Positioning of small-waterplane-area marine constructions with roll and pitch damping

摘要

In dynamic positioning systems for floating marine constructions a three-degrees-of-freedom multivariable controller, with feedback from the horizontal-plane positions and velocities in surge, sway and yaw, has been regarded as adequate for the control objective. However, for certain marine constructions with discernible coupling characteristics in the dynamics and kinematics between the horizontal-plane and the vertical-plane, undesirably large roll and pitch oscillations may be induced by the thruster actions applying the conventional horizontal-plane control strategy. In this paper a new multivariable control law accounting for both horizontal and vertical motions is proposed. It is shown that significant roll-pitch damping can be achieved. Moreover, the positioning performance in surge, sway and yaw is also improved because of suppressed roll-and pitch-induced horizontal-plane motions.