Z-shaped navigation for surface ships in rough seas based on constraint MPC

This paper proposes a constraint MPC (Model Predictive Control) based ship motion control strategy for Z-shaped navigation, which aims to increase ship safety and reduce crew fatigue and energy consumption costs in rough seas. The strategy uses a time-driven and event-driven dual trigger release mechanism to control the yaw path, helping to avoid hazardous navigation areas. By limiting the rudder angle and adjusting the ship's wave encounter angle, safe and stable navigation is ensured and capsizing in rough seas is effectively prevented. The mathematical model is created, and the model predictive control method is used to predict and control the motion state of the ship with constraints on the control variables. The stability of the algorithm is demonstrated using the Lyapunov stability criterion, and the MATLAB simulation platform verifies its validity, robustness, and superiority. The simulation shows that the control strategy can avoid the dangerous area of navigation under the premise of maintaining a good control effect and preventing the accident of capsizing caused by steering with large rudder angles in rough seas. The proposed strategy could be further developed for the autonomous control of MASS (Maritime Autonomous Surface Ship).