At the beginning of the new millennium the PID controller continues to be a key component of industrial control. During this century many different structures of control have been proposed to overcome the limitation of the PID controllers. Because of their simplicity and usefulness, they give a very useful solution to an important part of the industrial processes.

The present-day structure of PID controllers is quite different from the original analog PID controllers. Now the implementation of the PID is based on digital design, these digital PIDs include many algorithms such as...