so - is the work around - tuning by pid error - then set the F-error accordingly? or better yet - monitor the pid error instead of the f-error (set it high) and have the pid error trigger the estop? (that would be hal doable I think)
sam On 11/1/2012 9:09 AM, Peter C. Wallace wrote: > 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 > > ------------------------------------------------------------------------------ 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
