gene heskett wrote: > On Sunday, January 29, 2012 12:00:01 PM andy pugh did opine: > > >> On 29 January 2012 13:23, John Thornton <bjt...@gmail.com> wrote: >> >>> 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. >>> > > Bingo John. > > To get more specific, FF0 is an adjustment based on the commanded parameter of the PID. FF1 is based on the first derivative of the commanded parameter, FF2 is based on the second derivative. In a positioning servo, then FF0 is proportional to the position, FF1 is proportional to velocity and FF2 is proportional to acceleration.
In a velocity servo, perhaps a closed-loop spindle speed control, FF0 would be proportional to velocity, FF1 would be proportional to acceleration, and FF2 would be proportional to change in acceleration, sometimes referred to as "jerk". 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
