Kharitonov's Theorem and Routh Criterion for Stability Margin of Interval Systems

摘要

In this paper, it is shown that the gain margin and phase margin of interval system can be determined analytically using Kharitonov's theorem and V. Krishnamurthi's corollary on Routh criterion without using graphical and iterative techniques. Further, it is proved that the existing results of Anderson et al. [2] on the stability of low-order interval systems using Kharitonov's theorem are only applicable for absolute stability of the interval system and it is not applicable for relative stability of the interval systems, i.e., for phase margin. The proposed technique and stability analysis for low-order interval systems are verified with examples.