On Thursday 07 May 2020 13:19:23 Dan Henderson wrote: > I believe this is open loop. Isn’t PID only used in closed loop > control? > Its (the PID is) a waste of processor time if open loop. I don't use one of those in any spindle run by a vfd, the vfd is generally stiff enough control by itself. If I thread on that machine, it will have a spindle encoder, but its only job is to glue the axis motion being driven to cut the thread, to the spindle rotation, in the case of a g33.1, going both in and out of the hole. If you aren't useing a PID for the spindle, that leaves motion I think.
I think its time we saw your .hal file. Can you insert it into a mail? > On Thu, May 7, 2020 at 11:03 AM Gene Heskett <ghesk...@shentel.net> wrote: > > On Thursday 07 May 2020 11:27:57 Jon Elson wrote: > > > On 05/06/2020 09:20 PM, Dan Henderson wrote: > > > > I’ve confirmed the fluctuation occurs when spindle-at-speed is > > > > configured. When I remove this feature, the spindle rpm appears > > > > to stabilize. It’s almost like it gets caught in a loop trying > > > > to chase its tail. > > > > > > This is VERY common in servo systems, and is due to delay in > > > response of the object being controlled. > > > You need to slow down the response of the PID to ignore the > > > delay. This may be possible by adding > > > D to it. > > > > > > Jon > > > > But my msg was that a near module generated spindle.N.at-speed was > > never to be injected into any signal path leading back to a PID. > > That near's output s/b only to that input to motion, and possibly to > > an indicator led in the gui so the operator can be advised if its > > acting funkity. Flickering could be worn brushes in a brushed PMDC > > motor for instance. > > > > What you are describing as delays can often be fixed by the proper > > re-ordering of the addf's involved for the oscillating axis. That > > aspect of configuring LinuxCNC hasn't been mentioned recently or I > > wouldn't even have included that paragraph in my reply. > > > > And from Dan's description above, I think this is an entirely > > different critter from a timeing delay. > > > > Cheers Jon & stay well, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
