| This research is aimed at the stabilization of large flexible structures using distributed Finite Element (FE) modeling, decentralized and robust control theory concepts, and computational tools. Flexible structures of the type considered in this work arise in Large Space Structure (LSS) and in other applications.; The distributed modeling combines the subsystem decomposition viewpoint in large-scale system theory and the Component Mode Synthesis (CMS) methods in structural analysis (84). With this method, we can model a large structure with subsystem models, each of which is to model a local structure dynamic behavior. The decomposition of structures facilitates the design of the decentralized control laws. A systematic modeling approach was developed in this work for automatically generating subsystem models, each of which describes the dynamics of a structure component and interconnections with other components, for an interconnected beam structure.; Decentralized control for LSS consists of localized control actions, i.e. applying local controllers at subsystems and using local information (states or outputs) in dynamic feedbacks to obtain the global stability. In a decentralized control method, a local controller is designed based on local subsystem model but neglecting interconnection terms. However, when the interconnections among subsystems are too strong, standard decentralized control may fail. In this work, we developed decentralized control method for interconnected beam structures.; Several methods were explored in this work and two have yielded successful results. These were joint decoupling control and joint node {dollar}Hsb{lcub}infty{rcub}{dollar} control. The first one uses additional control to decouple all connected subsystems and design local controllers based on decoupled subsystem models. The second one is based on {dollar}Hsb{lcub}infty{rcub}{dollar} control that minimizes the interconnections among all connected subsystems, and the design of local controllers based on subsystem models with minimized interconnection terms. |
