John Kasunich wrote: > I have long had my own thoughts on this issue. Our software encoder > counter has a velocity output which is much less quantized than the > position output. Some (but not all) hardware drivers also have a > velocity output. If the PID loop had both position and velocity > feedback inputs, it could use the velocity feedback for the D term. > > This has the potential to be better than any filter - the encoder > counter (hardware or software) simply has more information to work with. > The software encoder counter generates its velocity output by looking > at not only how many counts arrived, but _when_ they arrived (with base > period time resolution). I'm pretty sure the latest hostmot2 driver > does the same - in that case it knows when pulses arrived with > sub-microsecond resolution, and the velocity output can be very smooth.
The hm2 encoder driver is currently using 1 MHz for the encoder edge timestamp clock frequency. The hardware supports more, maybe I should bump it up... -- Sebastian Kuzminsky ------------------------------------------------------------------------------ This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
