Autonomous underwater mappingusing terrain- and sonar navigation
Ove Kent HagenForsvarets forskningsinstitutt, FFI
Geodesi- og hydrografidagene 2014Sola, 13. november 2014
Outline
• HUGIN AUV and underwater mapping– Underwater navigation– Mapping sensors
• Data-driven navigation techniques– Terrain navigation– Sonar navigation
• Autonomous mapping concepts– Autonomous survey– Autonomous mine hunting
• Plans
AUV research at FFI
Batteries
SAS
Autonomy ATRNavigation
Camera
Underwater mapping
Global referenced vehicle position and orientation+
Sensor data referenced in vehicle reference frame– Sensor processing: acoustic signals to bathymetry– Lever arms and reference systems alignments– Time synchronization
= Global referenced sensor data
Ormen LangeNorsk Hydro
Sigsbee, Gulf of MexicoC&C Technologies
Sensors near sea floor- High resolution- Increased stability
< 800 m < 2400 m
HUGIN AUVKongsberg Maritime
NavPReal-time system on HUGIN AUVs
NavLab (commercially available)Post-processing, simulation, analysis and development
HUGIN Navigation System
AUV Navigation
Problem: GPS does not work under water!
Solution:- Inertial navigation system (INS)- Aided by any available sensor
State-of-the-art DVL-aided INS for AUVs
AUV trajectory
Elliptic Position Uncertainty
Honeywell HG9900• 0.8 nm/h• 0.003 °/h
Doppler Velocity Log (DVL) Inertial Measurement Unit (IMU)
WHN 600• 0.2% • ±1mm/s
- Orientation found by processing accurate accelerometers and gyros - Position drift:
~ 0.1% travelled distance, straight line~ 0.01% travelled distance, lawn mower pattern, 1km lines
IMU
+DV
L
DVL
Navigation post-processing (NavLab): Simulated Survey
Trajectory
Estimated postionaccuracy (1σ)
Green Real-time pos acc (1σ)Red Post proc pos acc (1σ)
GPS-fix
AUV navigation autonomy levels
• Supervised– AUV may be commanded– Requires infrastructure for positioning– E.g.: Mother ship with GPS and acoustic tracking
of AUV (USBL)
• Semi-autonomous– AUV operates autonomously– Requires infrastructure for positioning– E.g.: GPS-fix, GPS-buoy transponder navigation,
sea floor transponder navigation, …
• Autonomous– AUV operates autonomously– No infrastructure for positioning– E.g.: terrain navigation, sonar navigation, …
GPS
USBL
Transpondernavigation
TerrainNavigation
Mapping sensors
EM 3000Multibeam echosounder
HISASSynthetic Aperture Sonar Combined
SAS imaging and bathymetry
Courtesy Royal Norwegian Navy
Courtesy Royal Norwegian Navy
Resolution > 2 cm Resolution ~ 6 cm
SAS Image SAS Bathymetry
SAS image fused with bathymetry
Holmengraa sunk 1944 outside Horten
Terrain navigation with loose INS coupling• Search area based on INS estimate• Correlate bathymetric
measurements with an a priori known digital terrain model (DTM)
• Find best position estimate within search area
• Send position estimate and accuracy to the INS
HUGIN Terrain Navigation SystemCommercially available for HUGIN AUVs
TerrLab: simulation, development, analysis and post-processingTerrP : real-time system
Point Mass Filter
Hagen & Ånonsen, MTS/IEEE OCEANS 2010, Seattle
HUGIN AUV, Barents Sea, 2009Test of terrain navigation during long covert transit in open sea
• DTM from EM710 with 10 m resolution
• Straight line transit ~50 km or ~27 nm
• HUGIN navigated autonomously, monitored on USBL
• ~ 4 m difference at end of transit
East [km]
Nor
th [k
m]
-18 -16 -14 -12 -10 -8 -6 -4 -2 0
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
300
310
320
330
340
350
360
370
380
390
East [m]
Nor
th [m
]
-5 0 5 10
-15
-10
-5
0
5
10
HUGIN INS
USBL
HUGIN AUV, Oslo fjord, 2010Test of covert transit in fjord
10.5 10.55 10.6 10.65 10.7
59.18
59.2
59.22
59.24
59.26
59.28
59.3
59.32
59.34
59.36
0
5
10
100
350
Bolærne
←Åsgårdstrand
• DTM created from EM710: 10 m resolution
• TerrP used only DVL (4 beams)
• HUGIN navigated autonomously for ~5 hours (about 36 km), monitored on USBL
• The difference between HUGIN’s GPS and the INS after resurfacing was ~ 5 m
Ånonsen & Hagen, MTS/IEEE OCEANS 2010, Seattle
East
Nor
th
-155
-150
-145
-140
-135
1.42 1.43 1.44 1.45 1.46 1.47 1.48 1.49 1.5 1.51
x 104
0
100
200
300
400
500
600
700
Eastings [m]
Nor
thin
gs [m
]
Navigation solution and TerrNav position fixes, meters
NavPNavLabTerrP RQTerrP OK
Mappingmode
Navigation mode
HUGIN AUV, Larvik, 2011Test of local covert terrain navigation
• Map built in-mission at start• Used for navigation upon return
East
Nor
th
-160
-155
-150
-145
-140
-135
EM 710H.U. Sverdrup II
EM2000HUGINin-mission
Ånonsen & Hagen, MTS/IEEE OCEANS 2011, Kona
H.U. Sverdrup II, West Coast fjords, 2013Test of terrain navigation against simulated GPS jamming/spoofing
Hagen & Ånonsen, MTS Journal, vol 48(2), 2014
Line-by-line terrain navigation• Use of sparse maps - search area only partially covered• Estimate position difference along the line• Simulation results (conservative)
– Side scan bathymetry (~1 m res) with SAS DTM (~ 0.18 m res)
10.426 10.427 10.428 10.429 10.43 10.431 10.432 10.433 10.434 10.43559.4675
59.468
59.4685
59.469
59.4695
59.47
59.4705
59.471
59.4715
0 20 40 60 80 100 120 140 1600
2
4
6
8
10
12
14
Time [s]
RM
S S
tdD
ev[m
]
20% overlap30% overlap50% overlapSAS Line DTM SSB measurements
Overlap
Sonar ATR navigation
Automatic target recognition (ATR) – association - invariant to poseEstimates position difference
0 0.5 1 1.5 2 2.5 3 3.5-10
-5
0
5
Time [h]
y [m
]
DVLDVL+FBNFeature Observations
0 0.5 1 1.5 2 2.5 3 3.5-10
-5
0
5
Time [h]
Horizontal position error and std (1σ)
x [m
]
DVLDVL+FBNFeature Observations
Feature-based sonar navigation
Feature tracker, similar pose, line-by-lineEstimates position and heading difference
Resolution 4 cm x 4 cm
Autonomous mapping: survey
Supervised mappingwith GPS+USBL
Cross-line autonomous navigation and mapping: - DVL-aided INS- Terrain navigation- Sonar ATR navigation Supervised mapping
with GPS+USBL
Line-by-line autonomous navigation and mapping:- DVL-aided INS- Terrain navigation- Sonar navigation
• Accurate real-time navigation required to ensure coverage • Navigation accuracy requirements to be met by post-processing• Navigation post-processing inherently increases mapping data consistency
Autonomous mapping: mine hunting
Transit 1
DVL-aided INS
Line-by-line terrain- and sonar navigation
Detection
Transit 2
DVL-aided INS
Independent global position error
Detect & Classifyby SAS image
Identify byoptical image
FFI Plans 2014/2015
• Finish development of line-by-line terrain navigation delta measurements– SSB measurements vs SSB DTM line– SSB measurements vs SAS line DTM– SAS line bathymetry vs SAS line DTM
• Finish development of line-by-line feature tracker based sonar navigation delta measurements
• Integrate the delta measurements with NavLab4, navigation post-processing
• Test on dedicated data set collected in Barents Sea 2014
Can also be used in real-time
Questions?http://www.ffi.no/no/Forskningen/Avdeling-Maritime-systemer/hugin