Multibody dynamic formulation and bidirectional interaction analysis of a coupled 6-PUS wave compensation platform-hull system

As offshore personnel and cargo transfer operations extend toward deep-sea regions and high-sea-state environments, six-degree-of-freedom (6-DOF) wave compensation platforms based on parallel mechanisms are developing toward larger scale. When such equipment performs compensatory motions under high sea states, the inertial loads generated by its moving components and payload can act significantly on the vessel, thereby intensifying the dynamic coupling between the hull and the platform. To reveal the coupling mechanism between large-scale wave compensation platform and hull, this paper establishes a dynamic model of a coupled 6-PUS wave compensation platform-hull system within a unified robotics-based multibody dynamics framework. The motions of hull and the platform are selected as generalized coordinates, and a coupled dynamic model capable of characterizing the bidirectional interaction between hull motion and compensation platform motion is derived. Based on this model, a time-domain numerical simulation program independent of commercial multibody dynamics software is developed, and the effects of key parameters on the coupling characteristics are analyzed. The proposed modeling method provides a theoretical basis for analyzing coupling effects between large-scale wave compensation platform and hull.