Mixed H2/H∞ Fixed-Structure Control via Semi-Infinite optimization

In the context of nite-dimensional linear time-invariant systems, the mixed H2/H∞ control has been the subject of numerous investigations mainly focused on Riccati equation or convex optimization approaches. This paper proposes a mixed H2/H∞ xed-structure control design based on a global optimization approach applied to a semi/innite minimization problem which is exactly equivalent to the original H2/H∞ problem. This method, that generalizes the mixed H2/H∞ PID control of Chen et al. (Chen et al., 1995), is presented, with reference to the basic unity-feedback system, to design a xed-structure controller by means of a recently devised genetic/interval algorithm (Guarino Lo Bianco and Piazzi, 1996). Computational results for an example, with comparisons, are also included.