3-D MANEUVER AND VIBRATION CONTROL OF FLEXIBLE SPACECRAFT USING THE MOMENTUM EXCHANGE FEEDBACK-CONTROL CONCEPT

Mechanical subsystems (motions) interact with each other through the b oundary forces or torques which are associated with the time rate of c hange of the linear or angular momentum of the subsystems according to Newton's Second Law. The basic idea of the momentum exchange feedback control is to use the time rate of change of the momentum of the subs ystems as a part of the feedback control law to suppress the relative motions of the subsystems such as flexible vibrations or tether swing motions. In the present paper, the momentum exchange control concept i s applied to a general 3-D maneuver of a rigid hub with two symmetric flexible appendages. The three-axis control torques acting on the hub include a nonlinear feedback of the rigid body motion and the time rat e of change of the momentum resulting from the flexible motion. An ene rgy Lyapunov function is used to establish the system global stability , and the lower and upper bounds of the control law for system stabili ty are obtained. Both the analytical and numerical results are present ed to verify the control concept.