Flexible structure model construction for control system design

The determination of the 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 development and the application, on a 2 d.o.f flexible pointing system, of a new method for flexible mode selection in order to determine a reduced order model for control design. This method mixes model reduction, controller synthesis and analysis in a constructive procedure where the reduced order model is built up mode by mode. The flexible example considered and its control design issues are first presented. The application on this example of an iterative frequency-weighted model reduction method with weights for stability preservation is then recalled. It is shown how its limitations lead to the idea of the constructive method, which is presented and applied to the example