Unfortunately the drives I have played with could not bat switch. But the one torque mode BLDC set up I have worked with was a PITA to tune, until I set up a dual PID loop in Linuxcnc (essentially turning it into a velocity controlled system.)
----- Original Message ----- From: "dragon" <tfishw...@gmail.com> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Sent: Wednesday, March 1, 2017 10:59:48 AM Subject: Re: [Emc-users] Running servo amplifiers in velocity mode vs. torque mode Thanks Chris... Yeah, if no one chimes in with some actual experience I might just have to do that experiment. That Cel-Con should be capable of some pretty decent speeds and does have a bit of mass so that should be a good test. On 03/01/2017 09:23 AM, Chris Radek wrote: > On Wed, Mar 01, 2017 at 07:46:24AM -0600, dragon wrote: > >> better to run the servo amplifiers in velocity mode or torque mode. I > > I think the benefits of velocity mode are that it better tolerates > (still gives smooth motion with) low encoder resolution and low servo > cycle update rates, and it's much easier to tune the position loop > (the part in linuxcnc/hal). > > Some old CNCs had 100Hz servo cycles and fairly rough position > feedback. If you didn't want to see stair steps on the taper you > were cutting on your lathe, you really wanted velocity mode so it > would keep moving in about the same direction between updates. > > The drawback of velocity mode is the amp is much more complicated, > and you have to tune the velocity loop in the amp, and you might > even need extra parts, such as tachs, to give velocity feedback in > hardware. > > Today with millisecond or faster servo cycles, and really fine > encoders, I bet you can get similar results with both setups. > > If you can select with a switch, why not try tuning up an axis both > ways and see what works best? I'd love to see your results if you > do this. > > Chris > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users