Weighted balanced model reduction of a flexible structure

The determination of structural modes which are important for control is a major issue in the field of active control of flexible structures. The paper is devoted to the application of an iterative model reduction proposed by Enns (1984) to a 2-DOF flexible pointing system. The framework of weighted balanced reduction is first recalled, together with the choice of weights preserving closed-loop stability. An illustrative example and the control design methodology are then presented. Enns' iterative reduction procedure is applied and the results obtained are reviewed. Improvements are proposed to trade off model order and controller robustness.