International Journal of Engineering Trends and Technology
PID controllers are the most popular controller system used in industries; robust PID controller gives more robust output than classical PID controller. This paper concentrates on the work done on the PID control system especially on time delaying systems like network control systems. The different works which have already been done are summarized here like gain margin, phase margin methods. The absolute focal point on time delayed system are the delays induced by network and the packet losses. This survey paper covers the study on such methods that compensates these terms.