Robust stabilization of interval plant family using H∞ -optimization technique

The robust stabilization problem (RSP) of an interval plant family is considered. By representing the nominal plant with the normalized coprime factorization description, the RSP of interval plant family is converted to a particular H_∞ control problem. An analytical formula for calculating the parametric stability radius δ_max of the closed-loop system consisting of the interval plant family and the H_∞ controller is given. Using δ_max, the stability margin ε_IP, of the closed-loop system, described in terms of the H_∞-norm of the uncertain factors in the NCF description, is calculated. Numerical example shows that ε_IP is larger than the stability margin of the general unstructured uncertainties case