부산대학교 도서관

This article addresses the robust trajectory tracking control strategy of differential-driven unmanned surface vessels, with the propeller servo loop taken into consideration. The proposed strategy takes duty cycles of propeller motors as control input and thereby can be directly applied in practice without any modification. Compared to the existing methods, the proposed method provides the framework of position control considering propeller servo loop and improves robustness to external disturbances. The controller design procedure is divided into three stages through backstepping technique. Disturbance observers are constructed to provide estimations of composite disturbances, which guarantee robustness in the presence of external disturbances and model uncertainties. An auxiliary system is introduced to handle the input saturation of duty cycles. With a linear growth condition of the output of propeller motors, a rigorous proof is presented to show tracking errors are uniformly ultimately bounded. Simulation and experiments illustrate the effectiveness of the proposed control strategy.