Raoul, What did you compare? Why did you start this project? Lead me through your thought process. I have the most interest in feedrate modification but if the part quality can be improved and increase the feed then we have two of the three. Faster - check Better - check Cheaper - ? Thanks in advance for the education. Stuart
On Sat, Nov 23, 2019 at 10:09 AM Herzog Raoul <raoul.her...@heig-vd.ch> wrote: > dear Stuart, > > comparative examples between OpenCN and what, LinuxCNC, commercial CNC's ? > And comparing what, machining time, surface quality ? > > Not so easy, but one thing is clear : the jerk control is absolutely > necessary for a CNC, otherwise for a given quality of the machined part you > need to lower really a lot feedrate. > > best regards, > > Raoul > > -----Message d'origine----- > De : Stuart Stevenson <stus...@gmail.com> > Envoyé : samedi 23 novembre 2019 16:51 > À : EMC developers <emc-developers@lists.sourceforge.net> > Objet : Re: [Emc-developers] announcement OpenCN, a new fork of LinuxCNC > --> Precalculations > > Would it be possible to post some comparative example pictures/videos so I > can better understand what you are fixing? > Thanks > Stuart > > On Sat, Nov 23, 2019, 5:43 AM Herzog Raoul <raoul.her...@heig-vd.ch> > wrote: > > > dear Andrew, > > > > The RS274 interpreter is still the original, important concepts like > > HAL, pins etc, are still there. > > > > Even with high end drives, you cannot simply stream position data, the > > reference signals for each drive *must* respect the physical > > constraints regarding max jerk, max acceleration and max speed ! > > > > Important for understanding : there is NOT ANY trajectory planning > > INSIDE the drive, only feedback loops and feedforward. > > > > best regards, > > > > Raoul > > > > -----Message d'origine----- > > De : Andrew <pkm...@gmail.com> > > Envoyé : samedi 23 novembre 2019 12:24 À : EMC developers > > <emc-developers@lists.sourceforge.net> > > Objet : Re: [Emc-developers] announcement OpenCN, a new fork of > > LinuxCNC > > --> Precalculations > > > > Just wondering what's left from LinuxCNC there ) With such intelligent > > servo drives you just have to stream the position data (you made the > > new TP for that!). > > Do you use Ethercat I/O too? > > > > сб, 23 лист. 2019 о 12:17 Herzog Raoul <raoul.her...@heig-vd.ch> пише: > > > > > dear Nicklas, > > > > > > there is no feedback control loop in OpenCN. > > > Feedback and Feedforward is only inside the drives. > > > > > > We use TSD80E drives from the manufacturer Triamec ( > > > https://www.triamec.com/de/triamec-servo-drives.html). > > > The sampling frequency for the PWM, current control loop and > > > position control loop is 100 kHz ! > > > The setpoint values coming from EtherCat at a rate of 10 kHz are > > > fine interpolated in the drive and upsampled to 100 kHz. > > > > > > One remark regarding our feedrate planning. > > > At any time, at least one of the constraints is "active", meaning > > > that either the max jerk is delivered, or the max acceleration, or > > > the max > > speed. > > > Sometimes this is called "Bangbang", maybe a misleading term since > > > there are no jumps in acceleration. > > > Time optimality automatically leads to this "Bangbang" property. > > > > > > best regards, > > > > > > Raoul > > > > > > -----Message d'origine----- > > > De : N <nicklas.karlsso...@gmail.com> Envoyé : samedi 23 novembre > > > 2019 10:51 À : EMC developers <emc-developers@lists.sourceforge.net> > > > Objet : Re: [Emc-developers] announcement OpenCN, a new fork of > > > LinuxCNC > > > --> Precalculations > > > > > > > dear Nicklas, > > > > > > > > of course, feedforwards are utilized (and well parametrized) in > > > > the > > > *drives*, otherwise excessive tracking errors appear. > > > > > > > > But this is done in the *drive*, *not* in OpenCN. > > > > OpenCN calculates physically realizable setpoint values (according > > > > to > > > "optimal control theory"). > > > > > > Sounds really good. Physical realisable will be movement calculated > > > with feedforward of maximum and minimum voltage with a perfect > > > model, sounds simple but to calculate then it is time to slow down > > > to exactly hit a point running at the limits is suprisingly hard to > > > get correct for > > all cases. > > > > > > Then there must be some room for the control law. You have gone > > > further and included unperfect model and dynamics from the feedback > > > in some way or other? > > > > > > > > > Regards Nicklas Karlsson > > > > > > > > > _______________________________________________ > > > Emc-developers mailing list > > > Emc-developers@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > > > > > > _______________________________________________ > > > Emc-developers mailing list > > > Emc-developers@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > > > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > -- Addressee is the intended audience. 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