Alt-BEAM Archive

Message #03100



To: beam beam@corp.sgi.com
From: Richard Piotter richfile@rconnect.com
Date: Sat, 08 May 1999 19:24:34 -0500
Subject: [alt-beam] Re: Analog driver signals from uCore And Uni-motor locomotion.


Dennison, Look at My web page and check out the PCB for Walkman Jr.
You'll see that Walkman Jr. has it's microcore and drivers setup much
like you describe! The drivers were mistakenly attached to the inputs of
the Nvs, and it works. I never found out it was even wired wrong for
over a quarter year!!! (:

Dennison wrote:
>
> Hey, after reading that thing about the stepper motors I got to thinking.
> One of the things I had been looking at was speed control for motors driven
> by a uCore or bicore (etc...) The thing I had thought of was to use PWM at
> the enable lines of a '245 and drive the enable with a bicore or other
> osscilator. Simple, and effective, but it wasn't exactly what I want. Now,
> looking at the timeing diagram i did for a report I did on NV's (no it's
> terrible for many reasons, I won't post it) one immediatly notices that an
> NV is a RC timer, with a threshold device on the end (the inverter). The
> inverter is what turns the analog into digital. The motors are connected via
> this digital output. Here's a thought, why not drive motors with the 'in'
> side of the inverter, useing the Analog slope from the charge side of the
> cap. I realize you can't exactly drive stuff directly, but It would seem
> possible to develop some sort of perhaps an amplifying type transistor
> H-bridge or something do drive useing this part. The important thing would
> be that you the motor signals have to be clearly analog. In this fashion you
> could control the volt difference across the motor, besides being just
> digital, and subsequently the speed of the motor. While this might not be
> very important for things such as walkers, it would be an advantage in lone
> Bicore Heads.
>
> Why?
>
> Well a year or more ago I built an nice little horizontal swing HEAD, and I
> posted to the list my observation that my head, was able to 'walk around'.
> It's basically a version of an 'inertia' drive (ooh! REad on before you go
> crazy) You can try it yourself, make the base of your head light, and swing
> the head in big sweeps, you'll notice that the head will move around, due to
> the inertia of the device. And it will bump around in a pretty random
> fashion. But here's a kicker, It's too difficult right now to produce
> controlled, reliable motion, ALTHOUGH it shows very high potential to be
> phototropic. A solar powered device would be phototropic based on the
> Miniball Principle. Since although the head has a large swing it still
> points primarilly in the direction of the brightest light, so it 'bumps'
> itself somewhat twards this brightest light source. NEAT HUH? Well one Idea
> I was thinking about to make it more directional was the speed of the motor.
> If you could control the speed of the motor, you could vary the inertia of
> the device in different swings, and when it's swinign in different
> directions. So, that seemed like a viable idea for the whole ordeal.
>
> Anyway, If anyone goes about submiting this into Chiu's contest, because it
> is a spanking neat method of locomotion, and really innovative, just try to
> give me a little credit, because I did do a little work on my part to be
> able to post this, experimenting and such. I plan to submit a bot like this
> myself, or a magneto driven device, but It's always possible I won't get
> around to it. So, maybe I'll call it D-Drive, or something. Or more
> technical, like Angular Momentum Drive. I think I've explained how the
> device works, hope the concept isn't too confusing, or my words to simple!
> :-)
>
> Dennison

--


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

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