Ship Heading Control Based On Composite Nonlinear Feedback

As a common maritime vehicle,ships undertake various complex tasks.Because the ship’s mechanical structure is complex,and when the ship is sailing on the sea,the ship’s sailing speed and loading capacity are not static.These factors make it difficult to determine the precise mathematical model of the ship’s motion.Therefore,When the sailing conditions of the ship are changed,we hope to design a control law so that the ship can still run smoothly,and the dynamic performance is better.The article mainly considers the influence of ship speed and load changes on the motion model of ship heading control.When a ship is sailing,changes in sailing speed and load will cause parameter perturbation in the controlled model.Therefore,the article use composite nonlinear feedback control to keep it stable when the uncertain parameters of system are changed.And when the heading angle of the ship is changed,it can switch to the new course quickly and without overshoot.First,the article designs a composite nonlinear controller based on state feedback.According to the boundary information of the uncertain parameters,the paper obtains a robust linear controller by solving the riccati equation,and then designs a composite nonlinear controller based on the linear controller.We analyze the influence of different forms of nonlinear functions on system performance.Then through mathematical proof,it is proved that when the system parameters are perturbed,the linear robust controller and the composite nonlinear feedback controller have good robustness.Finally,through simulation analysis,and compared with the control methods in other documents,It proves that the composite nonlinear feedback controller not only has strong robustness,but also has relatively good dynamic performance.Secondly,when the state information is not available,the article constructs a state observer,uses the output information of the system to estimate the state of the system,and then uses the estimated state information to design a robust linear controller,and designs a composite nonlinear controller based on the linear controller.It is proved by mathematical derivation that the linear robust controller and the composite nonlinear controller have good robustness to parameter perturbation.Finally,through simulation,it is proved that compared with the linear controller,the composite nonlinear feedback controller can drive the system state to converge to the true value faster,and the system input can tend to zero faster.Compared with the control methods in other documents,under the action of the composite nonlinear controller,the closed-loop system not only has good robustness,but also has better dynamic performance.