NEAR MINIMUM-TIME 3-DIMENSIONAL MANEUVERS OF RIGID AND FLEXIBLE SPACECRAFT

An approach is presented to accomplish large angle, nonlinear, three d imensional attitude maneuvers in either near minimum-time or near mini mum-fuel. The method permits the specification of a torque shaped refe rence maneuver of the near minimum-time (bang-bang) or near minimum-fu el (bang-off-bang) type; the instantaneous switches are replaced by co ntrollably sharp spline switches to reduce excitation of flexible degr ees of freedom. A Lyapunov method is used to design tracking-type cont rol perturbations to suppress errors due to disturbances and model err ors. The method is illustrated by numerical simulations and some exper imental results using the ASTREX test article.