>From what I know of control theory you are right. You will not find a set of gains that work for both gear ratios. The gears are doing their job and changing the apparent momentum of the spindle and available motor torque by quite a lot.
I think you will need an input to the controller to tell it which gear is in use. You WILL need to find two independent solutions. Either solve in each case analytically, implement an "auto tune" routine or you can do it by experiment but that takes a long time If it oscillates the P gain is high. Usually they say to rain P until it starts to oscillate then back off 10% or so and then increase "I" slowly. This article is pretty good intro to PIDs. See the part where he talks about "windup" which I guess is why you motor was slow. (one thing, his "next arrows are tiny, took be a while to find them) http://brettbeauregard.com/blog/2011/04/improving-the- beginners-pid-introduction/ Good tuning advice here https://en.wikipedia.org/wiki/PID_controller#Loop_tuning On Mon, Oct 30, 2017 at 10:49 AM, Gene Heskett <[email protected]> wrote: > Greetings all; > > I've been playing with pid settings for the spindle on the G0704 until > I'm discouraged at ever coming up with a setting that is useable in both > high and low gears of the head. What works great at 300 revs in low gear > sound like its ripping the teeth off the gears from oscillation caused > by way too much Pgain when in high gear. Pgain of 2.0 is almost too much > in high gear, while nearly 4 is decent in low gear. > > So the thought has presented itself that I should do one of two things. > > 1, Throw a mux2 in series with the paths to each of the inputs to the > pid, and switch the mux2's with a signal from switches on the knob, and > having separate settings in the ini files []spindle_9] group for each > side of the mux2's. > > or 2, a separate pid, with one mux2 to select which pid's output to feed > on to the servo amp. > > Which is computationally less cpu usage 1, a 6 pack of mux2's, or another > pid with separate settings and just one mux2 to select which pid gets > sent to the spindle servo? > > I'd like to re-instate a 4th axis at the same time, which will mean a > bunch of rewireing to move the spindle power start controls to the db26 > connector on the 5i25 at the same time. The worst part of that is that > its nearly 6.5 feet up in the air. And the garage has been re-arranged > so I'd have to make a table to set that box on if I pulled it back down, > so I'll probably work on it while standing on a 3 foot stepladder. > > Thanks everybody for any revelant data. > > > 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> > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
