Active Disturbance Rejection Control for Rudder-Fin Coordinated Heading Holding

An effective and robust control strategy is vital for surface vessel stability under uncertain marine conditions. This paper presents an Active Disturbance Rejection Control (ADRC) approach for rudder-fin coordinated heading control, aiming to suppress wave-induced roll while maintaining heading accuracy. The ADRC integrates a tracking differentiator, nonlinear state error feedback, and an extended state observer for real-time disturbance estimation and compensation. Simulation results show that roll motion is effectively suppressed, with performance enhancement exceeding 60% in most cases and peaking at 64.40% under beam-sea conditions. Both roll and yaw standard deviations are significantly reduced, indicating strong disturbance rejection. Control surface usage remains moderate, and disturbance estimation errors are consistently below 0.001 across all channels. These results confirm the accuracy and robustness of the ESO, supporting the applicability of ADRC for intelligent marine autopilot systems.