Study On Intelligent Active Disturbance Rejection Control For Ship Dynamic Positioning Systems

Due to the complexity of the marine environment and the uncertainty of the ship mathematical model,the ship's dynamic positioning control is affected by the external disturbances and the internal disturbances greatly.At the same time,with the constant exploration to the ocean,a higher dynamic positioning accuracy is required to finish the complicated tasks of offshore drilling platform positioning,submarine pipeline,cable laying and so on.Therefore,it has drawn much attention to improve the control performance of the ship's dynamic positioning control system.This paper studies the intelligent auto-disturbance rejection control of ship's dynamic positioning system and the main work is as follows:Firstly,the dynamic positioning system simulation model is established,including the mathematical model of dynamic positioning ships,the mathematical model of external environment interference and dynamic mathematical model of the unmodeled system.The model consider about the external and internal disturbances in the dynamic positioning control,which provides an effective basis for the subsequent simulation verification.Secondly,Active Disturbance Rejection Control(ADRC)can achieve a good disturbance inhibiting through the extended state observer to estimate the unknown and then compensate the system.However,Nonlinear Active Disturbance Rejection Control(NLADRC)has a limited range of immunity and parameter tuning difficulties,while Linear Active Disturbance Rejection Control(LADRC)has poor control accuracy.In order to solve this problem,we design a ship dynamic positioning controller with Switching Active Disturbance Rejection Control(SADRC).This method can obtain the advantages of LADRC and NLADRC to achieve an ideal control effect.Finally,a simulation experiment is made,using Beihaijiu" 115" and a mooring oil tanker as objects respectively.The simulation results show that SADRC has higher control accuracy and anti-interference ability.Lastly,There is also the problem of the oscillation at the switching time of LADRC/NLADRC switching and the large effect on the anti-interference range due to the characteristics of "small error with large control;large error with small control" of the nonlinear feedback control rule.Aiming at this problem,an automatic anti-disturbance shift controller is designed basing on RBF neural network.The RBF neural network is used to compensate the oscillation deviation.At the same time,the linear feedback control law(PD rule)is the application used in the feedback control.Finally,simulation experiments are taken,using Beihaijiu"115" ship and a mooring oil tanker respectively.The simulation results show that the improved controller has better stability and universality.