Attitude dynamics and control of a large flexible space structure by means of a minimum complexity model

A technique for deriving a low-order model of a large, deformable space vehicle, with a configuration resembling that of the International Space Station, is proposed. The modeling approach is based on a hybrid Newtonian–Lagrangian approach, where a generalized Euler equation is written for rotational degrees of freedom, whereas the dynamics of states associated to deformation by means of a Galërkin approach is derived by means of a Lagrangian formulation. The assumed modes method is adopted, where modal characteristics of the main deformable structure are estimated on the basis of its real characteristics, estimated by means a finite element model of the actual truss configuration. A cluster of control moment gyroscopes is considered as the actuator for attitude control. Open- and closed-loop maneuvers are considered, in order to highlight coupling between rotational and deformation degrees of freedom. The modeling tools allows for a quick search of gains which minimizes structural excitations during large angle slews.