Nonlinear passive weather optimal positioning control (WOPC) system for ships and rigs: experimental results

Nonlinear weather optimal control of ships exposed to environmental disturbances is discussed. Emphasis is placed on weather vaning, that is the ship should be orientated such that the moment in yaw due to mean current, wind and wave forces is zero and at the same time maintain a "xed position and heading. The main problem in doing this is that the environmental forces acting on the ship are impossible to measure with su$cient accuracy. A new concept for weather optimal position control (WOPC) based on nonlinear control theory is invented and presented for the "rst time in this paper. Experiments with a model ship are used to document the performance of the controller. The proposed controller and the concept of WOPC were patented by the authors in cooperation with ABB Industri AS, Oslo in December 1998 under patent no. NO308.334. 2001 Elsevier Science Ltd. All rights reserved.