Composite observer-based anti-disturbance fault-tolerant stabilization control for sea launch platform with actuator faults and input saturation

This paper proposes a composite observer-based anti-disturbance and fault-tolerant stabilization for three-degree-of-freedom (3-DOF) sea launch platforms with actuator faults and input saturation. This composite observer-based anti-disturbance and fault-tolerant stabilization control scheme is built through integrating a disturbance observer and a fault observer with the backstepping technique together with an actuator saturation compensator and the robustifying term. The disturbance observer is utilized to provide on-line estimates of the time-varying disturbance in the ocean environment. The actuator fault observer is exploited to achieve the on-line fault estimations of actuator faults. The actuator saturation compensator is employed to attenuate the adverse effects of actuator saturation. The robustifying term is used to attenuate norm-bounded unmodeled dynamics. It is proved that the composite observer-based anti-disturbance and fault-tolerant stabilization controller can achieve the attenuation and rejection of disturbances and faults simultaneously. It is proved by illustrative simulations that the composite observer-based anti-disturbance and fault-tolerant stabilization control strategy can strongly stabilize the sea launch platform.