Adaptive event-triggered predictive control method for the autonomous berthing of inland ships

To achieve autonomous berthing for inland underactuated twin-propeller twin-rudder ships under environmental disturbances, an autonomous berthing trajectory tracking controller based on adaptive event-triggered predictive control (AETPC) is proposed. Firstly, the Maneuvering Mathematical Group (MMG) model of the inland ship, considering the propeller four-quadrant working conditions and twin-propeller and twin-rudder drive, is established. Based on this MMG model, a Model Predictive Control (MPC) controller is designed to facilitate trajectory tracking during autonomous berthing, taking into account multiple constraints, energy consumption, and control performance in its objective function. Additionally, to enhance the real-time performance and energy efficiency of the controller, an event-triggered mechanism is designed to adaptively adjust the prediction horizon in the MPC. Simulation experiments using a scaled model ship demonstrate that in berthing trajectory tracking control, the mean squared error of the AETPC controller in tracking path points is 0.0152 higher than that of the MPC controller, with no significant difference in tracking error between the two controllers. However, AETPC can reduce the number of control actions by 22.8% and shortens the controller computation time by 147.78 s in comparison of conventional MPC.