Dynamics and control of a two-body floating system under realistic environmental loads

In this paper a systematic study of the dynamics of turret FPSO in single and tandem configuration is carried out for further application in the formulation of control strategy of the shuttle vessel. As a preliminary step equilibria are calculated along with their stability properties for a range of values of the main parameters defining each configuration: wind speed, significant height and mean period of waves and relative angles of incidence. The influence of the position of the turret is also assessed. Static solutions are obtained numerically due to the complexity of the mathematical models and then their stability properties are investigated through time-domain simulations. The system displays a variety of different regimes of solutions in which both their number and their stability may change as one or more parameters are varied. The results are summarized in a series of bifurcation diagrams in which the evolution of steady-state heading response of the ships is displayed as a function of parameters characterizing the environmental state. Finally the application of the bifurcation diagram for a control strategy for the shuttle vessel is suggested.