Research On Ship Dynamic Positioning Capability Analysis System

Dynamic positioning capability analysis is one of the key technologies of the dynamic positioning system.On the one hand,it can evaluate the ability of the ship dynamic positioning system.On the other hand,it can be used as the basis of the design.According to the technical characteristics of ship dynamic positioning system,this thesis studies the key technologies of dynamic positioning capability analysis,including environmental load analysis,thruster system model,thrust allocation optimization strategy and dynamic positioning capability analysis methods.Based on the static analysis method of dynamic positioning capability analysis,the software with independent intellectual property rights is designed and developed.As application examples,dynamic positioning capability of “Tongtu” dredging vessel and YH6020 tug are calculated by use of methods and software mentioned above.The main work of this thesis is as follows:(1)The calculation methods of environmental load are studied and the models are established,including wind load model,current load model and wave load model.Meanwhile,the dynamic positioning thruster system is also studied in this thesis.And two main measures are put forward to improve the thrust utilization of the propeller by discussing the hydrodynamic interaction of ship propeller with the hull,propeller and current.(2)The optimization strategies and methods of thrust allocation are studied,and its mathematical model is also established.At the same time,the SQP and PHR are applied to the thrust allocation optimization problem,and the simulation results verify the feasibility of the two methods.Aiming at the deficiency of SQP and PHR,GA is introduced to get the improved GA-PSO on the basis of the PSO in this thesis.And the improved GA-PSO is also applied to the thrust allocation optimization problem.The simulation shows that compared with SQP and PHR,GA-PSO can keep the thrust allocation reasonable and stable,and reduces system energy consumption.The result also shows that GA-PSO has a better effect on the thrust allocation optimization problem.(3)Aiming at the thrust allocation problem of propeller-rudder pairs,the method that equivalent decomposition is used to deal with the non-convex thrust region of propeller-rudder pairs in this thesis.The simulation shows that this convex method optimizes the thrust allocation problem of propeller-rudder pairs,and verifies the feasibility of the method.Moreover,it is shown that the rudder can make the ship bear more environmental loads and reduce system energy consumption.(4)Based on the above theoretical research that is the key technologies of the dynamic positioning capability analysis,the overall flow chart of the dynamic positioning capability analysis software and each functional module are designed.Besides,based on VS2008 platform,the METI_DPCAP software is developed by using VC++ and MATLAB mixed programming in this thesis.(5)Based on the developed METI_DPCAP software,the engineering application research on dynamic positioning capability analysis is carried out by the “Tongtu” dredging vessel and the YH6020 tug.And it provides a basis for the design of their dynamic positioning system.In addition,compared with analysis results of Kongsberg StartCap v.2.7.2 software,the results show that the analysis results of METI_DPCAP software in this thesis are consistent with the trend,and the error range is small,which verifies the correctness of the dynamic positioning capability analysis method and the practical engineering of the software.