On Wednesday 02 September 2015 12:20:35 Gene Heskett wrote: > On Wednesday 02 September 2015 05:56:56 Gene Heskett wrote: > > On Wednesday 02 September 2015 04:50:24 andy pugh wrote: > > > On 2 September 2015 at 03:05, Gene Heskett <[email protected]> wrote: > > > >> You need the Limit3 _before_ the PID, not after. > > > > > > > > It IS in front of it Andy. > > > > > > That's odd then. > > > > > > So, you have > > > motion.spindle-speed-out-rps => limit3.0.in > > > limit3.0.out => pid.4.command ? > > > > > > I trust there _isn't_ a limit3 on the feedback to the PID? > > > >[...] > > I'd look right now, but that &^$ box has crashed. I have got to find > > a better one. > > > > Thanks Andy. > > > > Cheers, Gene Heskett > > Box rebooted. And I found when searching for the gearchange, that it > was loadrt'd but never used! Nuked that line in the hal file. > > What pncconf did do was to setup a mux16, but only used 2 inputs. And > as near as I can figure, its triggered automatically by > pid.s.maxoutput. > > This is also used to correct the rpm request from motion that I get > when I typoe s1000 m3 into the mdi command line, by dividing it by the > gain setting input, the output of which goes into a "scale" module's > gain control. > > I nuked all the gains in pid.s to zero except FF0, leaving that at > 1.00, and started experimenting with the limit3 in front of the > pid.s.command input. By diddling the mux16's in0 value I was able to > get output speeds that except for speeds below 250 rpm are slowed by > drive friction, and only about 50 revs or so high at a requested 2500. > > Then I started playing with the limit3's maxa. 500 still took 15 or so > seconds to do a reverse, way too gentle. I finally wound up with its > maxa set at 150000, which still gave a good turnaround time even from > 2500 revs but was obviously gentler done. And no windup/overshoot at > any tested speed down to 100 revs. The C7 lamp on the motor PSU > brightens noticeably of course but the caps have about a 10% margin > between actual and rated voltage. > > So now I go back out and see if I can stiffen its control up with some > feedback as I can grab the spindle at 500 rpm and pull it down to > about 275 with a bit of effort. > > This does seem like progress, but this mux16 gearchange bothers me, I > get the impression it was intended to actually change gears on the > fly, but I can't find such an output in this .hal file. It looks as > if the drive gain is changed on the fly, perhaps by sensing that the > head is in low gear from the maxerror output of the pid. > > Is there a tut in the wiki on this use of a mux16 for a gearchange? > My search foo is weak.
Most of the howto's I find on the net are for position servos, not velocity such as a spindle controller. Different ballgame. ;o) > > Thanks John, Andy and everybody else that can pipe up here. Well, using my hand on the spindle to check for working torque, this is what I wound up for pid.s settings. [SPINDLE_9] P = 12500 I = 2.25 D = 0.00 FF0 = 1.00 FF1 = 0.05 FF2 = 0.00 Crazy, but it works! And I can't stop it from 100 revs by hand, a considerable improvement. This is in high gear. Progress of a kind I guess, and considerably more accurate that previously. And I still didn't note any windup/overshoot. But a noisy t-storm has moved in, so I quit for a bit. I balanced the Igain and the scaling in the mux16.in00 to get sub 5% speed errors at 100 and 2500 revs, so that problem is solved within the real world usable rpms range. Now, I need to figure out how to make the backgear work for low speed. In the meantime I can carve Mahogany rather precisely when it gets here. That ought to be yet this week. 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> ------------------------------------------------------------------------------ Monitor Your Dynamic Infrastructure at Any Scale With Datadog! Get real-time metrics from all of your servers, apps and tools in one place. SourceForge users - Click here to start your Free Trial of Datadog now! http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
