Friday, October 12, 2012

Future Drone Power - Part III: Fill'r Up

Bluefin-9 AUV (Bluefin Robotics)
As a follow-up to our posts on powering drones in the future, Bluefin Robotics recently announced a unique concept: deep sea stations that recharge autonomous underwater vehicles.  The system is designed to wirelessly charge a Bluefin 9 AUV's 1.5 kWh lithium-polymer Subsea Battery using inductive coils. In addition to recharging the vehicle, the system has the added bonus of downloading data from the vehicle and transmitting it back to a home base.  The glut of data collected by modern 2 and 3D imaging sonars will require this sort of flexibility on long endurance AUV missions.

The future naval implications of this technology are expansive, however the actual implementation might be challenging.  The system would work well in a permanent installation with AUVs on patrol keeping keep a navy port clear of mines or swimmers.  In an expeditionary environment for say a mine-hunting mission, recharging stations might be installed by buoy tenders and kept powered from surface buoys with solar panels.  Alternatively, a variant of the system could be installed aboard submarines, in which a UUV could swim in, charge up/download data, and swim out.

Tuesday, October 9, 2012

Israeli Shot-Down Drone Sea Launched?

Sea-launched Ababil UAV
Much speculation has occured regarding the mystery UAV the Israeli Air Force shot down over the Negev Desert last Saturday.  A number of interesting theories have been proposed, including those connecting the drone with naval activity:
  • The Hezbollah-affiliated al-Mayadeen channel reported Sunday that the drone originated in Lebanon and flew 100 km into Israeli airspace, however the United Nations Interim Force in Lebanon did not detect any UAVs leaving Lebanese airspace.  Lebanese Hezbollah (LH) has been bolstering its UAV force with Iranian built tactical UAVs, so it might be possible that an aircraft flew undetected through across the border.  The Israelis confirmed the drone did not originate in Gaza and some sources to point to Lebanon.  The problem is that the aircraft would have flown at least 200 km and LH probably doesn't possess any UAVs in the inventory capable of this range.
  • Twitterati @drunkenpredator speculates that the aircraft might have been an Ababil 3, launched at sea from a small fishing boat or other craft.    Some reports indicate that the aircraft arrived in Israeli airspace from over the Mediterranean, flying west to east. The Ababil (max range likely 150 km) can be launched from a tiny footprint using a pneumatic rail or rocket boosters and has been tested at sea by the Iranians.  This theory seems unlikely though, in that it appears there is no way for the Ababil to recover at sea.  Non-state actors, even those as well-kitted as LH, would be unlikely to use a limited inventory of these valuable assets for one-way trips.  And although LH has demonstrated maritime capacity in the form of anti-ship missiles and cargo ships to smuggle said weapons, they likely don't have a real surface capability, even using small craft.
  • It was an American carrier-launched UAV!  This would be interesting indeed, but completely implausible given there are currently no U.S. CVNs in the Mediterranean.
  • Here, more speculation that the unidentified aircraft came from a ship - a space ship.  I'm going go with a no on this one.
Israeli CH-53s examine UAV wreckage. (Hiam Horenstein)
So where exactly did the mystery UAV orginate?  The UAV's wreckage has been recovered and forensics are underway, and it's likely there is some close-up gun-camera footage (possibly from the F-16 that fired the missile, rather than the one that filmed the released video of the shoot-down) which would enable the Israelis to identify the type of UAV.  Whether or not they publicize that information is another question. The Lebanon origin point sounds like the most likely option.  LH may have flown the UAV over the sea to avoid land-based air detection and vectored it into shore once it reached the target area in Israel.  It would not be far-fetched that LH lost communications with an Ababil or other tactical UAV and the drone just kept flying to its maximum physical range.  Alternatively, the UAV might represent an Ababil modified to fly longer ranges or some other identified vehicle. 

Undersea Vehicle Navigation and Autonomy

Changing operational and environmental factors will drive future unmanned naval systems away from remote operation and towards autonomy.  Today, a man-in-the loop is generally required to re-task platforms as the weather deteriorates, operational priorities shift, or maintenance problems occur.  Automation will allow dynamic retasking to take place without human intervention. Additionally, unmanned systems will increasingly operate beyond line-of-sight from their controllers and in areas prone to GPS or other electronic jamming, spoofing, and interference by adversary forces.   Moreover, as noted in the U.S. Air Force’s 2010 Science and Technology Roadmap, autonomous vehicles will enable “operational advantages over adversaries who are limited to human planning and decision speeds.”  Unmanned Underwater Vehicles (UUVs) require automation for the reasons mentioned above plus the simple fact that normal methods of navigation such as GPS do not work due to the limitations of electromagnetic propagation underwater. 

The most fundamental function of vehicle autonomy is the ability to safely navigate from point a to point b without human intervention.  Recognizing the need for non-GPS methods of navigation, the Office of Naval Research issued a Broad Area Announcement back in 2009, calling for research on "new and innovative navigation technologies that will provide more accurate, reliable, maintainable and affordable systems for Naval air, surface, subsurface, and ground platforms and forces." Last week, ONR awarded a $1.2 million contract to Pennsylvania State's Applied Research Laboratory to develop a bathymetric navigation system which could work on UUVs and submarines.  The basic concept of bathymetric navigation dates back hundreds of years to when mariners used a lead line to test the depth of a channel to ensure safe passage.  In modern terms, the technology is the underwater equivalent of the Tomahawk Land Attack Missile's Digital Scene Matching Area Correlation (DSMAC), which compares a stored image of a scene as the missile flies over the ground with a digital photo the missile snaps.  Bathymetric navigation will require detailed ocean floor maps and advanced imaging sonars such as those from Blueview (see above).

ONR is also exploring LIDAR for underwater navigation.  Blue/green lasers penetrate the water column best and can produce higher resolution than sonar, with some systems claiming to resolve details to 1mm.   LIDAR ocean mapping can even be performed from the air, although water clarity and depth can effect the laser's ability to reach the ocean floor.  One of the drawbacks of bathymetric navigation, regardless of sensor type, is that the surface of the ocean floor is dynamic and charts require constant updating due to seismic activity, marine growth, man-made construction, and debris.
Another navigation method, acoustic positioning, measures range and bearing to fixed sea floor transponders, similar to an underwater GPS system.  This technology (see Sonardyne video) has been successfully used for autonomous underwater vehicle navigation in the offshore oil industry and is another possibility for future naval AUVs. 

Monday, October 8, 2012

DARPA RQ-4A Air-to-Air Refueling Program Analysis

Air-to-air refueling (AAR) has been commonplace in manned aviation for more than six decades.  Today, remotely piloted vehicles fly hundreds, and sometimes thousands of miles from their launch bases to for intelligence, surveillance, and reconnaissance missions.  The inability to refuel in-flight limits time on station and increases the number of aircraft required to surveil a given target location.  DARPA's KQ-X program, initiated in 2010, was designed to prove the technologies required to refuel UAVs in-flight.

DARPA has released videos of the close-proximity test flight of two modified RQ-4A Global Hawk unmanned aerial vehicles.  The final test flight last May demonstrated the ability of close formation flight for most of a 2.5-hour engagement at 44,800 feet.  Although the UAVs did not actually pass fuel, post-flight analysis indicated that 60% of  attempts would achieve contact between the
"Navy style" refueling probe and drogue. 

Perspective from receiving aircraft.
Perspective from drogue-equipped aircraft.
This article in Air Force magazine provides an interesting background on the history and technical aspects of the program.  The Navy's Unmanned Combat Air System (UCAS) Aircraft Carrier Demonstration (UCAS-D) program has utilized a surrogate Boeing F/A-18D equipped with X-47B avionics to test AAR technologies.  NAVAIR plans to perform an actual air-to-air refueling with an X-47B in 2014.  The follow-on UCLASS program will likely be the first system to use this technology operationally.