The motions of the vessel and the offshore platform topsides are quite complex during lifting operations by the dynamic positioning (DP) crane vessel. To ensure the safety of the operation, it is necessary to maintain the stability of the topside movement to avoid collisions between the crane vessel and the topside. This paper numerically and experimentally investigates the coupling motions of the crane vessel HYSY201 and 3000-ton topside. The in-house code is developed to investigate the 9 DOF motion of the vessel and the 3 DOF motion of the topside. In the numerical simulation, the fuzzy method and the PID algorithm are combined to develop the fuzzy PID controller, and the genetic algorithm is applied to solve the thrust distribution problem. The dedicated experiments of the DP lifting operation are carried out at Tianjin University. Comparisons between the experimental results and the numerical results are carried out. The numerical results are agreed well with the experimental results, demonstrating the stability and feasibility of the dynamic positioning control system and the accuracy of the coupling motion solution. The dynamic response of DP crane and topsides, as well as the thrust distribution under different environmental conditions are discussed.
With the development of marine resources exploration, the traditional mooring system is hard to satisfy the safety of the operation in the deep sea. The crane vessel with the dynamic positioning system is unrestricted by the water depth and can guarantee the stability of lifting topsides, which greatly improves operational efficiency. It is of great significance to understand the crane-topside coupling response characteristics of the lifting operations by the DP crane.
Numerous studies have analyzed the coupling motion response of the crane vessel and topsides. Huang et al. (2018) deduced the 6 DOF motion equations of the rectangular topsides and the lifting cable dynamic tension based on the second Lagrange equation. Luo et al. (2020) developed a coupling motion model of mooring-crane vessel-rigging-large topsides and conducted numerical simulations to analyze the motion response characteristics of the lifting topsides under different waves. Luo et al. (2021) experimentally investigated the dynamic response of the crane vessel under mooring positioning to analyze the effects of different lifting heights on the crane vessel and the motion response characteristics of the topside under surging waves. Firdaus et al. (2022) investigated the coupling motion responses of a floating crane barge and a lifted module during lifting operation based on the time domain by physical model tests. Makarov and Harada (2023) performed numerical studies of the wave-induced motions of a crane vessel with a hanging load and tested the linear and nonlinear methods for determining the wave excitation force and restoring force.
