On Monday 30 November 2020 17:23:47 Peter C. Wallace wrote: > On Mon, 30 Nov 2020, Gene Heskett wrote: > > Date: Mon, 30 Nov 2020 17:07:04 -0500 > > From: Gene Heskett <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: "Enhanced Machine Controller (EMC)" > > <[email protected]> Subject: [Emc-users] crazy > > > > Greetings all the pid experts; > > > > I changed out the bob for one w/o the input capacitors, looks 1 > > million times better on the scope > > > > Playing with what little servo I have configured so far, trying to > > get it to actually act like a servo. I don't have a valid SCALE yet > > but expect it will be large so I set it to 1150. Hooked the encoder > > feed back back up in hal. Couldn't make it move, pwmgen limited to > > about a 2% duty cycle. Not enough to move the motor. looking at the > > pid_a with halconfig, I saw that pid_a.maxerror was set to .0005. > > Curious, since it was at that point sitting around 1000 out of > > balance, I did a setp to set it to 1000. Motor almost jumped off the > > stepladder and ran toward balance at a good clip but eventually > > stopped when encoder feedback into pid_a.feedback was about 2 from > > equalling pid_a.cmd. That .0005 was an old setting, but worked when > > a stepper was doing the shaft twisting. I certainly don't remember > > adding it 5+ years ago. > > > > That was set in the .hal file but I've no clue why. Whats the > > default if its not set? It is not in the .ini file > > Default if not set is 0 which means the error is unbounded.
Cleared out of the file now. Thanks Peter. > Maxerror is bound on stepgen loops since the stepgen hardware is > an almost perfect velocity mode device (so FF1 does 99.99% > of the work). The advantage of the bound is that servo thread > jitter creates bogus position feedback errors and by bounding > these errors you reduce their effect on motion. This has largely > been made obsolete by the DPLL that reduces the stepgen and > encoder position sampling jitter to a small fraction of a > microsecond. [...] Stay safe and well now. 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
