Applying the Bisection Search Method to Search the Maximum Environmental Conditions in DPCap Analysis for Marine Vessels

作者：Xu, Shengwen^*; Wang, Xuefeng; Wang, Lei; Meng, Shuai

来源：International Journal of Offshore and Polar Engineering, 2015, 25(2): 104-111.

DOI：10.17736/ijope.2015.jc641

• DPCap analysis
• bisection search method
• thrust allocation logic
• marine research tool

Dynamic positioning capability (DPCap) analysis can assist in determining the maximum environmental forces that a dynamically positioned (DP) vessel can counteract for given headings. The maximum environmental forces are represented by the maximum wind velocity of the environmental condition, which is generally searched by the incremental search method from 0 to the maximum wind velocity that the vessel cannot counteract if the environmental forces corresponding to the wind velocity increase. Thrust allocation logic is the module by which we check whether the vessel can withstand the aforementioned environmental forces. When the thrust region is nonconvex, the computing effort of the thrust allocation logic generally becomes high. To reduce the computing effort, we employed a bisection search method. Analytically speaking, compared to the incremental search method, the bisection search method can reduce the number of searching steps dramatically. A DPCap analysis for a semisubmersible unit was performed to demonstrate the effectiveness and efficiency of the method. The bisection search method can ensure that the DPCap analysis program performs as a very robust, effective, and efficient marine research tool that gives reliable guidance to the designer of the vessel's dynamic positioning system (DPS). The further utilization of the bisection search method to search the wind gust is also discussed.

• 出版日期2015-6
• 单位上海交通大学