Modeling And Simulation Of Semi-submersible Six-DOF’s Ship Motion Research

With the development of modern social science and technology, the realistic of requirements of the ship navigation simulator will be higher,so people will improve the accuracy of the mathematical model of ship motion. In order to show comprehensive and accurate ship’s gesture, the six-DOF ship motion mathematical model will be in a very important role.Together, the precision of dynamic positioning and the maneuvering performance of dynamic positioning vessels are constantly improved, especially the semi-submersible ship working in the deep-sea area. Whether a heading controller and a positioning controller of dynamic positioning system good or not will play a crucial role when it is facing different working conditions.This paper is based on the previous research and the "Tai An Kou" semi-submersible vessel is the simulation mother ship. We strive to establish a6-DOF responsive ship motion mathematical model based on the semi-submersible ship and heading controllers under different working conditions and a position controller of dynamic positions system based on the control models. In summary, the study goes as following:1.In this paper, based on the idea modeling respectively and analysis of ship motion and force, six-DOF mathematical model iScreated under different propulsion mode of the ship in the combined wind, waves and currents. And through force analysis of the ship,the calculation model of hull hydrodynamic forces and moments,six-DOF of freedom of fluid power and torque,six-DOF of freedom external disturbance force and torque and so on are established. Finally we use numerical analysis method of fourth-order Runge-Kutta for computer simulation. Through experimental analysis and compared with the relevant literature of six-DOF,the mathematical model of this design meet the basic requirements.2.At the same time,different control strategies suitable for different working conditions of ordinary working conditions and high sea conditions through the resurch of ship of modern control are identified. This paper uses genetic algorithms and hybrid intelligent control algorithm combined with PID control algorithm. Through this design, we can make better use of the advantages and disadvantages between various algorithms to make it better adapted to the ship control under different conditions.3. Based on the characteristics of the semi-submersible vessels working in the deep-sea area,we design the ship heading controller under ordinary conditions and high sea conditions,which is based on the ordinary conditions of genetic algorithm-PD control and high sea conditions of hybrid intelligent-PID control. Through the experimental analysis, the heading controller designed for different conditions basically meet the control requirements.4. The adaptive dynamic positioning controller is designed based on hybrid intelligent control according to the characteristics of ship dynamic positioning hybrid intelligent control strategy test. Through experimentalanalysis, the results showed that the response time,rise time and basically requirements can be controlled within the scope of interference with a certain resistance to the external environment.It also has good robustness,low overshoot rate and good control quality and so on.