Abstract
Offshore platforms and windmills are constructed by assembling huge mechanical structures transported by heavy lift vessels. The construction process comprises two interconnected operations, the dynamic positioning (DP) of the vessel and the lifting of heavy loads. The DP system is commonly designed and tuned for the case that there is no load or for the case that the heavy load is free-hanging (mode 1). During the transition from the free-hanging to the case that the vessel is connected to a heavy load which is mounted to the platform (mode 2), the DP system may not be able to preserve the position stability of the vessel, jeopardizing human and system safety. The goal of this work is to design an intelligent monitoring system for the early detection of the transition between the two construction modes by adopting a nonlinear state estimation approach. Simulation results are used for illustrating the effectiveness of the proposed construction mode detection system.
Highlights
The vision of waterborne transport includes autonomous shipping operations aiming at enhancing their sustainability, efficiency and safety
During the transition from the freehanging to the case that the vessel is connected to a heavy load which is mounted to the platform, the dynamic positioning (DP) system may not be able to preserve the position stability of the vessel, jeopardizing human and system safety
Where l is the position of the load in NorthEast-Down coordinate system (NED); Ml 3×3 is the mass matrix of the load; Dl 3×3 is the damping matrix of the load; gl = [0, 0, Ml g]T is the mass gravity of the load, in which Ml is the mass of the load; and R3 3×3 is the rotation matrix from Body-fixed coordinate system (BODY) to NED in 3 DoFs
Summary
The vision of waterborne transport includes autonomous shipping operations aiming at enhancing their sustainability, efficiency and safety. The use of a digital monitoring system to detect the construction mode would assist the operators with decision making, and increase reliability during construction under hazardous environ ment Such system can improve safety of offshore heavy lifting, de crease the risk level of such operations during hazardous environment, and paves the way for higher level of autonomy with less manned op eration on board. The impact of using the proposed monitoring system in offshore heavy lift operations is twofold It can increase the level of au tonomy by replacing human decision about the switching of the con struction mode with the automatic decision of a digital system. The proposed method can assist the DP system and crane con troller on board, and can improve the performance of the DP system with fast detection of mode switch, leading to a safer and more stable vessel position during offshore heavy lift.
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