Fin-Rudder Joint Control Based on Improved Linear-Quadratic-Regulator Algorithm

Abstract

Navigation accidents and disasters frequently occur when ships sail at sea due to extreme weather, wind, and wave conditions. The disturbance of wind and waves affects the stability of the ship's course and makes the ship roll violently. Ships are usually equipped with an autopilot to control the course and a fin stabilizer to reduce rolling during navigation and improve stability and safety. Fin-rudder joint control system considers the coupling effect of the ship's horizontal plane motion, thereby improving the performance of the rudder and the fin stabilizer. This paper presents an improved linear-quadratic-regulator control algorithm. A rate control law with no static error is proposed based on the traditional linearquadratic regulator to eliminate the static error of the state vector and achieve a better control effect. Additionally, a closed-loop state observer is used to estimate the system's state vector, and a dynamic corrector is designed to reduce rolling and heading angle deviation caused by sea wave interference. The simulation results show that the designed fin-rudder joint controller with the improved linear-quadratic regulator algorithm can achieve more than 80% roll reduction effect at level 3 and 5 sea states, and has better course keeping ability compared with the rudder control.INDEX TERMS Fin-rudder joint control, LQR algorithm, roll reduction, rate control law with no static error, dynamic corrector.

Ship Autonomous Berthing Simulation Based on Covariance Matrix Adaptation Evolution Strategy

“…Some researchers [14] implemented ship motion control of a large cruise ship based on the LQR, and the simulation experiments show that the ship handling experimental effect is good under certain wind conditions. The advantages of the LQR in ship motion control is confirmed by simulation experiments in some studies [13,[15][16][17]. Liu et al summarized the main automatic berthing control algorithms at the current stage and showed the inadequacies of various algorithms in actual control.…”

“…Tian [16] The yaw-checking maneuver was optimized under the straight sailing condition by an LQR controller. Simulation Zhao et al [17] Based on the LQR, a controller without static error was utilized to achieve heading stabilization. Simulation…”