Numerical Motion Analysis of ROV Applying ANCF to Tether Cable Considering Its Mechanical Property

Suzuki, Hiroyuki (Osaka University) | Tomobe, Hiroto (Osaka University) | Kuwano, Asako (Osaka University) | Htun, Thant Zin (Osaka University) | Inoue, Tomoya (Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

OnePetro 

ABSTRACT

We have been developing an accurate numerical motion simulator for remotely operated vehicles (ROVs) with tether cable. This simulator is constructed using computational fluid dynamics (CFD) based motion simulation for the ROV and absolute nodal coordinate formulation (ANCF) for the tether cable. Previously, we considered the peculiar winding of the tether cable. However, some mechanical properties of the tether cable and correct boundary condition on the ROV have not been studied yet. This study aims to investigate the mechanical properties of tether cables and some results of the motion simulation considering the anisotropy of the tether cable, and boundary condition of the cable on the ROV body are reported.

INTRODUCTION

Recently, many autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) have been developed and operated for the purpose of ocean resource development and marine-organism research, among others.

Among such underwater vehicles, ROVs equipped with a video camera are operated to observe the surrounding environment and to collect resources and/or organism samples using a manipulator. Therefore, the ROV operator must be trained by advanced operating techniques. Additionally, a precise motion analysis method is needed to construct an accurate motion simulator. Many numerical motion simulations of ROV and tether cable have been carried out, but most of them have used lumped-mass method for the motion expression of the tether cable (for example, Yamaguchi et.al. 2017). The characteristics of the tether cable, however, are not expressed precisely in these simulations.

Therefore, development of a precise motion analysis method of an ROV with a tether cable has been started at Osaka University. The method consists of two parts: first is the motion analysis of the ROV based on a six degrees of freedom (6 DOF) motion equation with the hydrodynamic coefficients derived from the result of computational fluid dynamics (CFD) (Ohbiki, 2014), and second is the motion simulation of the tether cable by applying the absolute nodal coordinate formulation (ANCF) (Shabana, et.al. 1999).