Auto-Berthing Control of Marine Surface Vehicle Based on Concise Backstepping

An auto-berthing control strategy for 3-DOF (degrees of freedom) underactuated marine surface vehicles based on concise backstepping is presented in this paper. Firstly, differential homeomorphic method is used to simplify and make the 3-DOF underactuated marine surface vehicle motion model without external disturbances and model uncertainties has the structure of the general nonlinear system. Then, an auto-berthing controller for the transformed marine surface vehicle model is designed based on the backstepping, dynamic surface control (DSC) technology and Lyapunov direct method. The concise backstepping method can not only simplify the design process of the nonlinear controller but decrease the number of design parameters. Further, in order to illustrate the robustness of the designed controller, simulation experiments are carried out under the external disturbances. Theoretical analysis is provided to prove that the designed controller has a concise structure and is easy to implement in engineering. In addition, it can ensure that all signals of the system are bounded. Simulation results illustrate the effectiveness of the developed control scheme.