Research On Rudder Roll Stabilization Control System Based On Robust Optimal Control

When a ship is sailing in the ocean,it must be affected by external environmental factors such as wind,waves,currents,etc.,which will cause the ship to produce complex motions and complex coupled oscillation.The oscillation will interfere with the normal work and life of the crew,reduce the comfort of riding,affect the use of ship equipment,and even capsize the ship.For general ships,the first problem to be solved in the course of sailing is yaw and roll.Rudder roll stabilization is an effective stabilizer,which is to reduce roll while maintaining heading.Due to the advantages of low cost and convenient modification,technology of rudder roll stabilization has been widely developed and applied at home and abroad.This paper mainly studies the rudder roll stabilization control system,the main research contents are as follows:First of all,under the complex sea conditions,we establish different coordinate systems according to the different reference points selected,and analyze the relationship between different coordinate systems;We study the motion characteristics of the ship in the motion coordinate system,and analyze the six degrees of freedom motion of the ship;Next,the ship is analyzed based on the Newtonian dynamics principle;Then,according to the motion characteristics of the ship,the force in the direction of three coordinate axes and the torque generated,the six degrees of freedom motion equation of the ship is established.We mainly study the ship rudder roll stabilization system on the basis of the needs of this paper,so we only need to consider the three degrees of freedom of ship,roll,yaw and sway,and their coupling,and establish the three degrees of freedom motion equation of ship.For the ship’s interference forces and moments,we only consider the wave interference as the external environment interference,and establish the mathematical model of ship’s wave interference.Secondly,according to the mathematical model of ship wave interference,the computer simulation model of ship motion is established with Matlab / Simulink.In the process of establishing the computer simulation model,we equate the wave interference to the ship roll for analysis.In the selection of control algorithm,because the rudder has the constraints of maximum rudder angle and rudder angular velocity,and it is expected to reduce the ship’s roll and yaw to zero.We choose LQR optimal control algorithm to design the rudder roll stabilization controller.The LQR optimal control algorithm can only be used for linear system,so we need to linearize our mathematical model and simulate it.Comparing the simulation results of ship roll equivalent to ocean wave interference,it is verified that LQR controller of rudder roll stabilization has better stabilization efficiency.Finally,considering the uncertainty of ship nonlinear motion and environmental disturbance,a robust compensator is added to the LQR optimal controller designed by us to design the robust optimal controller for rudder roll stabilization.The simulation model is built in Matlab / Simulink combined with the mathematical model of ship motion.The simulation results of robust optimal controller and LQR optimal controller are compared,and the ship has better stabilization efficiency and better stability under the regulation of robust optimal controller of rudder roll stabilization.