Wellposedness of optimal control problems for systems with unbounded controls and partially analytic generators

Wellposedness of differential and algebraic Riccati equations for control systems with unbounded control operators is considered. It is shown that the full-classical Riccati theory is recovered for a class of dynamics, whose generators are partially analytic. Partial analyticity is quantitatively expressed by the validity of the so-called "singular estimates", which is imposed on the composition operator E[sup At]B (A is the generator, B is unbounded control operator. This class comprises the PDE coupled systems with hyperbolic and parabolic components. Two illustrative examples are given in the paper: boumdary/point control of thermal plates with hyperbolic character and point control of structural acoustic interactions. The latter are described by wave equation coupled at an interface to a plate equation.