Ulyx and DriX join forces for deep-sea exploration

First time cooperative navigation of DriX and Ulyx for Ifremer in sea-trials off the coast of La Ciotat

credits: Exail / Ifremer

In february, Exail had the opportunity to be part of an exciting milestone in autonomous maritime technology. DriX H-8, Exail’s medium range unmanned surface vessel (USV), and Ulyx, Ifremer’s 6000m depth autonomous underwater vehicle (AUV) developed with Exail’s contribution, were operated together for the first time in a collaborative mission for Ifremer, the French National Research Institute for Ocean Science. This operation conducted off the coast of La Ciotat, south of France, showcased both partners state-of-the-art capabilities in autonomous systems and sensor technologies. The Ulyx was deployed from Ifremer’s vessel Europe and DriX was operated remotely from the Exail Remote Operation Center in La Ciotat Shipyard.

credits: Exail / Ifremer

Testing Sams for high-resolution seabed mapping

Ifremer’s goal of the sea-trials was to test and qualify several advanced technologies. One of the key objectives was to validate the functional integration and operational performances of the Sams 150—Exail’s Synthetic Aperture Mapping Sonar, in various survey scenarios on Ulyx AUV. The Sams 150 provides exceptional imaging capabilities, allowing for detailed seabed mapping and detection of underwater objects. It combines the operability of traditional sidescan sonar with the enhanced capabilities of synthetic aperture sonar (SAS) technology. Its tight integration with Exail’s Phins inertial navigation system (INS) on the AUV and other positioning systems ensures superior motion compensation and can deliver centimetric georeferenced images by design.

The characteristics of the Sams-150 perfectly align with Ulyx’s mission objectives. The vehicle is designed to conduct seabed surveys across an extensive range of scales. It begins with large-coverage MBES profiles at metric resolution, followed by high-resolution imaging using the Sams 150, even in rough topography conditions. Finally, it can perform photogrammetric optical mapping while hovering close to the seafloor.

Ifremer in collaboration with Exail’s sonar teams has developed and implemented adapted strategies to different diving scenarios in order to obtain the best system performance from 30 to 70m altitude.

The result of the Sams-150 trials confirms consistent, high-resolution sonar imagery down to 5 cm from 50m height above sea-floor, surpassing conventional survey methods in efficiency, coverage and data integrity.

credits: Exail / Ifremer

A second objective for Ifremer’s team was to conduct a series of tests to evaluate cooperative operation of Ulyx and Drix. The aim is to use Drix as a surface relay, ensuring acoustic positioning and communication with the AUV while bridging the space to the mother vessel by Drix’s Sat comm and CortiX* software interfaces. For Ifremer, the capability to monitor and position the AUV independently of vessel operations is a potential game-changer for high-profile deep-sea AUV missions.

Drix being specifically designed for optimized operation of hydro-acoustic equipment, the positioning performances using Exail's Gaps were proven to be significantly improved: in test conditions down to 2,300 m depth flawless positioning from Drix was achieved while positioning from L’Europe experienced loss of signal beyond 1300m. The hydrodynamic hull design of Drix, combined with the installation of equipment in the gondola, 2m below the surface, creates a very low noise environment enhancing performance of the acoustic equipment.

Acoustic monitoring of the AUV include data transfer capabilities between the AUV and Drix, using a “Micromodem” designed and manufactured by Woods Hole Oceanographic Institution (WHOI). The tests aimed to assess how effectively two autonomous platforms can exchange critical information, and implement a relay to the mothership by ensuring that the systems cooperate harmoniously during complex missions. Based on the same principle of very low noise platform, the results were promising, all tested scenarios being validated. 

credits: Exail / Ifremer

A milestone in autonomous multi-system exploration

“We are thrilled to witness DriX and Ulyx collaborating for the first time. This partnership with Ifremer underscores Exail's dedication to advancing autonomous systems and sensor technologies, providing unmatched capabilities for complex marine operations.”, says Olivier Moisan, DriX Operations Manager. Beyond developing platforms, we are also creating autonomous collaborative behaviors through software like CortiX. “

This collaborative operation between DriX and Ulyx is an exciting milestone. If DriX has already been used with several other AUV and underwater robots, it was the first time the two platforms worked together, showcasing how their unique capabilities complement each other. For Ifremer, the demonstration of monitoring Ulyx’s complex multi-functional dives in depths down to 6,000m, with minimal constraints on ship operations, is a significant step towards multi-system exploration using AUV, ROV and USV in a comprehensive scheme optimizing operation efficiency. The ability to combine a highly versatile USV with an AUV opens up numerous possibilities for future missions, particularly in, environmental monitoring, and deep-sea exploration or inspection.

credits: Exail / Ifremer