Design of dynamic output feedback decentralized controllers via a separation procedure

This paper investigates the well-known separation properties that hold in t he design of unconstrained output feedback controllers and tries to general ize them to cope with the design of structurally constrained decentralized controls. This problem, which until now has been open, presents additional constraints which destroy the useful properties that lead to separation. Ne cessary and sufficient conditions for decentralized stability and H-2 norm minimization are given, providing a framework in which a suitable an hoc se paration procedure is developed. A numerical algorithm based on cross-decom position is presented and applied in two situations: first, when separation Fails to provide a feasible solution; and then, to improve the obtained co ntroller. An example and a comprehensive benchmark illustrate and validate the method.