Robust identification and vibration suppression of a flexible structure

A robust vibration suppression design involving the use of H_∞ optimal control theory is studied for a complex flexible structure. The digital control architecture involves non-colocated feedback utilizing active piezoceramic actuators and position sensor data. The modal properties of the multi-input-multi-output structure are first determined from experimental data in order to obtain an identified state-space model. This model forms the basis for the H_∞ vibration suppression design. Performance specifications are developed which obtain adequate damping in the structure while maintaining controller integrity without the destabilization of higher modes. A controller optimized for these H_∞ performance specifications is implemented on the actual test structure. Experimental structural perturbations are also examined in order to determine the robustness of the vibration suppression design. The experimental study indicates that the H_∞ design substantially increases damping in the targeted frequency region and conforms to predicted analytical simulations.