> Hello Everybody, > > what Sebastian so eloquently described is what I originally meant, > however what the other people that replied added is also relevant I > think. The linear velocity phase results in a constant acceleration that > will have a Dirac delta function in its first order derivative, and that > is not desirable, due to the frequencies introduced.
Jerk could change value instantly since it depends on voltage. There is a more less linear correlation between current and torque. Derivative of current depends on inductance and voltage. Then jerk is integrated to acceleration it will be a continuous function. These are physical limitations in an ordinary servo motor. I brought it up because I thought to keep within physical limitations is a good idea. > I must admit that my understanding of DC motor internals is somewhat > buried, also the last time I implemented a state control is 15y ago...So > I ll not follow up on these suggestions, although they would probably > tackle the problem at the root. The DC machine model is rather simple if you understand electrical circuits. Dynamic model will be the same after commutation for a BLDC and very similar after a transformation for a PMSM, size of constants may however vary. > Many years ago I implemented a sin^2(x) acceleration profile that was > jerk free, ... There must be some jerk otherwise there will be neither acceleration nor velocity. I think a limit on the jerk will be a good solution. I wrote some equation earlier and jerk i limited by speed because there will be a speed dependent back-emf in the motor, jerk to increase speed is not possible at maximum speed. ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
