Robust H-infinity Stabilization of a Large Flexible Structure via Normalized Coprime Factor Plant Description

Abstract

In this paper, the design of robust H-infinity controllers for a large flexible test structure is dealt with. The design method involves shaping the open-loop singular values with pre- and/or post-compensator and then designing suboptimal controllers to robustly stabilize a normalized coprime factorization of this weighted plant model. Its main features are that the weighting can beperformed directly on the rate and position outputs of the flexible structure and there is no undesirable cancellation of the plant polesby the controller. We also provide some simple guidelines for specifying the desired loop shapes in the designs. The effect of the weighting selection and the distance to the optimality (suboptimality) are investigated. The robustness and the performance of the controllers are analyzed using the singular values of the related closed-loop transfer functions.