Non-cooperative differential game based output feedback control for spacecraft attitude regulation

Abstract

Retired spacecraft attitude takeover control using two types of cellular space modules, namely orientation cellular space module (OCSM) and rate cellular space module (RCSM), is considered in this paper. Both the OCSM and the RCSM are endowed with identical mechanical actuators for providing 3-axis torques for attitude regulation. The difference is: the OCSM is equipped with orientation sensors which provide unit-length vector measurements to determine attitude, while the RCSM is mounted with rate sensors which measure angular velocities. Correspondingly, the attitude takeover controller is composed of a pre-wrap proportional control part and an output (angular velocity) feedback control part, which are executed by the OCSM and the RCSM respectively. A gain-scheduled control framework is adopted in order to formulate the rate feedback control part as subcontrollers for RCSMs. Two kinds of output feedback subcontrollers are proposed: a static output feedback control scheme with constant gains which are yielded from the linear–differential-game-based output feedback control; and a dynamic output feedback control scheme which is developed using the Kalman–Yakubovich–Popov Lemma and the linear–differential-game-based state feedback control. Both output feedback control schemes possess robustness to modeling errors, since the stability of the closed-loop systems hinge on the passivity theorem rather than the inertia properties of the retired spacecraft. Numerical simulation results show the effectiveness of the proposed controllers for attitude takeover control of a retired spacecraft fixed with the OCSM and the RCSM. A comparison between the proposed methods and an existing method is carried out to show the benefits of the proposed controllers.