Re: [Emc-users] tuning question

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

On Oct 9, 2010, at 9:51 AM, Peter C. Wallace wrote:

> On Sat, 9 Oct 2010, Stuart Stevenson wrote:
> 
>> Date: Sat, 9 Oct 2010 10:08:34 -0500
>> From: Stuart Stevenson <st...@gm...>
>> Reply-To: "Enhanced Machine Controller (EMC)"
>>    <emc...@li...>
>> To: EMC2-Users-List <Emc...@li...>
>> Subject: [Emc-users] tuning question
>> 
>> Gentlemen,
>> assessment please
>> 
>> Fanuc AC servo amp w/+-10 V velocity input - encoder feedback from motor
>> Fanuc AC servo motor
>> PPMC
>> EMC2 2.5.0-pre
>> Touchy GUI
>> 
>> http://www.mpm1.com:8080/machines/enshu.ini
>> 
>> the following are the variations from the .ini file and the resultant
>> screenshots
>> 
>> FF1 0
>> FF2 0
>> http://www.mpm1.com:8080/machines/Screentshot1.png
>> 
>> FF1 0
>> FF2 0
>> Pgain 50
>> http://www.mpm1.com:8080/machines/Screentshot2.png
>> 
>> FF1 .5
>> FF2 0
>> Pgain 50
>> http://www.mpm1.com:8080/machines/Screentshot3.png
>> 
>> 
>> Pgain 50
>> http://www.mpm1.com:8080/machines/Screentshot4.png
>> 
>> 
>> in screenshots 1 2 and 3 notice the squared trace on the beginning of the
>> accel and decel
>> I get this on all axes including the spindle and am unable to tune it away
>> I have tried many different combinations of tuning values
>> the best trace is the spindle with a max accel of 2 - this allowed a much
>> higher Pgain and stiffened the spindle considerably
>> the spindle has very little inertia as it drives only the gearbox and
>> spindle
>> I see the squared traces on the spindle
>> the ending traces work smooth until I start getting the tuning a lot tighter
>> then the traces tend to even out on all axes
>> do you believe this is a result of the marriage between the fanuc hardware,
>> ppmc and emc2?
>> motion of the axes feels, looks and cuts smooth and accurate - the following
>> error spikes are the focus
>> suggestions, comments
>> thanks
>> Stuart
>> 
>> -- 
>> dos centavos
> 
> screenshots 1,2 and three look like simply not enough FF1 (error proportional 
> to velocity)
> 
> screenshots 4 looks like FF1 is correct and you are seeing residual errors 
> (jerk = derivative of accel) These might be due to phase lag so could be 
> partially ameliorated by bumping up the sample rate.
> 
> 2 pfennigs
> 
BTW I did notice that TRAJ   period is set to 10 X servo rate. Setting both at 2 KHz might spiffy things up a bit. 

Dave
> 
> ------------------------------------------------------------------------------
> Beautiful is writing same markup. Internet Explorer 9 supports
> standards for HTML5, CSS3, SVG 1.1,  ECMAScript5, and DOM L2 & L3.
> Spend less time writing and  rewriting code and more time creating great
> experiences on the web. Be a part of the beta today.
> http://p.sf.net/sfu/beautyoftheweb
> _______________________________________________
> Emc-users mailing list
> Emc...@li...
> https://lists.sourceforge.net/lists/listinfo/emc-users