Control-Oriented Modeling and Cascade Control of Container Ships

The development of autonomous ship motion control is gaining importance in the maritime transportation industry as autonomous ships can improve safety, efficiency, capacity, and environmental impact while reducing labor costs. However, most research on this topic has focused on nonlinear ship models coupled with complex control system designs, which are not feasible for some scenarios such as executing turning maneuver in real-time application for typical mass-produced cargo ships due to needs for high computational capability. To address this issue, this paper presents a practical control-oriented ship model using a superposed nonlinear propeller model on a linear ship motion dynamics. The developed model is validated using standard turning circle tests and a cascaded control algorithm is designed for waypoint tracking. The algorithm is tested with different scenarios to evaluate its ability to move the ship along prescribed trajectories, and simulation results show successful performance of the controller. Overall, this approach provides a reliable and practical solution for controlling autonomous ships in real-time applications.