I think the difference between position and velocity is how the error signal is computed. After you have that. I don't think a PID algorithm cares if it is controlling temperature, heading, airspeed or position. Originally the algorithm was invented for steering ships at sea on a constant heading.
So, yes, do whatever you need to get the error. It is always observed minus set point. So if you need to control speed both of these need to be speed. Then look at the noise in the error. Quantization noise can be an issue. It is easy to have noise larger than signal. My point about spindles being different was that the noise in the measurement can be worse. On Mon, Oct 30, 2017 at 5:59 PM, andy pugh <[email protected]> wrote: > On 30 October 2017 at 23:52, Chris Albertson <[email protected]> > wrote: > > I think I see a reason why advice about PIDs used an axis and a spindle > > might differ. The axis servo will have a huge about of gearing so the > > motor will run fast and the controller will see a lot of edges per PID > loop > > interval. > > The big difference is that with an axis when you are in position you > set the output to zero to stop moving. With a spindle when you are at > speed you keep the output constant. > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1916 > > ------------------------------------------------------------ > ------------------ > 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 > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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
