In this paper, a Takagi-Sugeno (T-S) fuzzy model approach combined with a parallel distributed compensation (PDC) scheme is proposed for time-delay control of the response of a tension leg platform (TLP) system subjected to an external wave force. A global PDC-based fuzzy logic controller is constructed by blending all local state feedback controllers. A fuzzy-model-based control is thereby developed which can attenuate the influence of the external wave force. The controller is evaluated in terms of stability analysis, and the linear matrix inequality (LMI) conditions guaranteeing the stability of the TLP system derived via Lyapunov theory. A simulation example is given to show the feasibility of the proposed fuzzy control approach. The example shows the concept of half-circle fuzzy number can be used in fuzzy control and the proposed control method can be employed in practical engineering problems of oceanic structure.

Fuzzy Control for an Oceanic Structure: A Case Study in Time-delay TLP System

The stability of an oceanic structure with T-S fuzzy models

http://www.vliz.be/imisdocs/publications/230280.pdf

Wave run-up on cylindrical and cone shaped foundations for offshore wind turbines

Offshore compliant structures such as guyed platforms, tension leg platforms and articulated towers are economically attractive for deep water conditions because of their reduced structural weight compared to conventional platforms. The foundations of these kinds of structures do not resist lateral environmental loads forces; instead, restoring moments are provided by a large buoyancy force, a set of guylines or a combination of both. These structures have a fundamental frequency well below the ocean wave’s lower frequency-bound. As a result of the relatively large displacements, geometric nonlinearity is an important consideration in the analysis of such a structure. This paper presents a literature review on offshore compliant structures. The review focuses on the static and dynamic response of the structure due to various environmental conditions, such as wind, waves and current. Emphasis is placed on modeling techniques and methods of solution. Many modeling and analysis techniques are common to the aerospace and ocean engineering communities due to the similarities in structural and environmental complexities. For example, aerodynamic loads on offshore platforms are a significant part of any analysis. Also, fluid loading models bear great similarities to mechanistic wind loading models. It is in this vein that a review paper with the focus on offshore structures is included in a journal of aerospace engineering.

J.R. Huston

Papers

Wave interaction with tension leg platforms