A novel approach to the analysis and synthesis of controllers for parametrically uncertain systems

The authors present a novel characterization of Hurwitz polynomials and demonstrate its usefulness in analyzing parametrically uncertain systems and synthesizing robust controllers for such systems. The characterization is a variant of the Nyquist stability theorem, but, unlike this theorem, it can prove that a polynomial is Hurwitz from only approximate knowledge of the polynomial´s phase at finitely many points along the imaginary axis. Applications to robust stability analysis and controller synthesis are presented along with numerical examples showing the theorem´s versatility