Nonlinear attitude and shape control of spacecraft with articulated appendages and reaction wheels

Three-dimensional attitude and shape control problems are studied for a cla ss of spacecraft with articulated appendages and reaction wheels. A number of special cases of such attitude control problems have been studied previo usly, In this paper, we provide a new unified formulation and a new compreh ensive set of results for planning of attitude and shape maneuvers of a spa cecraft, assuming that joint actuators and reaction wheels provide a suffic iently rich set of inputs, The development is based on a nonlinear, drift-f ree, control model that characterizes the attitude and shape change dynamic s, assuming zero angular momentum of the system, Controllability results ar e presented for the general ease, and specialized results are identified fo r interesting multibody spacecraft configurations. These results are made e xplicit by providing computable formulas for the Lie brackets in terms of t he spacecraft geometry, mass properties, and shape. Constructive motion pla nning approaches are described to achieve spacecraft attitude and shape cha nge maneuvers. A distinct feature of these approaches is that they require only simple computations, as is desirable for on-line implementation. Empha sis is given to the interplay between the shape change dynamics and the att itude change dynamics in achieving the maneuver planning objectives.