Station-keeping Control of an Underactuated Stratospheric Airship

This paper studies the station-keeping control of underactuated stratospheric airships in the presence of model uncertainties and wind field, and a T–S fuzzy model-based adaptive backstepping SMC (sliding mode controller) is proposed. Firstly, a fuzzy dynamics model is constructed to represent the local dynamic behaviors of the given 6-DOF nonlinear dynamics of an airship. And different from the traditional algorithm, the station-keeping control is resorted to path-following control. Then, the guidance-based path-following principle is adopted to obtain the guidance law, and the backstepping technique is used to obtain the desired velocities. In order to solve the problem of model uncertainties between T–S fuzzy model and nominal model, the sliding mode control approach is adopted. Adaptive terms are designed to estimate the upper bound of the uncertainties. Besides, a wind field observer is designed to estimate the speed and direction of the wind. The stabilization of the system is discussed using Lyapunov stability theory. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed method.