Scott, Thanks. I will look at this when I get a chance. I may end up reworking an old Bezier spline driver module to straight step direction code if it comes to that.
More later, EBo -- On Feb 3 2013 7:17 PM, Scott Hasse wrote: > For simple simker EDM I implemented reversing in a gcode loop sensing > an > analog input: > > > http://code.google.com/p/sector67-sandbox/wiki/FrequencyBasedAnalogInput > > this was simple for my application, could stand to be refined > somewhat, and > would get complicated for anything but straight down/up. > > Scott > > > On Sun, Feb 3, 2013 at 7:50 PM, EBo <e...@sandien.com> wrote: > >> On Feb 3 2013 3:08 PM, John Kasunich wrote: >> > On Sun, Feb 3, 2013, at 03:59 PM, EBo wrote: >> > >> >> >> >> possibly, but a more principled hack would be to interface it at >> the >> >> point where it calls the low lever Catmull-Rom spline, and just >> >> evaluate >> >> it in reverse. I do not know how difficult that would be, but it >> >> would >> >> require the ability to move in the negitive direction. I have >> >> written >> >> things like this for moving along splines with custom code, but I >> >> would >> >> have to look into how to do this in EMC-s low level motion >> planning. >> >> Probably the easiest thing to do would be to set up a >> >> "reverse-motion" >> >> pin in HAL, and then evaluate it internally, or modify the >> adaptive >> >> move >> >> command to allow positive/negitive feedback voltage which would >> >> imply >> >> forward/reverse of motion. Anyway that is my thought off the >> cuff. >> >> >> > >> > Where things get ugly is when you try to do this in a general way. >> > For >> > example, what happens if you ask for negative feed while in a >> spindle >> > synchronized move (single-point threading or rigid tapping)? >> > Actually, >> > that issue must have already been dealt with - adaptive feed would >> > cause the problems in that case even for positive scale factors. >> But >> > that was just an example. What about probing moves? What about >> > the blend between successive non-co-linear straight lines? What >> > about >> > a profile that consists of many 0.002" long lines? Can you back >> up >> > more than 0.002"? >> > >> > Sure, you can say "an EDM will never make a spindle synchronized >> > move", but changes to the motion module need to do sane things >> > regardless of what kind of a machine is being controlled. >> >> I was not saying that it could only go back a single move alone a >> single spline. I just said it needed to be reversible. I will have >> o >> think about the spindle-synchronization as I may need that exact >> functionality to make certain parts. ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
