Analyzing Robustness and Accuracy of Different Controllers for Underactuated Ships

Abstract

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.