Ricerc@Sapienza

Large Space Structures (LSS) are required for the advancement of modern space activities and represent a challenging research topic. In particular, large space antennas are a key technology for communications and Earth Observation (EO). However, in-orbit disturbances affecting the deployed configuration can deteriorate the accuracy of the communications system. Perturbations originated by on board sources (e.g. thrusters jetting, fuel sloshing) and thermal deformation can be transmitted from the satellite platform to the flexible supporting frame of the antenna and to the reflector. Furthermore, their elastic dynamics is coupled with the spacecraft rigid body motion and the choice of a suitable integrated control strategy is crucial to avoid the complete failure of the mission caused by instability phenomena. As the performance requirements of these systems become more and more demanding, their elastic dynamics starts to be a serious concern using traditional control systems. In this research, an intelligent adaptive structure concept is investigated. The in-orbit dynamics of a satellite equipped with large flexible appendages will be studied considering orbital perturbations, thermal solicitations and attitude control commands. The flexible structure will be configured with a network of distributed smart materials actuators and sensors guided by a controller to actively modify the response of the system. The active elements are embedded within truss elements, one of the most widespread passive structural solution in the space field. As for that, this control approach can be suitable to different types of space antennas (i.e. mesh reflectors, SAR-like panels, long mast concepts). After an optimization procedure to assess the best placement and authority of devices, different strategies will be implemented to coordinate the simultaneous action of the actuators devices, react to a variety of disturbances and ensure the mission requirements are fulfilled.