Fuel Optimal Reorientation of Axisymmetric Spacecraft

摘要

The problem of reorienting axisymmetric spacecraft by using reaction control jets and at the same time minimizing fuel expenditure is analyzed. The reorientations considered are not limited to small angle rotations, and axial cross-coupling is not neglected. However, only rest-to-rest maneuvers are studied and the vehicle is modeled as a rigid body free from disturbance torques. It is assumed that the attitude control thrustors can provide large enough torques for the thrust durations to be negligible compared to the maneuver periods. The Pontryagin Maximum Principle is used to determine the optimality of control profiles involving only two thrustor firings - an initial and a terminating thrust. These maneuvers are found to be optimal for a large class of reorientations and this method appears to have great practical potential, typically offering an average spacecraft fuel saving of 10 to 25 percent over current techniques. (Author)