Algebraic criterion and robustness of the stability margin of a discrete dynamic system

The work examines the problem of determining the robustness of the stability margin of a discrete dynamical system. To solve the problem, it is proposed to use the scheme of coefficient perturbation in the algebraic criterion of stability of discrete systems. Such solution will be of interest in the case of constructing the region corresponding to the given stability margin in the discrete system parameter space (including numerical one) under the conditions of uncertainty in defining all or part of the system parameters. Stability margin is characterized by the parameter explicitly included into the recalculated coefficients of the characteristic polynomial. An example of determination of robustness of stability margin in particular case for the fourth-order characteristic polynomial with interval coefficients is presented.