New hybrid adaptive control approach for aircraft with centre of gravity variation

Owing to centre of gravity (C.G.) variations, an aircraft may deviate from its nominal dynamics, which poses special problems to the flight control system. To overcome the limitations of accurate mathematical model and poor robust performance of the conventional method, a new hybrid C.G. estimation-sliding-mode adaptive control approach is proposed. A two-loop sliding-mode based adaptive control scheme is designed to guarantee the robustness of the closed-loop system towards potential uncertainties and disturbances. In addition, online C.G. estimation based on adaptive weight data fusion is introduced to guarantee smaller dynamic inversion errors. The parameter adaptation rules for the hybrid adaptive controller are obtained by the Lyapunov stability theory and Barbalat´s lemma. The simulation results demonstrate that the proposed approach can quickly adapt to the changing dynamics of the aircraft and provide consistent performance under varying C.G. locations.