Nonlinear robustness analysis of flight control laws for highly augmented aircraft

In this paper, a novel hybrid optimisation algorithm is applied to the problem of analysing the robustness of a nonlinear flight control law in the presence of multiple variations in key aircraft parameters over continuous regions of the flight envelope. The analysis employs a typical nonlinear clearance criterion used by the European aerospace industry together with a simulation model of a high performance aircraft with a full authority control law which is gain scheduled over the flight envelope. The hybrid algorithm incorporates global (differential evolution) and local (sequential quadratic programming) optimisation algorithms to improve convergence properties and reduce computational overheads. The proposed approach is shown to have the potential to significantly improve both the reliability and efficiency of the industrial flight clearance process.