Alt-BEAM Archive
Message #05865
To: beam@sgiblab.sgi.com
From: Richard Piotter richfile@rconnect.com
Date: Thu, 26 Aug 1999 21:41:56 -0500
Subject: [alt-beam] Re: New Guy Questions
Best suggestion is a 500K* or less multi turn potentiometer. They are
SENSITIVE. Solarbotics sells one that takes 20 turns to go from one
reach to the other. That allows precision adjustment. Also, a slight
help from gravity as always great. How many batteries are you using? if
it's 4 AA/AAA type batteries, I'm thinking that the extra power is
introducing the pulse. I use a 9 volt battery and a small 5 volt
regulator on the power input on the chip on my robots. Works great.
Otherwise, you could see if it runs on 3 AA/AAA type batteries instead.
I'll bet you can put it into single process mode and keep it there then.
Good Luck!
Brad Guillot wrote:
>
> Thanks for all the help. the circuit i used was a 4 nueron microcore,
> and this is weird, it will not work on full batteries! i have to breakem
> in for a few munites in saturaton before i can stabalize the loop. any
> suggestions? , also i am havig a real hard time triming the motors with
> the massive 1 meg pot from radio shack. so my next question, was the
> bigger pot a bad idea? (fixed one problem, found 2 more, bad patteren)
>
> Once again thanks for all of your help!
>
> bg
>
> Bob Shannon wrote:
> >
> > Ben Hitchcock wrote:
> >
> > > >From: Bruce Robinson
> > >
> > > >Let us not overlook the original H-bridge design Mark Tilden described.
> > > >He used a 74HC139 chip to prevent smoking a bridge. (It doesn't matter
> > > >whether the inputs are active high or active low).
> > > >
> > > >This is a decoder chip: it takes two inputs, and for each of the four
> > > >possible input combinations, it makes ONE output go low (the others
> > > >remain high). If you use an H-bridge design that triggers on a low
> > > >signal, you can use it directly with this chip. If your H-bridge design
> > > >triggers on high signals, then you'll have to use a couple of inverters
> > > >on the 74HC139 outputs.
> > > >
> > > >Another point -- the '139 chip is a dual device -- it has two
> > > >independent decoders, so you can manage two H-bridges with one chip.
> > >
> > >
> > >
> > > Ahh yes, but I fitted ALL the electronics into the servo cases. All except
> > > the batteries. I simply didn't have room for another chip in there. Also,
> > > if you are going to use a 74HC139 chip to protect the H-bridge, then why not
> > > just use that (or similar) chip as the motor driver?
> >
> > Hmmm, maybe because it says that BEAM devices perform no digital
> > computation in Living Machines?
> >
> > Exactly how is the 139 BEAM tech?
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--
Richard Piotter
richfile@rconnect.com
The Richfiles Robotics & TI web page:
http://richfiles.calc.org
For the BEAM Robotics list:
BEAM Robotics Tek FAQ
http://people.ne.mediaone.net/bushbo/beam/FAQ.html
5866 Thu, 26 Aug 1999 23:30:41 -0400 [alt-beam] Re: New Guy Questions beam@sgiblab.sgi.com Bob Shannon
Tom Mairs wrote:
> Well by that argument any thing that uses a gate of any kind would not be
> BEAM. This is going to re-open the whole ignorant argument of what is and
> isn't BEAM. A decoder is just a collection of gates performing a selection
> task. Would it be any more BEAM if the entire thing was made from discrete
> transistors but did the same thing? Any time you use a high or low signal
> level to determine the out come of an event to be either on or off, you are
> using digital computation. I sincerely hope you were joking....
Yes actually.
But I had just been reading Living Machines again when the message came in.
I started to think, and realized that LEM does a similar thing with AND gates
between the Microcore and Bicores, so I'm hoping that there's been a change of
heart
about digital logic. I think I'd overlooked that when I first read the paper,
so it kinds of
took me by supprise.
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