Alt-BEAM Archive

Message #10512



To: beam@sgiblab.sgi.com
From: "Dennison Bertram" dibst11+@pitt.edu
Date: Sat, 19 Feb 2000 15:20:27 -0800
Subject: [alt-beam] Re: It is still relevant. solarbotics pager mtr+fan


Actually I would like to point out that any discusion like this is very
relevant to BEAM. You never know where people will get a great idea from
discusion's like this aren't detrimental to the list. Each e-mail message I
don't think needs to specifically refer to BEAM. We are discussing ideas,
and this certianlly does has a purpose and I like reading them, and we would
lose out if people automatically took conversations 'off line' because it
wasn't BEAM enough. I've been following this thread with great interest.

dennison

> I feel I must apologize to the list for starting this thread...
> Sorry...
> I will only address non beam topics off list...
> If you do not know how to do this it is simple just cut out my url and
> plaste it into the "To: " ... I would be more than happy to entertain any
> aviation related discussion... BUT NOT ON BEAM!!!!
> Again, Sorry BEAMers...
> Timothy...
>
> >At 07:49 AM 2/20/2000 , Bob Shannon wrote:
> >>Ahhh, can you list production aircraft with counter-rotating props?
> >>
> >>And how many more can you lise with both props rotating in the same
> >>direction?
> >
> >One jumps to my mind: the V-22 OSPREY tilt-rotor. Oh, and the Piper
> >Seminole (still in production? Dunno...) And (outside the requested spec)
> >originally, the Wright Flyer, and more notably in WW2, the P-38
Lightning.
> >
> >Granted, it is NOT very prevalent because the added expense of a 2nd
> >gearbox and 2nd type of propeller. BUT, if you look at the boating
> >industry, there are many twin-engine designs using counter-rotating
> >propellers, for the same reason - torque steer cancellation.
> >
> >Regards,
> >Dave
> >---------------------------------------------------------------
> >"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> >that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> > 2 vowels. Pronounciation? _SMITH_".
> > http://www.solarbotics.com
>
> ______________________________________________________
>


10513 20 Feb 00 14:26:01 CST [alt-beam] Re: BEAM: Tendency toward miniaturization] beam@sgiblab.sgi.com Steven Dang To me, it seems that along the path that you have planned for yourse=
lf,
you will encounter what you are seeking to avoid, walker neural nets and
nervous nets. These nets are the basis of the walker's survival in addit=
ion
to sensors. Without these the walker is just a paperweight. So although=
your
goal is very valid, you will find that avoiding advanced control systems =
is
impossible. That is without moving to microprocessors

Steven

> This is where having a local BEAM club where several =

> afficionado's can invest in a bigger and badder RJP would be
> excellent. I am imagining a pool table size plexi glass aquarium
> type design in which we'll have a complex terrain structure and
> a moving SUN and definitely some RAIN :). Of course careful
> preparation is needed for such a project and it is probably insane
> to even think of this but I don't see myself staying interested in
> furthering my BEAM interests for very long if I can't set such
> challenges and meet them. So for me it isn't going to be the
> walker microcore optimizing due to my lack of electronic
> skills. But rather building a walker that can survive in that
> environment for long periods of time.
> =

> Andy

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10514 Sun, 20 Feb 2000 12:32:52 -0800 [alt-beam] Re: walker dying beam@sgiblab.sgi.com Wilf Rigter After a few weeks of overwork and battling the flu , I'm easing back into
normal life including my occasional but irrepressable 2 bits worth.

The 7805 is the problem: toss it out and all will be well.

Here is the reason: Dropout! The output of the 7805 is probably about 3V. The
6V supply is too low for the 7805 as it needs at least 8V to stay in
regulation. Moreover, since the maximum output of the bicore is at 3V and the
hbridge uses a 6V supply it is quite likely (depending on the particular
hbridge circuit) that this mismatch in the signals causes the hbridge to
partially turn on which sucks the life out of the battery.

The good news is that 6V is perfectly ok for both bicore and the motors. Make
seperate (star) connections from the battery to the bicore and the h-bridges.
You may need to provide some power supply filter components for the bicore. Try
adding a 10-100 ohm resistor between the 6V line and pin 20 of the 240 and add
a 0.1 uf cap in parallel with a 100uf cap between pin 20 and pin 10. A separate
100uf cap across the hbridge should also help keep motor noise out of the power
supply.

Two bits and a whole lot of words later, I hope this is of some help.

regards

wilf

Mike Kulesza wrote:

> I finished a walker last night, but for some reason, after everytime I turn
> it on, it slows down stops altogether after about 10 seconds. The indicator
> LED's also glow less bright. And I know its not the battery, because its
> brand new... Here are the specs: Does anyone know what's wrong?
>
> - Master-Slave Bicore with reverser (Ian's complete walker circuit)
> - 74HC240
> - 2 h-bridges
> - 2 Lithium 3V batteries in series
> - 7805 voltage regulator (bicore gets 5V, motors get 6V)
> - 4 Green indicator LEDs
> - 1 Red LED to show when the tactile sensor is turned on
> - 2 .22 uF caps for each neuron = .44 uF per neuron
> - Front and rear motors are different... but both efficient and alike in
> performance.
> - No filtering caps (o.1 uF across IC and/or motors)
> - Entire circuit on a pcb (flux scraped off)
>
> and thats about it.... thanks for the input, and especially for that on the
> pager motor and fan.
>
> ______________________________________________________
>


10515 Sun, 20 Feb 2000 15:43:49 EST [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com RoboDR@aol.com This may be of interest to some of you..... Tiny RC helis includng a 48g
helicopter..... check it out.
Pixel">http://www.planetinternet.be/pixel/">Pixel Homepage



10516 Sun, 20 Feb 2000 12:47:30 PST [alt-beam] Re: solarbotics pager mtr+fan beam@sgiblab.sgi.com "Timothy Flytch" Well thanks for the encouragement... I've been slammed hard!!! on my other
list for non topic discussion...
I would like to ad that the v-22 osprey uses counter rotating rotors because
of precession problems in the forward flight mode... not to counter tork...
Timothy...
______________________________________________________



10517 Sun, 20 Feb 2000 15:51:22 EST [alt-beam] Re: It is still relevant. solarbotics pager mtr+fan beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 2/20/00 3:23:33 PM Eastern Standard Time,
dibst11+@pitt.edu writes:

> Actually I would like to point out that any discusion like this is very
> relevant to BEAM. You never know where people will get a great idea from
> discusion's like this
I agree. One could go so far as to say that kitchen stoves are not a proper
topic for a BEAM list. But, we have all seen what Mr. Tilden has done with
oven timer units. If anyone thinks that ANY topic does not somehow, no matter
how obscure, yield ideas or insight from an unknown direction, than that
person is blindly restricting growth. Think about it, and tell the topic
police to get a real job.

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870



10518 Sun, 20 Feb 2000 15:56:53 -0500 (EST) [alt-beam] what is it? beam@sgiblab.sgi.com Aaron Letts When you take apart a piece of electronics, often
there are integrated circuits in it. They all have
some numbers and stuff on the top. I was wondering if
there is a place to go, or a way to find out what each
one does. I am assuming that the number on the top of
them is an identification number.
Thanks for the help,





Aaron
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10519 Sat, 19 Feb 2000 17:54:55 -0500 Re: FYI: ANN: fire-fighting robot contest at Penn State (3-25)
> Well this actually does sound like it would be fun, and they've only got 4
> bots in the competition so far...Are you suggesting we make a team? Cuz
I'd
> be all for it, although your idea of multi-bots didn't seem like it
applied
> to this contest on the 25th. I'm right in Philly so it's pretty close for
me.
> If you or anybody else is honestly interested we better hurry with only a
> month left, so you can either keep this on the list or you can email me
> directly at
> CIRCITZ@AOL.COM
> Dan
> << http://www.ecsel.psu.edu/~avanzato/robots/contests/
> >>
>

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