Necessary and sufficient dominance conditions for robust decentralization of VS tracking control

The tracking control of linear MIMO systems described by input-output models is considered. The presence of known "weak" interactions among subsystems may allow the designer to achieve objectives by using independent controllers of lower complexity. If unknown, but structured and bounded uncertain interconnections exist, a controller might be designed that guarantees tracking performance in the worst case, i.e. robust decentralization problem. Necessary and sufficient conditions for robust asymptotic VSC in the presence of structured uncertain interconnections are derived. The relationship with necessary and sufficient conditions for finite-gain robust steady-state tracking is discussed. A simulation of a robust decentralized VS scheme for asymptotic tracking is presented.