Underactuated Ships' Trajectory Tracking Based on Decoupling Control

The tracking control problem is concern for conventional surface ships. First, we consider external disturbances and design the mathematical model of ship motion. Then, an output feedback method is developed using a decoupling control algorithm and increment feedback based on an iterative nonlinear sliding mode designing approach. Third, the algorithm removes the constraints of requiring a known reference heading and constant angular velocity excitation, eliminating the need to estimate uncertain model parameters or wind and current disturbances. Trajectory tracking of the underactuated ships can be accomplished when only the plane trajectory and vessel position are known. It doesn't need to estimate system uncertainty, external disturbances, and yaw rate PE (persistent excitation) conditions. Finally, the simulation was carried out by applying the nonlinear hydrodynamic model of MV YU LONG. The results show the controller can effectively track the circular arc and sine curve trajectory. The controller does not depend on the accuracy of the model and can solve the problem of uncertain external interference well, and the control effect is good.