Three dimensional reorientation of a spacecraft containing a single reaction wheel and a single movable appendage

In this paper, we consider a three dimensional reorientation problem for a multibody spacecraft containing a single reaction wheel, whose axis is fixed in the spacecraft, and a single movable appendage. If the appendage is fixed relative to the spacecraft, the spacecraft can only be rotated about the axis of the reaction wheel and it is impossible to achieve arbitrary reorientation manoeuvres. However, it is shown that when the appendage is movable, the spacecraft can be reoriented from an arbitrary initial orientation to an arbitrary final orientation with prescribed accuracy. The reorientation manoeuvre is accomplished by the reaction wheel in coordination with the periodic motions of the movable appendage. An algorithm is provided for synthesizing open loop controls that accomplish a specified reorientation manoeuvre. The algorithm can be applied to reorientation of a spacecraft in case of thruster or reaction wheel failures. Simulation results are reported