Abstract: A critical system comprises a control pathway comprising an actuation unit having a nonlinear behavior, that is able to be controlled by applying an input quantity and whose state is characterized by an output quantity. The behavior of the actuation unit being described by a flat nonlinear model, wherein the system comprises an estimation unit comprising a dynamic inversion linearization module calculating from the measured output quantity, the input quantity of the equivalent linear model; an estimation module estimating a flat output quantity from the input quantity of the equivalent linear model; and a computing module computing a residual based on the estimated flat output quantity and a measured flat output quantity, corresponding to the measured output quantity.

Abstract: A critical system comprises a control pathway comprising an actuation unit having a nonlinear behavior, that is able to be controlled by applying an input quantity and whose state is characterized by an output quantity. The behavior of the actuation unit being described by a flat nonlinear model, wherein the system comprises an estimation unit comprising a dynamic inversion linearization module calculating from the measured output quantity, the input quantity of the equivalent linear model; an estimation module estimating a flat output quantity from the input quantity of the equivalent linear model; and a computing module computing a residual based on the estimated flat output quantity and a measured flat output quantity, corresponding to the measured output quantity.

Abstract: Methods and devices for detecting oscillatory faults in a positional servocontrol arrangement for an aircraft control surface are provided. The detection device estimates a reference position of the control surface and, with the aid of a model in which at each iteration a residual value of the previous iteration, multiplied by a dynamic gain, is injected, detects an oscillatory fault with the aid of this reference position.

Abstract: Method and device for detecting oscillatory faults in a positional servocontrol arrangement for an aircraft control surface. The detection device comprises means for estimating a reference position of the control surface, with the aid of a model in which at each iteration a residual value of the previous iteration, multiplied by a dynamic gain, is injected, and means for detecting an oscillatory fault with the aid of this reference position.