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 <[email protected]> wrote: > On Mon, 10 Feb 2020 at 10:30, andrew beck <[email protected]> > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
