Oceanographic Surveys with a 50 hour Endurance Autonomous Underwater Vehicle
Authors: Griffiths G. , Birch K.G. , Millard N.W. , McPhail S.D. , Stevenson P. , Pebody M. , Perrett J.R. , Webb A.T. , Squires M. , Harris A. 
Published: October 2008

Autonomous Underwater Vehicles (AUVs) are becoming accepted data-gathering tools within the marine science community in Europe, the US and elsewhere. Technology can now provide vehicles with a useful range and depth envelope. For example, the Southampton Oceanography Centre's Autosub-1 vehicle has already covered 263 km in a single oceanographic survey mission, reaching depths of 500 m off Bermuda in September 1998. The challenge now is to 'free the technology from the research community. Potential direct and indirect benefits from the offshore energy industry's use of AUVs have been quantified. For one company, the benefits of using survey class AUVs has been estimated at $60m over 5 years. The economics become more attractive as the industry moves to deeper water. While today's AUVs of long endurance are limited in depth, developments on the horizon in composite materials and high capacity, lightweight secondary batteries will enable 1000 km range, eight-day endurance and at least 1600 m diving depth to be in active service within the next two years.

This paper will review the oceanographic survey achievements of the Autosub AUV over its 216 missions (to December 1999), working in UK, US and Bermudan waters. Moving to the future, the paper will illustrate how such an AUV could be used in the offshore industry for survey, monitoring and emergency response. Finally, we will describe the present Autosub development programme, scheduled to deliver an operational 1000 km, 1600 m vehicle by mid 2000.

Introduction

The Autosub AUV was conceived as a survey vehicle to complement research ship programs by the provision of a cost effective tool to collect water column and seafloor information. Included within the design brief was the aim to address the widest possible scientific community hence allowing varied missions and payloads. This requirement ensured that flexibility was fundamental to the technology design. Hence for Autosub-1 there was no fixed sensor suite, the vehicle sub-systems were modular and thus offered a simple upgrade path as new technologies became available. One other by-product which is envisaged but not yet proven is the opportunity to change the vehicle characteristics i.e. size and shape, without a major re-design program. (Fig 1)

The first vehicle, Autosub -1 was constructed in 8 months, being completed in May 1996. The short production cycle was only possible because of the extensive development programme which had been underway for the previous 5 years.

The first phase saw Autosub-1 progress from its first 'in water' missions in Empress Dock, Southampton, (June 1996) to completion of the acceptance trials in just under one year (April 1997)

Oban 97

The Autosub performance and acceptance trial criteria have been described by Millard et al (1), the main objectives were:Profiling autonomously from close to the surface to near the seabed in at least 100m of water;Mission lengths of at least 6 hours, with satellite fixes updating the dead reckoning(DR) vehicle navigation; andCollection of meaningful scientific data.