ADAPTIVE NONLINEAR ATTITUDE-CONTROL AND MOMENTUM MANAGEMENT OF SPACECRAFT

An indirect adaptive nonlinear controller is investigated for attitude control and momentum management of evolutionary spacecraft. The contr ol law is based on the theory of nonlinear feedback linearization. A n ew state transformation is introduced: one that converts the original nonlinear system into normal canonical form. Once in canonical form, n onlinear feedback is used to generate a linear response in the transfo rmed coordinates. To make the nonlinear controller adaptive, a paramet er identification scheme, utilizing an extended Kalman filter, is adde d for mass property estimation. Probing signals are introduced to enha nce the observability of the mass properties. Simulation results show that the adaptive nonlinear controller stabilizes the International Sp ace Station during mass property changes, successfully performs moment um management, and provides real time estimates of the mass properties in a realistic environment.