Multimode vibration control of a flexible structure using H-infinity-basedrobust control

This paper presents the experimental results of a robust control scheme to suppress the vibration of a flexible structure, The feedback controller is designed using the H-infinity-based robust control theory. For this purpose , a flexible bridge tower connected with a crane structure is considered to control its first five vibration modes using a static state feedback contr oller A five-degrees-of-freedom reduced-order lumped parameter mass model i s derived by neglecting high-frequency vibration modes, The neglected vibra tion modes constitute the unstructured system uncertainties. An attempt has been made to reduce the unmodeled uncertainties by placing actuators and/o r sensors at the node points of a neglected mode. The H-infinity-based cont rol law is able to suppress the low-order vibration modes without any spill over instability due to neglected modes. The proposed control scheme is als o shown to be robust against parameter variations. The performance of the c ontrol scheme is verified both by simulation and experimental studies.