The Optimal Mix of Passive and Active Control in Structures

This paper shows how to redesign a structure to make it easier to control. Beginning with any active controller (say, designed to give the "ideal" performance), we divide this controller into two parts - one that can be synthesized simply by structure redesign (called the passive control) and one that is to be synthesized as an active controller. Given that the total closed loop response must not be changed from the "ideal", the passive part of the controller is designed so as to minimize the amount of control power needed for the active part. Necessary and sufficient conditions for a globally optimum structure is given, and gradient calculation are not required. The algorithm converges to the globally optimum in a finite number of iterations.