Alt-BEAM Archive
Message #05855
To: beam@sgiblab.sgi.com
From: "Ben Hitchcock" beh01@uow.edu.au
Date: Wed, 25 Aug 1999 23:31:03 +0000
Subject: [alt-beam] Re: New Guy Questions
Hey Arno,
Welcome!
>
> Hello list
>I have a few questions i would like to get anserwed that are proballly
>redundant and stupid for the advanced builders.
Not at all. I always read the replies to even the most obvious of
questions, and usually learn something. For some reason this happens more
often than not when Wilf is around... ;)
> 1.when driving hobby servoes on a 2 mortor 4 leged walker, which is
>better to use, a 74xx245 or an h-bridge? i ask because 3 245's wound
>drive a servo @3v. This is my main concern, to get it walking and then
>add all the things to make it a robot.
I have used TWO gates from a 74HC14 to drive a hobby servo motor (One for
each motor lead), and the walker walked. The torque wasn't fantastic, but
it did work. Using 3 245's would give you gobs of torque, plenty to drive a
piddly little walker.
For the rear legs, I used the H-bridge chip that came with the servo. This
was very small, and works extremely well. Of course, I hooked it up with
both inputs high the first time, and it smoked. That's why I'm only using
ONE H-bridge on my 2 motor walker. The one I had earmarked for the front
got fried. After that I rewired my microcore to be active low, instead of
active high.
It's really up to you. Some people prefer H-bridges, some prefer inverters.
I use whatever is either smallest or is within easy reach on my
table/junkbox.
> 2. Sorry to be general, but could anyone explain/ give a good site in
>how to incorperate a head into a walker for reversing and turning?
You may have to experiment yourself here. Heads exist, walkers exist, but
integrating a head and a walker is not for the faint of heart. Not the
least of your problems is that a head makes for a higher center of gravity -
and I'm sure you can see what that would to to a walker that is only just
able to keep from falling over!
Good luck!
Ben Hitchcock
5856 Thu, 26 Aug 1999 09:58:13 +0800 Broken CDROM: Laser diodes & Motors
> BEAMers,
>
> So I got two broken CDROM drives. And collected 4 electormotors, all seem
to
> be the same. They are usable I heard. Right?
> And what about the laserdiodes? I read a part of the laser article posted
> earlier, but I don't see how a laserdiode (man, they are small!!!) can be
> used as part of a bot. Well, I suppose as some sort of vision system or
so.
> But has anybody done it before?
>
> Cya,
> Arno
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