Modeling and controller design of an offshore wind service operation vessel with parallel active motion compensated gangway

Abstract

The parallel active motion compensated gangway of offshore wind service operation vessel (SOV) is an emerging technology to control the large motion during the transfer process of staff and equipment. The low frequency responses of surge, sway, and yaw motion of SOV are controlled by the DP system, and the other corresponding residual motion responses of the SOV are compensated by the active parallel platform. The modeling and controller design is proposed considering the coupled SOV and the active parallel platform in time domain. The Cummins equation is solved to obtain the motion responses of SOV, and the state-space model is used to replace the convolution part through the system identification method for the fast solution of control algorithm, which is verified by the Bode diagram. The lower surface of active parallel platform is fixed on the SOV, and its responses are obtained by filtering and coordinating transformation of SOV motion responses. The length of each electric cylinder is calculated in real-time by the inverse kinematics of active parallel platform to achieve the motion requirements of upper surface, and the limiting significant wave height of the SOV is determined.