Fault detection and isolation for nonlinear F16 models using a gain-varying UIO approach

This paper presents a gain-varying UIO (unknown input observer) method for actuator FDI (fault detection and isolation) problems. A novel residual scheme together with a piecewise threshold and a moving horizon threshold is proposed. This design methodology is applied to a nonlinear F16 system with polynomial coefficient models, where the F16 plant and UIOs may use different aerodynamics coefficient models. The simulation results show that a satisfactory FDI performance can be achieved even when the system is under the environment of model uncertainties, exogenous noise and measurement errors.