Awesome Todd What Mesa card did you use? And do you mind if I pick your brains on this rather than reinventing the wheel. I would love to see a config that works so I can compare it with what I have and make the needed changes.
Also did you find the motion was uneven or did it just work as expected. Regards Andrew On Tue, Feb 11, 2020, 11:20 AM Todd Zuercher <to...@pgrahamdunn.com> wrote: > It works very much similar to running them with an analog input. The > encoder feedback can also be handy for double checking the tuning of your > servo drives. > > You simply disconnect the position feedback from the stepgen and use the > feedback from the encoders to connect to the PID and the joint position-fb. > > You will need to tune the feedback loop, P=1000 will no longer be valid, > and will likely have to be significantly less (guess 1/2-2/3) > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: andrew beck <andrewbeck0...@gmail.com> > Sent: Monday, February 10, 2020 4:46 PM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] closing the loop in linuxcnc with a 7i76 mesa > card and step direction control > > [EXTERNAL EMAIL] Be sure links are safe. > > Actually all I want to do is be able to home to index. Which I might be > able to do now. As my servo can output a encoder Z pulse. > > And I want to have linuxcnc remember where it is if I disable the servos. > That is now a massive deal but I get a bit sick of continously homing the > machine every time I push the E stop in and disable power to servos. It > would be nice to have the encoders still counting once the servos are > disabled. ( drives would still be on just not running a PID loop.) > > And yes I was wondering what trying to run a PID loop on a position servo > loop causes. > > Regards > > Andrew > > > > On Tue, Feb 11, 2020, 2:14 AM andy pugh <bodge...@gmail.com> wrote: > > > On Mon, 10 Feb 2020 at 10:30, andrew beck <andrewbeck0...@gmail.com> > > wrote: > > > On the back burner though I want to > > "close the loop" back into linuxcnc with a 7i84 mesa card I think. > > Has anyone done that before with a step direction control system? > > > > What do you anticipate gaining from bringing the encoders back to > LinuxCNC? > > > > If this is a stepper system (it's not clear without inbox-mining) then > > a PID will naturally attempt to run the motors faster, with the > > reverse of the hoped-for result. > > It is probably possible to simultaneously reduce the feed rate with > > adaptve feed and then attempt to recover the lost steps, but I don't > > know if anyone has tried that. > > > > If it is a step-servo system then the drives will already be doing all > > that they can. You won't gain much from bringing the motor encoder > > data in to LinuxCNC. > > However, you might be able to gain accuracy by adding linear scales to > > the system, and using the feedback from them to modify the motor > > position commands. > > > > -- > > atp > > "A motorcycle is a bicycle with a pandemonium attachment and is > > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
