Unmanned Systems Maritime Search and Rescue: IVER3 AUV

OceanServer. (n.d.). IVER3 [digital image]. Retrieved from www.iver-auv.com/AP_003_Iver3.pdf

The US Navy deployed three IVER3-580 Autonomous Underwater Vehicles (AUV) to Argentina during the recent search for the Argentine submarine A.R.A. San Juan, missing in the South Atlantic Ocean since November 15th (US Navy, 2017).  The IVER3 AUV can operate at depths of up to 100 meters at speeds of up to 4 knots for up to 14 hours (Overview, 2017).  Active search sensors include a side scan sonar, which is utilized to obtain an image of the ocean floor to detect objects, and a swath bathymetry sonar to map the depth of the ocean floor below the vehicle (IVER3, n.d.).  Navigational sensors include GPS for fixing the vehicle’s location on the surface, a doppler velocity log (DVL) and inertial navigation system (INS) for determining vehicle location under the surface, and a forward-looking echo sounder in the bow for collision avoidance (IVER3, n.d.).  The vehicle can also be equipped with LED lights and a GoPro camera for obtaining photos or videos (IVER3, n.d.).  Together these sensor systems are utilized to sweep a given area, detect possible objects of interest, and obtain imagery of these objects.

OceanServer. (n.d.). IVER3 Sensors [digital image]. Retrieved from www.iver-auv.com/AP_003_Iver3.pdf

The IVER3 has multiple proprioceptive and exteroceptive sensors designed for the maritime environment.  Maritime proprioceptive sensors, or those which provide the vehicle with an internal status and orientation, include GPS with Wide Area Augmentation System (WAAS) correction (increased accuracy) for navigation on the surface, and a DVL, depth sensor, and compass for subsurface navigation (IVER3, n.d.).  While not specifically stated, it is likely that the vehicle also has a voltmeter for determining remaining battery life, a shaft counter for determining shaft RPM for comparison to vessel speed, and onboard fail safes designed to direct the vehicle to surface in the event a fault is detected.  Marine exteroceptive sensors, those used for determining relative position underwater to neighboring objects via active or passive means, include side scan sonar, a swath bathymetry sonar, and forward-looking echo sounder.  These active sensors all use sound waves to detect objects underwater, as visibility underwater can often only be measured in feet or inches. 

While the IVER3 is an extremely capable AUV, the vehicle’s 100 meter, or 328 foot, depth rating limits the effectiveness for detection of submerged objects in all but relatively shallow ocean water.  This is considerable considering that the Bluefin 12D, also utilized by the US Navy in the search for the A.R.A. San Juan, can operate at a depth of 5000 feet (US Navy, 2017).  Increasing the depth rating for the IVER3 will expand the vehicle’s effective operational area and increase its effectiveness during offshore, underwater search and rescue operations.  It is important to note that greater depth ratings are available, although a maximum rating is not stated by OceanServer, the manufacturer of the IVER3 (Overview, 2017).   

There are several ways an AUV such as the IVER3 could be used with an Unmanned Aerial System (UAS).  For one, the UAS could provide the AUV operator with position updates from the AUV while the mission progresses.  This could be accomplished either by the AUV surfacing and broadcasting its position to the UAS, or using a towed array which would float on the surface and provide a position signal from the AUV to the UAS, which the UAS would then broadcast to the operator.  The opposite could also be true; the UAS could also pass updated GPS position data to the AUV while it remains underwater.  However, this would be most effectively used for an AUV capable of week to month long underwater durations, as there would likely be minimal position drift given the IVER3’s maximum underwater endurance of 14 hours.  As the IVER3 is equipped with wireless 802.11n ethernet, it would also be possible to utilize a UAS to receive wireless data downloads from the AUV without a need for the AUV to return to the launch point to download acquired data (Overview, 2017).  The UAS could then either transmit this data to the operator or return to the operator to have the data downloaded.  Lastly, the UAS and AUV could work in conjunction, with the UAS searching for surface debris fields, and then directing the waiting AUV to the location of the detected debris so that additional underwater searching can commence.

Finally, the use of AUVs is significantly more advantageous then the use of manned underwater vessels for underwater search operations.  For one, the small size of AVUs such as the IVER3 enable the vessel to operate in extremely shallow water only a few feet deep to water hundreds of feet deep.  Due to their size, manned underwater vessels would be limited to water depths measured in tens of feet, limiting their operational flexibility.  AUVs are also more compact than manned underwater vessels, enabling the AUV to be rapidly transported and deployed, whereas large manned vessels could take days or weeks to transit to a search area.  AUVs are also less expensive to operate than manned vessels which require large pressure hulls, as well as complex oxygen and environmental systems for crew survivability in the ocean’s depths.  Most importantly, AUVs do not need to rest or be fed, enabling the vehicle to operate non-stop collecting data; they are limited only by the amount of fuel or electrical power that can be stored onboard.  While manned and unmanned, or autonomous, underwater vehicles can be equipped with identical sensor systems, such as sonar, unmanned systems can employ these sensor systems in water depths not suitable for manned vessels, as mentioned above.  The smaller size of unmanned systems also enables them to operate more easily in tightly confined areas or to access formations such as underwater caverns that would be too small for manned vehicles to access.  Detection of sensitive magnetic fields using a magnetometer is also more advantageous with an AUV as opposed to a manned vehicle due to the near elimination of ferrous metals, used in pressure hull construction, which could disrupt readings.  

References

IVER3. (n.d.). Retrieved from http://www.iver-auv.com/AP_003_Iver3.pdf.

Overview: Iver 3-580-Standard AUV. (2017). Retrieved from http://www.iver-auv.com/iver3S.html.

US Navy Deploys Unmanned Submersibles in Argentine Submarine Search. (2017). Retrieved from http://www.navy.mil/submit/display.asp?story_id=103420.