I think I'll disagree with Andy a bit on this. While the minimum following error I could achieve with a single torque vs dual loops in Linuxcnc was about the same. The tuning was much easier, and I believe that my drives are running much cooler (not working as hard dithering) using the dual loops. It is a bit like comparing balancing a pencil on end on your finger vs a broom handle, the longer one is much easier to balance. Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031
-----Original Message----- From: andy pugh <bodge...@gmail.com> Sent: Wednesday, November 25, 2020 4:20 AM To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Suggestions for a retrofit. [EXTERNAL EMAIL] Be sure links are safe. On Wed, 25 Nov 2020 at 04:01, John Figie <zephyr9...@gmail.com> wrote: > I looked over the information you provided. It is not clear to me how > the 7i80hv_16_sv.. "SV" sections work. The card provides a PWM output > for the 7i40, the encoder feedback comes back to the 7i40 and then > back to LinuxCNC servo thread where the loop is closed? So is this > then just a single control loop instead of the typical nested Position > and Velocity loops that one would have with a velocity mode drive > using velocity feedback to the drive and position feedback for LinuxCNCs > position loop? Yes, this is torque-mode operation. If you only have one feedback device per axis then you can only have one loop.... (Obviously you could use the same feedback device for two loops, but I have a feeling that that doesn't add anything. That is a question for the PID theorists) You could, internally to LinuxCNC, set up a velocity loop using motor encoders and a position loop using glass scales. But I have two machines working well enough for my purposes with a single torque-mode loop. -- 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
