Suboptimal Asymmetric Spacecraft Maneuvers Using Two Controls

Extensive literature exists for controlling the attitude motion of rigid and flexible spacecraft. For a fully functioning spacecraft, it is assumed that all actuators required for completing the control task are available. Many different control strategies have been proposed for handling the nominal three-axis control case. More specialized literature has considered off-nominal cases where actuator failures have occurred. The nonlinear necessary conditions are handled by introducing a multiple shooting method, which enforces both the end and interior points that define the optimal solution. Fixed final time maneuver strategies are developed and demonstrated. No simplifications are introduced into the spacecraft dynamics problem or the resulting control formulation. The most challenging part of the algorithm involves solving for the highly sensitive optimal switch times.