Decentralized fuzzy-integral-sliding control for a class of TITO uncertain nonlinear systems with application to a 2-DOF helicopter model

In this paper, a novel fuzzy-integral-sliding controller (FISC) is designed for coupled nonlinear two-input two-output (TITO) systems. Decomposing the original system into two subsystems, the coupling effects are modelled as uncertainties. In order to ensure the robustness properties with respect to system uncertainties and external disturbances, the sliding mode technique with a proportional integral (PI) sliding surface is adopted. On the other hand, to avoid the chattering phenomenon, the Takagi-Sugeno fuzzy rules are incorporated into the control algorithm, which forms a fuzzy sliding controller. The stability analysis is also presented based on the Lyapunov stability theorem. The proposed FISC is then applied to control the elevation and azimuth angles of Humusoft CE150, as a two degree of freedom (DOF) laboratory helicopter model with highly cross-coupled dynamics. The simulation results are also presented to demonstrate the performance of the proposed control scheme.