On Thursday 30 November 2017 10:27:39 andy pugh wrote: > On 30 November 2017 at 14:13, Gene Heskett <[email protected]> wrote: > > Yes, and its math I should have explored, but I had no clue that > > there was that big a geardown in the head, even in high gear, before > > I ordered that 1000 line encoder. That says the motor, running wide > > open, is turning about 20 k rpms. > > There is something very wrong with your maths still, I think. > > Your 7000:1 gear ratio is simply wrong. I think you divided > revolutions by counts (I recall you saying that encoder resolution > didn't matter, but you were using rawcounts, so it most certainly > does). > So, a 1000:1 error there. (There isn't _room_ in the head for a 7000:1 > gear ratio) > > Also, you keep confusing RPM and Revs Per Second. That too, but I have a new problem now, and need an answer to 2 questions.
1. is the feedback signal in phase or out of phase with the command? 2. and this is for Jon. I have a fixed gain scale setting that prevents the pwm from exceeding a 98% duty cycle. The pwmgen is running at 20 kilkohertz, and when the pid is outputting 46 something it is up against this limit, with a 1.06 u-sec recharge time. The data that you get from the Pico site says half a microsecond is needed to recharge the gate drivers. So this should be enough. The 12 volts is nominally 11.6. BUT, its sitting out there right now at that minimum of 1.06 microsecnds off time, with the spindle turning about .8 rps. It ought to be at 3 grand. Clicking fwd, no reaction, add a + button click and it hits that 3 grand in about 1/2 a second. 30 seconds later it starts to slow, and in another minute its down to about .8 rps and running steadily. Motor is seeing a noisy 2 volts, and it has almost zero torque. While this is "percolating", I'm going to reduce that scale, wideing the off time to see what effect it might have. 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
