Active FTC for Non-linear Aircraft based on Feedback Linearization and Robust Estimation

Abstract

The current work concerns the development of a novel approach to robust fault estimation to achieve active Fault Tolerant Control (FTC) for a nonlinear aircraft system. The novelty lies in the combination of a feedback linearization controller, with a state/fault estimator. The active FTC system combines these to compensate for the faults acting in the control system. The paper focuses on the development of an active FTC scheme applied to a nonlinear unmanned airborne vehicle (UAV) system with different faults acting on three actuators and with wind turbulence affecting the vertical force. The aircraft dynamics are approximately linearized on-line using a dynamic inversion controller based on differential geometry theory. For the linearized system with bounded input disturbance, a robust state-space observer is designed to simultaneously estimate system states and actuator faults by solving a Lyapunov equation. The FTC scheme is achieved via a linear matrix inequality (LMI) approach, based on the estimated states/faults. The simulation results demonstrate the efficiency and robustness of the proposed design.