On Thu, 2008-02-21 at 10:14 +0100, jros wrote: > El mié, 20-02-2008 a las 21:47 -0500, Matthew Glenn Shaver escribió: > > On Wed, 2008-02-20 at 11:42 -0500, John Kasunich wrote: > > > I think that is exactly how it works, but I'd have to check the source > > > to be sure of the exact shape of the line. The only other possibility > > > is that the lines runs straight from MIN_FERROR at zero speed to FERROR > > > at max speed, without the flat part and bend that you show in your > > > drawing. > > > > I think it's the way you describe John (no flat part) > no flat part??
Sorry, actually there is a flat part of the curve, but it's vertical (parallel to the Y axis on your graph which denominates the value of FERROR), not horizontal. > > . I think the > > algorithm is: > > > > [Following Error Check] > > | > > <Is actual_ferror <= min_ferror>-YES-[End Of Check:Return NOERROR] > > | > The previous line means a there is a flat part indeed, and I think it is > compatible with what the manual says > > "...The > maximum allowable following error will always be greater than > MIN_FERROR. This prevents > small following errors for stationary axes from inadvertently > aborting motion. ..." So a "stationary axis" would be traveling at a velocity of zero, so the line on the graph should begin at the coordinates of X(velocity) 0.0, Y(FERROR) MIN_FERROR. > I assume that in case of parallel kinematiks' following error is > measured in joint coordinates... I would guess they are always joint values, as joints are the only real things that can move (or fail to move as the case may be ;) ). The goal is to control the trajectory, or to "stay on the path", limited by acceleration, so as long as we are on the path, even if the tool tip feed rate has been reduced to keep acceleration rates below the limits of axis performance, all is still well! I hope I'm right about the above statements; somehow it doesn't explain the corner rounding behavior that gets more pronounced as feed rate goes up. I guess the rounding is limited by MIN_FERROR? I will say these are good questions you're asking! > Thanks very much > > Javier Ros > > > > NO > > | > > ...compare velocity to ferror, etc... > > > > Thanks, > > Matt ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
