Fault-tolerant flight control design for effective and reliable aircraft systems

Effectiveness in flight control is achieved by maintaining specified performance despite the presence of faults and reliability implies taking the necessary measures to correct the fault before it leads to substantial performance deterioration and instability. In order to achieve both effectiveness and reliability, in this paper, we propose a fault-tolerant control (FTC) approach that is able to simultaneously compensate for actuator faults, model mismatch and parameter variations in aircraft systems. The proposed control design successfully combines the properties of active and passive FTCs to accommodate faults while retaining acceptable system performance. A passive baseline controller is designed using sliding mode theory and an active controller is designed using a model reference adaptive approach. The proposed control paradigm retains system performance under fault free conditions and triggers corrective measures only when necessary, hence ensuring flight effectiveness and enhancing system’s reliability. The proposed approach was validated using an aircraft system subject to a wide range of fault scenarios. Comparison analysis of the system performance, when only the passive controller is considered, was also carried out to highlight the effectiveness of the proposed approach. The obtained results show that the proposed fault-tolerant flight controller is able to maintain acceptable performance and retain system stability even in the event of major loss in actuator effectiveness.