Robust Global Stabilization and Disturbance Rejection of an Underactuated Nonholonomic Airship

This paper considers the problem of controlling both the planar position and the orientation of an underactuated airship with a reduced number of actuators in the presence of a persistent wind disturbance. The airship is a nonholonomic system described by a set of nonlinear equations and the dynamics are subjected to bounded uncertainties. A smooth and time-varying coordinate transformation is proposed to reduce the disturbance rejection problem of the airship to that of a simple linear time-invariant system. A new robust feedback controller provides global stabilization and asymptotical rejection against the wind disturbance under the plant uncertainties. The proposed design method is simple and straightforward. Experiments are performed to validate the effectiveness of the proposed controller.