Attitude Control Of Underactuated Multibody Spacecraft

. A three dimensional reorientation problem for an underactuated multibody spacecraft is studied. Formulae for approximating the change in orientation of the base body of the spacecraft, induced by appropriately constructed small amplitude periodic joint motions, are derived. These formulae are used to construct joint motions that cause a desired reorientation maneuver to be performed within a prescribed accuracy. The computation of these joint motions requires solving a system of simple linear algebraic equations and can be efficiently implemented on-line. Keywords. attitude control, space robotics, nonlinear control. 1. INTRODUCTION This paper addresses a three dimensional attitude control problem for a multibody spacecraft consisting of a base body and appendage links. The base body is rigid and has three rotational degrees of freedom. The links are rigid and are interconnected by joints in the form of an open kinematic tree. For simplicity, all joints are assumed to be single degre..