Attitude Stabilization of Spacecraft Perturbed by Tether-Captured Debris

In this paper, we studied the attitude dynamics and control problem of a tethered space robot system, which are perturbed by a librational tether. First, the dynamics of the platform is developed with considering the librational tether. Secondly, a nonlinear disturbance observer is proposed based on attitude rate observations. Finally, a robust attitude controller is developed by using the disturbance observer an a PD controller, and the advantages from the proposed controller is demonstrated by numerical simulations.