Viesturs Lācis wrote: > 2011/12/13 Jon Elson <el...@pico-systems.com>: > >> Watch out for the CUI AMT-10x encoders at Digi-Key, they have a lag >> responding to acceleration, and >> may not be well-suited to CNC systems such as EMC2. >> > > Thanks for the warning, Jon! > I happen to have bought these encoders for one of the machines... > Do I understand correctly that they are working fine, but I will need > to decrease max acceleration to get better performance of the encoder? > The problem is there is a lag between acceleration and the encoder responding to it. If your servo loop can be tuned for good performance, you are lucky. The more massive the load, the better, I guess. The worst case is a low-inertia motor sitting on the bench. But, if you cannot get the loop response tuned properly, then there really is nothing you can do to fix that. The problem is that when velocity changes, the encoder does not correctly report position. It reports what the position WOULD have been if there had not been an acceleration.
Decreasing max accel will help prevent exciting any unstable response from G-code, but external forces acting on the system cannot be controlled that way, and may excite instability. In other words, reducing accel masks the problem, instead of solving it. Reducing gain will help, but can make the servo response less accurate. Jon ------------------------------------------------------------------------------ Systems Optimization Self Assessment Improve efficiency and utilization of IT resources. Drive out cost and improve service delivery. Take 5 minutes to use this Systems Optimization Self Assessment. http://www.accelacomm.com/jaw/sdnl/114/51450054/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
