Optimal solar pressure attitude control of spacecraft—I: Inertially-fixed attitude stabilization

Abstract

This paper is divided into two parts. Part I presents the development of a solar pressure control system to impart arbitrary inertially-fixed attitudes to nonspinning axisymmetric spacecraft. A controller configuration consisting of two rotatable mirror-like surfaces, representing the minimum hardware implementation, is proposed. A control strategy involving nominal controls to counter the gravitational torques and optimal feedback controls to provide stability to the system is developed. The feasibility of employing suboptimal controls resulting in reduced software requirements is explored. The validity of the system is established for all times of the year and in orbits that encounter the Earth's shadow. In Part II of the paper, the capability of the same controller is extended to accomplish large-angle attitude maneuvers of the spacecraft. The entire approach leads to a versatile semipassive attitude control system.