High-order Fully-actuated System Approach Based Fault-tolerant Attitude Tracking Control via Extended State Observer

This paper addresses the attitude fault-tolerant control of a rigid spacecraft subject to multiple actuator faults, uncertain inertia, unknown disturbances, and unknown system state variables. A high-order fully-actuated (HOFA) model is derived based on the state-space representation by using variable elimination method. The extended state observer (ESO) is employed to estimate the unknown state variables and their derivatives, as well as the generalized disturbances, which include uncertain inertia, external disturbances, and bias fault. The assumption that the system states are known, which is required in the HOFA approach, is relaxed. The controller designed based on the HOFA approach ensures a linear closed-loop system and incorporates ESO for compensating the total disturbances. The tracking error is guaranteed to converge to a small neighborhood of the origin and the closed-loop system is proved to be bounded. Numerical simulations are conducted to demonstrate the effectiveness of the proposed control law.