Robust H∞ control design for systems with structured parameter uncertainty

In a recent paper a unification of the L₂ (LQG) and H^∞ control design problems was obtained in terms of modified algebraic Riccati equations. In this study these results are extended to guarantee robust L₂ and H^∞ performance in the presence of structured real-valued parameter variations in the state-space model. For design flexibility the authors consider two distinct types of uncertainty bounds, for both full- and reduced-order dynamic compensation. An important special case of these results generates L ₂/H^∞ controller designs with guaranteed gain margins