RE: running servo's

> -----Original Message-----
> From: Jan [SMTP:postmaster@...]
> Sent: Thursday, December 16, 1999 11:55 AM
> To: CAD_CAM_EDM_DRO@...
> Subject: [CAD_CAM_EDM_DRO] running servo's
>
>
> My problem is that when I disconnect the original DAC cable from the
> amp's, the servo's are drifting the moment I switch on the machine. Can
> this come from the fact there is to much gain on the amp's? (I don't like
> to turn this pot-meter as I still want to work with the original
> controller and this value is yet tuned for the machine.)
>
> Then with this fault and connecting to the DAC of the STG-board, starting
> EMC; out of E-stop and put the machine-on, I can be impressed to see that
> I have a speedy machine, still it would be great when he waited for a
> command to move.
>
> So I thought that this movement came from the fact that I reversed the DAC
> cable, so one movement could compensate the other, tried that out, the
> result was even worse as I had a servo flipping one side to another for
> just a couple of degrees (shaking is maybe a better word).
>

Jan;

The servo oscillating usually indicates too much proportional or
differential gain, whereas the runaway is often caused by reversed polarity
(which is effectively the same thing as having the encoder reversed). You
might try reversing the DAC cable again and reducing gain. Just a guess, as
I'm not really familiar with your system.

Doug

> Tried also with other PID value but no improvement was seen.
>
> So what knowledge am I missing ?
>
> and what is BIAS? I do not find a description of this parameter.
>
> Thanks in advance for your reply.
>
> Jan.
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