An adaptive unknown input observer for fault detection and isolation of aircraft actuator faults

This paper presents a method for fault detection and isolation based on linearized aircraft models. A model-matching approach is employed using a bank of adaptive linear unknown input observers (UIOs). The well-known UIO technique allows for the rejection of structured disturbances, while the addition of an adaptive term handles the unknown nonlinearities in the system. Both the observer error and the estimate of the nonlinearity are used in the formation of the residual. Nonlinear aircraft simulations verify the performance of the proposed method.