Hα Control for Offshore Structures with Persistent Disturbances

This paper investigates the problem of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> control for offshore structures with persistent disturbances. The time delay is introduced into the controller as a positive factor to counteract the persistent disturbances, such as wind and wave loads. Using Lyapunov stability theory and an integral matrix inequality, a new bounded real lemma is derived and, based on this, an H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> controller with input delay for the system is designed. Finally, a numerical example is given to demonstrate effectiveness of the proposed methods