On Mon, 17 Oct 2011, Tom Easterday wrote: > Date: Mon, 17 Oct 2011 14:07:07 -0400 > From: Tom Easterday <tom-...@bgp.nu> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] config without encoders > > On Oct 17, 2011, at 1:07 PM, Peter C. Wallace wrote: >> Actually that sounds very good! >> >> You have an acceleration of 300 IPS/S and a slew velocity of 50 IPS (that is >> .050" per servo thread) I would not be at all surprised that the following >> error can not be improved > > I clearly don't understand. Since there is no actual feedback how can there > be ANY following error?
There _is_ feedback, the step generator is a programmable rate generator with a position control feedback loop to compensate for timebase differences (EMC and hardware), and direction change delays > >> (at least at 1KHz sample rate and the > > Are saying that it might improve if I can run the thread faster? > > I don't currently have a base thread, but I could. Could I put it in the > base thread, at a much faster rate, rather then in the servo thread (since I > don't seem to be able to set the servo thread down)? > >> Step generator driver tha is not optomized for such high accelerations and >> velocities). > > What is the driver optimized for? What should we expect? Well its not optomized for extremely fast acceleration (300 IPS/S is FAST) > >> Like I said before, you might have better luck using a normal PID loop at >> these speeds (this amounts to taking your encoder config, disconnecting the >> encoder feedback to the PID component and connecting the stepgens feedback in >> place of the encoder feedback. With a PID loop you have the FF2 parameter >> avaialble to tune out the lag on acceleration > > I can't go back to the encoder config until the parts come in for our > differential to single ended converters. But, I am anxious to try it. > I am also anxious to try the PWM/Dir version, but I haven't gotten a firmware > load yet... I dont think you understood what I said above, I was not asking to you to go back to encoders but rather to close the stepgen position loop with a PID component that has as its inputs the commanded position from EMC (as before) but substitute the encoder postion input with the stepgens feeback position This has the advantage of a more complete control loop than provided by the Stepgen position mode driver > > -Tom > > > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure contains a > definitive record of customers, application performance, security > threats, fraudulent activity and more. Splunk takes this data and makes > sense of it. Business sense. IT sense. Common sense. > http://p.sf.net/sfu/splunk-d2d-oct > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2d-oct _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
