Analyzing Robustness and Accuracy of Different Controllers for Underactuated Ships

Most ships that carry cargo from one place to another are underactuated. Therefore, controlling such vessels is challenging, and even a few major accidents in the industry can be attributed to ineffective control by a human operator. Automated control can significantly aid in the prevention of such incidents. This paper demonstrates the practical implementation of a path-following algorithm for an underactuated scaled model of a container ship. In this research, two different control strategies have been compared against each other: Proportional Derivative Control (PD) and Sliding Mode Control (SMC). The underactuated vessel is made to track a given set of waypoints, and the performance of the controllers is measured. For this study, a 1:75.5 scaled free-running model of the KRISO Container Ship (KCS) is chosen as the test ship. Simulations were done using a numerical model of the vessel's dynamics and the controllers are compared for their accuracy and robustness.