> >> Hello, > >> > >> I want to ask if anybody has worked on different acceleration profiles > >> for linuxcnc ? I am looking for something that would remove the > >> discontinuity in the first derivative of the acceleration ? > >> > >> BR > >> Max. > > > > I guess to start with the DC motor model for example here > > https://www.electrical4u.com/torque-equation-of-dc-motor/ would be a good > > idea. Driving this with a limited voltage and current would probably be a > > good model for the limitations. > > I think Max is asking about changes to the LinuxCNC trajectory planner > that implement variable (non-constant) acceleration, aka "limited jerk". > > Currently when you start from a stand-still, command a move, and come to > rest at the end of the move, LinuxCNC implements a trapezoidal velocity > profile. This starts with a constant-acceleration phase until it > reaches the maximum speed for the move, then enters a constant-velocity, > zero-acceleration "cruise phase", and finishes with a > constant-deceleration phase back to zero velocity. Each phase > transition has an instant of infinite jerk, when acceleration goes from > one constant value to another in a single motion cycle. > > I think Yishin Li (https://github.com/yishinli) has done some work in > the area of jerk-limited trajectory planning, but AFAIK it has not shown > up as a pull request to our repo yet.
Jerk depends on the inductance in the motor model and voltage at inductance. In motor model theres is: DC bus voltage, back emf depending on motor speed and resistive voltage drop. If resistive voltage drop is small jerk limits will depend on speed and reach zero at maximum speed. To use a constant will not work. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
