On Monday 25 May 2020 20:43:45 Gene Heskett wrote: > On Monday 25 May 2020 18:33:29 Jon Elson wrote: > > On 05/25/2020 02:50 PM, N wrote: > > > Do anyone here have any suggestion for FERROR and MIN_FERROR > > > values? > > > > It depends on your "user units", as well as the general > > accuracy and speed of the machine. > > FERROR is a multiplier to velocity in user units/second that > > is added to MIN_FERROR. > > MIN_FERROR is the allowable following error with the machine > > not moving. > > > > On a servo system, you should have Halscope graph the > > following error and find out what > > your actual errors are, and then set MIN_FERROR > > accordingly. Then, set FERROR to > > accommodate larger error at rapid traverse speed. > > > > There's no one good value for everybody. > > > > Jon > > Perhaps this might be a good time to discuss/develop a recommended > good practice procedure to be applied to a machine w/o PID's as > there's none in the pi running the sheldon, and none in the D5215MW > running the 6040. > > Can you recommend a procedure that Just Works, where the machine is > expected to follow what the TP actually outputs, with a tolerance > setting profile that its capable of staying inside of? > > Without PID's, where do we get a following error that we can see on > the halscope? Or do I need to put PID's in before this makes sense? > Or do I make a sub2 out of a sum2 just to develop the error signal? > Eventually that would use up the cpu cycles saved by not using the > PID's. And it all, to me, adds up to more give between the TP and > what the machine does, allowing more error than w/o the PID. > > Seems to me there should be some "rules of thumb" to apply here.
I just tried an experiment. Since there are no pid's in that sheldon setup, I commented out the *ERROR entries in the .ini file. Interesting as it made zero difference in how it ran. So, it appears that I'll need to synth an error signal, and the best way I can think of it to subtract the command to a stepgen from the feedback, or vice-versa, but w/o an encoder actually measuring that axis, its not going to tell me anything but the time lags caused by the addf order. Food to feed a "what if" at some point... Perhaps if I cab break into the encoder? Acc to fedex I should get those 3 phase closed loop motors late today. AIUI, they do have an error output, but its yay or nay I think, but the 3NM is way too long to fit behind the apron and drive the X. I do intend to put one of the 3NM's on the Z. Lots of room there. That 1600 oz/in there now is so much overkill its not even funny. It rattles the whole machine when it moves. That should at least give me an error stop if the motor doesn't follow orders. Stay well everybody. 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
