Mathematical Models for Model-Based Control in Offshore Pipelay Operations

Abstract

This paper considers mathematical models for model-based controller design in offshore pipelay operations. Three classes of models for control design are discussed, real-world models suitable for controller design verification, controller and observer models which are used on-line in the control system implementation. The control application place requirements on the model with respect to the computational time, dynamic behavior, stability and accuracy. Models such as the beam model, two catenary models, as well as general finite element (FE) models obtained from computer programs were not able to meet all of the requirements, and two recent dynamic models designed for control are presented, which bridge the gap between the simple analytical and more complex FE models. For completeness, modeling of the pipelay vessel, stinger and roller interaction, soil and seabed interaction and environmental loads are discussed.

Offshore Pipelay Operations From a Control Perspective

“…For implementation in a computer, the continuous model must be discretized, e.g., by the finite element method. Details on mathematical pipe models are beyond the scope of this paper, and the reader is encouraged to consult [24] and the references therein.…”

“…However, simpler models such as the robot-equation-based model presented in [38] are better suited for model-based feedback control in real-time. In the accompanying paper [24], mathematical models used for pipelay design and simulation are considered for control applications.…”

The Model Test of Deep Water S-Lay Stinger Using Dynamical Substructure Method

“…However, in the actual pipelaying process, both the pipeline and stinger struc ture are in a marine environment and are dragged by a dynamic floating body. The stinger's performance as a deformable body under the dynamic excitation was difficult to predict, and although ' a number of research studies [14][15][16] have analyzed pipeline stress dynamically, but few works considered the stiffness of the stinger in this case [17,18], This oversight is primarily attributable to the strong nonlinear issues between the stinger and the pipeline. During the laying of large diameter pipelines in ultra deep water, the overbend section of the pipeline material enters a nonlinear stage.…”

A Comparative Analysis of Energy Consumption by Conventional and Anchor Based Dynamic Positioning of Ship

“…The rapid development of the world economy has created a demand for various types of vessels in the offshore sector, such as: oil-seeking vessels [7,8], rescue vessels [9], pipeline laying vessels [10][11][12], oil rig service vessels [13], ships for servicing offshore wind farms [13], or floating hotel ships for crews working on platforms or offshore wind farms [14,15]. These types of vessels are usually equipped with a dynamic positioning system and a set of powerful thrusters.…”