Actuator and sensor selection for robust performance

Two input output (IO) selection methods are proposed, aimed at finding the IO sets for which a robustly performing controller exists. To avoid time-consuming "synthesis and use H/sub /spl infin// controller existence conditions instead, the structure in the combined uncertainty/performance block is "eliminated". The first (sufficiency-based) method augments the plant by diagonal scalings, while the second (necessity-based) method absorbs uncertainty representation into the plant.