Spatial trajectory tracking control for unmanned airships based on active disturbance rejection control

In this paper, to address the spatial trajectory tracking problem of unmanned airships, a robust controller based on active disturbance rejection control is presented. By transforming the airship model to a standardized form, a straightforward design approach is adopted for the design of the controller. Active disturbance rejection control is composed of a tracking differentiator, an extended state observer, and a nonlinear state error feedback. The proposed controller replaces the conventional tracking differentiator with a third-order differentiator. The new tracking differentiator provides higher tracking precision and smoother transient process. The external disturbances and model uncertainties are observed by the extended state observer and compensated in the controller design, subsequently. Comparisons with technologies frequently used in the trajectory tracking are made through numerical simulation. The comparisons validate that the proposed controller provides satisfying performance and robustness in the presence of model uncertainty and external disturbance.