So, looking at one of the links for servo tuning is our FF0 = Velocity Feed Forward Gain. FF1 = Position Feed Forward Gain. FF2 = Acceleration Feed Forward Gain or Friction Feed Forward Gain.
I would like to update the docs with some descriptive text in addition to "0th order feed forward gain" as that and the other descriptions only seem to make sense to a mathematics professor. " Position Feed Forward Gain. Compensates for position-based effects in a system. Its effect is similar to having a spring attached to the stage. (DAC counts / position counts) Velocity Feed Forward Gain. Compensates for velocity-based friction or similar effects in a system. (DAC counts * (commanded position counts / sample period)) Acceleration Feed Forward Gain. Compensates for mass in a system. (DAC counts / (commanded position counts / sample period^2 )) Friction Feed Forward Gain. Compensates for Friction in a stage. (DAC counts) " Thanks John On 1/28/2012 10:28 AM, Jon Elson wrote: > John Thornton wrote: >> Jon, >> >> What is FF0 used for if it should be set to 0 for a motion axis? >> > I used to think it was useless, but if you use the PID for a spindle > speed control, > for instance, then it is quite useful for a velocity servo. It serves > about the same > purpose as FF1 in a positioning servo. In a positioning servo, it would > add an > offset proportional to position. In a velocity servo, it would add an > offset > proportional to speed, thereby correcting for finite gain in the loop. > > Jon > > ------------------------------------------------------------------------------ > Try before you buy = See our experts in action! > The most comprehensive online learning library for Microsoft developers > is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, > Metro Style Apps, more. Free future releases when you subscribe now! > http://p.sf.net/sfu/learndevnow-dev2 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
