Research On Parameter Identification Method Of Mathematical Model Of Dynamic Positioning Vessel

With the rapid development of economic and the gradual depletion of land resources, theproblem of energy and resource becomes more and more sharp. People gradually turn toexplore the vast ocean resources. But the ocean environment is complex and changeable.Without the advanced technology and equipment to support the ship, marine development isincapable of action. So many offshore ships are equipped with special ship motion controlsystem, a dynamic positioning ship is one of a kind. Dynamic positioning vessel is a shipwhich only depend on its own propulsion system automatically for keeping the position andheading(fixed position or intended track)of the ship. Hydrodynamic is the force which ship byin the water. Hydrodynamic coefficient is the value that the partial derivatives of shipmovement parameters in the start point. Hydrodynamic coefficient is the basis forestablishment the ship motion equation. Hydrodynamic coefficient is very important forsimulation ship maneuvering motion and prediction manipulation performance by the shipmaneuvering motion equation. Therefore, Hydrodynamic coefficients must be precise for agood simulation performance by ship model.A dynamic positioning vessel was chosen as the research object of this paper.Hydrodynamic coefficients of the dynamic positioning vessel is analyzed and identified.Some research works has been made as follows:Firstly, this paper derives the general ship motion mathematical model. In order toestablish a dynamic positioning ship motion mathematical model, the forces which thedynamic positioning ship by are analyzed, and study the motion of the dynamic positioning,based on the dynamic positioning vessel motion characteristics, the motion model of dynamicpositioning vessel and the model of environmental interference force(wind, wave and oceancurrent etc) are established and educed. Then, the hydrodynamic coefficients andhydrodynamics are analyzed. And the dynamic positioning ship motion mathematical modeland environmental disturbance model was verified by simulation.Secondly, this paper introduced nonlinear estimation filter of the dynamic positioningvessel, and through the nonlinear estimation filter of dynamic positioning vessel estimated themotion parameters and the environmental disturbance force, providing data for lateridentification. Besides, the stability of nonlinear estimation filter was proved throughLyapunov stability theorem.Lastly, some parameter identification methods have been studied. Analyzing the basicprinciples and the characteristics of least square method and genetic algorithms, it has been considered that the selections of crossover probability and mutation probability are veryimportant to algorithm. A method was proposed which combined with the least squaresmethod and adaptive genetic algorithm. The method which is proposed in this paper is appliedfor identification the inertia matrix and linear hydrodynamic damping matrix of dynamicpositioning vessel model. The method has good robustness and global search capability.Through the analysis of identification results, this parameter identification method which wasused to identify the inertia matrix and linear hydrodynamic damping matrix of dynamicpositioning vessel model was proven to be effective and feasible.