On Friday 22 November 2019 20:07:22 Gene Heskett wrote: > On Friday 22 November 2019 19:07:33 Dmitry Yurtaev wrote: > > > This all sounds as if its is only applicable to servo systems, us > > > hobbyists with steppers running everything might as well sit back > > > and enjoy the "what ifs" since steppers have their own > > > insurmountable jerk problems when useing common $40 50 volt > > > drivers, and mesa cards. > > > > but us hobbyists with even cheaper surplus modern servo drives, > > which use sub-millisecond position control cycle period, motors with > > 22bit encoders and dual feedback are very intrigued. especially if > > it will be possible to replace ethercat stuff with another protocol > > :) > > > > /dmitry > > Much of that comes from a much (10x) higher frequency of servo-thread. > I don't know if my rpi4 can do it, but I may experiment to see if a 2 > kilohertz servo-thread is an improvement. So I sped it up to 2khz, > works fine from a login from here. I'll leave it that way for a while, > zero latency excursions while carving a lathe pawn out of 67F air. I > actually have 2 threads running as there is a 100 hz thread with all > the jog from hand dials stuff in it. I can't turn the jog dials much > faster than that anyway. ;-)
I just looked at that .hal file again, and that thread is running at 200 hertz. At 200, max jog speed is a hair faster and noticeably smoother. I'm still tweeking on it, to find the maximum performance I can get out of a pi4. The pi3 before it had noticeably lower performance limits. In particular, the usb-3 interface to compiler storage on an SSD brings the rpi4 up into intel territory for build speeds, both of kernels and linuxcnc dpkg installable debs. The rpi4 is growing its own food IOW. > > _______________________________________________ > > Emc-developers mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > Cheers, Gene Heskett 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-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
