On Thu, Oct 06, 2011 at 07:31:39PM -0700, Bruce Klawiter wrote: > I can not get rid of this dithering or ocsillation while the axes are at rest > See IMAGE 4
I think what happens is you get within deadband, the output goes to zero, the amp offset causes a certain drift in a certain direction (same every time), the axis drifts out of deadband, pid corrects, the process repeats. I think I remember these are velocity mode with tachs - forgive me for not going back and checking the old messages - if so, set deadband to zero, and try eliminating it by adjusting the offset pot on the amp. I think deadband just makes this problem worse. I think you will always see one count's worth of dithering. You can slow it down by adjusting offset. Deadband increases it to two (or more) counts worth. If you have high quality velocity information from your encoder hardware (not sure if you do), using that for pid helps too. > > I also noticed while moving one axis the other axes will jerk, if you look at > IMAGE 8 > you can see the Z axis (green trace) which is at rest, has spikes while the X > axis is moving. I think this has got to be noise on the encoder lines. I bet you will see that the axis actually moves (jumps in position) when this happens. I would expect it to move four encoder counts - you should be able to see it easily with an indicator. ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2dcopy2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
