Research On Intelligent Algorithm Of Ship Dynamic Positioning Control System

The dynamic positioning(DP)vessels can maintain the position on the sea by the thrusters on the vessel.Compared with the traditional mooring positioning vessels,positioning result of DP vesseels is not limited by the depth of water,and the DP vessels have been widely used in the ocean exploitation and exploration.The dynamic poisoning control algorithms are the core of the DP controller.The research of the DP control algorithm is significant for the research and application of the DP system.In this thesis,two dynamic positioning control systems are designed based on intelligent algorithms,and numerical simulation and model test had been carried out based on HYSY 201.Two dynamic positioning control systems are designed in this thesis.A DP system is mainly composed of filtering algorithm,control algorithm and thrust allocation algorithm.The low-pass + notch filtering algorithm is used to filter the ship motions.Based on PID control algorithm,two sets of dynamic positioning control algorithm are designed by using neural network algorithm and expert system.One of them is BP neural network PID control algorithm which could realize the self-tuning of PID parameters in a certain range,and the other one is PID neural network expert control algorithm which could adjust the PID parameters with the change of ship position on the basis of the initial PID control parameters.The objective function and constraint conditions are established for the thrust allocation problem,and the genetic algorithm is selected as the thrust allocation algorithm.The numerical simulation based on dynamic positioning control systems is carried out by C language code,and the results are fitted with the field measured results of HYSY 201,which shows the dynamic positioning control systems can maintain the vessel position effective.A dynamic positioning system for model test is designed based on LabVIEW code and NI hardware.The model test of HYSY 201 model with scale ratio of 1:38was carried out in the towing tank of Tianjin University.The feasibility and practicality of the control system designed in this thesis are verified by analyzing the model test results.A set of numerical simulations based on dynamic positioning control systems designed in this thesis are calculated in multiple environmental conditions and wave directions.The motions of ship,the thrust forces and direction angles of thrusters obtained from the numerical simulations are analyzed,and the influence of the significant wave height,peak period and environmental load direction on ship motions and thruster states is explored.