Re: handbook info -- autotuning

[Ray Henry <rehenry-at-up.net>]

Hi Les

Thanks for the info.  I know of at least one who is using ZN on the basis of 
it.  I'll look into it and add this to the book.

Ray

On Monday 10 June 2002 07:36, you wrote:
> Ray,
>
> I have successfully used Zeigler-Nichols closed loop tuning with EMC. It
> might be the best
> method (there are many) because it requires minimum instrumentation.
> Proportional gain
> alone is  slowly increased until a small sustained oscillation is observed.
> If one can simply
> estimate that frequency that is enough (with the gain setting that caused
> it) to get
> calculated P,I, and D values.
>
> Zeigler Nichols theory concerns linear systems- so a machine with lots of
> non linearity
> like stick slip or other non velocity related friction might not tune well.
>
> It works well enough with my large ballscrew/linear rail machine.
>
> It is also possible to get the parameters from a single bump or jog with
> any stable machine
> setting but you must acquire motion vs time. If the EMC data logging
> feature worked
> (at a proper sample rate) it could supply those parameters. I have tried
> this but the
> log file is always garbage for some reason.
>
> A math description of ZN tuning is at:
> http://www.shu.ac.uk/schools/eng/teaching/rw/pidtutorial.htm
>
> It appears that EMC is actually fast enough to do some anti-vibration
> control!
> If the servo bandwidth is higher that some structural resonances the system
> could (in theory) remain stable through and beyond them. I might play with
> that later-but it's not pressing. I just always want to run the machines
> faster
> faster faster... until I run in to a thermal limit (burning up work).
>
> Les
> Leslie Watts
> L M Watts Furniture
> Tiger, Georgia USA
> http://www.rabun.net/~leswatts/wattsfurniturewp.html
> engineering page:
> http://www.rabun.net/~leswatts/shop.html
> ----- Original Message -----
> From: "Ray Henry" <rehenry-at-up.net>
> To: "Multiple recipients of list" <emc-at-nist.gov>
> Sent: Sunday, June 09, 2002 10:16 PM
> Subject: handbook info -- autotuning
>
> > List
> >
> > I found the following statement in the handbook.
> >
> > "There are several auto tuning and computational tuning procedures but
>
> these
>
> > have not been tested with EMC."
> >
> > Is this true?  Do any of you have further information on this subject.
> >
> > Let me know if you are willing to dig into this a bit further.
> >
> > Ray