A general study of maximal robust stability regions

In the study of robust stability, the largest coefficient region of a given stable polynomial that guarantees stability preservation under perturbation of coefficients is to be determined. A general consideration including both Hurwitz and Schur polynomials is treated in this paper. For this purpose, the notion ofperturbation constant is introduced. As a consequence of our results, we also introduce a general Kharitonov-type stability test which is based on testing the stability and perturbation constant of a single polynomial.The work of C. K. Chui was supported by SDIO/1ST managed by ARO under Contract No. DAAL 03-87-K-0025, and that of H. N. Mhaskar was supported in part by the Center for Approximation Theory, Texas A&M University.