Study On Fractional-order Active Disturbance Rejection Control For Ship Dynamic Positioning Systems

With the continuous deepening of human exploration of the ocean,the scope of exploration has gradually expanded to the deep sea,and people have gradually deepened their research on positioning systems for deep sea operation ships.Traditional anchor positioning is no longer sufficient for deep sea operations.The new power system is more and more widely used in various ships and platforms.Research on dynamic positioning has important theoretical significance and use value.The core of the dynamic positioning system includes two parts:control algorithm and inference allocation method.This paper mainly studies the dynamic positioning control system and completes the following tasks:(1)The principles of fractional order control and auto disturbance rejection control are discussed,which is the theoretical basis of the control algorithm in this paper.(2)Established a ship's Manoeuvring Model Group(MMG)and a ship's dynamic positioning mathematical model,and the disturbance force model of the ship is established considering the disturbance of wind,wave and current.(3)Combined the theory of fractional calculus,designed the fractional PID controller and applied it to the ship's dynamic positioning system for the first time.Through comparison and analysis with integer order PID controllers,it can be seen that fractional order PID controllers have the advantages of fast response,strong robustness,and high control accuracy;in ship dynamic positioning systems,fractional order PID controllers can be used faster under ideal sea conditions.The ship reached the desired position.(4)Aiming at the problem of many parameters and complicated adjustment of the fractional order controller in the ship's dynamic positioning system,this paper proposes to introduce the Hybrid-PSO algorithm.into the controller design,and set the parameters of the fractional order PID controller online.The simulation results show that the algorithm avoids the defects of the traditional PSO algorithm to a certain extent,and the convergence speed is faster;the optimized controller parameters can stabilize the control effect and improve the control quality.(5)In order to better solve the problem of dealing with external disturbances in the ship's dynamic positioning system,based on the theory of fractional calculus theory and auto disturbance rejection control,this paper combines fractional PID control and auto disturbance rejection control to design Fractional order anti-disturbance controller,at the same time,the introduction of Hybrid-PSO algorithm for parameter tuning to achieve the best control effect.Simulated experiments were carried out on the controlled objects of two marine positioning vessels,"Offshore Oil 681" and "Beihai Rescue 115".The simulation results show that the optimized controller can make the system reach a good stable state,with higher control accuracy and faster of the response speed,and its immunity performance is increased.After replacing the ship model and testing,the control effect is still good.It shows that the fractional order disturbance rejection controller designed in this paper has universal applicability.