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This work shows how to use a differential geometry tool to design a novel nonlinear active fault tolerant flight control system for aircraft. The proposed control scheme consists of two main subsystems: a controller, which is designed for the nominal plant, and a fault detection and diagnosis module, which provides fault estimation. A further feedback loop exploits the fault estimation to accommodate faults affecting the system. The estimate convergence and the stability of the active fault tolerant flight controller are theoretically proved. Finally, high fidelity simulations show the effectiveness of the scheme. [ABSTRACT FROM AUTHOR]

Abstract: A method for oscillatory fault detection and isolation is presented and used to detect oscillatory failures of redundant aircraft sensors involved in the computation of flight control laws. The objective is to switch off the erroneous sensor and to compute a consolidated parameter using data from valid sensors, in order to eliminate any anomaly before propagation in the control loop. The benefit of the presented method is to improve the consolidation process with a fault detection and isolation approach when only few sources (less than three) are valid. Different techniques are compared to accurately detect any behavioral change of the sensor outputs. The approach is validated on a normalized real flight data set. [Copyright &y& Elsevier]

Abstract: This paper deals with industrial practices and strategies for Fault Tolerant Control (FTC) and Fault Detection and Isolation (FDI) in civil aircraft by focusing mainly on a typical Airbus Electrical Flight Control System (EFCS). This system is designed to meet very stringent requirements in terms of safety, availability and reliability that characterized the system dependability. Fault tolerance is designed into the system by the use of stringent processes and rules, which are summarized in the paper. The strategy for monitoring (fault detection) of the system components, as a part of the design for fault tolerance, is also described in this paper. Real application examples and implementation methodology are outlined. Finally, future trends and challenges are presented. This paper is a full version of the invited plenary talk presented by the author on the 1st July 2009 at the 7th IFAC Symposium Safeprocess ''09, Barcelona. [Copyright &y& Elsevier]

Abstract: This paper describes a reconfiguring flight control algorithm for damaged aircraft based upon a modular approach. This approach combines real time physical model identification with adaptive nonlinear dynamic inversion (NDI). The sensitivity of NDI to modeling errors is eliminated here by making use of a real time identified model of the aircraft. In failure situations, the damaged aircraft model is identified by the two step method and this updated model is supplied to the model-based adaptive NDI routine, which reconfigures for the fault in real time. Reconfiguration test results for damaged aircraft models indicate good fault handling capabilities of this fault tolerant control set-up, for component as well as structural faults. [Copyright &y& Elsevier]

Abstract: This paper focuses on failure detection in the electrical flight control system of Airbus aircraft. Fault tolerance is designed into the system by the use of stringent processes and rules, which are summarized below. Monitoring of the system components is part of this fault-tolerant design. This paper covers the particular case of oscillatory failure monitoring in the electrical flight control system. The main characteristics and consequences of these failures are presented. The detection of oscillatory failures on the A380 is considered, together with the concept of analytical redundancy to detect these failures. A nonlinear actuator model is used to generate a residual on which the failure is detected by oscillation counting. Real application and benefits of the overall method are also presented. The results are highly satisfactory and the overall method is currently implemented on A380 flight control computers. [ABSTRACT FROM AUTHOR]