On Wed, 09 Dec 2009 08:24:15 -0600, cavelamb wrote:

Pete Keillor wrote:
On Wed, 09 Dec 2009 07:06:14 -0600, cavelamb
wrote:

Pete Keillor wrote:
On Tue, 08 Dec 2009 22:06:17 -0600, Don Foreman
wrote:

"Karl Townsend" wrote in message
anews.com...
You described the exact issue. Mechanically, I've got it geared
down to raise/lower 12"/minute with a total travel of 60 inches.
Gets hard to gear it much slower. My "plan A" is two stats so you
have a dead band, then play with % run to get response without
oscillation. I suppose if you knew exactly what percent on/off was
optimum you could just gear it for 100% on.
You can't know that because it will change significantly with cloud
cover, sun angle, wind, etc.


It ain't hard, it just ain't cheap. I used a double reduction
Sumitomo cycloid drive of 3400:1 to drive the continuous filter I
invented. Web movement maximum was 60"/hour, min was close to zero.
I'd mark the web, go have a cup of coffee, come back and stick a
ruler on it to make sure it was working.

Pete Keillor

Well, not to be contradictory, but it is both easy and cheep - in
software.

Once you have the drive running that can handle the mechanical loads,
controlling the speed is simple stuff.

Richard

Yeah, you're right if discontinuous works, as in this case. I wanted
continuous motion in the case I described.

Pete Keillor


Pulse width modulate.

The motor will integrate that into continuous motion.

If the requirements get REAL slow, you may have to pulse both ways.
Drive forward Tx
Drive backwards Tc-n

Keep the motor energized so it doesn't wander off position.



....Monitor the motor position so you can actively control it (speaking of
bloatware).

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