> On 03/22/2017 12:50 PM, Nicklas Karlsson wrote: > >> 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. > > > -- > Sebastian Kuzminsky > > ------------------------------------------------------------------------------ > 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
I think this is correct: L*di/dt=u <=> (DC_bus_voltage - maximum_resistive_voltage_drop - back_emf)/(inductance=L) = di/dt = jerk_limit_max L*di/dt=u <=> (DC_bus_voltage - maximum_resistive_voltage_drop + back_emf)/(inductance=L) = di/dt = jerk_limit_min Regards Nicklas Karlsson ------------------------------------------------------------------------------ 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
