Path Following Control for a Stratospheric Airship Based on Disturbance Observer

A planar path following control method based on dynamic inversion theory and disturbance observer approach for a stratospheric airship with modeling uncertainties is presented in this paper. Firstly, a six-DOF dynamical model of the stratospheric airship is established and force analysis is given in detail. From the model, the errors and their derivatives for six controlled states of the airship are derived, a dynamic inversion control law is developed and a disturbance observer is designed to estimate unknown terms in the control law. Then, the closed-loop system equation is deduced and it is proved that the six errors and their derivatives converge to a small neighborhood of the origin with arbitrary accuracy. Finally, simulation results for the airship to follow a circular path are presented to verify effectiveness of the proposed method.