Fuzzy logic based speed optimization and path following control for sail-assisted ships

This note aims to solve the speed optimization and path following control for sail-assisted ships. The ideology of retrofitting a common bulk carrier with wing sails is investigated. Based on an established mathematical model with four degrees of freedom, we proceed with the subsequent analysis. First, a novel speed optimization scheme combining the extremum seeking (ES) algorithm with the self-tuning fuzzy logic system is proposed. After adequate online training, the fuzzy logic system is capable to maximize the ship's speed with less chattering. Next, an adaptive fuzzy control law for such a ship is developed under the skeleton of line of sight (LOS) guidance. The uncertainties are offset by fuzzy approximation and the least parameters updating is acquired. The derived control outputs are characterized by rudder angles, which conforms to the nautical practice. Finally, the proposed scheme is testified in the simulated sea environment.