Substructure-based controller design method for flexible structures

Abstract

In this paper, a decentralized procedure for designing controllers for flexible structures is presented. With decentralized control design methods, the system to be controlled is divided into subsystems for which controllers are designed. These are then combined in some way to form a controller applicable to the original system. In the proposed method, the structure to be controlled is considered as a collection of substructures. For each substructure, a subcontroller is designed with linear quadratic optimal control theory, although any method can be used. Then, a controller synthesis scheme called Substructural Controller Synthesis (SCS) is used to assemble the subcontrollers into a system controller, which is used to control the whole structure. The proposed method is closely related to component mode synthesis methods of structural dynamics and to decentralized control using overlapping subsystems. It is attractive because, unlike most decentralized methods, an explicit decomposition is generally not needed since substructure models often exist a priori. Also, an SCS controller is very adaptable because each subcontroller is designed based on an individual substructure model; therefore, the controller can be updated very economically if part of the structure changes. A plane truss example is used to illustrate the proposed method.