I think there might be some confusion about what we are reading in via voltage to frequency using a software encoder velocity in this case. The analog value read as a frequency between 500 and 1000Hz is a scaled version of the voltage of the EDM process itself. Our relatively naive understanding is that this value can be used to determine when to further plunge, stay in place or retreat, and the gcode at http://code.google.com/p/sector67-sandbox/wiki/FrequencyBasedAnalogInputhas a loop of code with logical if/then "bands" between 500 and 1000 that are set appropriately to control the plunge/stay/retreat behavior of the Z axis depending on the analog value read.
For instance if the input is 500 Hz that would mean basically zero voltage, a shorted electrode that needs to be backed off. An input of 1000Hz would mean top-of-the-range voltage that needs to be plunged further. Of course the physical axis has momentum, but the voltage value being read as analog input in this case might change quite dramatically as the electrode is for instance too close, and as such I don't believe this analog value has meaningful "momentum" such that it would need to be smoothed. In fact my understanding is that we'd want the fastest retreat (for instance) response possible and smoothing would only hurt that. Again, we are not measuring motion with this input but voltage. I don't know the actual frequency that the motion control loop runs with, as that depends on the speed of the gcode loop interpretation, analog read, etc., but in our testing the motion response was sufficiently fast to successfully achieve basically stable arcing EDM in both steel and aluminum, with further refinements very likely possible as we learn more about the very interesting EDM process. Hope that helps clarify, and I'm certainly open to any advice and correction. Scott ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
