Three Axis Rotational Maneuver and Vibration Stabilization of Elastic Spacecraft

We present a control law for three-axis rotational maneuvers of a spacecraft-beam-tip body configuration based on nonlinear inversion and modal velocity feedback. A decoupling attitude control law is presented such that in the closed-loop system the attitude angles of the spacecraft are independently controlled using the control moments acting on the space vehicle. This controller asymptotically decouples the flexible dynamics from the rigid one and also allows the decomposition of the elastic dynamics into two subsystems representing the transverse deflections of the beam in two orthogonal planes. These low-order sub-systems are used for the derivation of a modal velocity feedback stabilizer using the force and moment actuators at the end body. Simulation results are presented to show the capability of the controller.