Robust Stability Analysis

In the previous chapters the stability property of a given time-delay system was studied. In engineering applications, it is now very common that one does not know exactly the system under investigation; that is, the system contains some elements (blocks) that are uncertain. Usually it is known that these uncertain elements belong to some specific admissible domains, which in turn depend on the nature of the elements and also on the information available about the system. In other words, it is known only that the system belongs to the family of systems that arises when the uncertain elements (blocks) range over the admissible domains and therefore one may treat the family as a new object for analysis. This family is referred to as anuncertain system.When it is possible to show that all systems of the family are stable, the stability of the original system that is a particular member of the family is guaranteed.