Nonlinear dynamics and output feedback control of multiple spacecraft in elliptical orbits

Considers the problem of relative position control for multiple spacecraft formation flying. Specifically, the nonlinear dynamics describing the motion of a follower spacecraft relative to a leader spacecraft are developed for the case where the leader spacecraft is in an elliptical orbit. Next, a Lyapunov-based, nonlinear, output feedback control law is designed which guarantees global uniform ultimate boundedness of the position and velocity tracking errors in the presence of unknown, spacecraft masses and disturbance force parameters. Simulation results are provided to illustrate the performance of the output feedback control design methodology for formation maintenance in ideal, naturally attractive orbits.