On Saturday 30 August 2014 17:10:10 Andy Pugh did opine And Gene did reply: > > On 30 Aug 2014, at 21:03, Gene Heskett <[email protected]> wrote: > > > > 1140 revs. But with those same settings, an s50 entry only gets me > > about 25 rpms > > Does it actually matter? I generally work on lathe speed being "too > fast" or "too slow" and the actual RPM is irrelevant. > > But, why not use lincurve or closed-loop PID if you really care?
That is closed loop Andy. Encoder velocity is fed back to pid.s.feedback. 1/1 ratio. There is one more module we need though. We need a module that is triggered by an A|B edge that writes to a register according to which signal had an edge, and which direction the edge went, meaning 4 registers, then sums each of those 4 registers & then bit shifts it to the right 2 places for a sum weight of .25 per register applied to the sum of those 4 registers. Net result would be a scale factor of 1, but with the tolerance of the slot windows & photocel response filtered out because every step presented to the real world would then be the average of the last 4. I may even take a whack at it myself since I see how easily the boot.comp module can be edited and installed for this pwm servo's amp/drivers startup sequence. Applied directly to the 5i25's pwmgen value pin, it needed some tweaking to make it work as it should for me. Putting a low pass between them could be done, but what happens to the pid's nyquist charts when we do? That I can do for S&G. Right now it seems dead stable even with an outrageous Pgain of 250 with an FF0 of 100. Unforch, this would be nice for software encoder de-noising, but I have no clue how to get the A/B signals out of the 5i25 encoder in real time. Those input pins are, unless the gpio can hijack them, probably not available to hal. Perhaps it could be done with a 4 register wide shift register, shifting in the present value while shifting the now 5th one out. But it is an idea I will check out. Obviously I need to know more about the 5i25 than I do. :( Thanks Andy. 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> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
