An un-tethered ROV for routine access and intervention in the deep sea

Abstract

Certain enabling technologies coupled with recent advances in robotic systems make it possible to consider supplementing many of the functions performed by vehicles with appropriately designed semi-autonomous systems. These systems are effectively a hybrid cross between ROV and AUV systems and poised to enable an important new class of undersea vehicle capable of intervention tasks under direct human control. It is now possible to radically redefine the meaning of the words “tethered vehicle” to include virtual tethering via acoustic and optical means or through the use of an extremely small optical fiber, providing not power but only high bandwidth communications. Battery-powered, hybrid-tethered vehicles will be able to perform a range of tasks that might otherwise require a conventional ROV. These functions will be performed at much lower cost by requiring less complex ships because of a greatly reduced dependence on complex, large, specialized tether and vehicle handling equipment, and a reduced need for dynamic positioning capability. Several key emerging technologies and capabilities make such a vehicle possible. Advances in both acoustic and optical “wireless” underwater communications and mico-tethers as pioneered by the HROV Nereus offer the potential to transform ROV type operations. By utilizing multiband acoustics and WHOI's newly developed through-water optical transceivers, variable bandwidth communications are possible. In late 2012, Nereus was interfaced to a specially configured acoustic and optical communications system and a series of field demonstrations conducted offshore, including highly interactive and complex manipulations, demonstrating what we term as the Nereid Technology.