Admissibility with Unstable and Nonproper Weights

In systems and control theory, many problems require the definition of a standard model consisting of physical plant, disturbances and reference signals, and control objectives. For example, one approach of controlling the longitudinal motion of fighter airplanes is to optimize certain weighted closed-loop transfer matrix with weighting filters that are in general interpreted as the models of reference input and disturbances (Chiang and Safonov, Robust Control Toolbox User’s Guide, 1992, [CS92], Kwakernaak, 15th Triennial World Congress, 2002, [Kwa02]).