An intelligent hierarchical approach to actuator fault diagnosis and accommodation

This paper presents a novel intelligent hierarchical approach to automatically detecting, isolating, and accommodating faults in flight control systems. The proposed architecture has three main components. First, a new nonlinear fault diagnosis scheme is used to detect the occurrence of any faults and to determine the particular component that has failed. Second, a controller module consists of a primary nominal controller and a secondary adaptive fault-tolerant controller. While the nominal controller can be any existing conventional flight control system, the secondary neural network (NN) based nonlinear adaptive controller is designed to maintain acceptable control performance after the detection of fault occurrence. Third, a reconfiguration supervisor makes decision regarding controller reconfiguration and control reallocation by using on-line diagnostic information. Following failures of primary aerodynamic actuators, flight safety can be maintained by utilizing alternative actuation systems for critical stability and control augmentation tasks. The effectiveness of the proposed integrated fault diagnosis and accommodation approach has been illustrated by using the research civil aircraft model (RCAM) developed by the group for aeronautical research and technology in Europe (GARTEUR). Extensive simulation studies have clearly shown the benefits of the proposed adaptive fault-tolerant control scheme using on-line diagnostic information