any interest / help https://www.pmdcorp.com/resources/type/articles/get/mathematics-of-motion-control-profiles-article
On Sun, 29 Aug 2021, 18:40 Chris Albertson, <albertson.ch...@gmail.com> wrote: > In the general case there may be no closed form solution so numeric > integration is the only possible solution. I don't think there is any > other way to do it other than numeric integration except to require the > user to supply a function for closed form integrals. But for a 3-axis > mill that uses trivial kinematics there is an easy closed form integral. > So the problem is very different depending on what kind of machine you want > to control. For people here, almost all are using trivial kinematics. > > The problem is also VERY different based on another decision. Do you want > only simple jerk limiting or do you want an optimal path? In other words, > do you simply take your foot off the gas to avoid going over the speed > limit or do you want to drive to work in the absolute minimum time but > without speeding. Those are different problems. The first one is easy to > do, the second takes quite a lot of effort. > > Jerk limited, optimal paths for non trivial kinematics is a very hard > problem. Putting a simple jerk limit on a simple machine is easy, Marlin > does this on my 3D printer and it runs on an Aruino. > > > > > On Sun, Aug 29, 2021 at 10:07 AM Curtis Dutton <curtd...@gmail.com> wrote: > > > I'm not sure about all this yet, brainstorming here... > > > > After looking at TinyG code for handling jerk limitation in the joint > > control it appears that they are using the forward physics equations and > > numerically integrating to avoid violations. > > > > Since numerical integration needs to be used for jerk equations (as well > as > > snap crackle and pop...) The forward kinematic equations will need to be > > fed into the integrator for non trivial kinematics. > > > > The integrator should be pluggable as well. We should find an open source > > library for this as numerical integration methods are always advancing > and > > high performance integration is not easy to implement. > > > > > > > > > > > > On Sun, Aug 29, 2021 at 11:55 AM Andy Pugh <bodge...@gmail.com> wrote: > > > > > > > > > > > > On 29 Aug 2021, at 11:40, Alexander Brock <a.br...@hhv-rheinklang.de > > > > > wrote: > > > > > > > > The idea can be implemented in C and for simple cases like 1D > funktions > > > > it should be fairly straight-forward. > > > > > > My point is that the kinematics modules already exist, and not all of > > > them are under our control. Various users’ machines are out there with > > > their own custom kinematics. > > > Also, AFAIK if they are kernel modules then they have to be written in > C. > > > > > > Hence my suggestion of calling the kinematics function repeatedly to > > > perform simple numerical differentiation. > > > > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
