Ship control of unberthing manoeuvring using an online estimation model under disturbance

Because a ship’s manoeuvrability changes nonlinearly with speed variations, designing controllers for berthing and unberthing requires a motion model that reflects these variations. This study proposes a control method with an online estimation model, where parameters are estimated based on observed ship motion. Using the gradient descent method for model estimation stabilizes updates in the presence of noise. To compensate for steady disturbances such as tidal currents, the effect of external force is estimated and used to calculate corrections for control inputs. The proposed method was verified by simulations under multiple disturbance conditions. The control system using the online estimation model demonstrated stable control in unberthing manoeuvring and effective disturbance compensation under steady deviation conditions.