In this paper the hydrodynamic parameters that characterize the behavior of a typical unmanned underwater vehicle are evaluated. A complete method for identifying these parameters is described. The method is developed to give a brief and accurate estimate of these parameters in all six degrees of freedom using basic properties of the vehicle such as dimensions, mass and shape. The method is based on both empirical and analytical results for typical reference geometries (ellipsoids, cubes, etc.). The method is developed to be applicable for a wide variety of UUV designs as these typically varies substantially. The method is then applied to a small observation class ROV. The results are first verified using an experimental method in which the full scale ROV is towed using a planar motion mechanism. An additional verification is performed with numerical simulations using Computational Fluid Dynamics and a radiation/diffraction program. The method shows promising results for both damping and added mass for the tested case. The translational degrees of freedom are more accurate than the rotational degrees of freedom which are expected as most empirical and analytical data are for translational degrees of freedom. The case study also reveals that the relative difference between the numerical simulations and the experimental results are similar to the relative difference between the proposed method and the experiment.

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This paper presents a finite element model for representing the cable dynamics of a typical ROV(Remotely Operated Vehicle) umbilical. The goal is to produce a model able to capture the most important dynamic effects of the umbilical affecting the ROV by solving the Euler-Bernoulli beam equations using finite element method. The model is general and is applicable to a wide variety of deep-sea ROV systems. The presented model is demonstrated by numerical examples for umbilical and ROV systems, both for steady state and dynamic response. The model is further validated by comparison with published results.

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Increasing autonomy, efficiency and safety for Remotely Operated Vehicles (ROVs) is crucial for future subsea operations and requires accurate models for optimal control, operations and design. This involves precise modeling of the cable in conjunction with the ROV response. This paper presents a novel threedimensional cable model for Remotely Operated Vehicles using Euler-Bernoulli beam theory. The presented model is implemented in Matlab and takes into account the most important effects related to the response of underwater cables and ROVs. Following beam theory bending stiffness is also included, making the model applicable for low tension scenarios. The presented model is modified to allow for compression of the cable. The resulting non-linear equations are discretized spatially by the Galerkin finite element method and solved temporally by the Newmark-β time integration scheme. The model is verified experimentally in ocean tank experiments on a real ROV system. A numerical example is presented and the results are compared to previous published results. Lastly, a sensitivity analysis for the hydrodynamic parameters is presented.