A thrust allocation method for DP vessels equipped with rudders

The thrust allocation unit is an important part of dynamic positioning system. Many dynamic positioning vessels are equipped with propellers and rudders, but the complex hydrodynamic characteristics of the propeller-rudder combination make thrust allocation a challenging task. However, research on thrust allocation methods has primarily focused on azimuth thrusters, and only limited attention has been given to the propeller-rudder combination. In this study, we propose a model-based thrust allocation method that incorporates an interaction model between the rudder and propeller, while also considering other factors such as the energy consumption and actuator mechanics. The proposed thrust allocation method is tested by using the dynamic positioning model test in a basin and the experimental results show that our method effectively maintains vessel position even in adverse sea conditions, with the thrust allocation results following the control commands well. The experimental results validate the effectiveness of the proposed thrust allocation method, indicating its potential application in real ship dynamic positioning systems.