-mails about non-technical topics.

Mark

I have sat back and listened to you rant about how patent law, and
copyright law, and trademark law aren’t technical. To be blunt your wrong,
they are. Beam is a field of robotics where right now it is the beginners,
the enthusiast that make a large part of the advancement. It is this lists
job to supply any and all information that they may need. Now honestly if
you think that patents and trademarks and copyrights are not important
facets of BEAM, and that they out weight your precious technical robotics…I
can give you a list of robotics list servers where that is all they talk
about.


Sincerely,
Jim Cook
beamboter@hotmail.com
http://www.geocities.com/Boter-99

P.S. All e-mail servers come with delete buttons…you don’t want to read what
I write, use it.






______________________________________________________



7177 Sat, 30 Oct 1999 14:36:35 EDT [alt-beam] Re: Micro Motors, Skitters, and BeetleBots beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 10/30/99 9:22:54 AM Eastern Daylight Time,
bshannon@tiac.net writes:

> Look at the Popular Electronic photovore article. The list was jumping up
> and down
> about how Tilden should sue, but then we learn that Tilden did not
originate
> the
> 1381 based SE. We are building myths here.
>
Which is what started this thread again. Someone came out with a product or
two, and the loyal started discussing a lynching. Actually, Mark, this needs
to be discussed, and it would not hurt a freakin' bit if Tilden himself took
a minute or two of his time to say a word or two on the subject to the whole
group. Yeah, yeah, he is just SO busy. Well, except when he wants to scold us
about not being responsible for his web site updates or something. Always
seems to be time for that, aye?


See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



7178 Sat, 30 Oct 1999 14:55:47 EDT [alt-beam] Re: Micro Motors, Skitters, and BeetleBots (fwd) beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 10/30/99 12:05:52 PM Eastern Daylight Time, mwd@sgi.com
writes:

> Like we spoke about many months ago.
Does anyone, know of a topic that drew such a heavy, long, response from Mark
D. on anything? Anything at all? Could you say the last time he bothered to
write the list at all? And how many words? Shakespeare would say,"Me thinks
he doth protest to much". What's the deal?

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



7179 Sat, 30 Oct 1999 15:18:52 EDT [alt-beam] Re: aquabot beam@sgiblab.sgi.com JVernonM@aol.com Hi Greg,
Couple more things. If your light is bright enough to charge your bot, it's
probably bright enough to grow a nice, healthy crop of algae. I have tried
chlorine and sea salt. I have been told chlorine will break down some
materials over time. But it seems to be better at keeping algae down. Sea
salt works and doesn't evaporate out and need to be replaced. More tank
cleanings and water changes may be needed.
In a small container, with a VERY active bot, you may luck out and break
the surface enough to oxygenate the water and keep surface bacteria growth to
a minimum (that is, if the critter works 24hrs. a day). If not, within 3-4
days, you will notice a thin film, like an oil slick, covering the surface of
the water. This is a naturally occurring "harmful" bacteria colony. This will
happen in chlorinated as well as water treated with sea salt. If the bot
don't do it, the only solutions are aeration, mechanical filtering, or daily
water changes. I'm working on a bot design to oxygenate the water as it
floats on the surface. Filters, pumps, and air bubbles create currents in the
tank that interfere heavily with the operation of the bot. Water critters
look easy at first, but the situation is very complex. Even in a small,
controlled environment. Good luck.

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



7180 Sun, 31 Oct 1993 14:54:15 -0600 [alt-beam] Re: Bicores...some technical questions beam@sgiblab.sgi.com SG At 10:20 AM 10/30/99 -0700, you wrote:
>
>Sorry for the animated GIF file size but did anyone get this to work and if
>so, does the color = voltage make sense?
>

it werks fine. you have to use your web browser to read it though.
i'm just trying to get a hold of what the colors represent,
but my mind doesn't move as fast as the animation.
THANX! This really is helpful!
-Sparky

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