The key stability determinants for low-order interval polynomials

This paper aims to derive key stability determinants from Kahritonov polynomials and Routh-Hurwitz criterion. One analyzes Kahritonov´s four determinants using only orthogonal aspect of experimental design first. The key stability determinants then are derived for low-order system by both orthogonal property and Routh-Hurwitz criterion. The reasons why there is no available key rules for high order system are analyzed as well. Examples are described in detail to demonstrate key determinants and corresponding inequalities. They are proved to be efficient and useful to save procedure and time of judging system stability for specified characteristic equation with interval polynomials.