Abstract: This paper is motivated by the problem of the robust stability of interval polynomials. The problem primarily formulated and solved by Kharitonov attracts great attention of control theory researches. In this paper, Kharitonov's four-polynomial concept is generalized for the analysis of conditions for robust relative-stability properties of continuous time-invariant control systems having characteristic polynomials with coefficients subjected to perturbation with prescribed ranges.
Key words: Stability problem, control theory, continous time control system.