Contraction Based Adaptive Backstepping Control of Dynamic Positioning Vessels

Dynamic positioning vessel is continuously exposed to environmental disturbances of wind, currents and waves. An adaptive backstepping controller is designed for dynamic positioning vessel by considering the trajectory convergence of the positioning system. At each step of recursive design, subsystem is made contracting, and global exponential convergence is guaranteed. An adaptive strategy is used to estimate the bounded disturbance caused by wind, currents and waves, and the estimate is bounded with respect to a true value. Using coordinate transformation for contraction analysis, it is proved that the ship’s position and heading can globally and exponentially convergent to the desired value. Numerical simulation on a dynamic vessel is given to demonstrate strong robustness of the proposed controller under different sea conditions. © 2020, Editorial Office of Ship Building of China. All right reserved.