Optimal Identification of Potential-Radiation Hydrodynamics for Moored Floating Structures - A New General Approach in State Space

Abstract

In this paper, a new state-space model of the potential-radiation hydrodynamics in moored ocean engineering floating structures and its parameter identification are presented. The raw data for this goal are the added mass and potential-damping matrices in frequency discrete domain. In a preliminary study of existing approaches in the literature, two mathematical models and their estimation are comparatively analysed in detail. These served in the development of the new approach that shares certain main advantages of the previous approaches. The model is identified in a least-squares sense using a weighted norm and a free control parameter to accomplish a trade-off between quality and stability. This reduces numerical instability problems and also keeps the analytical and computational benefits of a para- metric state-space model. The model can be conveniently expressed in any usual canonical form in state space. The application of the model acceptably accurate reproduces the behaviour of the poten- tial-radiation hydrodynamic forces in time. Case studies involving a semisubmersible and buoys are shown to demonstrate the features of the proposed approach.