Fully actuated system approach to attitude control of flexible spacecraft with nonlinear time-varying inertia

A high-order fully actuated (HOFA) system approach is proposed for the attitude control problem of a flexible spacecraft with nonlinear and time-varying inertia. Different from most existing results, the proposed method guarantees a linear time-invariant closed-loop system with arbitrarily assignable eigenvalues. Firstly, the HOFA model for the attitude system is derived from the original dynamic equations of the system by using state transformation and variable elimination. Then, by using the full-actuation characteristics of the obtained HOFA system, the nonlinearity in the system is completely canceled and a linear time-invariant system with arbitrarily assignable eigenvalues is derived. Finally, the control laws are designed for both problems of attitude stabilization and attitude maneuvering, and simulations are carried out based on practical engineering parameters, which demonstrate the effects of the proposed method.