On Thu, 2 Feb 2012, Viesturs L?cis wrote:
Date: Thu, 2 Feb 2012 22:50:52 +0200
From: "[UTF-8] Viesturs L?cis" <viesturs.la...@gmail.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] US Digital encoders?
2012/2/2 andy pugh <bodge...@gmail.com>:
On 2 February 2012 15:09, Viesturs L??cis <viesturs.la...@gmail.com> wrote:
Could it be anything else, but the encoder problem?
It could be an unfortunate resonance between the mechanical frequency
of the machine frame and the servo loop. This might be why increasing
the servo frequency was helpful.
Increasing servo servo period frequency from 1 kHz to 2kHz helped.
But any further increase up to 5 kHz did not provide any additional improvement.
Even more, with 5kHz (and RTAI errors) I actually have returned at
starting point.
I had some courses, covering resonances, and the conclusion is that
there should have been additional changes in behavior, when further
changes in servo update rate were made. And it should not had gone
back to the initial behavior. But that theory...
Is it possible that you have some binding or tracking issues? The 7I39L has a
current limit of 15A/phase If you exceed ths current, you will suddenly have a
drastic change in your tuning as you will lose the inherent damping of a
voltage mode drive. The current limit should never be reached in a properly
tuned system but it may be happening when you have the oscillation.
The way to check for this is look for the red overcurrent light on the 7I39
when you execute rapid accelerations (or perhaps due to resonance or binding)
2012/2/2 Sven Wesley <svenne.d...@gmail.com>:
Did you try my suggestion to ground the encoder, as written in my previous
mail?
Sorry, I forgot. The thing is that I did not find that there was not
an issue with lost encoder pulses anyway...
Viesturs
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