Alt-BEAM Archive
Message #08371
To: beam@sgiblab.sgi.com
From: JVernonM@aol.com
Date: Sat, 18 Dec 1999 12:34:56 EST
Subject: [alt-beam] Re: Solarbotics Miller Engines
In a message dated 12/18/99 6:18:37 AM Eastern Standard Time,
dave@solarbotics.com writes:
> We recently licensed this solarengine design from the Mr.
> Andrew Miller of AM Innovations.
Dave, I hope you didn't pay to much for that license. Seems there are several
public domain engines out there. Geez, and I thought this was just a cool
hobby.
See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870
8372 Sat, 18 Dec 1999 09:54:42 -0800 [alt-beam] Re: BI ped "'beam@sgiblab.sgi.com'" Wilf Rigter
Aim for the stars and the moon is in your backyard. To put it in
perspective, look at the extreme of human balance and motion and design a
ballet bot.
wilf
> -----Original Message-----
> From: Bruce Robinson [SMTP:Bruce_Robinson@telus.net]
> Sent: Friday, December 17, 1999 11:18 PM
> To: beam@sgiblab.sgi.com
> Subject: Re: Bi ped
>
--8<--
> Dynamic balance is a whole other ballgame. Your robot is constantly
> falling, but always in control. I've heard that the biggest problem is
> stopping (shift from dynamic to static balance).
>
> Sounds like fun ... if you have a high frustration tolerance.
>
> Bruce
>
>
8373 Sat, 18 Dec 1999 10:34:15 PST [alt-beam] Re: PCB iron on transfers beam@sgiblab.sgi.com "Timothy Flytcher" Good points... I'd also like to ad that "Board houses" don't really want
your business... I mean, just set up for a one time batch of sixty boards is
a lot of work... So it's not really profitable for them... Most of there
business is in the thousands... One initial major set up then repeat
business every month or so from then on... At EBs we ordered them like I
order personal checks from my bank... 1000 at a time whenever needed...
>>Chris, you might want to consider photo-etching. A number of firms now
>>make PCB's pre-coated with a photo-resist.
>>
>>Design your layout, print it onto transparency overlays, place it on a
>>piece of pre-coated PCB material, weight it with a transparent plate,
>>and expose it to UV according to instructions. Then develop the plate
>>and etch.
>(snip)
>
> It may be a slight inconvenience, but use the sun. Won't get any
>better source of parallel light. Besides what you may have heard it is
>easy to get GREAT quality at home with the kits. If you follow the advise
>of those who know how to do it. If you use quality copper boards and
>quality silvering components, you will get very reliable boards at a very
>reduced price. Not everyone wants to make 60 boards at once, then you are
>going to pay out the nose for the boards. Even so, if it is a small
>board....use a bigger copper board and cut-n-paste to fill the board. Like
>what was mentioned before in an earlier message, follow the instructions
>and you will succeed. Board houses can do it better, but their primary
>function it to produce lots of them and fast. Hope this helps.
>
>Robert
______________________________________________________
8374 Sat, 18 Dec 1999 13:34:35 EST [alt-beam] 1381-Chloroplast beam@sgiblab.sgi.com JVernonM@aol.com OK, I don't get it. The 1381-Chloroplast that Wilf just posted does pretty
much the same thing as the original Chloroplast. But, does it with 3 more
parts. Why? The 1381 is very hard to get in Europe and down under. So, again,
why? Maybe I'm to dense to see it, but why is it necessary to reinvent the
same engine with more parts? Also, Ian, why not just hook enough of those
solar cells in series to get the required voltage. If you did that you would
have a power house equivalent to more than 4 AA batteries. Simple, effective,
hook 'er right up. Unless, of course, they are like 6 inches wide or
something. I guess Ian is going for a conservation of parts. So, why does
that guideline go out the window when reinventing the Chloroplast. Like I
said, I don't get it.
See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870
8375 Sat, 18 Dec 1999 11:11:10 -0800 [alt-beam] Re: Bi ped beam@sgiblab.sgi.com Bruce Robinson Ian wrote:
>
> ... If you just stand there and lift one leg
> your going to fall over. You need to first get
> the COG over one of the feet by lowering just
> the leg your going to balance on and rotate at
> the ankle at the same time. You are now standing
> at a slight angle with the COG over the foot
> with the lowered leg. I'm I missing something here?
Nope. You got it exactly right.
In your original configuration, you will have problems lowering the leg,
because you will have to counter-rotate both the knee and hip motors to
keep the foot parallel to the floor in a front-to-back direction. This
will try to push the foot forward (or the hips back) thus upsetting your
fore-and-aft balance. Two additional motors in the ankle will allow the
leg to bend without shifting the foot (of course you have to operate
three motors to lower the leg).
In your original configuration, you CAN still shift the COG, however.
Try this. Rotate the motors of BOTH ankle joints (non-supporting ankle
rotates a little faster). The foot of the supporting leg will adjust to
allow the COG to be directly over it. The foot of the non-supporting leg
will tilt, causing that side to rise up. This works best with wide feet.
It also works better if the ankle joint is very low, as close to the
bottom of the foot as you can get.
Bruce
8376 Sat, 18 Dec 1999 11:24:44 -0800 (PST) [alt-beam] Re: Bi ped beam@sgiblab.sgi.com Darrell Johnson
--- Ian wrote:
>
> Well ya. If you just stand there and lift one leg
> your going to fall over.
> You need to first get the COG over one of the feet
> by lowering just the leg
> your going to balance on and rotate at the ankle at
> the same time. You are
> now standing at a slight angle with the COG over the
> foot with the lowered
> leg. I'm I missing something here?
>
Well, what you are missing is the ability of the bot
to spread it's legs apart so they can be used for
dynamic balance. Go to the MIT leg labratory and look
at Geekbot:
http://www.ai.mit.edu/projects/leglab/robots/robots.html
notice how it keeps itself balanced. To have a bot
shift it's weight from side to side, it'g going to
need movement in that axis. Most of the MIT bots,
while cool looking, are planar bots, that need to be
guided in a straight line, or in a circle, as they
can't keep thier balance side to side. If you look at
thier concept of the M2, it combines the side to side
of Geekbot, with the planar walking ability of the
others.. This allows for a 3D walker that could walk
untethered.
The way you are describing your leg setup, if you get
shifted over just a tad too far your bot is going to
fall and there will be nothing to prevent it from
correcting itself. Now if you have the side to side
joint at the hips, you can control balance using the
weight of the other leg.
Oh, and Bruce, as for you FEDEX example.. what you are
leaving out is all the countless times students have
wanted to follow thier dreams, contrary to what thier
college professors said, and failed miserably. We
don't get to hear those stories, because they aren't
happy success stories.
But Ian, by all means, if you think you can do it, go
for it. Just don't think it's going to be easy,
because it won't be. It's going to take you *years* to
achieve decent results. I see lots of web pages out
there from little unknown groups of people working on
bipedal walkers.. and they're all the same: The same
lofty goals of using some kind of Fancy Schmancy Fuzzy
Logic sumpthin sumpthin Controller That Doesn't Exist
Yet, but We're Working On It. Combined with the
Ultra-realistic Computer Generated Simulation of the
walker walking over Simulated Rough Terrain. That's
usually about as far as they get, unless it's somebody
working under some kind of funding from
government/private business.
This will be my last rant on this matter.. It seems my
practicality makes people upset, and all this typing
is making my wrists hurt.
Hopefully I will be proven wrong. :)
I'd love to see a capable biped walker developed by
someone still in high school. Then I'll stop being so
bitter and jaded. ;)
goodz luckz
-darrell
=====
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8377 Sat, 18 Dec 1999 11:23:41 PST [alt-beam] Re: Bi ped beam@sgiblab.sgi.com "Timothy Flytcher" The backwards leg, as I understand it, is simply more efficient... More
forward motion for less input... Birds are build for light weight and
speed... Takes a minimum speed to get into the air... A good jump too...
Where we humans are "designed" for agility more than speed... Just think
what a chair would look like if our knees went the other way...LOL...
Timothy...
>Correct me if I'm wrong but in this bot, as in bipeds like birds, the leg
>geometry is quite different from a human leg. The bot's "knee" flexes the
>"wrong" way because the knee joint is really the ankle joint and the ankle
>is equal to the toe joint. Aside from coolness, what is the advantage? For
>fun play the MOV in reverse and now tell me if that doesn't look more
>human.
>
>wilf
>
> > -----Original Message-----
> > From: Ian [SMTP:Ian@beam-online.com]
> > Sent: Friday, December 17, 1999 11:00 PM
> > To: beam@sgiblab.sgi.com
> > Subject: Re: Bi ped
> >
> > Hey, About the design idea I had about keeping the foot strait seems to
>be
> > employed in this walker....
> >
> > http://www.aist.go.jp/MEL/soshiki/robot/undo/kajita/biped-e.html
> >
> > More on my idea is in an earlier email.
> >
> > Laterz
> > \^^^^^^^^/
> > (.)(.)
> > -------------------------.oooO-- (__) --Oooo.--------------------------
> >
> > There is only one true "SyNeT"
> > BEAM Online - http://www.beam-online.com
______________________________________________________
8378 Sat, 18 Dec 1999 14:14:34 -0500 [alt-beam] Re: PCB iron on transfers "Richard Caudle" > Good points... I'd also like to ad that "Board houses" don't really want
> your business... I mean, just set up for a one time batch of sixty boards
is
> a lot of work... So it's not really profitable for them...
Oh yeah?
www.expresspcb.com
Software is free! Quantities from 2 to 200! Two sided boards! Good
pricing and you can order them off the internet! Usually under 5 days to
your door!
Richard
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