Reliable decentralized control with integral action

Reliable stability with type-m integral action is considered in the linear, time-invariant, multi-input multi-output two-channel decentralized feedback system. The objective is to achieve closed-loop stability under normal operation of both controllers as well as the possible failure of either one of the two controllers. Necessary and sufficient conditions on the given plant are obtained for existence of reliable decentralized controllers achieving integral action. All reliable decentralized controllers with integral action are characterized using algebraic design methods.