Friday, February 13, 2015

Surf Zone Robotic Platform

Editor's note: Reprinted with permission from the Naval Postgraduate School's CRUSER News.
By Frederick E. Gaghan, Director of Program Development, Applied Research Associates 

The near-shore environment is one of the most dynamic and technically challenging for both man and machine. Significant research efforts have been conducted to investigate sea-floor crawling robots, but they usually involve “water-proofing” a standard ground robot and attempting to operate it underwater. These designs often experience difficulties in maintaining positional accuracy or operability due to the water flow and wave action.

Over the course of several months, ARA studied two key engineering concepts for the Strategic Environmental Research and Development Program (SERDP) that directly affect the ability of a
robotic system to operate in the surf-zone (SZ); 1) platform hull shape and, 2) propulsion.

To address platform shape a study was completed of a horseshoe crab’s carapace as a biomimetic representation for the hull shape of a robotic system (Figure 1). It was hypothesized that a hull shape based on a horseshoe crab would provide the appropriate balance between lift and drag, and allow hydrodynamic forces in the Very Shallow Water (VSW)/SZ to assist in the ability to station keep and maneuver without the need for excessive weight or a complex propulsion system to achieve platform stability and traction. The study focused on answering the following questions:

• Can a biomimetic hull design provide better stability in the dynamic wave conditions found in the VSW/SZ?
• Is the required scale of this hull design sufficient for carrying a usable payload and other system components?
• What are the maximum flow vectors for which the biomimetic hull can remain effective?
• What are the resultant forces from those maximum flow vectors?
Figure 1 (baseline model)                    Figure 2 (Archimedes Screw)
Several biomimetic hulls were modeled and underwent simulated and empirical testing in a water channel. The empirical testing was used to validate the data obtained from the Computational
Fluid Dynamics simulations used to identify a more effective hull shape.

To address locomotive factors a separate study was completed using an Archimedes screw drive as the mode of propulsion to assess platform traction and mobility (Figure 2). An Archimedes screw was chosen because of its ability to operate in various mediums with varying flow rates. It was hypothesized that an Archimedes screw with optimal geometry could provide the tractive force to propel a robotic system. Archimedes screw drives have been successfully used on larger underwater robots, such as those found in the deep sea mining industry, but it has not been widely applied to a robotic system in the near shore environment.

A test bed was designed to measure the speed, forces, and displacements created by an Archimedes screw interacting with various mediums. Several drive designs with different barrel diameters, flange heights, and flange depths were empirically tested to record efficacies in a range of mediums, including water, sand, and pebbles to answer the following questions:
Figure 3
• Can the Archimedes screw drive be scaled appropriately for a small to medium robotic system?
• What performance characteristics (speed, efficiency, tractive force) would this system provide?
• How will the system perform across a variety of medium?

Results of the two studies confirmed that is possible to design a biomimetic hull shape to improve stability and an optimized geometry for an Archimedes screw that would provide good tractive force on the aquatic floor in the dynamic wave conditions found in the VSW/SZ (Figure 3).

Wednesday, February 11, 2015

Using Unmanned Systems For Anti-Piracy

Second Prize Winner, 2015 CIMSEC High School Essay Contest (reprinted with the permission of CIMSEC).
The issue I would like to address in this essay is piracy. Piracy has been a threat to the safety of the seas since the seas were first used for transport and it has been a danger ever since. From the Barbary Corsairs to the privateers of the Caribbean, pirates have found ways to succeed or even thrive no matter the situation. For years pirate skiffs from Somalia have been attacking marine traffic to hold the ships and/or their crews for ransom. These brazen attacks have drawn the attention of the media and even, in the case of the Maersk Alabama, Hollywood. Of course any security issue that comes to the attention of the general public has first passed through the halls of numerous defense ministries across the globe so it should come as no surprise that before, during, and after these events, efforts were made by various navies including the US Navy and a coalition task force from the European Union to combat this growing problem. In this essay I would like to address what they have done and how it could be done better and in a more sustainable manner.
The primaryMQ-4C Triton BAMS UAS approach was taken thus far is to use large surface combatants such as frigates and destroyers as escorts for merchant ships as well as touring African nations and training their respective navies in counter-piracy operations. These measures, when combined with better safety measures taken by commercial vessels, have been extremely effective since 2012 and attacks off Somalia have become almost vanishingly rare at this point in time.1 This being said, these measures are fairly expensive both in money and in combat forces and while the threat off the Horn of Africa has been put into remission temporarily, the underlying issues that lead to the growth of piracy in the region remain.2 Thus if the governments responsible for this crackdown on piracy wish to continue to suppress piracy without devoting significant monetary resources and a handful of large surface combatants to the region a change in strategy is required.
Currently the platforms responsible for this mission are surface combatants and Maritime Patrol and Reconnaissance Aircraft or MPRAs. These platforms belong to three multinational forces and four single state task forces are deployed in the region.3 This, in my opinion, is overkill. While the current system has worked, it is large and inefficient and when the political will runs out this bureaucratic nightmare will be one of the first things to go. Thus there is a need for immediate change.
First of all, the platforms now being used for security operations are not ideal for the job. The P-3s and other manned MPRAs used for wide area maritime surveillance in the area are high value assets in the navies of their respective countries and can be used for missions as diverse anti-submarine to search and rescue missions. In contrast, the MQ-4C Triton Unmanned Aerial System was designed without the anti-surface and anti-sub capabilities of most MPRAs and focused instead on long endurance patrol of large bodies of water. With an acquisition cost only 68% of the P-8A (the US Navy’s current MPRA)4 along with lower operational costs, the Triton is the clear choice for maritime patrol in low threat environments such as the coast of Somalia.
As for surface combatants, the frigates and destroyers currently allocated for these missions are large and often significantly over-armed for confrontations with pirates in small motorboats. An alternative would be smaller platforms, both manned and unmanned, which could provide sufficient armament and speed to effectively combat the threat while requiring significantly less time, money, and logistical support.
The manned platforms suited to this task that are available for use today are the Cyclone patrol ships, eight of which are currently forward based in the Persian Gulf, the Mk. VI Patrol Boat, and the Mk. V Special Operations craft. These craft could be used as a rapid response force, responding to threats at speeds of between 35 knots (the Cyclone) and 50 knots (the Mk V) with Intelligence, Surveillance, and Reconnaissance (or ISR) support from Triton UASs in the area. Of course these platforms unfortunately lack the persistence afforded by larger displacement surface combatants, which is where the Unmanned Surface Vehicle comes in. While the manned platforms listed above are an ideal and sufficient force to deal with crises such as the successful hijacking of a ship, they lack the ability to stay on station in the shipping lanes for long durations. Having these vessels in position to intercept any threats detected by airborne search radar is essential to prevent hijackings before they happen. The US Navy as well as a number of others have invested in the development of USVs primarily to protect large combatants from swarms of small, hostile boats armed with short range anti-ship missiles. Unfortunately the USVs currently in inventory are not armed but models in the near future will be.
With all these niches filled, a comprehensive anti-piracy strategy begins to emerge. First, a small, manned contingency response group, based in the gulf and rotated through ports in Yemen and other friendly nations will be constantly in the area to safeguard against crises. Second, the unmanned surface element will patrol threatened areas regularly to defend shipping against small-scale attacks and will be constantly on station, ready to intercept threats if and when directed to do so. Finally, the Triton element will provide a persistent “eye in the sky” for surface elements.
Piracy is an issue, both off the horn of Africa and around the world but as we have seen in the past few years it can be beaten. I believe that with a force such as the one described here, navies around the world could use the advantages of new technology to fight this age old threat.
1. US Office of Naval Intelligence, Piracy Analysis and Warning Weekly Report for 8-14 January 2015, pp. 2 Table 1, Available on-line: 
2. Jon Gornall, Somali Piracy Threat Always on the Horizon, 16 December 2014, The National
4. US Government Accountability Office, Defense Acquisitions: Assessment of Selected Weapon Programs,  March 2013, pp. 109, 115, Available on-line: 
 About the Author
Griffin Cannon is a senior at the Vermont Commons School in South Burlington, Vermont. His interests include spending time with his younger siblings, the outdoors, tennis, and skiing. He finds military and political issues fascinating and spends time every day keeping up to date on the defense world. As a graduating senior he plans on attending university at the Naval Academy or on a NROTC scholarship. Griffin hopes to pursue a career in either engineering or defense policy after serving in the Navy. 

Wednesday, January 21, 2015

Worth a Listen: CIMSEC's Unmanned Naval Vessel Podcast

seacontrolemblemThe Center for International Maritime Security's most recent "Sea Control" podcast features an interesting and wide-ranging discussion on future unmanned and optionally-manned naval systems.  Much of the discussion revolves around the challenges of operating large surface ships without manpower, to include some of the more mundane functions, such as maintenance.

Alex Clarke, of the Phoenix Think Tank, proposed the concept of an "unmanned wingman" for Offshore Patrol Vessels performing remote operations.  He also mentioned the possibility of USVs taking on the role of the T-AGOs towed array sonar operations for anti-submarine warfare. Essentially, this concept mirrors what DARPA's ACTUV program intends to do. 

Other topics of consideration are unmanned alternatives to aircraft carriers, the difficult question of whether destroying an unmanned vehicle is an act of war, and command and control schemes. 

Monday, January 19, 2015

Short Range Wireless Power Transfer (WPT) for UAV/UAS Battery Charging

Editor's note: Reprinted with permission from the Naval Postgraduate School's CRUSER News.

by Professor David Jenn, NPS Electrical Engineering Faculty, jenn(at)

There are numerous advantages of wireless power transfer (WPT) for many remote energy source and battery charging applications. In a WPT system, power is transmitted wirelessly from a base station to a client. The concept was first demonstrated for vehicle propulsion in the mid 1960s. More recently, WPT has been used for charging wireless devices, and commercial WPT charging technologies have appeared on the market under the names Witricity and Energous.

Measurement setup used to obtain efficiency and coil installed in a UAV hull
(photo courtesy NPS).
In a typical WPT system, prime power is provided by the base station, converted to radio frequency, and then transferred through space to a receiving coil or antenna. On the client side the received power is filtered, transformed in voltage, and subsequently delivered to the battery or power plant.

Inductive systems use two coils with one located in the charging station and the second in the device. Energy is transferred by the magnetic fields linking the coils. At the receiving coil, circuits are required to rectify and condition the output voltage for charging the battery. Inductive systems generally operate at low frequencies (< 10 MHz). Efficiencies greater than 95% have been achieved, but only at very short distances (a maximum of several cm) and alignment of the coils is critical.

Radiative WPT systems use two antennas rather than coils, and the energy is transferred by a propagating wave. The receiving antenna has an integrated rectifier, and is called a rectenna. Radiative systems operate at higher frequencies than inductive systems (> 1 GHz), and suffer a (1/distance)2 propagation loss. High gain antennas can be used to increase the received power, but they become physically large. The use of antennas has advantages though. Solid state arrays allow full control of the antenna excitation, which permits scanning and focusing of the beam. This capability relaxes the alignment requirements between the two antennas. Radiative systems can be designed to operate at distances of tens of meters or more.

A disadvantage of radiative systems is that it they are more susceptible to environmental conditions. To minimize loss, a clear line-of-sight in air is desirable. Therefore, this approach cannot be used for
vehicles submerged in water or buried in wet ground. However it can be used for ground vehicles, air vehicles on the ground, or even warfighter packed equipment.

Other issues that must be considered when using electromagnetic energy are safety and interference. Because of the short ranges and relatively low power involved, safety should not be an issue and the interference introduced by a practical WPT system will be limited to same platform (self) interference.

In Phase I of the study (completed in FY14) both approaches were simulated using commercial software. For the inductive case, working at 100 kHz, efficiencies over 90% were achieved at short ranges (less than 30 mm). A frequency of 100 kHz was used to allow the system to operate in seawater without suffering decreased efficiency due to the water resistance. For the radiative approach, the transmission loss between antennas was less than 1 dB at ranges less than 3 m when near field focusing was employed. The results are important because they demonstrate that efficient transmission of energy can take place between the WPT ground station and a client for both approaches.

The next phase in the research is to demonstrate efficient rectifying and battery charging circuits. It includes the design of a practical interface between the coils, and optimization of the rectifying and charging circuit. The demonstration of an inductive system is planned in FY15.
Full Report available at  

Friday, January 16, 2015

Representation of Unmanned Systems in Naval Analytical Modeling and Simulation: What are we really simulating?

Editor's Note: This article is reprinted with permission from the Naval Postgraduate School's "CRUSER News.

By Professor Curtis Blais, faculty at the Naval Postgraduate School's Modeling, Virtual Environments and Simulation (MOVES) Institute. Contact: clblais(at) 

Combat models are used in major assessments such as Quadrennial Defense Reviews for Naval system acquisition and future force structure decisions. For several years, the Navy has been adding capabilities to the Synthetic Theater Operations Research Model (STORM) originally developed by the U.S. Air Force. Similarly, the Army and Marine Corps employ a specific analytical model called the Combined Arms Analysis Tool for the 21st Century (COMBATXXI) to evaluate major proposed changes in materiel and associated warfighting operations and tactics. The CRUSER Charter identifies numerous Naval initiatives for study and development of unmanned systems, such as the Unmanned Carrier Launched Airborne Surveillance and Strike (UCLASS) squadron, Large Diameter Unmanned Undersea Vehicles (LDUUVs), and an integrated Family of Robotic Systems to augment the capabilities of the Marine Air Ground Task Force (MAGTF) / Fleet.

Image Courtesy of NPS MOVES Institute
The Unmanned Systems Integrated Roadmap FY2013-2038 indicates the Presidential Budget for Fiscal Year 2014 was over four billion dollars (covering research, development, test, and evaluation, procurement, and operations and maintenance). With such current initiatives and high-valued expenditures occurring with respect to unmanned systems, there is concern that expected improvements to warfighter effectiveness, through tactics, techniques, or procedures, are not well supported by analytical processes and findings.

Initial investigation of models such as STORM and COMBATXXI that support studies for major decisions indicates that these simulations are largely deficient in representations of such emerging systems. Without such representations, it is not possible
to conduct studies investigating future force structures (e.g., 2020 and beyond) involving significant employment of unmanned systems. Instead, it appears that decisions are being made without an analytical basis that can show the benefits, limitations, and challenges (manpower, training, logistics,
combat service support, vulnerabilities, etc.) of introduction of such systems into the battlespace.
Starting in late 2014, we began investigating capabilities of these critical Naval analytical models to identify improvements needed in representations of unmanned system capabilities that can improve the scope and value of studies conducted using such tools. This is an initial effort to bring improved representations of unmanned systems into analytical environments, recognizing that it is part of a larger need to bring such representations into gaming environments for concept exploration, into constructive simulations for experimentation and mission planning, and into training environments for low-level (operator) to high-level (staff) skill development.

Interestingly, the initial research is raising a new thesis—that current analytical models actually possess, though unintentionally, a higher fidelity representation of autonomous systems than they do of human-operated systems! If this is true, users of current models must change their perspectives considerably. It is well recognized that a major challenge in modeling and simulation is representation of the human element in combat, reflecting human characteristics such as training, fatigue, unit cohesion, intuition, etc. The lack of such modeling extends to the operation of systems by humans, including the operation of robotic systems (teleoperated). In many respects, it may be argued that current models of the battlespace provide a reasonably accurate depiction of diverse land, air, sea autonomous systems interacting in the battlespace, while poorly representing the human element in the operation of warfare systems. How this change in perspective in understanding the capabilities and validity of current models will affect the modeling & simulation and analytical communities remains to be seen but clearly needs further study. A key issue becomes determining how to better distinguish humans and human-operated systems from autonomous systems so that the models can more correctly represent all of these systems, and their interactions, in the battlespace.

Monday, January 12, 2015

Largest Autonomous Underwater Vehicle Swarm

Researchers at Austria's University of Graz have demonstrated the largest collection of swarming autonomous underwater vehicles with their Collective Cognitive Robots (CoCoRo) project.  A total of 41 autonomous underwater vehicles (AUVs) were assembled for recent swarm testing at the University's Artificial Life Lab. Though funded by the European Union's Seventh Framework Programme for Research (FP7) with the intention of developing civilian innovations for environmental monitoring and research, CoCoRo has implications for future military unmanned underwater vehicle swarm activity. 

Under development since 2011, CoCoRo's swarm demonstration consists of three types of robots: Jeff is an agile fish-like robot with various pressure and magnetic sensors for obstacle detection, avoidance, and navigation.  The swarm also featured 20 saucer-shaped Lily robots that randomly search for objects while communicating with each other using blue-LED lights.  The final robot is a semi-submersible catamaran base station which serves as a platform for the vehicles to autonomously dock allowing the swarm to communicate its location (via GPS) and activities with humans as well as to other base stations.  Eventually, using this method, swarms in multiple geographic areas could coordinate search areas with one another. A dock could also provide a future means to recharge the AUVs and transport them from one location to another.
Bio-inspired algorithms enable the swarm to work together to locate magnetic targets and aggregate around them.  On a larger scale, this behavior has viability for naval unmanned underwater vehicles that could be used in underwater surveys, search and recovery, or mine counter-measures operations

Sunday, December 28, 2014

2014: The Year in Naval Drones

It's time for our annual wrap-up of the stories on unmanned naval systems that most resonated on this site, social media feeds, and the public writ large.  Here are the top naval drone stories of the year:

The introduction of UAVs for maritime missions by non-state actors, specifically migrant rescue and anti-piracy, became reality.

The Royal Navy established a UAV Squadron to intitutionalize its ScanEagle operations.

Despite continued operational testing with the X-47B prototype, politics and indecision created further delays with the U.S. Navy's UCLASS RFP (still not released by the way).

Unmanned systems were key in the Malaysian Airlines Flight #370 Search.

The MQ-8C Fire Scout made significant strides towards its first operational deployment.

The U.S. Navy's Swarming USV program, really a plug and play unmanned craft system, garnered significant interest.

Interestingly, the story that seemed to pick up the most momentum in non-military circles was the Navy's Ghostswimmer UUV.  And that's interesting because this system is neither really new, nor particularly likely to ever be employed operationally.