On Kharitonov-Type Results for Complex-Coefficient
ABDOLLAH KATBAB, E. I. Juty, David Washington · 1990
A new Kharitonov-type result for stability analysis of real Schur polynomials, after being transformed through a newly de- fined transformation technique, was recently proposed which devel- ops necessary and sufficient conditions for the stability of the trans- formed polynomials only. In this paper we generalize these results for the case of complex coefficient case and prove that the stabil- ity of eight corner polynomials are both necessary and sufficient for the stability of the whole transformed family of interval polynomi- als. We also comment on the sufficiency conditions of this test for the stability of the original interval polynomial family. Moreover, we elaborate on checking the stability of the required corner poly- nomials, and also show how to reduce the number of required poly- nomials for low-order cases. Some illustrative examples are given. The results may be found useful for testing the interval stability of 2-dimensional digital filters.