Greetings,
I was wondering if anyone can teach me how to tune a servo within +- one encoder count. I read that it's possible and I've seen that some companies advertise that their products are +- one encoder count, but I wasn't able to get it.

My system is a Dynomotion Kflop+Kanalog controlling Granite Devices VSD-E drives through +-10V. My motors are cheap chinese BLDC motors, with US Digital rotary encoders, 2000CPR. Right now I have the system tuned to +-20 counts, and the system is very stable. With the belt drive and lead screws, that means that +-20 counts corresponds to having a control that is +-.00025".
Here's the math:
Belt Drive: 2:1
Lead Screw: 5 turns per inch
Counts per inch: 8000ppr * 2 * 5 = 80000
Resoluton = 20 counts / 80000 = .00025

What I was thinking of doing though is experimenting with some linear scales though, and some of those are only .00025" resolution, meaning that if I did +-20 counts, my overall control resolution would go to .005", which would not give a good part.

I learned some of the basics of servo tuning from the Galil website:
On-Line Tutorials - Galil: We Move The World
On there I learned that you have to tune the P and D first, then tune the feed forwards and then the I, but I wasn't able to get it to +-1 encoder count.

Can anyone post a video or something of how to really tune a servo system properly.
Thank you.
Dave