Output feedback control for spacecraft formation flying with coupled translation and attitude dynamics

In this paper, we address an output feedback tracking control problem for the coupled translation and attitude motion of a follower spacecraft relative to a leader spacecraft. It is assumed that i) the leader spacecraft is tracking a given desired translation and attitude motion trajectory and ii) the translation and angular velocity measurements of the two spacecraft are not available for feedback. First, the mutually coupled translation and attitude motion dynamics of the follower spacecraft relative to a leader spacecraft are described. Next, a suitable high-pass filter is employed to estimate the follower spacecraft relative translation and angular velocities using measurements of its relative translational position and attitude orientation. Using a Lyapunov framework, a nonlinear output feedback control law is designed that ensures the semi-global asymptotic convergence of the follower spacecraft relative translation and attitude position tracking errors, despite the lack of translation and angular velocity measurements of the two spacecraft. Finally, an illustrative numerical simulation is presented to demonstrate the effectiveness of the proposed control design methodology.