Determination of Hydrodynamic Parameters for Remotely Operated Vehicles

Abstract

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.

Development of a Simulation Platform for Underwater Transportation using Two Hovering Autonomous Underwater Vehicles

“…Moreover, assumptions are made while calculating the hydrodynamic parameters using the empirical data. For instance, DNV standards are used which assumes that the vehicle has 3 planes of symmetry and two of the three sides are equal in dimension or the difference is up to 10% [10]. These assumptions bring about uncertainties in the dynamic model.…”

“…Therefore, nonlinear damping terms are dominant. Only the 2 nd order nonlinear damping terms are considered because it is difficult to calculate the higher order terms and are also less significant [10].…”

Time Domain Modeling of ROV Umbilical using Beam Equations

“…(12) are estimated using the empirical method proposed by Eidsvik et. al (Eidsvik and Schjølberg, 2016). The ROV is assumed to operate in low speeds and has three plane symmetry.…”

“…For UUVs the hydrodynamic properties are of paramount importance. The hydrodynamic properties greatly affect the performance and maneuverability of the vehicles and knowledge of these properties are therefore important in design and operation (Eidsvik and Schjølberg, 2016). AUVs typically do not have an umbilical cable, this combined with a much simpler geometry greatly simplifies the problem of identifying the vehicle properties.…”

Hydrodynamic calculation and analysis of a complex-shaped underwater robot based on computational fluid dynamics and prototype test

“…7 The empirical formula method simplifies the robot as a combination of various geometries. It is effective in solving the hydrodynamic force on a robot with a simple structure, 8,9 but the calculated result is imprecise for a robot of complex structure, so this method is seldom used.…”