On 8 July 2010 02:43, Chris Radek <ch...@timeguy.com> wrote: > One step more complicated is to have dual pid loops, a torque loop > inside a velocity. I'm not sure what you'd use for torque/current > feedback, though. Normally that's current sensing in hardware, and > you have no equivalent that I can see.
I _think_ what you would have in such a dual PID loop would be a loop closed by velocity but controlled by duty-cycle (and motor torque is at least approximately directly proportional to PWM duty cycle) driven by a loop closed by position and controlled by velocity. ie the Axis position goes into the first loop and the error becomes a velocity demand for the second loop, where the velocity error becomes a torque/current demand. Adding current feedback would probably be a third loop in the chain. But take everything I say with a pinch of salt, I have only tuned one servo axis ever, and that only well enough to prove out a motor driver. -- atp ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
