At Euronaval 2024, Naval Group has been showcasing its advancements in Unmanned Underwater Vehicle (UUV) technology, particularly through its SEAGENT product line as well as the UCUV (Unmanned Combat Underwater Vehicle) project. These developments in UUV technology align with France's 2024-2030 Military Programming Law, which prioritizes naval autonomy and underwater combat readiness.

The SEAGENT range encompasses autonomous underwater systems of various sizes and types. The SEAGENT M includes smaller autonomous underwater vehicles, such as reconnaissance UUVs in the form of autonomous torpedoes, which are expected to become increasingly prevalent in naval forces.

For larger underwater autonomous systems, Naval Group offers the SEAGENT XL. This system will be designed around an oceanic drone. To begin with, Naval Group showcased a demonstrator of about 10 m in length. Therefore, the SEAGENT XL is conceived to potentially complement conventional submarines in part of their detection and weaponry missions.

One of the most significant developments presented by Naval Group is the Unmanned Combat Underwater Vehicle (UCUV), showcased at the French Ministry of Defence’s booth. One year ago, Naval Group had been awarded a framework agreement by the French Directorate General of Armaments (DGA) to develop a UCUV demonstrator. This agreement follows a contract awarded in May 2023, for studying the main use cases and system architecture of a UCUV. The project aims to conduct studies and evaluate technologies identified to address naval combat primary use cases, ultimately designing and developing the UCUV demonstrator.

Currently, Naval Group is focusing on developing a version of the ADC (Controlled Decision-making Autonomy) to enhance mission planning, monitoring, and secure surface and underwater navigation. These functions are essential for an enduring and multi-mission autonomous system. Other parts of the challenge are to develop technological components addressing long-endurance challenges, underwater detection, and sub-order implementation. This project places France among the few countries engaged in defining, developing, and evaluating a first XL-UUV (Extra Large Autonomous Underwater Vehicle). It confirms the Ministry of Armed Forces' commitment to leveraging technological breakthroughs and innovation in robotics, drones, and artificial intelligence (AI) to study a new naval capability that could provide an operational response to new conflict spaces and asymmetric combat in the medium term.

Naval Group's XL-UUV Demonstrator, which completed sea qualification in late summer 2023, will be a centrepiece of the UCUV project. It will allow for rapid evaluation of key technologies, such as Controlled Decision-making Autonomy and energy systems, necessary to confirm technical choices related to the future UCUV demonstrator's design.

Thanks to a conversation with Aymeric Moullart de Torcy, Responsible for Unmanned Systems & Cyber Marketing at NAVAL GROUP, FW MAG could better understand the roadmap and challenges in the development of combat AUVs.

Naval Group already possesses sound knowledge of navigation (positioning, course plotting, etc.) and diving (ballast and depth control, trim adjustment, pressure management, etc.) functions onboard submarines and underwater assets in general.

Nonetheless, there are three areas, tackled by the different UUV/AUV projects, that represent the main technology challenges, namely energy, communications, and artificial intelligence (AI) functions.

UUVs face significant energy challenges that limit their operational capabilities. The primary issue is the limited energy storage capacity, which directly impacts mission range and duration. Most UUVs rely on batteries, which, despite advancements, still constrain operational longevity. UUVs must efficiently manage their limited energy resources across various systems, including propulsion, sensors, communication, and mission-specific equipment. The underwater environment presents additional challenges, with pressure, temperature variations, and corrosion affecting battery performance. As these vehicles become more autonomous and incorporate AI, their computing and data processing needs increase, further straining energy resources. The integration of multiple sensors also adds to the overall energy management challenge. Researchers and engineers are actively working on solutions, including more efficient batteries, innovative energy harvesting technologies, and new recharging methods.

As far as communications are concerned, UUVs face significant communications challenges due to the unique properties of the underwater environment. The primary issues stem from the use of acoustic signals, which have extremely limited bandwidth, slow propagation speeds, and rapid attenuation underwater. These factors severely restrict data transmission rates, range, and real-time communication capabilities. Environmental variables like water temperature, salinity, and pressure further complicate signal propagation, making the acoustic channel highly unpredictable. As a result, UUVs are often limited to transmitting only basic telemetry and command data in real-time, with more substantial sensor data typically stored onboard for later retrieval. These limitations drive the need for greater autonomy in UUV operations and pose ongoing challenges for researchers working to improve underwater communication technologies. The constraints on communication also impact energy management and raise security concerns, as acoustic channels are vulnerable to interception and jamming.

Lastly, Naval Group’s approach to AI algorithms for UCUV is quite unique. Functions under development will include a virtual crew of 3 and a hypervisor/virtual machine monitor. In substance, 3 different virtual machines/functions are at study for navigation and control (pilot), operations (sensors and weapons operator), and systems management (technician/maintenance specialist). The hypervisor's role is essential in providing the security and robustness necessary for advanced autonomous underwater operations, especially in situations where direct human intervention is impossible. This approach would enable the AUV to efficiently manage complex systems, adapt to challenges, and maintain reliable operation in the demanding underwater environment.

Given these factors, Aymeric Moullart de Torcy assesses that “it is reasonable to expect that we will see increasingly capable UUVs in the next 5-10 years. However, ‘fully autonomous’ vehicles that can handle any underwater situation with limited human oversight or intervention may take longer, possibly 15-20 years or more”.

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