PID

Why set the deadband to 1.5-2X the encoder scale? And how to know the encoder scale or check them if I calculated it wrong?

The encoder scale is the distance your machine moves for one encoder count. It is a setting in your ini config file. If the scale is set wrong the machine won't move the correct distance.

Having a small dead and setting can help to quiet servo dithering by telling the pid "your close enough.