Research On Relative Dynamic Positioning Between Shutter Tanker And FPOS

In FPSO (Floating Production Shortage and Offloading) system, the shuttle tankerundertakes the task of unloading crude oil from FPSO and transporting it to the land. Duringthe uninstalling process, tanker has to stay close to the FPSO and keep a proper relativeposition. It is because the complexity of the sea environment that the tanker faces unknownand risk during the process. Ship dynamic positioning technology could keep a ship at acertain area preciously. The use of this technology in the shuttle tanker could provide strongguarantee technically during the unloading process thus the unloading process could be saferand more effective. The main contents of this paper are as follows:First, mathematical model of a shuttle tanker and FPSO are built for simulation, mainlyincluding the kinematics and dynamics. FPSO is bound by the mooring system. It movescontinually within a certain area under the influence of marine environmental forces, so finiteelement analysis is used for mooring lines. The mathematical model of the FPSO of turretmooring mode is built. Mathematical model of marine environment of the wind, waves andflow is built for simulation. Finally, the Matlab simulation software is used for the simulationof the models of shuttle tanker and FPSO that have been built.Secondly, the knowledge of fuzzy control, immune system mechanism and grayprediction are introduced. Fuzzy immune controller of dynamic positioning system isdesigned according to the principles of the fuzzy control and the immune system. Finally, theprinciple of gray prediction is introduced, a gray prediction model is built used for forecasterror trend between current position or heading of the tanker and set position of shuttle tanker,thus to determine advance control input of shuttle tanker dynamic positioning controller.Controller could be achieved the control tasks in time and self-adaptive ability is improved.Finally, unloading process is analyzed in detail. A control strategy is designed to reduceenergy consumption and improve economic benefits of the shuttle tanker dynamic positioningsystem. In order to validate the performance of the shuttle tanker controller under the controlstrategy, we design simulation test using Matlab simulation software. From the result ofsimulation, we can see the control strategy and controller of dynamic positioning system ofshuttle tanker can reach the target of unloading crude oil from FPSO.The main work of this paper is the establishment of mathematical model of shuttle tankerand FPSO for simulation. Mathematical model of marine environment of the wind, waves andflow is also built for simulation. Base on the Mathematical built above, the design of dynamic Positioning controller of shuttle tanker as well as control strategy during the process offollowing FPSO are designed too. Finally, simulation experiment is done about the abovedesign content.