Phased Predictive Berthing Control in Low-Speed Maneuvering for Autonomous Inland Ships

Abstract

To address the challenges of safe and efficient automatic berthing for underactuated inland ships without tugboat or lateral thruster assistance, this article introduces a phased predictive berthing control (PPBC) method designed for low-speed conditions with uncertainties. A maneuvering modeling group (MMG) model is initially developed, incorporating twin-propeller and twin-rudder configurations, environmental disturbances (i.e., wind and currents), and model uncertainties. Three distinct berthing strategies, i.e., bow-in berthing, parallel berthing, and stern-in berthing, are formulated to ensure the applicability for most of berthing scenarios with phased states constraints. A time-delay observer is designed to estimate environmental disturbances and model uncertainties, on the basis of which a reliable predictive model is constructed by using the low-speed MMG model and the estimated disturbances and uncertainties. Leveraging this model, a model predictive control (MPC) method is designed to achieve the trajectory tracking of berthing control, while accounting for both control input and phased-state constraints. Simulation results demonstrate that the proposed PPBC method outperforms conventional proportional–integral–derivative, sliding mode control, and standard MPC methods in terms of trajectory, heading, and speed tracking error across a range of evaluated berthing scenarios.