On the Dynamic Resilience and Novel Control Structures for Plants with Multiple Dead Times

Abstract New H 2 optimal structures of dead time compensators (DTC) for MIMO plants with multiple I/O delays, derived recently via extensions of the loop shifting technique, are explored, interpreted and used to question the long standing result that states that dynamic resilience and performance of such systems can sometimes be improved by adding artificially dead times to the plant. Through treatment of performance bounds in simpler cases of plants with input delays and output delays it is shown that such increases in delays do not necessarily improve performance. It is further demonstrated that the improved resilience gained by the optimal DTCs is due to novel inter-channel feedforward components and that unlike the ad hoc procedures for constructing DTCs and the optimal methods for the single delay case, the structure of the optimal DTC depends on the exogenous inputs and the control goals. Simple examples demonstrate the results.