On 07/23/2010 12:47 PM, Ignoramus7608 wrote:
Called AMC and as always, talked to a great guy.

Just wanted to post this summary so as to make it available to anyone
looking for same.

Pot 1, Loop Gain, is the one responsible for responsiveness of the
motor to error in commanded parameter (speed in my case, as I run in
velocity mode). To adjust it, turn it clockwise until the motor starts
vibrating when commanded zero. Then back out 1-2 turns. Gunner pretty
much said the same thing.

Ha! That's what I figured.

Pot 3, Reference Gain, has nothing to do with stability of the servo
system and represents only the proportion of how much speed you get
for a given volts input. Fully clockwise it means 100% available
speed.

Well....

It has nothing to do with the stability of the _drive_, but it affects
the overall gain of the position servo. When you change the setting on
that pot it'll change the gain that EMC 'sees'. Turning up the gain on
that pot has the same effect as turning up all the gains in EMC.

So, set it such that the voltage range of the drive, without topping out
in speed, matches the voltage range that EMC will send. Then don't ever
touch it -- putting inspection paint on it to seal it would not be a bad
idea, or even a drop of beeswax.

I will make some adjustments tonight based on that, so as to get a
stable system operating at top performance. During tuning, I turned
down Ref gain, for no good reason as it turns out. So my motors do not
operate at top speed avaliable from the drive.

i


--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html