Attitude control of payload subject to wave interaction for offshore lifting/lowering with openfoam

Yan, M, Ma, X, Li, Y and Bai, W ORCID: https://orcid.org/0000-0002-3537-207X (2020) Attitude control of payload subject to wave interaction for offshore lifting/lowering with openfoam. In: The 30th International Ocean and Polar Engineering Conference, 11 October 2020 - 16 October 2020, Virtual.

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Abstract

© 2020 by the International Society of Offshore and Polar Engineers (ISOPE). The purpose of present paper is to evaluate how the forces and moments acting on the cylinder or the cuboid payload change with the relative postures between the wave incident direction and the offshore crane payload, and to develop a PID controller for the payload to hold its posture in the presence of external wave forces. Aiming at this purpose, numerical results of regular wave interaction with a vertically suspending cylinder are presented first to validate the NWT model, and then a series of simulation experiments which offer results of the forces and the moments exerted by the regular waves on one fixed suspending cylinder and cuboid payload with different postures. With some certain posture, the suspending cylinder and cuboid payload suffer the minimal forces and moments. After that, the PID controller is raised and applied on a free heave decay cylinder for validation. Lastly, the same PID controller is applied on the cuboid payload subjected to wave forces. The results show the controller works well in keeping the payload with a certain posture. All of the present works provide the fundamentals for further research on safe control of offshore lifting or lowering.