Robust stability conditions of interval time-delay systems

Since the number of eigenvalues of interval time-delay systems is infinite, it is necessary to develop a 2-D algebraic test for stability of time-delay systems. Constructing a 2-D s-z hybrid polynomial with interval parameters based on the characteristic polynomial of given interval time-delay system, we show that the robust stability of the interval 2-D polynomial can ensure the interval delay system to be stable, and we provide some complex Schur test algorithms for the robust stability of 2-D s-z hybrid interval polynomial.