On Monday, January 3, 2022 11:45:13 PM EST Sam Sokolik wrote: > I think it is just easy to have 2 pid's and sum them.. (one on the motor > encoder with P,D and feed forward - the other with scales and the I term) > Then you are not re-writing the pid component for some odd corner case. > > sam
Corner case? Assuming addf's are in order, a block diagram plz. ... One of the targets in my case would be the pi that's running my Sheldon. It has the 3 phase stepper servos, but their are no PID's, whatever comes out of motion goes direct to the stepgen, and the stepgen is its own feedback source. The encoder in these motors is not fed back to LCNC, only to the drive, which does its own thing, among others using only enough motor current to get to where it is told to go. Quite a large improvement in energy used right there. If its loaded too hard, or has run into the immovable object and can't get there, it kills the motor driver and reports the error to LCNC. In my case it toggles F2 off, which in turn kills the AC power to the machine, which is the reset/re-enable for these drivers. I pull the tool from the tool post, hit F2 to power up the machine again, rehome the machine, figure out what I did wrong, fix it, put the tool back on the toolpost and touch r. I do not know how the additional loop time of adding 2 PID's to its control would be handled by a pi4. This started out as a pi3, and the 3 was pushed quite a bit to keep up with a 1 kilohertz servo loop, so much so I moved the hand dial controls to a separate, only 200hz thread, the pi4 has lots more reserve. If your don't mind an occasional stutter the pi4 can cruise the web while making burn holes your shirt swarf. FF is not kind to irq latency, but we all knew that. I'm also not sure how scales could be mounted on the Sheldon and be protected against hot swarf. Might need some pix from others that have done it before me. Just thinking out loud. And as near as I can tell its working fine as as is. 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, 1940) 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
