Large motion dynamics of a spacecraft with a closed-loop, articulated, flexible appendage

Two issues are treated with regard to the modeling of closed-loop, flexible spacecraft: the efficient formulation of complex equations of motion; and the potential uses for large motions of the component mode representations with good results in the substructure synthesis of small motions. Partial angular velocity matrices and partial velocity matrices are used to simplify expression formation for generalized inertia forces and the dynamical mass matrix. The strategy includes cutting the loop at a hinge, writing equations for the resulting system, and adding loop closure constraints. The equations of motion, constraints, mode shapes, and numerical results are discussed. Hybrid modes produce a representative response, even where normal modes were inadequate. It is concluded that hybrid modes composed of a few normal modes augmented by residual flexibility attachment or inertia relief modes are superior to normal modes alone.