On Friday 09 August 2019 01:28:36 nkp216 . wrote: > Question on servo tuning. > > there is such an opinion: > > "I don't think deadband is useful > in velocity mode. You will always get dithering between adjacent > counts - deadband just makes it dither across a bigger discontinuity." > > https://sourceforge.net/p/emc/mailman/message/26413261/ > > is that correct?
I'm all steppers for axis drive and have never used it. But if Chris said it, thats right. Deadband is how far off it can be without going into a hunting oscillation. Raise it until it sits quietly when stopped. If there is backlash between the motor and encoder, remove it because it likely will hunt forever. I have only 1 velocity servo, the spindle in my G0704. There, encoder scale needs all the bits it can get so I've an unusual setup. Using the homemade optical index on the spindle, and a 1000 line A/B on the motors rear shaft I have hal switch the scales according to switches on the gearshift knob. That finally got rid of enough quantization noise, high enough effective scales, 7000+ in high gear, 14000+ in low gear, switched by hal and I've been amazed at the Pgain I can use in the PID. Just starting to go unstable at 40. Running at 20 for everyday use. I am unaware for how hard the motor is working while rigid tapping until the servo amp starts chirping the iron in the motor with its current limiter at around 17 amps into a 9.7 amp motor. > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
