Using AUVs in Under-Ice Scientific Missions James Ferguson, International Submarine Engineering Ltd. Presented at Arctic Change 08 11 Decenber 2008- Quebec City, Canada 1/16
ISE s s Experience in Arctic AUV Operations Preparation for AUV Surveys in the Lincoln Sea in support of Canada s s UNCLOS Submission 2/16
International Submarine Engineering Ltd (ISE). Canada s s Underwater Vehicle Company Founded in 1974 Located in Vancouver, BC 65 employees 220 Vehicles built including 28 AUVs 3/16
4/16 Autonomous Underwater Vehicle - What is it? Telescoping communications mast Lifting Lug Acoustic Communications Pop up recovery buoy and lift line Aft Control Surfaces Access port for data recovery and charging Free-flooding control bay Pressure hull with power source, vehicle control and dry payload Forward Control surfaces Free flooding payload bay Drain ports Principal Features High speed, stable survey platform Small footprint Low cost Major Limitations Low power Low bandwidth
USE of AUVs Under the Ice Primary reason is to go where manned systems cannot go Most work with AUVs has been done from the edge of the ice shelf - Requires a ship in attendance - Difficult to survey large areas due to fixed starting position On-ice operations do not require a ship but do need other infrastructure such as an aircraft or helicopter On-ice operations will be used in UNCLOS surveys - Large areas to be surveyed - Inability to reach survey area from the ice-shelf - success of DRDC and ISE s s 1995-6 6 operations AUV surveys will provide rapid area coverage and high resolution data 5/16
Payload computers Terrain based navigation Mission Management (adaptive ) Synthetic Aperture Sonar integration Hydrodynamic modelling High Bandwidth radio comms 1980-22 Lancaster Sound ice camps. ROV Ops 1982-33 Lancaster Sound ice camps. AUV development 1991-44 Alert, Lincoln Sea ice camps. AUV development 1995-66 Lincoln Sea ice camps. Theseus AUV operations Current Areas Arctic Experience of Research 6/16
Payload computers Terrain based navigation Mission Management (adaptive ) Synthetic Aperture Sonar integration Hydrodynamic modelling High Bandwidth radio comms Joint US-Canada - DoD project (DRDC and Spawar) Fibre Optic Cable Laying Vehicle designed, built and tested in 15 months Equipment built to be mobilized to Alert, Nunavit with CC130 Hercules, and to ice camps with Twin Otter or Bell Jet Ranger Tested in Arctic in 1995. Several cable laying missions in 1996. 96. Up to 460 km. Insured by Lloyd s s of London Current Areas of Research Theseus AUV Program 7/16
Length 10.7m Power 360 kwh AgZn battery Diameter 127 cm Navigation Honeywell INU EDO Western DVL Paroscientific Depth Gauge Weight 8600 kg Positioning Trackpoint II USBL Speed 4 knots Homing Datasonics iusbl Range >1350 km Avoidance Not used Cable 220 kg Payload 550 kg dry, 1910 wet Design December 1993 to June 1994 Fabrication May 1994 to September 1994 Open Water trials October 1994 to February 1995 Arctic Operations March and April 1995 and 1996 Theseus AUV Characteristics and Development Schedule 8/16
9/16 Theseus AUV Operations - 1995 and 1996 Modular design easily assembled and broken down on ice Design required all modules to fit through the door of a Twin Otter ter (DHC 6) Operations conducted through holes melted through the ice Launched with an overhead gantry Water depths during mission 70 to 850 meters Inverted USBL used by AUV to home in on recovery point Vehicle parked on bottom under ice hole, recovery lines attached with ROV
1990 s s AUV Operations What We Found Out Environment under-ice environment not well characterized - ambient noise levels - tidal currents - pingos and ice keels Navigation and Positioning State of the Art Not up to Under-Ice Ops - obstacle avoidance sonar - doppler velocity log (DVL) - small AUV size Inertial Navigation Unit (INU) - inverted USBL - GPS New Procedures for Operations must be Developed and Practised - Launch and recovery, - Lost vehicle location and recovery - INU alignment 10/16
The Navigation Challenge - Picking the Right Hardware Limit of Permissible AUV Navigational Error b a Planned Path of AUV x d a Launch Point a,b Limiting Line of Navigational Error a,c Limiting Line of Navigational Error d Recovery point x Range of Homing Transducer c 1990 s s Navigation system consisted of an aircraft quality RLG coupled with a DVL with assumed accuracy of 1% of distance travelled Positioning with ORE Trackpoint USBL and homing with a Datasonics s USBL assumed range about 5 to 6 km. Actual accuracy was better ~ 0.4% of distance travelled and homing range was as predicted. Tidal currents at recovery site ~ up to 2.8 knots! No ice movement Launch and recovery from shore fast ice 11/16
2009-2011 Operations using ISE Explorer AUVs Supporting NRCan UNCLOS Survey Requirements NRCan Explorer AUV Length 6 meters Diameter 0.7meters Weight 1800 kg Depth 5000 meters Range 425 km 2009 - Tests with Memorial University 3000 meter AUV 2010-11 11 Ops with NRCan 5000 meter AUVs 12/16
Position and Tracks do not represent actual mission plans 13/16
2010 AUV Operations What We are Finding Out Environment under-ice environment not well characterized - ambient noise levels - tidal currents - pingos and ice keels Navigation and Positioning State of the Art Not up to Under-Ice Ops - obstacle avoidance sonar - doppler velocity log (DVL) - small AUV size Inertial Navigation Unit (INU) - inverted USBL - GPS New Procedures for Operations must be Developed and Practised - Launch and recovery, - Lost vehicle location and recovery - INU alignment 14/16
The 2010 Navigation Challenge Limit of Permissible AUV Navigational Error b a Planned Path of AUV x d a Launch Point a,b Limiting Line of Navigational Error a,c Limiting Line of Navigational Error d Recovery point x Range of Homing Transducer c Navigation system based on IxSea INU coupled with an RDI DVL with assumed accuracy of 1% of distance travelled. Expect to do much better Positioning and homing with a Teledyne Benthos Low Frequency ATM - assumed range about 10 to 15 km. Tidal currents unknown. Ice movement expected to be ~ 1 km per p day Tests in 2009 to validate development assumptions as well as those for Plan B Plan B includes higher accuracy INUs, longer range positioning and homing systems 15/16
Conclusion The 2009-2011 AUV survey seasons should significantly augment the data being collected to support the Canadian submission to UNCLOS. Our hope is that the technology, procedures and know-how that are developed to undertake this project will be retained for more complete seabed mapping operations of the Lincoln Sea and other ice-covered covered regions of the Arctic. 16/16