Re: [Emc-users] Tune-upn AC servomotor

[Dave E. <den...@ch...>]

Hi Aram,

ZN tuning has been around for a long time (1943). I know of two  
emc'ers using it as a tuning method; both are engineers. Please note  
the response curves in your reference and the long settling times of  
ZN. OK, maybe for process control but maybe not the best for machine  
control especially with your servo amps and motors which should give  
you really nice performance.

Setup halscope to monitor following error and any other parameters  
you want to keep track of.

  I use only the first step of ZN, i.e. just to set P (gain). The  
instructions I got are slightly different from that listed in your  
reference. For step 1 set I and D to zero then increase P until the  
axis just sustains oscillation and multiply that value by 0.6. This  
is a good starting point for P.

Using MDI with F (velocity) at some high value, half max velocity to  
max velocity command short moves ...
just enough to reach full velocity adjust FF1 and monitor the results  
in terms of  following error. FF1 will affect the offset of your  
following error and can be adjusted so the following error is  
virtually on zero with small bumps at either end of the travel for  
acceleration and deceleration. When you get the following error as  
small as you can with FF1 go back and vary P a bit to see if you can  
improve the overall result. When you are satisfied with that  
adjustment then try small values for D and I. I've never been very  
successful at finding appropriate I's and D's but that may be machine  
related.

With my Mazak (200 ipm) I get following errors of about 0.015" with  
just P. Using FF1 brings this down to 0.0002" to 0.0005".
Attempts to adjust FF0, I and D gets me no closer so I leave them at  
zero.

Not quite on subject but interesting reading is:

http://www.sunist.org/shared%20documents/TRANSISTOR,%20IC,%20CIRCUIT% 
20...%20DATASHEETS/speed%20control%20DC%20motor%20using%20dsp.pdf

Hope this helps and good luck tuning.

Dave


On Dec 6, 2006, at 3:13 AM, Kasparov, Aram wrote:

>
>
> ________________________________
>
>
> Hi
>
> I found that local servo control shop has a web page information  
> about how to tune up servomotors.
>
> http://www.olympus-controls.com/whitepapers.php <http://kiccvan18/ 
> exchweb/bin/redir.asp?URL=http://www.olympus-controls.com/ 
> whitepapers.php>
>
> I am interesting in how close or useful that information to tune up  
> EMC2 AC servomotors?
>
> Thanks
>
> aramk
>
>
>
> <winmail.dat>
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