By Jeffrey M. Smith

 

At a time when the U.S. Navy is pushing to develop and field its planned Large Displacement Unmanned Undersea Vehicle (LDUUV) and developing an accelerated demonstration plan for an even bigger Extra Large Displacement UUV (XLDUUV), one new technology start-up sees opportunity at the opposite end of the spectrum. Riptide Autonomous Solutions has introduced a new product dubbed a micro-Unmanned Undersea Vehicle (UUV) and it has started to make deliveries of this new class of UUV into the Navy development labs and to commercial and academic clients.

 

UUVs have a history dating back to 1957 with the Special Purpose Underwater Research Vehicle (SPURV) developed by the University of Washington’s Applied Physics Laboratory. Academia and special government programs drove the early decades of research, but advancements were slow. Throughout the 1960s, 1970s, and 1980s, more rapid growth came for the Remotely Operated Undersea Vehicle (ROV) market. It is commonly said that the ROV’s single largest advantage is that it has a tether, which provides for the ability to remotely power the vehicle as well as provide operator-in-the-loop communications and control via real-time access to the vehicle’s sensor suite. It has also been said that the ROV’s single largest disadvantage is its tether, as it limits the range of the vehicle to the tether length and the tether and tether handling equipment can weigh 10 to 20 times more than the vehicle, making deployment and logistics a challenge.

In the late 1980s and early 1990s, advancements were made by several academic and scientific research organizations in the design of lower-cost, autonomous vehicles that leveraged available technologies in commercial computer processing coupled with lower-power ROV sensors. Several large U.S. defense contractors such as Boeing, Lockheed Martin, and Northrop Grumman led major program development efforts for the Navy during this period. With declining defense budgets in the early 2000s, smaller UUV start-ups established their footing on smaller procurements for U.S. and international defense, scientific, and commercial clients.

Since the 2010 timeframe, the market has grown steadily as the U.S. Navy released three large ($50M to $100M) multi-year programs for Autonomous Undersea Vehicles (AUVs) and oceanographic gliders, commercial oil and gas expanded to deeper fields off South America, Africa, and Asia, and environmental monitoring requirements grew. Recent market studies suggest the current UUV market globally is about $2B, and that it is set to double by 2020.

As the U.S. Navy lays out its strategy and future force structure, which is supported by numerous studies and war games, it views the stealth, survivability, and warfighting dominance of its undersea capabilities as providing a significant advantage. The long standing U.S. supremacy in undersea warfare has become increasingly challenged over time, however, as other nations field increasingly more robust and cost-effective platforms in growing numbers. To supplement limited submarine platform quantities, the U.S. Navy is looking to employ more unmanned systems to extend the sensor range of the submarine and act as force multipliers.

To date, military use of UUVs has largely been driven by Explosive Ordnance Disposal (EOD) requirements. They are used to perform the dull, dirty, or dangerous tasks that take the Sailor out of the minefield. They are launched from, recovered by, and often maintained on surface support craft that chaperone these vehicles by maintaining reasonably close stand-off ranges for missions that typically last from 8 to 24 hours. As the Submarine Force looks to operationally employ UUVs going forward, these same EOD mission durations and concepts of operations are not aligned to the submarine mission requirement. The submarine has vastly superior sensing capabilities and situational awareness compared to the UUV, not to mention decision making capability. Submarines need UUVs to go beyond their sensor coverage range and operate for some period of time (depending on the mission) without requiring the submarine to constantly provide care and direction. This allows the submarine to focus on higher priority missions versus shepherding one or more deployed UUVs. Unless the vehicle can operate on its own for a period of days to weeks, it offers limited operational utility to the submarine. This is what has driven the U.S. Navy to look to larger, more capable and costlier UUV platforms that can store enough energy to operate for these longer periods. As with all military systems, though, as price increases, quantities decrease, and there is a quality in quantity.

 


Examples of various Micro-UUV configurations

 

As a new market entrant, Riptide set out to develop a small, capable UUV platform that could be fielded affordably in high quantities. To accomplish this, it aligned to a standard A-sized sonobuoy form factor (4.88” diameter) and targeted a vehicle price on par with expendable, single-use systems like sonobuoys and Expendable Mobile ASW Training Targets (EMATTs). It sought to drive cost down while increasing flexibility through modularity in both hardware and software. As demonstrated by its initial pre-production deliveries, Riptide was able to produce a 300m-rated UUV via highly flexible 3D printing fabrication techniques. The vehicles built to date have both free-flooded or dry payload volumes. They have been configured with single and dual frequency sonars, 360 degree cameras, and acoustic modems with more configurations in production. The standard vehicle is approximately 40 inches long and weighs about 22 lbs. It is powered by 144 alkaline AA batteries for their reasonably good energy density (on par with rechargeable lithium), world-wide availability, and unrestricted safety and shipping regulations (unlike lithium). With the high emphasis Riptide put into the hydrodynamic and electrical efficiency of the vehicle, this enables most payloads to run for 24 to 48 hours, depending on payload power and vehicle speed.

How does that achieve the days-to-weeks requirement for the Submarine Force? For this new class of UUV, Riptide has established an exclusive partnership with Open Water Power. Open Water is in development of an aluminum seawater energy system that provides a significantly higher energy density than all known lithium battery chemistries, both rechargeable and non-rechargeable, as well as all known fuel cells. Under initial Navy certification testing, it was also found to be highly safe given that the aluminum alloy is readily machinable with no added safety precautions. Open Water has demonstrated multiple cell stacks operating at greater than 10X the energy density of rechargeable lithium. Riptide will commence initial trials of the Open Water energy system by May of 2017. Initial design concepts predict that the micro-UUV will be able to store approximately 5 kWh of energy, which will provide the vehicle with a range of about 1,500 nautical miles at 2.8 knots.

 


Open water Power Anode showing progression of aluminum consumption

 

In 2011, then Chief of Naval Operations Adm. Gary Roughead issued a challenge to the UUV industry to deliver a 1,000 nautical mile UUV. Many developed conceptual solutions, but the cost to deliver was prohibitive. Riptide, enabled by Open Water Power, is very close to delivering that capability in a highly affordable vehicle that weighs less than 25 lbs.

But what can it do? Ultimately, the vehicle, enabled by the power system, is the transport mechanism for the sensor or payload. The mission dictates the appropriate sensor. Reasonably high powered active sensors like sonars could be fielded for a few days to a week depending on their required power levels. Lower-power oceanographic sensors such as those used on gliders, hydrophones or magnetometers are ideal for longer-duration missions lasting up to a month. With an 8 to 10 knot speed capability, short-duration rapid expendable neutralization missions are also an option. In the past 18 months since starting out, Riptide has seen keen interest from various sensor providers for new, lower-cost, smaller variants of their standard sensor products. As quantities increase, greater savings are also realized, but it is important to note that secondary benefits exist as more systems are fielded, such as improved reliability and improved performance.

So, where is it going? In the U.S. Navy as well as in the global market, the demands for unmanned undersea systems are increasing. As with most operational needs, no platform is ideal for every scenario. Each platform offers advantages and disadvantages that need to be factored into their selection. With cost tending to be a major consideration, it is foreseen that there will be several XLDUUVs, potentially tens of LDUUVs, hundreds of Medium Displacement UUVs (MDUUVs), and possibly thousands of micro-UUVs. Each will offer its own unique set of capabilities for the future fleet.

Jeffrey M. Smith is the President of Riptide Autonomous Solutions. He has spent his 23-year plus career supporting the U.S. Navy and the Submarine Force.


From left to right: Riptide Autonomous Solutions Principal Software Engineer Dani Goldberg,
NSWC PCD Operator of Unmanned Systems Technology Ana Zeigler, NUWC Keyport UUV
Project Lead Steven Figueroa, SPAWAR Engineer Anthony Jones.