Based on what I saw in tp.c, the current method looks like trapezoidal motion with linear velocity blends (parabolic in position). Using splines is one angle I looked into, though there are significant mathematical hurdles. For example, it's not generally possible to parameterize a spline by arc length. In other words, as you move along the curve in time, your speed can vary, making it tough to control feedrate. Bezier-based blends are probably easier, though I don't know if there's an easy way to implement them. The current blending is really nice because it's a like a "crossfade" between two moves, so there's no explicit calculation of the blend arc. Maybe the same is true with S-curves and we get nice blends for free?
Thanks for your feedback, Rob On Sat, Sep 28, 2013 at 7:36 PM, EBo <[email protected]> wrote: > Robert, > > I thought LCNC already used s-curves for acceleration. If not, try a > simple Bezier spline (unless someone has either a better spline for > motion or a reason why Bezier's are bad. I would prefer they all be > NURBS, but THAT would be a lot of work). > > On Sep 28 2013 5:00 PM, Robert Ellenberg wrote: > > Hi Andy, > > I agree, a finite jerk profile would be a nice feature. That > > would be a > > good 2nd pass to take after lookahead is working. At that point, the > > machine will be able to pass quickly through small segments, which > > means > > hitting a lot of blends in a short time. Right now, the blends are > > not > > acceleration-continuous, so that could cause trouble at high speeds. > > I'll > > look into it a little more and see how challenging it would be to do > > S-curves instead of trapezoids. > > > > Best, > > -Rob > > > > > > On Sat, Sep 28, 2013 at 6:34 PM, andy pugh <[email protected]> > > wrote: > > > >> On 28 September 2013 23:20, Robert Ellenberg <[email protected]> > >> wrote: > >> > Thanks for the link to the documentation! I do plan to code this > >> myself, > >> > though I would welcome any input from other developers. > >> > >> I don't think many of us really understand that part of the code. > >> But > >> I think you can rely on our goodwill. > >> > >> Not wanting to make a hard job even harder, but if you could work-in > >> finite jerk into the equations too, then that would address another > >> moderately common request. > >> > >> -- > >> atp > >> If you can't fix it, you don't own it. > >> http://www.ifixit.com/Manifesto > >> > >> > >> > >> > ------------------------------------------------------------------------------ > >> October Webinars: Code for Performance > >> Free Intel webinars can help you accelerate application performance. > >> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the > >> most > >> from > >> the latest Intel processors and coprocessors. See abstracts and > >> register > > >> > >> > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > >> _______________________________________________ > >> Emc-developers mailing list > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-developers > >> > > > > > ------------------------------------------------------------------------------ > > October Webinars: Code for Performance > > Free Intel webinars can help you accelerate application performance. > > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the > > most from > > the latest Intel processors and coprocessors. See abstracts and > > register > > > > > > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > > _______________________________________________ > > Emc-developers mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most > from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers > ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
