Roger wrote: >Stephen Wille Padnos <spad...@...> writes: > > >>This is a function of the motor driver, not the control software. >> >> >Steve, >Your absolutely correct but I could imagine how software could be used to >emulate closed loop control with a step direction drive. In the case of a lost >step software could lower the axis speed/acceleration and add or subtract the >step value from the machines current position so that the trajectory planner >could take the lost step into account. > > If a step motor loses a step due to excessive loading, then it's likely to miss many steps. The one motor will be stalled while the software ramps the speed down on the other joints, so the part is already likelly to be ruined. At some random time, the stalled motor will start moving again, but it's trailing the position it should be in. The motion controller can't speed the motor up to catch up to where it should be (ask it for a little more, like you'd do with a servo), since it's already at or beyond its limits or it wouldn't have stalled in the first place.
>Not perfect but maybe good enough. > > Could be. This has been discussed at length, both here and by various Geckodrive folks. EMC2 has the ability to get feedback, and it has the ability to apply feed rate overrides in realtime. If you can figure out an algorithm to marry the two to get pseudo-servo steppers then I'd be happy to review your code - patches gratefully accepted ;) - Steve ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
