RE: [CAD_CAM_EDM_DRO] Re: Big servo motors drive recommendations

Yes there are 17 parameters to set on my analogue cards. I am glad all but
three are done by calculation and have already been set.
Asking a DIYer to do this may well be an impossible task.

Regs Mark

Dr. Mark Vaughan Ph'D. B.Eng. M0VAU
Managing Director
Vaughan Industries Ltd, reg in UK no 2561068
Water Care Technology Ltd, reg in UK no 4129351
Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288
RSGB DRM111(Cornwall)
-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Jon Elson
Sent: 27 May 2007 19:59
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Big servo motors drive recommendations

Mark Vaughan wrote:

> I've wondered why they don't copy some of the old analogue stuff.
>
> I suppose the issue is probably the fact that most digital engineers hate
> analogue work and so they keep clear, that little analogue I have seen on
> digital cards is very poorly done.

The smoothest and most stable performance is obtained with a
tachometer on the motor. This scares the average DIY
retrofitter beyond belief! And, for good reason, because to get
good performance, it takes an oscilloscope and a lot of fooling
around to tune the servo response. First you need to set the
bandwidth (compensation) for the torque (current) loop, then do
the same for the velocity loop. Then, you need to balance the
gains of the velocity (tach) feedback with the velocity command.
Finally, you need to tune the PID loop on the CNC computer.
That is a HELL of a lot of interacting adjustments! When one of
them is out of whack, it can take some time to figure out which
one it is.

Jon


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