ABSTRACT
One of the most important theoretical and practical aspects of automatic control is the systems' interconnection through a feedback process and generally the concept of feedback such that the system input will always depend on its corresponding output. Currently, control systems are based on computers' power gain, which enables them to work faster, more efficiently, and with greater reliability. In an era where almost everything works under the guidance and supervision of the computer, the realization of the automatic control problem with discrete manner is quite important. It is known that the analog automatic control is very crucial, not only because it is used in many scientific fields, but also because many digital controllers implement analog control algorithms. When designing a digital controller, it is necessary to recognize the fact that the mathematical model of a unit or process, in many cases, represents only an approximation of the relevant physics.
