Decentralized H∞ controller design for large-scale systems

The problem of disturbance attenuation for large-scale systems using decentralized control is considered. The design procedure developed here involves constructing H∞ local state feedback controls via the Riccati equation approach, and a complete solution to this problem is carried out merely by iteratively solving a set of local algebraic Riccati equations. It is shown that when all the states are available, the H∞ norm of the closed-loop transfer function over all linear constant decentralized control laws is not imrpoved by allowing feedback to be dynamic. With successively smaller values of the prespecified disturbance level, the local state feedback H∞ suboptimal control problem can be solved and the controller can be chosen to be static.