Dear Galil,
I am just now trying to tune my system and initially would like to optimize it to be stable at a crossover freq of 157 rad/s. Unfortunately my resolution at the moment is limited to 2 ticks/rev thus leaving my desired crossover freq in encoder counts at 50 ticks/s.
I realize the minimum velocity of the unit is 256 ticks/s so may have to work with this for now until I can improve my resolution.
My main question is however, why is the Crossover freq in the WSDK for Crossover tuning defined in rad/s when, other than the Encoder Resolution command for stepper motors, the controller has no concept of how many counts = 1 rad in my system...
Perhaps I'm missing something in the documentation?
Regards,
James
Galil_AndyH on 05/03/2007 - 09:04
James,
Regarding the rad/s. For this configuration in WSDK, the rad/s refers to the input profile of a sine wave at a particular frequency. Because the rad/s is the frequency of the sine wave, the actual resolution of the mechanics is not needed.
Because of the low resolution of your encoder, none of the auto-tuning methods will allow you to tune your system. With this low of resolution, any type of dynamic motion will be nearly impossible. You might be able to tune your system to move at a constant velocity, but you will probably not be able to use any KI, and you will have to use FV.
The minimum resolution of the speed is 2 counts per second with an update rate (TM) of 1ms (default).