Development and Experience of a Practical, Pressure-Tolerant, Lithium Battery for Underwater Use
For a number of years, lithium-ion batteries have promised energy and power densities that make them an attractive alternative to the silver-zinc batteries historically used in underwater vehicles. For AUV (Autonomous Underwater Vehicle) application, polymer-electrolyte cells offer the promise of pressure tolerance; this key attribute impacts vehicle design and operational logistics in a number of ways. Primarily, it facilitates the design of arbitrarily large battery packs by obviating many of the problems associated with large, heavy and expensive pressure vessels that would have been otherwise required to house batteries at depth. This allows a single AUV operator to recover the vehicle and remove and replace the batteries in minutes without the down time associated with servicing o-rings and seals. In a military context, this new operational paradigm has made back to back search and classify missions a practical reality. As with all new technologies there is a hiatus between availability, practical implementation and adoption. Many fundamental, logistical and practical engineering problems in design and manufacture have been solved in the past 5 years leading to a range of commercially available batteries with power densities exceeding 100Wh per neutrally buoyant Kg. This paper will explore these challenges, examining specific solutions derived from experience gained through the pressure testing of over 20,000 cells
Autosub6000: results of its engineering trials and first science missions
In September 2007 on RRS Discovery, the Autosub6000 Autonomous Underwater Vehicle (AUV)
completed its first deep water engineering trials, and less than a year later, fitted with a multibeam
bathymetric mapping sonar, carried out its first science missions, as part of a geology and
geophysics science cruise onboard the RRS James Cook to investigate potential geo-hazards
(such as tsunami generating landslides) on the European and North African margin. In the spirit of
true AUV autonomy, while the AUV was deployed, we used the ship for seabed coring operations,
and once the AUV was recovered, the high resolution bathymetry which it had obtained guided
the next coring operations. In this paper we will describe how we are tackling the issues that
specifically affect a deep diving AUV capable of operating with true autonomy, and independently
of the mother ship: How to carry enough energy for long endurance and range? How to operate
safely and efficiently with varying buoyancy? How to maintain accurate navigation throughout
missions lasting up to several days?
Cooperative Collection Development
The author discusses cooperative collection development from an historical perspective and examines some of the projects conceived and implemented during the past forty years. In many cases the projects failed even after years of concentrated effort. However, more important than these failures are new efforts that are being made. The major focus of this article is on both current regional projects and the more broadly based ARL-sponsored North American Collections Inventory Project. The author discusses these efforts and offers some specific judgments regarding the possibility that these projects will lead to a truly successful coordinated collection development project on a national basis.