An Advanced Spacecraft Autopilot Concept

Abstract

An autopilot is developed for rotation and translation control of a rigid spacecraft of arbitrary design, using reaction control jets as control effectors. The autopilot incorporates a six-dimensional phase space control law, and a linear programming algorithm for jet selection. The interaction of the control law and jet selection are investigated and a recommended configuration proposed. Simulations are performed to verify the performance of the new autopilot and comparisons are made with an existing spacecraft autopilot. The new autopilot is shown to require 35.4% fewer words of core memory, 20.5% less average CPU time, up to 65% fewer firings, and consume up to 25.7% less propellant for the cases tested. However, the cycle time required to perform the jet selection computations may render the new autopilot unsuitable for existing flight computer applications, without modifications. Finally, the new autopilot is shown to be capable of performing attitude control in the presence of a large number of jet failures.