Oscillatory Failure Case Detection for Aircraft Using Non-Homogeneous Differentiator in Noisy Environment

In this paper, the problem of Oscillatory Failure Case (OFC) detection in aircraft servo-loop control surfaces is addressed. OFC leads to strong interactions with loads and aeroelasticity and consequently must be detected as quick as possible. This paper proposes a hybrid monitoring scheme developed during ADDSAFE1 project for robust and early detection of such unauthorized oscillatory events. More precisely, a hybrid robust non-homogeneous finite-time differentiator is firstly used to provide bounded and accurate derivatives in noisy environment. Fault reconstruction is next made by solving on-line a nonlinear equation using a gradient descent method. The detection is finally done by the decision making rules currently used for in-service Airbus A380 airplane. Robustness and performance of the proposed scheme are tested using a high fidelity benchmark and intensive Monte Carlo simulations based on several flight D20scenarios specified in ADDSAFE. The performance indicators highlight that the proposed scheme can be a viable solution for realistic issues. Note that the term “viable” covers some important aspects which are often under-estimated (or missing) in the classical academic publications: tuning, complexity of the design, real time capability, etc.