Adaptive Fault-Tolerant Control Allocation of Flexible Satellite with Infinite-Dimensional Model

Abstract

This paper proposes a fault-tolerant control allocation (FTCA) scheme for a flexible satellite. A novel control strategy is implemented, which fulfills the satellite mission and also decreases vibrations, saturation time of the actuators, and required energy. Avoiding spillover instability, an infinite-dimensional model of the flexible satellite is considered, which is one of the important benefits of the proposed control scheme over the previously presented FTCA methods. External disturbances, the uncertainty of moment of inertia, actuator fault and failure, imprecision in fault estimation, and control constraints are considered. The designed control system is comprised of two modules: the virtual control module that designs the virtual control law to stabilize the satellite and control vibrations without any in-domain actuators on panels, and a distribution control module that distributes the virtual control law among actuators based on their fault information and distance of bound of the control limit. The proposed virtual control law consists of an observer-based PD-like nominal control and adaptive control parts, and the internal reaction torque is estimated using a nonlinear observer. The closed-loop uniformly ultimately bounded (UUB) stability is achieved using Lyapunov criteria. A numerical example illustrates the effectiveness of the proposed approach regarding attitude stabilization and vibration control objectives.