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 <[email protected]> Envoyé : samedi 23 novembre 2019 10:51 À : EMC developers <[email protected]> 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
