On Wednesday 07 October 2015 11:43:40 Peter C. Wallace wrote: > On Tue, 6 Oct 2015, Gene Heskett wrote: > > The above settings seem to have brought it under control, but one > > question, 2 actually, remain. > > > > 1. MAX_OUTPUT was set for 32.5 by PNCconf, but looking at it with a > > halmeter it appeared to be setting a restriction on how much > > "catchup" was available, so I had raised that to 50 some months ago, > > and tonight I raised it to 100, which seemed to alleviate the Z > > coasting far enough after it had hit the home switch, to hit the top > > of the slot in the post with the nut holder brackets leg about 2mm > > above the switch. With MAX_OUTOUT at 100, and some pretty > > aggressive accels that I may raise some more, it stops a few thou > > short of banging the top of the slot in the post. I came back in > > with it working, but the FERROR at 0.0001 is a nothing add, because > > MIN_FERROR is still 1.0. And it was tripping off at that 1.0 & very > > small change. > > Umm... not sure if backwards FERROR limits make any kind of sense... > > I would set the PIDs maxoutput to 0 (no limit) limiting the PIDs > output should not be needed
I'll do that. I never understood why PNCconf did that. > I would set MIN_FERROR to say .0005 inch and FERROR to say .002 to > start if you get following errors with these settings something is > wrong in the tuning or stepgen headroom. That can be done too. > > _any_ significant deviation from the commanded path indicate some kind > of problem in the stepgen setup, In my test setup here, properly tuned > the stepgen output will stay withn 50 uinch of command with 1200 IPM > and 3G accel. (not that any mechanics could) This is using the DPLL so > read jitter is reduced to about 50 ns but at your speeds, read jitter > should only cause say 100 uinch of position uncertainty (assuming > worst case 100 usec at 60 IPM) As if my machine could dream of getting that close. :) > > Was this correct for a millimeter machine? > > Yes, PID tuning does not change from mm to inch as long as the input > and output units are commensurate (and they are in the stepgen case: > PID input is position error in machine units, PID output is a velocity > command in machine units per second) > > > Where tuning changes is on things like analog velocity mode servos > wherw the PID output is scaled in volts. I encourage people to _not_ > do this but rather scale the analog output in machine units per second > so the PID tuning parameters are independent of machine units. Thanks Peter, but can't do it instantly, it seems this escapee from a Mach setup BoB, has no output controls other than the relay if not supplied with a separate machine 5 & ground, so I am in the process of populating the top of this boxes lid with another buck regulator to make some 5 volts for this stupid boards I/O. And Dee just said she was hungry and so am I, and I know just the place to get some ham, eggs & a patty of hashbrowns and decent coffee. So we're headed out to do that next. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Full-scale, agent-less Infrastructure Monitoring from a single dashboard Integrate with 40+ ManageEngine ITSM Solutions for complete visibility Physical-Virtual-Cloud Infrastructure monitoring from one console Real user monitoring with APM Insights and performance trend reports Learn More http://pubads.g.doubleclick.net/gampad/clk?id=247754911&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
