Design of Loop-Shaping and Internal Model Controller for Unstable and Communication Delay System

Abstract

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