Simulation analysis of rudder roll stabilization during ship turning motion

Rudders are usually installed below the stem line and used to control the course of ships. Rudders are also used to stabilize the roll motion during ordinary operation, especially for ships with rudders as the only maneuvering device. However, ships also experience a certain amount of rolling and heeling during turning. The present work aims to investigate the effect of rudders on ship roll reduction control during ship turns. The nonlinear 4-DOF motion model for a multipurpose naval vessel with forces and moments caused by hydrodynamics, propellers, rudders and waves is established. Based on the simulation analysis of ship turning motion with static and dynamic rudder angles, a linear quadratic regulator (LQR) controller is developed to realize the rudder roll stabilization (RRS) control during turning. An improved control strategy is proposed to balance the RRS control effect and the effect on the turning circle. The simulation results show that the proposed control strategy has less influence on the turning circle while effectively reducing the roll motion during ship turns, and can be a reference for the RRS controller design during ship turns.