Geometric Controller for both FPWSO and Shuttle Tanker Dynamically Positioned∗

An integrated geometric control for an offloading operation from a FPWSO (Floating, Production, working, Storage and Offloading) to a shuttle tanker is proposed. The floating systems are in tandem configuration connected by a hawser. Both vessels maintain their position and heading by means of their sets of thrusters and propellers. The geometric theory is widely applied to control articulated multibody systems. The use of this theory for non-articulated vessels, with the control of the relative distance, results in a control law that commands both vessels integrally instead of commanding each vessel independently. Hence relative distance can be easily controlled, avoiding both an undesired proximity of the vessels, or excessive hawser tension. The control performance is assessed by means of numerical simulations and compared to a PD-like control with non-integrated controller. Relative distance is maintained very successfully as a result of this approach.