Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) "Sea Hunter"

DARPA ACTUV Conception - Late 2015

DARPA’s Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) program -- now known as Sea Hunter -- is an unmanned surface vessel to detect and track diesel-electric submarines. The program's lead contractor is Leidos (formerly SAIC) which used an autonomous surrogate vessel called Pathfinder to develop the ACTUV's technology.  


DARPA's Anti-submarine Drone Tests Towed Airborne Sensor

DARPA’s Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) program has developed and built a technology demonstration vessel that is currently undergoing open-water testing off the coast of California and recently set sail with its first payload: a prototype of a low-cost, elevated sensor mast developed through the Agency’s Towed Airborne Lift of Naval Systems (TALONS) research effort (DARPA Photo)

24 October 2016 - DARPA’s Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) program demonstration vessel is currently undergoing open-water testing off the coast of California and recently set sail with a prototype low-cost, elevated sensor mast developed through the Agency’s Towed Airborne Lift of Naval Systems (TALONS) research effort.

ACTUV seeks to lay the technical foundation for an entirely new class of ocean-going vessel—one able to traverse thousands of kilometers over the open seas for month at a time, without a single crew member aboard. Potential missions include submarine tracking and countermine activities. Towed behind boats or ships, TALONS could persistently carry intelligence, surveillance, reconnaissance (ISR), and communications payloads of up to 150 pounds between 500 and 1,500 feet in altitude—many times higher than current ships’ masts—and greatly extend the equipment’s range and effectiveness.

The demonstration took place over two days with 90 minutes of flight each day. The TALONS prototype started out from its “nest” installed on the back of the ACTUV vehicle. It then expanded its parachute and rose to an altitude of 1,000 feet, where it tested its onboard sensors and communications equipment. Once the test was complete, the prototype reeled itself in back to the nest. The entire process took place as the ACTUV vehicle maneuvered at operationally realistic speeds.

While aloft, TALONS demonstrated significant improvements to the range of the sensors and radios it carried compared to mounting them directly on a surface vessel. For example, TALONS’ surface-track radar extended its range by 500 percent—six times—compared to its range at sea level. Its electro-optical/infrared scanner doubled its observed discrimination range. The TALONS team plugged in a commercial handheld omnidirectional radio; that radio’s range more than tripled.

“I was delighted to explore the possibility of hosting TALONS on ACTUV and from my perspective, the testing could not have gone better,” said Scott Littlefield, DARPA program manager for ACTUV. “We just started at-sea testing of ACTUV in June, and until now we've been focused on getting the basic ship systems to work. TALONS was our first chance to demonstrate hosting a real payload and showing the versatility of ACTUV to do a wide variety of missions for which it wasn't originally designed.”

“TALONS showed the advantages of using a low-cost add-on elevated sensor to extend the vision and connectivity of a surface asset and ACTUV demonstrated its ability as a flexible and robust payload truck,” said Dan Patt, DARPA program manager for TALONS. “This demonstration was an important milestone in showing how clever use of unmanned systems could cost-effectively provide improved capabilities.”

Both Patt and Littlefield commended the teams collaborating on the demonstration for accomplishing the testing in a remarkably short period of time: less than 90 days from the go-ahead decision to the actual demonstration. The team members including Maritime Applied Physics Corporation and the Naval Surface Warfare Center Carderock Division (NSWCC) for TALONS, and the U.S. Navy Space and Naval Warfare Systems Command-Pacific (SSC-PAC) and Leidos for ACTUV.

“This ACTUV/TALONS demonstration is the latest in DARPA’s history of cross-program collaboration to develop breakthrough technologies for national security,” said Brad Tousley, director of DARPA’s Tactical Technology Office (TTO), which oversees both ACTUV and TALONS. “Where it’s a good fit, joint testing provides the opportunity to show the robustness and interoperability of each program’s research, as well to explore potential future uses that wouldn’t be evident by testing each program separately.”

TALONS is part of DARPA’s Phase 1 research for Tern, a joint program between DARPA and the U.S. Navy’s Office of Naval Research (ONR). Now that at-sea demonstration is complete, DARPA is transitioning TALONS to the Navy.

In September 2014, DARPA signed a Memorandum of Agreement (MOA) with ONR to jointly fund an extended test phase of an ACTUV prototype. In April 2016, a christening ceremony in Portland, Oregon, marked the vessel’s formal transition from a DARPA-led design and construction project to open-water testing conducted jointly with ONR. DARPA will collaborate with ONR to fully test the capabilities of the vessel and several innovative payloads over the next two years. Pending the results of those tests, the program could transition to the Navy by 2018.

Sea Hunter Completes Initial Performance Trials

25 July 2016 - Leidos today announced that the Sea Hunter unmanned surface vehicle completed initial performance trials on June 22nd off San Diego. The vessel is under development for the Defense Advanced Research Projects Agency (DARPA)'s Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) program.

The at-sea tests took place off the coast of San Diego, California.The 132-foot trimaran, christened Sea Hunter at a ceremony in April, met or surpassed all performance objectives for speed, maneuverability, stability, seakeeping, acceleration/deceleration, and fuel consumption, as well as establishing confidence in mechanical systems reliability in an open-ocean environment. Sea Hunter is designed to operate for extended periods at sea with no person on board and only sparse supervisory control throughout deployment. While initial vessel tests require a pilot on board the ship, later tests are planned to have no personnel on board.

The completion of Sea Hunter's performance trials is the first milestone in the two-year test program co-sponsored by DARPA and the Office of Naval Research. Testing in upcoming months is scheduled to include testing of sensors, the vessel's autonomy suite, compliance with maritime collision regulations, and proof-of-concept demonstrations for a variety of U.S. Navy missions.

DARPA Time-lapse Construction Video

16 February 2016 - Sea Hunter (ACTUV) preparing for sea trials (image courtesy of DARPA).

The Pathfinder surrogate vessel participated in Trident Spectre 2015 off the Mississippi Gulf Coast.

Sea Hunter is undergoing construction at Vigor Shipyard in Oregon and is expected to launch in early 2016.

Raytheon Delivers Sonar for DARPA's Unmanned Anti-submarine Warfare Vessel

18 November 2015 - Raytheon Company completed delivery of its latest Modular Scalable Sonar System (MS3), the fifth-generation hull-mounted sonar system, for the Defense Advanced Research Projects Agency (DARPA)'s Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) program.

The delivery is a culmination of efforts under a subcontract from Leidos, Inc., whose prototype trimaran is designed to serve as the program's unmanned vehicle. MS3 marks an improvement in the performance and reliability of proven sonar technologies. It performs active and passive search and tracking; incoming torpedo warning; and small-object avoidance for safer navigation. Sensor data from the system is used in the anti-submarine warfare (ASW) mission to help build a common operating picture for ACTUV. MS3 will be integrated into Leidos' trimaran for ACTUV, and will deliver these capabilities in an autonomous operating environment.

"MS3 builds on a legacy of sonar expertise, integrating a host of capabilities in a single sonar system," said Paul Ferraro, vice president of Advanced Technology for Raytheon's Integrated Defense Systems business. "MS3 will provide DARPA with exceptional performance – from detection to tracking – from an unmanned platform."About MS3

Flexible, affordable and high-performing, Raytheon's MS3 addresses current and emerging threats from undersea. It is the fifth-generation hull- and bow-mounted sonar, building on the proven capabilities of Raytheon sonars currently in service worldwide. MS3 features a streamlined inboard electronics suite that can be configured for a range of sonar capabilities, including ASW, anti-surface Warfare (ASuW) and mine warfare, for most hull and bow-mounted arrays and towed systems.

It was designed and developed with an open architecture for maximum flexibility, supporting phased upgrades or new construction programs. MS3's unique, modular architecture enables tailored, capable solutions to counter today's undersea threats with inherent scalability to adapt to the evolving threats of the future.

DARPA Seeks Automated Lookout Technology for Anti-sub Drone

26 March 2015 - DARPA’s Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) program seeks to develop a new type of unmanned surface vessel that could independently track adversaries’ ultra-quiet diesel-electric submarines over thousands of miles. One of the challenges that the ACTUV program is addressing is development of autonomous behaviors for complying with the International Regulations for Preventing Collisions at Sea, known as COLREGS. Substantial progress has been made in developing and implementing those behaviors. Currently, ACTUV’s system for sensing other vessels is based on radar, which provides a “90 percent solution” for detecting other ships. However, radar is less suitable for classification of the type of other vessels, for example determining whether the vessel is a powered vessel or a sailboat. Additionally, one of the requirements of COLREGS is to maintain “a proper lookout by sight and hearing.”

To help augment ACTUV’s capability for sensing and classifying other vessels, and to reduce reliance on radar as ACTUV’s primary sensor, DARPA has issued a Request for Information (RFI) about currently available technologies that could help ACTUV and future unmanned surface vessels perceive and classify nearby ships and other objects. DARPA is specifically interested in sensor systems and image-processing hardware and software that use passive (electro-optical/infrared, or EO/IR) or non-radar active (e.g., light detection and ranging, or LIDAR) approaches. The goal is to develop reliable, robust onboard systems that could detect and track nearby surface vessels and potential navigation hazards, classify those objects’ characteristics and provide input to ACTUV’s autonomy software to facilitate correct COLREGs behaviors.

“We’re looking for test-ready, multi-sensor approaches that push the boundaries of today’s automated sensing systems for unmanned surface vessels,” said Scott Littlefield, DARPA program manager. “Enhancing the ability of these kinds of vessels to sense their environment in all weather and traffic conditions, day or night, would significantly advance our ability to conduct a range of military missions.”

The RFI invites short responses that explore technology in maritime perception sensors and software along with classification software and algorithms for day shapes and navigation lights. Responses are due to DARPA April 28, 2015.

Leidos Anti-submarine Warfare Drone Surrogate Completes Voyage

26 January 2015 - Leidos announced today that its prototype maritime autonomy system for the Defense Advanced Research Projects Agency(DARPA)'s Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) program recently completed its first self-guided voyage between Gulfport and Pascagoula, Mississippi.  

The prototype maritime autonomy system was installed on a 42-foot work boat that served as a surrogate vessel to test sensor, maneuvering, and mission functions of the prototype ACTUV vessel. ACTUV seeks to develop an independently deployed, unmanned naval vessel that would operate under sparse remote supervisory control and safely follow the collision avoidance "rules of the sea" known as COLREGS.

Controlled only by the autonomy system, and with only a navigational chart of the area loaded into its memory and inputs from its commercial-off-the-shelf (COTS) radars, the surrogate vessel successfully sailed the complicated inshore environment of the Gulf Intracoastal Waterway. During its voyage of 35 nautical miles, the maritime autonomy system functioned as designed. The boat avoided all obstacles, buoys, land, shoal water, and other vessels in the area – all without any preplanned waypoints or human intervention. 

While Leidos continues to use the surrogate vessel to test ACTUV software and sensors, the company is continuing construction of Sea Hunter, the first ACTUV prototype vessel, in Clackamas, Oregon. Sea Hunter is scheduled to launch in late fall 2015 and begin testing in the Columbia River shortly thereafter.

Leidos Completes As-Sea Testing of Prototype Robotic Sub Hunter

18 November 2014 - Reston, Virginia-based Leidos completed a total of 42 days of at-sea demonstrations of the prototype maritime autonomy system designed to control all of the maneuvering and mission functions of the Defense Advanced Research Projects Agency's (DARPA) Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV).  Using a 32-foot work boat as a surrogate vessel, Leidos installed autonomy software and sensors to mimic the configuration intended for an eventual full-size ACTUV prototype. 

Manned vessels are obliged to obey a set of navigation rules published by the International Maritime Organization.  Generally referred to as COLREGS (collision regulations), those rules determine in the event of an encounter between vessels, which vessel has the right of way (the "stand on" vessel) and the appropriate behavior for both the "stand on" and "give way" vessel to avoid a collision.

The Leidos strategy to evaluate the prototype ACTUV autonomy system for COLREGS compliance includes both simulation and at-sea testing.  The team has completed approximately 26,000 simulation runs of the system.  Testing of COLREGS involves the ACTUV surrogate and one interfering vessel in a variety of meeting, crossing, overtaking and transit scenarios in both simulation and on the water test events.  

During a recent on-the-water test event, the surrogate boat autonomously navigated through narrow channels avoiding navigation aids and submerged hazards. The boat safely avoided surface ships it encountered along the route, satisfying COLREGS requirements in completely unscripted events. 

During 42 days of at-sea testing that included 101 individual scenarios, the autonomy system directed course and speed changes of the surrogate vessel to stay safely outside a 1-km standoff distance from the interfering vessel.  The test program demonstrated the ability of the ACTUV autonomy system to successfully maneuver and avoid collision with another vessel and paves the way for follow-on testing involving multiple interfering contacts and adversarial behaviors of interfering vessels. 

While continuing to use the surrogate vessel to test ACTUV software and sensors, construction of Sea Hunter, the first ACTUV vessel, continues at Christensen Shipyard in Clackamas, Oregon.  Sea Hunter is scheduled to launch in late summer 2015 and begin testing in the Columbia River shortly thereafter.

Navy Anti-submarine Warfare Drone Begins Construction

7 July 2014 - An autonomous unmanned vessel designed to track quiet diesel-electric submarines spanning miles of ocean depths for months at a time with minimal human input is now under construction and is expected to set sail for testing in 2015. Leidos (formerly SAIC), has begun construction on ACTUV (Autonomous Continuous Trail Unmanned Vessel) under a Defense Advanced Research Project Agency (DARPA) program for the design, development, and construction of a vessel originally conceived for an anti-submarine warfare mission.

"ACTUV's advanced sensor technology should allow for continuous surveillance which, combined with the vessel architecture and design, is expected to provide autonomous safe navigation supporting Navy missions around the world," said Leidos Group President, John Fratamico.

ACTUV carries other sensors and mission packages designed to allow it to conduct a variety of Intelligence, Surveillance and Reconnaissance and other alternate missions. With situational sensors that can ensure safe navigation, the ACTUV trimaran has electro optics, long range and short range radar.

"A cross-disciplinary Leidos team leveraged insights and innovation from across the organization to develop the concept of the autonomous unmanned vessel. It would help keep our troops out of harm's way and provide capability in more harsh environmental conditions for a longer period of time," added Fratamico.

Maritime and hydrodynamic engineers designed the platform, and scientists and experts designed autonomy for safe navigation, status and health reporting, and sensor control and processing. Analytics experts programmed the logic for identifying other vessels and predicting their behavior.

Leidos received direction to start construction of the ACTUV from DARPA Program Manager Scott Littlefield at the conclusion of a Production Readiness Review held in February.  Christensen Shipyard, Ltd. (CSL), is constructing ACTUV in Vancouver, Washingtonusing non-traditional composite structures and modular construction techniques under supervision of Leidos and Oregon Iron Works (Clackamas, Oregon).  CSL employs a lean manufacturing process with parallel work flow to complete ACTUV construction in approximately 15 months.  ACTUV is scheduled for launch on the Columbia River in 2015. 

SAIC Awards OpenClovis ACTUV Contract

20 March 2013 - OpenClovis Solutions, Inc., has signed a contract with SAIC (Science Applications International Corporation) to support the development of DARPA's Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) project with the SAFPlus platform.

The ACTUV program is intended to advance unmanned maritime system autonomy to enable independently deploying systems capable of missions spanning thousands of kilometers of range and months of endurance under a sparse remote supervisory control model. This includes autonomous compliance with maritime laws and conventions for safe navigation, autonomous system management for operational reliability, and autonomous interactions with an intelligent adversary.

"SAIC is pleased to work with OpenClovis in the development of our ACTUV system," said Mr. Robert McCummins, Engineering Manager, at SAIC. "As maritime systems continue to become more complex and demanding, it is critical that innovative solutions such as SAFPlus is used to achieve cost-effectiveness without compromising the quality of the program."

OpenClovis' SAFPlus, in conjunction with SAIC’s ACTUV project, aims to accomplish this very task. SAFPlus is the only HA solution on the market that supports the Real-time Operating System and Linux hybrid platform, which allows for real-time embedded performance on top of a stable Linux platform. The company is also the only provider on the market that provides a suite of application design and development tools, and is renowned for its best-in-class technical support and overall expertise.

"We are thrilled to have this opportunity," said V.K. Budhraja, CEO, OpenClovis. "The project looks to expand the horizons of what can be achieved in unmanned systems, and we believe that the technology being developed will yield enormous benefits for the future. Our ability to provide robust, adaptable, and reliable software with great follow-through on the technical support end has paid great dividends for customers in the past, and we are confident that our work with SAIC will achieve similar success."

The OpenClovis SAFPlus Platform consists of an extensive set of management software modules running on a distributed, model-driven core infrastructure, and is aligned with the Service Availability Forum (SA Forum) Application Interface Specifications for High Availability. Modules may be selected to best match the application and platform requirements. OpenClovis SAFPlus can be distributed across blades, shelves, and even racks, creating a seamless high availability platform and system management environment across heterogeneous network element building blocks.

Raytheon Awarded Subcontract for ACTUV Sonar

13 March 2013 - Raytheon has been awarded sub-contract by SAIC to supply its Modular Scalable Sonar System (MS3) as the ACTUV's primary search and detection sonar.  MS3 is a medium-frequency hull-mounted sonar capable of active and passive search, torpedo detection and alerts, and small object avoidance.

SAIC Reveals New Details on ASW Drone

21 December 2012- Science Applications International Corporation (SAIC) has released an updated promotional video revealing new details about the Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV).  More here.

Insights into Unmanned ASW

By Scott Cheney-Peters

24 August 2012 - Last week the U.S. government’s defense technology innovator, DARPA, awarded Science Applications International Corporation (SAIC) a $58M contract to develop the next phases of its Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vehicle (ACTUV) technology demonstrator. Besides a fine example of the DoD’s love of nested acronyms, the ACTUV program provides a peek into the promises and challenges of the future of unmanned ASW.

It’s important to note that note that the award is for a technology demonstration, not a program of record. The ACTUV will help the Navy mature technologies useful for future capabilities but is not expected to enter active fleet service itself. According to DARPA’s ACTUV website, the first, completed phase

"refined and validated the system concept and associated performance metrics, completing risk reduction testing to inform program risks associated with submarine tracking sensors and maritime autonomy.”

SAIC is tasked with phases 2-4, specifically to “design a vessel (phase 2); build a vessel (phase 3) and test the vessel (phase 4). Operational prototype at-sea testing is expected in mid-2015.

As stated in DARPA’s press release, the goal of the program is an “unmanned vessel that tracks quiet diesel electric submarines for months at a time spanning thousands of kilometers of ocean with minimal human input.” The website adds that an objective of generating a vessel design that “exceeds state-of-the art platform performance to provide complete propulsive overmatch against diesel electric submarines at a fraction of their size and cost.” In other words the vessel must be small and cheap (target cost goal of $20M apiece), yet robust enough to operate for 80 days and 6,200km without human maintainers or refueling.

The approach the program takes for propulsion will be interesting to see develop, as most long-range drone concepts have relied on solar panels or wave propulsion at the sacrifice of top speeds. Part of ACTUV’s endurance and speed will come from the drone’s design. According to, the SAIC-built concept’s use a trimaran hull seen (see the video) offers better speeds over long ranges than traditional monohull designs. Additionally, going sans-crew frees up space normally devoted to crew-support systems to fill with more fuel tanks.

Hunting its prey, the ACTUV will have an edge during lower sea-state levels and due to the necessity of diesel electric subs to snorkel with regularity. High sea-states and advanced air-independent propulsion (AIP) diesel subs pose a greater challenge, although the former is mitigated by the lack of crew-safety requirements (no need to worry about the wardroom’s pitchers of kool-aid flying into SUPPO’s lap).

As discussed in previous posts on our site, increasing a drone’s level of autonomy as DARPA intends with the ACTUV – through “a sparse remote supervisory control model” – will decrease its susceptibility to hacking. However the need for two-way contact through communication and command protocols will still create vulnerabilities to guard against. The more the ACTUV communicates, especially in transmission, the more it increases the chance of being detected. In fact, although as a smaller vessel it might have a radar cross section akin to a pleasure craft or fishing vessel, its speed, sensor suite, and the simple fact that it’s a surface vessel will probably make it rather easy to detect – especially by the sub it is following. As a whole, this vessel will probably not be that stealthy, more often used in “we don’t care you know we know” type situations.

Automated responses also create the possibility of a dependable error that an enemy can exploit (think of a video game that freezes every time one particular action is performed). This is a more remote worry as the error would have to unknown or uncorrected by the U.S., be discovered by a foe, and be of practical tactical use (it doesn’t matter much if the ACTUV shuts down when trying to avoid whales if you can’t drive the ACTUV into a whale).

Another interesting requirement is the need for ACTUV to abide by maritime traffic conventions and legal restrictions. In practice this means preventing it from, say, running over a civilian on a jet ski or straying into protected marine habitats. But the day will come when some unmanned surface or subsurface vehicle does cause damage, and the legal and operational fallout will be quite interesting to watch.

Lastly, as noted in Aviation week, the ACTUV will not perform organic ASW search functions, but will instead rely on other ASW assets and intel to cue its tracking opportunities. Once acquired, the vessel will use “onboard acoustic, electro-optical, radar and lidar sensors to acquire and follow its submarine target.”

If it proves successful, the ultimate benefit of an ACTUV follow-on is therefore that it will free up more expensive assets to do other things. As configured, an engagement would require integration with a weapon-delivery platform, most practically an aircraft. However, like the predator, which made its debut as a strictly ISR platform, a future iterations could quite conceivably carry their own weapons. The ACTUV is a program to keep an eye on.

Reposted with permission from The Center for International Maritime Security.

comments powered by Disqus

SAIC Awarded DARPA Contract to Build Anti-submarine Warfare Drone

22 August 2012 - The Anti-Submarine Warfare (ASW) Continuous Trail Unmanned Vessel (ACTUV) is a DARPA Tactical Technology Office project to develop an autonomous surface vehicle. The program’s objective is to detect, track, and classify diesel electric submarines during long duration missions of 60-90 days with no human maintenance or presence required. On August 14, Science Applications International was awarded a $58 million contract to perform Phases 2-4 of the program, which include design, construction, and operational testing.

The SAIC-proposed prototype will carry a sensor suite comprised of sonar, electro-optical imagers, radar, and lidar to navigate, avoid obstacles, and carry out its operational missions. Scott Littlefield, DARPA’s program manager, notes that the vessel will include “advanced software, robust autonomy for safe operations in accordance with maritime laws, and innovative sensors to continuously track the quietest of submarine targets.” Similar to Austal’s LCS 2 design, the craft’s tri-maran hull offers high speed and a longer unrefueled range than an equivalent sized monohull. 

The proliferation of quiet diesel and air independent propulsion submarines around the world are driving requirements for more affordable ASW platforms. More than 39 countries operate diesel submarines, which can be acquired for only a few hundred million dollars, a bargain in naval terms.

In addition to the anti-submarine warfare mission, SAIC’s modular USVs are envisioned to support ISR, mine countermeasures, and communications relay functions. An operational prototype is expected to begin at-sea testing in mid-2015.

comments powered by Disqus