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DARPA Lays Course for Unmanned Maritime Future

Three programs aim to revolutionize maritime operations.

The Defense Advanced Research Projects Agency (DARPA) intends to transform maritime operations with a fleet of three separate but complementary programs to develop unmanned vessel technologies.

The agency currently has three programs that could significantly impact naval operations by extending the range and payloads for unmanned vessels on and below the surface. They are Sea Train, No Manning Required Ship (NOMARS) and Manta Ray. Program managers for Sea Train and NOMARS recently participated in a joint SIGNAL Media interview. The program manager for Manta Ray was unable to be interviewed in time for the deadline.

Under the NOMARS program, DARPA and Serco Incorporated are developing a medium-sized unmanned surface vessel with increased availability, reliability and payload. The concept requires that no human need step onboard the vessel while it is at sea. By eliminating all constraints and requirements associated with humans, NOMARS opened up the design space to novel ship configurations and capabilities that could never be considered for crewed vessels, according to the program’s website.

Also, with no crew on board to perform maintenance, NOMARS requires new approaches for power generation, propulsion, machinery lineup and control schemes to ensure continuous functionality throughout a long mission in all weather, temperature and sea states, the website adds.

Gregory Avicola, DARPA’s NOMARS program manager, explained that the effort includes both hardware and software development. “I think we’re going to demonstrate significantly higher capability in an unmanned vessel. I’m really talking about the reliability and the availability and the maintenance of that vessel,” he said. “Using essentially commercial off-the-shelf parts but with novel design ideas for ships, we’re going to make a big difference there.”

The program aims to make a ship capable of monitoring its own health. “You can think of that as the autonomy function that acts as a chief engineer, if you will, for the ship, understanding its own space, rerouting equipment, replanning lineups, all that sort of stuff autonomously to maximize the health and the capability of the ship,” Avicola said. “Based upon where we are, I have high hopes for what we’re doing on that aspect. Obviously, the proof will be in the pudding a couple of years from now.”

That degree of self-health monitoring so far doesn’t exist, Avicola asserted. “To a great extent, there was nothing out there. There are some efforts in the manned ship community to make a smarter ship, but I think the big difference between what we’re doing and those is that because we don’t have a human onboard, we’re taking it to a greater extent.”

It helps that DARPA and Serco are not retrofitting autonomy to an existing ship design. “We also have the ability, since we’re designing the ship from scratch, to greatly increase the internal sensor suite that’s observing itself. We can put, for example, temperature sensors wherever we need. We can put flow-rate sensors wherever we need. We can monitor voltages and amperages wherever we need,” Avicola pointed out. “We’re able to design the hardware to support the software goals. That’s much more difficult if you’re trying to retrofit a ship.”

Meanwhile, the Sea Train program aims to demonstrate long-range deployment capabilities for a distributed fleet of tactical unmanned surface vessels. Researchers hope to enable extended transoceanic transit and long-range naval operations by exploiting the efficiencies of a system of connected vessels.

The goal is to demonstrate approaches that reduce wave-making resistance to overcome range limitations for medium unmanned surface vessels. “We’re specifically trying to target the wave-making resistance and reduce that so that they can go longer ranges without any other compromises in payload, fraction or just blindly adding much more fuel to the program,” Andrew Nuss, Sea Train program manager, told SIGNAL Media. “The impetus we have is to enable these platforms to go really long ranges. We’re targeting about three times what the current programs of record are targeting for medium-sized unmanned surface vessels.”

Longer ranges allow longer periods between refueling and provide flexibility for operational commanders. “That’s an important feature for these kinds of systems because we want them to be independently deployed, independently operated platforms. We don’t want them to have to always stay around a manned tanker, or oiler, or in-port refueling operation,” Nuss stated.

Like NOMARS, the Sea Train program aims to improve autonomy capabilities, but in this case, the need is to develop autonomy for cooperation among unmanned vessels. “We have autonomy needs to be able to have multiple vessels operate collaboratively together. This is allowing the vessels to come in close formation with each other, to determine when one’s a leader and one’s a follower, and a lot of the interactions that happen among them,” Nuss said.

Current unmanned surface vessel technologies use radar to locate other vessels, friendly or otherwise, and in most cases maneuver away to avoid collisions. “In our case, we have to find contacts, differentiate between contacts that are friendly ships or other ships. Then, more importantly, find my friend that I’m trying to collaboratively operate with, conduct a really close rendezvous proximity operation and sail in very close formation. That’s a very different capability than what’s currently available with unmanned surface vessels,” Nuss elaborated.

While radar will still be necessary for long-range detection, the Sea Train program is developing autonomy and “perception systems” as a building block for close collaboration capabilities. “What we’re developing within both of our teams is a lot of near-field perception capabilities. Near-field in modern terminology would be within a few hundred meters to rely on other sensor modalities like passive optical, like higher frequency radio frequency systems to find those contacts and make intelligent decisions about how to interact with those contacts,” Nuss said.

DARPA is working with two teams, one led by Applied Physical Sciences (APS) Company and the other by InMar Technologies. With the APS concept, the unmanned vessels physically link in a row. That allows them to burn less fuel, increasing range.

“There’s a hardpoint connection made between those vessels. The benefit of that is we get a long, slender hull form that’s generated by having those four vessels physically connected,” Nuss explained. “That allows us to have these really long, very efficient transits. But then once they get on station to go do whatever the mission is, they can physically separate, and they’re independently relevant, independently capable.”

InMar Technologies is taking a ducks-in-a-row approach without the physical connection. The technology applies to vessels with or without crews. “We’re opportunely placing the vessels so that the wave patterns that are generated from each of those vessels advantageously interact to decrease the overall amount of energy required to overcome the wave-making resistance,” Nuss explained. “The very simple analogy is the mama duck and the duckling concept where the mama duck swims ahead of the ducklings and generates this nice Kelvin wake, this nice ‘V’ that comes off the mama duck.”

One concept for DARPA’s Sea Train program physically connects vessels, while another takes a ducks-in-a-row approach in which the wake created by the first ship reduces the water resistance for the others. Credit: DARPA artist’s concept
One concept for DARPA’s Sea Train program physically connects vessels, while another takes a ducks-in-a-row approach in which the wake created by the first ship reduces the water resistance for the others. Credit: DARPA artist’s concept

NOMARS is about halfway through the 5-year duration of the program, and the team has been finalizing the design during a comprehensive design review. Next steps include the internal technologies on land prior to demonstrating the system at sea next year, with final testing late in 2024 and early 2025.

“What we do next, we take essentially the guts of the ship, all the things that make the ship work, and we lay it out on a pad, and we integrate that. Because of our unusual mechanical arrangements and the ultra-redundancy we’re trying to create, the very high reliability, we want to test that on land first,” Avicola offered. “We also want to make sure essentially that the software is compatible with the hardware before we button up the ship. We want to do all the deboning on the land in the course of the next year.”

APS, the team developing the physically connected train of ships, is building four demonstrator vessels. The first was expected to be completed in December. “That starts a pretty comprehensive, on-water test program that we will be executing effectively through most of the 2023 time period. We’ll start with a single vessel and then two, then three, then four-vessel on-water operations,” Nuss said. “That allows us at relevant scale and with pretty good-sized demonstrator vessels to buy down a lot of risks that are required for us to be able to realize this broader capability.”

InMar, the team taking the ducks-in-a-row approach, is developing the actual control algorithms that determine where and when to place each vessel relative to the others based on potential environmental conditions, vessel configurations, sizes and other factors. “We’re currently putting together a demonstration program plan for how we would go off and execute that similarly on water, at relevant scale, to be able to collect good science data to confirm our analytical models but also show our stakeholders at relevant scale what the capabilities could be,” Nuss said.

The two programs are independent but complement one another, the program managers indicated. They focus on different specific goals but both seek to develop capabilities for unmanned vessels to carry more payload for less money, allow for a more distributed force and increase ship availability.

“Manned ships just are inherently not very available. They spend a lot of their time not doing their warfighting mission because of the people, because of the maintenance requirements but also the crewing requirements, the training requirements, etc. If we do what we think we can do, we’re laying a path that takes the unmanned surface vessels from this niche experiment to something that is transformational,” Nuss suggested.

Avicola added that despite the two programs attempting to solve different problems, they do collaborate. “There are definitely places where the technologies overlap, and if their solution’s better than our solution, or our solution’s better than their solution, we’re always talking,” he asserted.

The Manta Ray program, meanwhile, is developing unmanned undersea vehicles that operate for extended durations without human support, offering persistent operations in forward environments. Such systems could allow traditional host vessels increased operational flexibility while providing traditional servicing ports with workload relief, according to the program’s website.

In December 2021, DARPA awarded Phase 2 contracts to Northrop Grumman Systems Corporation and Martin Defense Group LLC for the Manta Ray program.