Dynamic inversion of a Flight Critical actuator for fault diagnosis

Flight-Critical Systems (FCS) integrate usually actuators such as Electro Mechanical Actuators (EMA) controlled by Electronic Engine Control Units (EECU) or Flight Control Units (FCU). They are designed and developed regarding drastic safety requirements. Material Redundancy is therefore a safe design but requires an important amount of space, weight and costs. In this paper, observer-based fault detection methods are applied to a hybrid stepper motor (HSM) nonlinear model. First, state estimations are processed with an Extended Kalman Filter (EKF). After showing that the model is differentially flat, a nonlinear dynamic inversion (NLDI) is applied to the model in order to find its equivalent linear system. A Standard Kalman Filter (SKF) is then applied for fault detection. Faults due to short-circuits in the stator windings are considered.