Feedback plays an important in control system. Feedback is defined as some part of the output or the value of the output returned to the input side which can be utilized as a part of input to obtain the desired output and system containing feedback are known as feedback control system. In these systems, input value is supplied and the output of the feedback system is being compared continuously with the desired reference value in order to evaluate exact deviations of the output value from the reference value. Feedback control systems helps in modifying the system dynamic response with no change in system components. The three different applications of a feedback control system are:

1. Robot vehicle or a manipulator arm.
2. Space Craft
3. Elevator