Several new classes of unmanned vehicles will arrive at the unmanned undersea vehicle (UUV) homeport in Keyport, Wash., in late fiscal year (FY) 2020. With construction of the Orca-class Extra Large UUV (XLUUV) just commencing, a significant new capability is on the cusp of being delivered. At over 85 feet in length and 140,000 pounds, the XLUUV is intended to be pier-launched forward and complete its mission autonomously with little to no external communications or human interactions. Similarly, the Snakehead Large Diameter UUV (LDUUV) will complete design this year, allowing for autonomous operations from a host submarine’s dry-deck shelter.
Requirements for the next-generation medium-sized vehicle (Razorback) are currently being drafted, however this vehicle is intended to reduce diver operations by being launched and recovered via torpedo tube. As both Snakehead and Razorback are launched from submarine platforms, these vehicles are intended to reduce the burden on manned platforms by performing many of the lower-end, time-consuming tasks best suited for the unmanned platforms.
As innovative and impressive as these unmanned vehicles (UxVs) are, each is enabled by the advancements in emerging “core” technology areas such as autonomy, communications, and precision navigation. Equally important to future missions are integration of new payloads and increasing the endurance of the vehicles.
Recognizing the need to invest in these technology areas, the Navy started the “Core Technology Portfolio” in FY 2018 managed by the Unmanned Maritime Systems Program Office (PMS 406). This portfolio has three purposes: transition maturing technologies into the entire UUV family of systems; enable learning through fleet experimentation and industry engagement or demonstration; and drive standardization across UxVs.
Standardization efforts such as common autonomy architectures, common command and control, and common payload interfaces were the initial efforts to drive down costs, encourage commonality, and ensure re-use.
Common Autonomy Architectures: A barrier to rapidly fielding improvements has been that each UxV platform uses different autonomy architectures. Advancements made using one architecture required changes in order to be compatible with another, often proprietary design. Starting in 2018, a team of experts was tasked with developing the Unmanned Maritime Autonomy Architecture (UMAA). This standard focused on opening up autonomy interfaces for all UxVs, making them non-proprietary. The UMAA is still in its infancy. However, as these standards mature and more platforms use them, they will allow the Navy to rapidly advance autonomy across all platforms that share this architecture. This first UUV contract to use these architectures will be the Razorback, followed by LDUUV platforms.
Common Control System (CCS): Today’s unmanned platforms are controlled from many different consoles, increasing the number of operators, amount of training time, and physical space in operations centers. Starting next year, the Navy will require new programs to use the CCS software capable of controlling air, ground, and maritime unmanned vehicles from a single, common controller. This change will enable commonality on submarines, ships, and operations centers. As CCS is an air-centric software suite managed by Naval Air Systems Command, FY 2019 the Navy will focus on getting the maritime requirements, funding and a roadmap in place to enable seamless transition for future maritime programs.
Payload Integration Group (PIG): Chartered with standardizing payload interfaces for each vehicle class, the long-term vision is to make payloads “plug and play” based on the mission being performed without the need to return to a vendor for support. To accomplish this, the group is tasked with standardizing the payload interfaces for the medium UUV that will go out to industry next year.
Energy and Endurance: The Navy is working multiple efforts to develop and implement more energy-dense power solutions to increase the capability of the entire unmanned systems portfolio. Near-term efforts are focused on establishing efficient and technically acceptable requirements for testing rechargeable lithium-ion (Li-ion) battery systems; establishing updated, informed submarine “hostability” requirements; and developing propagation-resistant battery architectures to enable safe integration and deployment from Navy platforms.
The Navy has committed to Li-ion battery technology for UUV programs intended for submarine integration in the next several years for both its high energy density and recharge capabilities. Li-ion batteries are unique in that they contain enough stored energy to meet requirements but can pose a significant fire hazard upon failure. This poses a risk to both the submarine platform and its crew.
Good design principles and engineering solutions can eliminate fire hazards such as those that have been experienced in hover boards and Samsung phones. Previous Navy efforts focused on leveraging the low probability of failure for the certification of Li-ion-based systems. As rare as these failures are, the potential risk for larger systems (i.e., Snakehead, Razorback, etc.) embarked on a submarine is unacceptable.
In an effort to meet fleet requirements for increased endurance, a team of engineers and fleet operators have come together to achieve the certification of Li-ion-based systems using a systems-based approach. The team developed the submarine Li-ion embarkation strategy of prevention/detection/mitigation.
The prevention leg is grounded in the use of highly engineered battery systems with the goal being battery systems that are resistant to propagation upon failure. A robust quality-control process will help ensure that battery cells are screened to minimize the probability of failure. Additionally, the Navy has partnered with NASA to leverage the propagation-resistant battery architecture developed for manned space operations along with its battery design principles. An initial demonstration effort has begun with the integration of the NASA spacesuit battery in a small-size prototype UUV, which is being developed for submarine deployment.
The detection leg will alert the submarine crew of a failure early enough for it to take action, ensuring both survivability and resiliency. The Navy has partnered with Sandia National Laboratories and industry to develop a battery casualty detection system that is both coincident and redundant. Future efforts will incorporate emerging technology that will periodically scan the batteries for signs of internal faults allowing the submarine crew to simply discharge the battery, rendering it safe before a catastrophic failure occurs.
The third leg relies on a qualified, certified, crew-based mitigation concept of operations using organic shipboard capabilities (i.e., firefighting, smoke management, etc.). Crew training/certification and approved procedures will result in a standard for fighting a battery fire that is similar to Submarine Force Operational Training and Procedures. This was demonstrated aboard USS Boise (SSN 764) during a fleet engagement in which the crew helped the team refine and simplify the proposed torpedo room firefighting procedure for a Li-ion-powered Razorback UUV.
The submarine Li-ion embarkation strategy of prevention/detection/mitigation is changing the way engineers and fleet operators approach endurance, allowing the Navy to confidently develop Li-ion-based systems capable of being certified for submarine deployment.
As with the other core technology efforts, it is aimed at harnessing and standardizing ongoing activities across many Navy, Department of Defense, and industry laboratories and research centers and harvesting the best solutions for integration and deployment on a variety of unmanned platforms.
Collectively, investing in core technologies and rapidly maturing their evolution is critical to enabling the mission sets envisioned for UUVs. Some current technology paths may prove unsuccessful while new directions will emerge from continued research and testing. We should be prepared for these ups and downs, harvest the lessons learned, and move out smartly in a different direction.
As Navy Secretary Richard Spencer said in a recent speech, “An environment for exploration and experimentation must be tolerated. … We have to rub the rails.” The core technology effort for unmanned maritime systems is pushing ahead with all deliberate speed.
Dr. Joseph Fontaine, Head, Propulsion and Energy, Naval Undersea Warfare Center, Newport Division, contributed to this article.