A Novel Dynamic Berthing Scheme for An USV: DPFS Guidance and Two-dimensional Event Triggering ILC

This manuscript investigates a novel scheme designed for path planning and path following of the USV system to perform dynamic berthing tasks in the presence of structural uncertainties and simulated marine environments. The proposed cooperative scheme consists of the dynamic artificial potential field ship (DPFS) guidance principle and a two-dimensional trigger iterative learning control algorithm. The DPFS guidance principle employs a novel gravitational potential field to plan desired yaw angles and a spiral repulsive potential field to generate smoother reference paths. This principle is developed to plan the desired path for the unmanned dinghy to perform dynamic berthing tasks with the maintenance ship. To ensure the USV converges to the desired path with superior control accuracy, an improved iterative learning control algorithm is designed with a two-dimensional event-triggering mechanism. The event-triggering mechanism in the time domain reduces actuator wear by decreasing the transmission frequency of control input. As well as, in the iteration domain allows for the presetting of control error based on ocean engineering tasks, and the number of iterations can self-adjust accordingly. Utilizing the Lyapunov theorem, the proposed control scheme guarantees uniform convergence of full state tracking error over the iteration domain. The superiority and effectiveness of the proposed strategy are validated through numerical experiments conducted on the MATLAB platform under various external disturbances.