On Thu, 1 Nov 2012, EBo wrote: > Date: Thu, 01 Nov 2012 09:47:30 -0400 > From: EBo <e...@sandien.com> > Reply-To: EMC developers <emc-developers@lists.sourceforge.net> > To: emc-developers@lists.sourceforge.net > Subject: Re: [Emc-developers] ferror calculation incorrect in motion > > This is exactly why I asked for references so we could look at the > mathematical definitions and either experiment with working machines or > at least develop a simulation model which stress tests the various > aspects of the two approaches. I would rather a fully principled > approach to this (including reviewing the math) than the current list > thread direction.
This is really simple http://en.wikipedia.org/wiki/PID_controller Note that the first paragraph says: 'A PID controller calculates an "error" value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error by adjusting the process control inputs.' This is certainly my understanding (that the task of the PID controller is to minimize its input error) The current situation is that the PID loop and ferror have different setpoints but the same "process variable" so if you tune to minimize ferror you need to force the PID loop to minimize something different than its input error. This makes the integral term mostly unuseable (since the intergral term will force the input error to 0 and generate a ferror proportional to velocity*sampletime) Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
