VIBRATION CONTROL OF FLEXIBLE SPACECRAFT INTEGRATING A MOMENTUM EXCHANGE CONTROLLER AND A DISTRIBUTED PIEZOELECTRIC ACTUATOR

This investigation is to apply the so-called momentum exchange feedback control concept and distributed piezoelectric actuator technology to the vibration control of a flexible spacecraft. The flexible model to be investigated is a rigid hub with a cantilever flexible beam appendage which can undergo a single axis rotation. The proposed control system includes the attitude controller acting on the rigid hub, designed by the momentum exchange feedback control concept, and the uniform piezoelectric film actuator bonded on the surface of the beam appendage, designed by the state space LQR technique. The rationale for this hybrid control scheme is that the momentum exchange-feedback controller acting on the rigid hub can suppress the relatively large amplitude vibrations excited by, for example, rapid maneuvers or other large disturbances, whereas the piezoelectric film actuator is more suitable for suppression of microvibrations, i.e., fine tuning of the system at the final stage of operation, which is important for precision pointing or shape control. Therefore, by combining the advantages of both controllers, an improved performance for vibration control in both the macro- and micro-senses can result.