Alt-BEAM Archive

Message #06661



To: beam@sgiblab.sgi.com
From: Senior kyled@cruzers.com
Date: Mon, 11 Oct 1999 20:53:44 -0600
Subject: [alt-beam] Re: Aquabots


Check out this guys page on his remote controlled submarine:
http://sham.citeweb.net/bubulmain1_eng.html

Here's his home page:
http://sham.citeweb.net/

Pretty good work! Very creative with the whole project.
He uses a plastic toy thingy and a servo (Note: SIMPLE) to change the
bouancy of sub.

-Kyle

JVernonM@aol.com wrote:
>
> In a message dated 10/11/99 1:35:14 PM Eastern Daylight Time, 123abc@chek.com
> writes:
>
> > One thing I have noticed as far as aquabots go is the lack of a swim
> bladder.
> > Fish (and submarines) use this to change their depth. Suck water in to go
> > down. push water out to go up. I don't know how this would be done, but I
> > hope that will help anyone trying to make an Aquabot.
> >
> Yep, you are correct sir! I'm playing around with the concept now. It's more
> difficult than you might expect. A gearmotor or strong electromagnet are
> required. There's also the problem of gauging the changes in buoyancy
> effectively. And the real kicker, temperature. All the equations need to take
> in the problem of water density changing with temperature. I'll post results
> as I get to them.
>
> See ya,
> Jim
> http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



6662 Mon, 11 Oct 1999 20:59:58 -0600 [alt-beam] Re: What do I need? beam@sgiblab.sgi.com Senior Well, you'll have to do a bit of studying and decision making.
Some comments:
1 - It's hard to get 2 motor walkers to do much, like turning, but
reversing is no problem, and you could most likely tweak it to get it to
turn.
2 - It aint gonna be cheap. Motors that walkers use are extremely hard
to come by and especially when their cheap. You could use servos, which
are 10 bux a peice, but that right there is 20 dollars, which is out of
my budget.

Uh... that's about it.
You could use the traditional walker from:
http://www.golden.net/~amiller/

Or the bicore walker thing from Ian's site:
http://www.beam-online.com (it's in there somewhere...)

And check out the FAQ:
http://people.ne.mediaone.net/bushbo/beam/FAQ.html

After reading each of those sites carefully, you will know how to build
a walker! Ta da!

Happy Beaming,
Kyle

Chris wrote:
>
> Ok, Here's my deal. Since I'm only 15 and do not have a job I want to get the most bang for my buck. I need to know what I need to make a 2 motor walker with 4 touch sensors, 2 photodiode eyes, that can go backwards, right, left, forward, is nocturnal. By nocturnal I mean uses a solar cell in daytime to charge its batteries when it bicore is off, then at night it turns itself on. So I need to know what I need because I don't want to have to pay shipping and handling twice (or more). And I need a site that tells me how to hook these things up.
>
> I'm new to all of this BEAM stuff, but I pick things up fairly easily.
>
> Win a LAPTOP Computer and get your FREE E-mail Account at http://mail.chek.com



6663 Mon, 11 Oct 1999 21:09:12 -0700 [alt-beam] Re: how exactly does a bicore work? beam@sgiblab.sgi.com Sean Rigter Yes!

The bicore head circuit uses Pulse Width Modulation so the motor "goes"
both ways. But with the head application the caps are small so the
voltage waveform is switching rapidly and the motor's enertia makes it
move back and forth no more than a fraction of a turn. :It just vibrates
when locked on to a light source because the pulse in each direction is
the same width. if not locked on it slowly scans because of a small
mismatch in the left and right pulse width. The head turns towards a
light because more light falls on one PD than the other and the
imbalance turns the motor towards the light. Like our own eys the PD
should be crossed over left to right. For example, when a light falls
mostly on the left PD, it causes it's leakage current to increase more
that the right PD which makes the left pulse shorter than the right
pulse and moves the motor smoothly towards the right. This would make
the head photophobic and by crossing over the PD it becomes phototropic.
By making the caps a little larger the frequency (in low light) slower
and cause the head to visibly shake.

The bicore wastes quite a bit of power in switching the motor current
without actually moving the head especially when the head is locked on.
So new circuits were designed for controlling a head which offer some
advantage:

The monocore head circuit applies a straight left or right signal to the
motor until the head is locked and then oscillates and the powersmart
head use a different power saving technique which turns of the motor
drive off when the head is locked on and the light falling on the PDs is
balanced.

regards

wilf

regards

wilf

Evan Dudzik wrote

> i am just wondering, with a phototropic (head) bicore,
> does the motor go both ways, just different distances
> each way, or does it just go whichever way has the
> most light? i have been into BEAM for like 1 or 2
> years, but i have not done anything with the bicore
> yet... i am trying to get into doing bicore stuff. oh
> well. maybe i will make one. anyway...
>
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