Analysis of hybrid robust controller considering disturbance, noise and time-delay

In this paper, we aim to stabilize the unstable system by loop shaping method with H∞ controller. Moreover after stabilizing the system we need to modify the system which is unstable due to time-delay element by Internal Model Controller considering the uncertainty of control object and time-delay element. Time-delay will happen during the long distance communication. Therefore, when control object is located in long distance, the transmitted reference signal will be delayed certainly. For this reason even though we stabilize the control object by loop-shaping, it will be an unstable system by time-delay elements. In this paper we consider an unstable control object such as ballistic missile. Generally, missiles are required be controlled from long distance. Therefore we stabilize the control object with H∞ controller and later compensate the system which is unstable due to time-delay element by Internal Model Controller.