Oscillatory failure case detection in the missile Actuators electrical flight control system by adaptive unknown input observer

This paper focuses on failure detection in the electrical flight control system of the missile actuator, especially the particular case of oscillatory failure. The structure and function characteristics of circular equidistance type missile actuator was studied thoroughly, the main feature and consequences of these failures are analyzed and an approach of adaptive unknown input observer (UIO) based on the multi-model control theory is used to detect and isolate the missile actuator faults. The observers are constructed based on a modified form of the standard UIO to generate fault-dependent residual signals, such that when a model matches the system, the residual signal will be zero. Otherwise, the residual will be definitely non-zero and governed uniquely by the faulty signal. The simulation results shows that the approach is satisfactory and overcomes the drawback of the nonlinear actuator model.