Fault Detection and Estimation in Spacecraft via Intermediate-Variable-Based Fault Observers

This paper investigates fault detection and estimation for spacecraft systems using an intermediate-variable-based fault observer. Addressing actuator fault challenges in complex space environments, we first develop a fault detector to identify anomalies. Subsequently, we construct a novel observer framework by introducing intermediate variables that decouple fault dynamics from system states, fundamentally relaxing structural constraints of conventional methods. This approach achieves simultaneous and precise estimation of system states and faults. Rigorous Lyapunov stability analysis proves enhanced exponential convergence of estimation errors, demonstrating a significant theoretical advancement. Comprehensive numerical simulations validate the efficacy of the proposed methodology.