Dynamic modelling of a streamer of hydrophones towed with an autonomous underwater vehicle

Abstract

The paper addresses the dynamic modelling of an Autonomous Underwater Vehicle (AUV) towing a flexible cable. The considered problem arises in the framework of a H2020 European Project, named WiMUST, aimed at using a team of AUVs to perform geoseismic survey missions to study the sea-bottom and sea subsurface thorough acoustic signals. In the considered scenario, each AUV is equipped with a streamer, i.e. a flexible cable equipped with several hydrophones. For a proper elaboration of the acoustic data collected by the hydrophones, their positioning during the mission is required; however the lack of a proper hydrophones’ localization infrastructure in the WiMUST system make this not possible. Thus, we developed here the dynamic model of the AUV-streamer system with the final aim of using it in a localization algorithm. The dynamic model has been developed on the basis of the characteristics of a torpedo-shaped AUV, named Folaga, and assuming the streamer behaving as a chain of almost neutrally buoyant rigid bodies connected with unactuated spherical joints. The recursive Newton-Euler approach for industrial manipulators is adopted to develop the direct dynamic function to deal with scalability issues related to the large number of Degrees of Freedom of the system. Different simulation results are finally supplied for the model validation.