Grid-Based Set Point Generation Strategy for Position Control of Dynamic Positioning Assisted Mooring System

Unlike typical a dynamic positioning (DP) system, a DP-assisted mooring system must determine a set point (SP) that can ensure a mooring tension safety range to prevent an excessive increase in mooring tension. In this paper, a new algorithm for determining the SP is suggested in order to reduce the tension on all the mooring lines. To determine the SP, a working area around the vessel is represented by a rectangular grid. Thus, the size of the grid area is limited considering the offset of a vessel with a mooring system. At each grid’s nodes, the resultant tension from all the mooring lines is estimated using the time history of the tension and vessel’s position. The results of static analyses for each grid position are used to estimate the global tension. Consequently, the SP is automatically selected as a position satisfying criterion for minimizing the total tension. In order to validate the suggested algorithm, a motion simulation with the control system in the time domain and a discussion of the results are presented. Received 1 January 2019, revised 19 February 2019, accepted 22 February 2019 Corresponding author Seung Jae Lee: +82-51-410-4309, slee@kmou.ac.kr ORCID: https://orcid.org/0000-0001-8992-6915 It is noted that this paper is revised edition based on proceedings of Fall Conference of KSOE 2018 in Incheon. c 2019, The Korean Society of Ocean Engineers This is an open access article distributed under the terms of the creative commons attribution non-commercial license (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.