Navigation and control of the Nereus hybrid underwater vehicle for global ocean science to 10,903 m depth: Preliminary results

TLDR

Nereus can operate at depths exceeding 10,903 m, far surpassing the 7,000 m limit of the next deepest operational vehicle, enabling scientific observation and sampling at the ocean’s full depth. The study presents an overview of the navigation and control system design for the Nereus hybrid underwater robotic vehicle, aiming to make the entire seafloor accessible to oceanographic science. Nereus combines an untethered autonomous underwater vehicle mode for wide‑area sonar and camera surveys with a convertible tethered remotely operated vehicle configuration that uses a lightweight fiber‑optic tether, an electro‑hydraulic manipulator arm, and sampling instruments for close‑up imaging and collection. During sea trials in 2007 and 2009, including the Challenger Deep expedition, Nereus successfully performed scientific observation and sampling at depths over 10,903 m, demonstrating its operational capability.

Abstract

This paper reports an overview of the navigation and control system design for the new Nereus hybrid underwater robotic vehicle (HROV). Vehicle performance during its first sea trials in November 2007 near Hawaii, and in May and June 2009 in the Challenger Deep of the Mariana Trench is reported. During the latter expedition, the vehicle successfully performed scientific observation and sampling operations at depths exceeding 10,903 m. The Nereus underwater vehicle is designed to perform scientific survey and sampling to the full depth of the ocean - significantly deeper than the depth capability of all other present-day operational vehicles. For comparison, the second deepest underwater vehicle currently operational worldwide can dive to 7,000 m maximum depth. Nereus operates in two different modes. For broad-area survey, the vehicle can operate untethered as an autonomous underwater vehicle (AUV) capable of exploring and mapping the sea floor with sonars and cameras. Nereus can be converted at sea to become a tethered remotely operated vehicle (ROV) to enable close-up imaging and sampling. The ROV configuration incorporates a lightweight fiber-optic tether (for high-bandwidth, real-time video and data telemetry to the surface), an electro-hydraulic manipulator arm, and sampling instruments. The Nereus vehicle is designed to render all parts of the Earth's seafloor accessible to oceanographic science.