I want to know whats the basic difference betwenn analog and digital PID?
I want to control a servo motor for velocity and positioning, which would be better?
Digital system is more flexible, because it's easier to adjust its parameters. Here's a rule of thumb. If the rate of your digital control loop is 20-30 times the bandwidth of your plant (or greater), then you can apply the same analysis to the digital system as if it were analog.