[m_c]

Hi m_c,

With all due respect I don't think this is as significant as you make it sound. I think that the sample rates are probably both high enough to be essentially continuous with respect to the response of the system.

I once read a nice comparison of a good servo to an expert pilot who only makes small corrections, then waits to see how the airplane responds before making another correction. Or you could imagine driving a car and instantly commanding the steering wheel 1/2 rev and then checking back in 1 millisecond to make another change.

Most servo systems are lucky if they have a bandwidth of 100Hz. This corresponds to a response time of like 1 / (2 pi 100Hz) = 1600us which is ~18 KFLOP sample times.

It probably isn't that significant, but I do think it's still a concern in certain situations.
I've just ran the figures for the Kinco drives I've used, and the analogue input filtering can be adjusted between ~5 and 636Hz (it's one of the few parameters where they list the units). However, there are other response/bandwidth settings that have far higher setting options, but although Kinco English manuals are pretty good, they don't have the best description of what all the settings do.

And I've just found that the driver specifications list the sampling frequencies. Position modes samples at 1KHz, with Speed and Torque mode sampling the analogue input at 4KHz, speed mode sampling the motor speed at 4KHz, whereas torque mode sampling the motor current at 16KHz.
It has got me wondering if slowing the driver sampling/response rate would actually give a better tune?