Research On Active Disturbance Rejection Control Of Ship Dynamic Positioning System

With the proposal of the Ocean Power" strategy arid the continuous development of deep-sea resources,more and more scholars have focused their attention on the research of ship dynamic positioning systems.In the actual operation process,ship motion is a complex model with high nonlinearity and high uncertainty.Therefore,the research of its controller cannot be limited to the traditional control theory.In recent years,intelligent control theory and nonlinear control methods have been developing rapidly,the emergence of neural network algorithm,genetic algorithm,fuzzy control algorithm,sliding,mode variable structure control algorithm and ADRC algorithm provides a better choice for the design of dynamic positioning controller.Among them,the ADRC control technology absorbs and inherits the essence of the classic PID control algorithm "to eliminate errors based on errors",and use the special non-linear feedback mechanisms to compensate for disturbances,which can reflect its own advantages in many situations,especially in harsh environments.Due to its characteristics of simple structure,independent of accurate mathematical model and strong anti-interference ability,the ADRC is very suitable for the controller design of ship dynamic positioning system.Therefore,this paper studies the design of the control algorithm of ship dynamic positioning system based on the ADRC method.This paper first studies the characteristics of the ship's motion equation from the perspective of kinematics and dynamics,and establishes a mathematical model of the ship's low-frequency motion.The paper studies the unmodeled factors and uncertain factors in the ship model,considers the external disturbances caused by wind,wave and other environmental load changes,and reduces them to the "total disturbance" of the entire system,expanding into new state variables,and perform disturbance compensation for it.Then,according to the mathematical model of the ship used,the simulation is carried out to verify the reliability and effectiveness of the ship data used,and prepare for the subsequent controller design.On the basis of the previous work,the paper studies the structure and control principle of the auto disturbance rejection controller,and discusses each part in detail.In order to solve the problem that the ship will suddenly suffer large disturbances during the movement,the paper improves the nonlinear fal function in the expanded state observer,and uses the improved faln function in the auto disturbance rejection controller,and carries out simulation.The simulation results show that the improved ADRC improves the robustness of the system.Finally,the tuning principle of parameters of the ADRC and the basic principles of fuzzy control is analyzed,and the parameters in the nonlinear feedback law which are difficult to be adjusted are adjusted by combining with the fuzzy control principle.Under the background of dynamic positioning system,a fuzzy-ADRC is designed for ship motion.The designed controller was applied to the actual ship model and through MATLAB to verify the effectiveness of the designed algorithm.The simulation results show that the improved fuzzy auto disturbance rejection controller has stronger anti-interference characteristics and better robustness.