Hybrid Active and Semi-Active Control for Vibration Suppression in Flexible Structures

A new hybrid control methodology is presented for vibration suppression in flexible structures, where an active actuator is used to assist a nearby semi-active device to achieve a control performance close to that of a fully active system. The clipping phenomenon, typical of semi-active control, is reduced to a large extent by the proposed hybrid controller. The immersion and invariance methodology along with sliding mode control is used to create the hybrid controller. The result is that as the semi-active controller switches off in the hybrid controller, the active actuator injects the required energy into the system. A two degree of freedom system with cubic stiffness is used as an example system. Both simulation and experiment data are presented to demonstrate the usefulness of the proposed idea. The proposed hybrid controller shows robust results as compared to just using a semi-active controller.