Robust control of flexible structures against structural damage

This paper deals with the vibration suppression control problem of flexible structures against potential damage. The controller is required not only t o robustly stabilize the structure hut to satisfactorily suppress the vibra tion under all the predicted damages that might occur in the 20-bay truss s tructure under study. The damage to the flexible structure we consider here is represented by the various stiffness losses of predetermined elements. The structure with the predicted damages is modeled as an interval transfer function. The controller design is based on the mu-synthesis in conjunctio n with the extremal properties of interval systems. Unlike conventional mu- synthesis, the technique enables us to use a fixed-size uncertainty block [ four real blocks for the single input-single output (SISO) case] regardless of the number of parameters, resulting in a fast, reliable, and simple syn thesis procedure.