Positioning control for an unmanned airship using sliding mode control based on fuzzy approximation

This paper addresses the positioning problem of an unmanned airship in the presence of parametric uncertainties and external disturbances. A sliding mode controller (SMC) based on fuzzy approximation is proposed that steers an airship to remain fixed over a desired position. First, the dynamic model of an airship is derived and formulated. Second, a SMC is designed to actualize positioning control under the assumption that the airship model is accurately known. However, the airship model is partially or totally unknown in practice. In order to solve this problem, a fuzzy logic system is used to approximate the unknown model of the airship, and an adaptive law is adopted to update the optimal parameters. The stability and convergence of the closed-loop controller is proven by using the Lyapunov stability theorem. Finally, the effectiveness and robustness of the proposed controller are demonstrated via simulation results. Contrasting simulation results indicate that the proposed controller promotes the control precise and has better performance against the SMC.