CG—D—21—93
`
`Technical Survey and Evaluation of Underwater
`Sensors and Remotely Operated Vehicles
`
`Wi
`
`“-7-
`_—:_____—:
`
`7%
`
`Bradley G. DeRoos
`Grant Wilson
`
`
`
`
`
` Report No.
`
`
`i
`
`
`
`l"ii‘1
`MW
`
`
`
`
`
`Fred Lyon
`
`
`William S. Pope
`
`
`
`BATTELLE
`
`
`505 King Avenue
`
`FINAL REPORT
`
`May 1993
`
`
`
`Columbus, Ohio 43201 -2693
` U
`
`
`National Technical Information Service, Springfield, Virginia 22161
`
`This document is available to the U.S. public through the
`
`
`
`
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`
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`
`
`
`
`
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`
`
`9 4
`1
`1 4
`0 8 6 RAY-1008
`
`Prepared for:
`
`U.S. Coast Guard
`Research and Development Center
`1082 Shennecossett Road
`
`Groton, CT 06340-6096
`mm
`
`.3
`
`)
`
`I \.711,9,‘.,"0 1,6?8
`thimMMWMMl
`
`
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`U.S. Department of Transportation
`United States Coast Guard
`Office of Engineering, Logistics, and Development
`Washington, DC 20593-0001
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`Page 1 of 324
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`

`

`
`
`NOTICE
`
`This document is disseminated under the sponsorship of the
`Department of Transportation in the interest of information
`exchange. The United States Government assumes no liability
`for its contents or use thereof.
`
`The United States Government does not endorse products or
`manufacturers. Trade or manufacturers’ names appear herein
`solely because they are considered essential to the object of
`this report.
`
`The contents ofthis report reflect the views of the Coast Guard
`Research 8: Development Center. This report does not consti-
`
`tuteastandard,specification,[Mm
`
`D L. Motherway
`Technical Director, Acting
`United States Coast Guard
`
`Groton, CT 06340-6096
`
`Research 8: Development Center
`1082 Shennecossett Road
`
`__..J
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`RAY-1008
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`Page 2 of 324
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`
`
`1. Report No.
`CG-D—21-93
`
`4. Title and Subtitle
`
`
`2. Government Accession No.
`
`Technical Survey and Evaluation of Underwater Sensors
`and Remotely Operated Vehicles
`
`Battelle
`
`3. Recipient's Catalog No.
`
`Technical Report Documentation Page
`
`
`
`5. Re
`rtDate
`p0
`May 1993
`
`6. Performing Organization Code
`
`8. Performing Organization Report No.
`R&DC 17/93
`
`10. Work Unit No. (TRAIS)
`
`11. Contract or Grant No.
`
`
`
`
` 7. Author(s)
`
`
`Bradley G. DeRoos. Grant Wilson, Fred Lyon, William 3. Pope
`
`9. Performing Organization Name and Address
`
`
`505 King Avenue
`DTRS-57—89-C-00006
`
`
`Columbus. OH 43201
`
`
`13. Type of Report and Period Covered
`
`Final Report. November 1992
`
`
`12. Sponsoring Agency Name and Address
`to May 1993
`
`
`
`14. Sponsoring Agency Code
`Department of Transportation
`us. Coast Guard
`
`U-S- 0085* Guard
`Research and Development Center
`Office of Engineering, Logistics,
`1032 Shennecossett Road
`
`and Development
`Groton. CT 06340-6096
`
`
`20593-0001 Washington, o.c.
`
`15. Supplementary Notes
`
`0
`
`16. Abstract
`
`This report was developed under the technical direction of
`LT Michael J. Roer, USCG Research and Development Center.
`
`Accurate on-site assessment of vessel hull damage in the event of gr0unding, collision, structural
`failure, or other accident is required to make timely and informed decisions relating to vessel
`disposition (1.9., Iightering, towing, sinking.) The capabilities of underwater vehicles and sensors as
`they relate to the performance of damage assessment are analyzed in this report. The vehicle types
`analyzed include free-swimming remotely operated vehilces (ROVs). autonomous undersea vehicles
`(AUVs), towed vehicles, crawling vehicles. and composite vehicles. The sensor types analyzed include
`photographic, video. laser, and acoustic imaging systems, oil/water interface sensors, oil
`concentration monitors, and non-destructive test methods. A conceptual inspection vehicle system is
`presented based on an evaluation of the damage assessment mission.
`
`.
`
` .
`
`17' K°Y WW“
`
`,
`Marine Inspection
`Vessel inspectlon
`Remotely Operated Vehicles
`imaging Sensors
`
`.
`
`19. Security Classif. (of this report)
`
`UNCi ASSIi-lt—l)
`
`Form DOT F 1700.7 (8/72)
`
`.
`
`
`
`Document is available to the US. public through
`the National Technical Information Service,
`Springfield, Virginia
`22161
`
`
`
`
`20. SECURlTY CLASSIF. (at this page)
`22, Price
`
`
`21. No. of Pages
`31 8
`
`
`
`UNCLASSIFIED
`
`Reproduction of term and completed page is authorized
`,
`_
`RAY-1008
`U l
`Page 3 of 324
`
`18. Distribution Statement
`
`

`

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`

`

`
`
`TABLE OF CONTENTS
`
`1.0 INTRODUCTION ..............................................
`
`1.1 Statement of the Problem .....................................
`
`1.2 Objectives ...............................................
`1.3 Organization .............................................
`1.4 Investigation and Analysis Techniques .............................
`
`1.4.1 Literature Search and Market Survey ........................
`1.4.2 Conceptual Design Development ..........................
`1.4.3 Multifactor Evaluation Process ............................
`
`2.0 MISSION ANALYSIS ............................................
`
`2.1 Oceanographic and Environmental Conditions ........................
`
`2.1.1 Primary Environmental Conditions .........................
`2.1.2 Secondary Environmental Conditions ........................
`2.1.3 Geographic Areas ....................................
`
`2.2 Operator Survey Analysis .....................................
`2.3 Ship Damage Categorization ...................................
`
`2.3.1 Accident Causes and Effects .............................
`
`2.3.2 Hole and Crack Distribution Analysis .......................
`
`Base
`
`1
`
`l
`
`l
`2
`3
`
`3
`3
`6
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`7
`
`7
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`8
`8
`9
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`13
`15
`
`15
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`17
`
`17
`2.3.2.1 Size Analysis ................................
`17
`2.3.2.2 Location and Extent Analysis for Large Vessels ...........
`2.3.2.3 Location and Extent Analysis for Tank Barges ............ 21
`
`2.3.3 Oil Outflow Analysis for Grounding and Collision ................ 23
`2.3.4 Area Coverage Requirements ............................ 25
`
`2.4 Coast Guard Strike Team Casualty Decision Analysis Summary ............. 26
`2.5 Functional Flow Block Diagram ................................. 28
`2.6 Summary of Inspection System Performance Requirements ....... ..........
`29
`
`3.0 SUBSYSTEM EVALUATION METHODOLOGY
`AND TECHNOLOGY OVERVIEWS ..................................
`
`3.1 Muiti-Factor Evaluation Process (MFEP) ...........................
`
`31
`
`31
`
`3.1.1 Description ................................... 31
`3.1.2 Critical Factors and Weighting ............... _ ...........
`3.1.3 Performance Rating Curves ..................... 3 .......... 34
`
`|
`i
`
`3.2 Vehicle System Overview ............................ _1.
`
`. .....
`
`35
`
`3.2.1 Technology Review ................................. 35
`
`3.2.1.1 Free-Swimming Remotely Operated Vehicles ............ 35
`
`37
`3.2.1.1.1 Propulsion .................... .........
`3.2.1.1.2 Navigation ............................ 43
`31.21.13 Command, Control, and Display .............. 45
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`TABLE OF CONTENTS (Continued)
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`Bags:
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`3.2.1.1.4 Deck Handling/Tether Management
`
`......... 47
`
`3.2.1.2 Autonomous Undersea Vehicles (AUV)
`
`............... 47
`
`3.2.1.2.! Hull and Structure ....................... 49
`3.2.1.2.2 Propulsion Systems ...................... 51
`3.2.1.2.3 Power Generating Systems .................. 51
`32.1.2.4 Emergency Systems ...................... 53
`3.2.1.2.5 Control/Programming ..................... 53
`3.2.1.2.6 Communications ........................ 58
`32.1.2.7 Instrumentation ......................... 59
`
`32.1.2.8 Deployment and Recovery .................. 60
`3.2.1.2.9 Summary ............................ 61
`
`3.2.1.3 Towed Vehicles ............................... 66
`
`3.2.1.4 Crawling Vehicles ............................. 70
`3.2.1.5 Specialized Vehicles (Crawler/Swimmer) ............... 73
`
`3.2.2 Summary .........................................
`3.3 Sensor System Overview .....................................
`
`3.3.1 Technology Review ..................................
`
`74
`74
`
`74
`
`3.3.1.1. Photographic/Video Imaging Systems ................. 74
`
`O
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`3.3.1.1.! Television Cameras ...................... 78
`3.3.1.1.2 sun Cameras ..........................
`86
`3.3.1.1.3 Comparison of Photographic/Video Imaging Systems
`.
`86
`3.3.1.1.4 Stereoscopic Video Systems ................. 91
`3.3.1.1.5 Polarization Cameras ..................... 93
`
`3.3.1.2 Laser Imaging Systems .......................... 94
`
`3.3.1.2.1 Lasers for Photographic Size and Range
`Determination ......................... 95
`3.3.1.2.2 Scanning Lasers for Two-Dimensional and Three-
`Dimensional Mapping .................... 98
`3.3.1.2.3 Laser Scanning and Illumination Systems for Image
`Enhancement ......................... 102
`
`3.3.1.2.4 Laser Safety ........................... 109
`
`.
`
`3.3.1.3 Sonar Systems ............................... 109
`
`3.3.1.3.! Side-Scan Sonar ........................ 117
`
`3.3.1.3.2 Forward-Look Sonar ..................... 124
`3.3.1.3.3 Bathymeric Sonar ....................... 129
`3.3.1.3.4 Profiling Sonar ......................... 133
`
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`TABLE OF CONTENTS (Continued)
`
`liege
`
`3.3.1.3.5 3D Mapping Sonars ...................... 139
`
`3.3.1.4 Other Key Sensor Technologies ..................... 142
`
`3.3.1.4.1 Oil Sensors ........................... 142
`
`3.3.1.4.2 Eddy Current Sensors ..................... 143
`
`3.3.2 Summary ......................................... 144
`
`3.4 Oil/Water Interface Sensor Analysis .............................. 145
`
`3.4.1 Technology Review .................................. 145
`
`3.4.1.1 Level Measurement Methods ...................... 145
`3.4.1.2 Considerations for Sensor Selection .................. 150
`
`3.4.2 Technology Implementation ............................. 150
`3.4.3 New Technologies Applicable to Oil/Water Interface Detection ........ 152
`
`3.4.3.1 Electro Magnetic Level Indication (EMLI) .............. 152
`3.4.3.2 Apparatus for Determining Liquid/Gas Interfaces
`Through a Ship Wall ........................... 153
`3.4.3.3 Liquid-Level Sensor with Optical Fibers.
`.............. 153
`
`3.4.4 Summary ......................................... 154
`
`3.5 Non-Destructive Tests ....................................... 156
`
`4.0 VEHICLE AND SENSOR SYSTEM MFEPS AND
`CONCEPTUAL SYSTEM DEVELOPMENT ............................. 158
`
`4.1 Vehicle System MFEP ....................................... 158
`
`4.1.1 Vehicle System MFEP Overview .......................... 158
`4.1.2 System Ranking ..................................... 161
`
`4.2 Sensor System MFEP ....................................... 162
`
`4.2.1 Sensor System MFEP Overview ........................... 162
`
`4.3 Conceptual System Development ................................. 166
`
`4.3.1 Component Integration ................................. 166
`
`4.3.1.1 Underwater Vehicle ............................ 166
`4.3.1.2 Sensors .................................... 170
`
`4.3.2 Navigation and Positioning Requirements ..................... 171
`4.3.3 Information Management ............................... 172
`
`5.0 CONCLUSIONS AND RECOMMENDATIONS ........................... 173
`
`APPENDIX A. UN! INSPECTION MISSION FUNCTIONAL
`FLOW BLOCK DIAGRAM ................................. A-l
`
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`TABLE OF CONTENTS (Continued)
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`Egg;
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`O
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`APPENDIX B. OPERATOR SURVEY RESULTS ............................. B-l
`
`APPENDIX C. NIFEP WORKSHEETS AND TABLES .......................... C-l
`
`APPENDIX D. VEHICLE SYSTEMS DATABASE ............................ D-l
`
`ROVS ............................................... D-2
`AUVS .............................................. D-3
`CRAWLERS .......................................... D-4
`
`APPENDIX E. ENVIRONMENTAL ANALYSIS ............................. E~1
`
`APPENDIX F. REFERENCES ...................................... .
`
`. N
`
`LIST OF TABLES
`
`TABLE 2-1. MODERATE OPERATING ENVIRONMENT ......................
`
`TABLE 2-2.
`
`SEVERE OPERATING ENVIRONWNT ........................
`
`TABLE 2-3. DAMAGE AREA - FREQUENCY OF OCCURRENCE OF HOLES
`IN SPECIFIED AREA INTERVALS ............................
`
`TABLE 2-4.
`
`CRACK LENGTH - FREQUENCY OF OCCURRENCE BY
`SPECIFIED LENGTH INTERVALS ............................
`
`TABLE 2-5.
`
`OIL DISCHARGE CHARACTERIZATION FOR
`VESSEL COLLISION DAMAGE ..............................
`
`12
`
`12
`
`18
`
`18
`
`25
`
`TABLE 2-6.
`
`AREA COVERAGE REQUIREMENTS .......................... 26
`
`TABLE 2-7.
`
`SYSTEM OPERATING REQUIREMENTS ........................
`
`TABLE 3-1. WAVE CHARACTERISTICS FOR VARIOUS SEA STATES ............
`TABLE 3-2.
`SEA SQUIRT OPERATING SPECIFICATIONS .....................
`
`TABLE 3-3.
`
`XP-21 OPERATING SPECIFICATIONS .........................
`
`30
`
`42
`62
`
`63
`
`TABLE 34. MANTA OPERATING SPECIFICATIONS ........................ 68
`
`TABLE 3-5.
`TABLE 3-6.
`
`71
`ASTROS 200 SYSTEM SPECIFICATIONS .......................
`THE ELECTROMAGNETIC SPECTRUM ........................ 75
`
`TABLE 3-7.
`
`CAMERA LIGHT SEPARATION REQUIRENIENTS .................
`
`82
`
`TABLE 3-8.
`
`KEY PARAMETERS FOR STILL CAMERAS
`AND VIDEO IMAGING ...................................
`
`TABLE 39.
`
`EXAMPLES OF LASER FOR UNDERWATER APPLICATIONS' .........
`
`90
`
`95
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`LIST OF TABLES (Continued)
`
`Em
`
`TABLE 3-10.
`
`SPOTRANGE“ SPECIFICATIONS ............................ 99
`
`TABLE 3-11.
`
`NCEL 3-D SURFACE MAPPING SYSTEM
`DESIGN SPECIFICATIONS ................................. 101
`
`TABLE 3-12.
`
`SPOTSCAN“ SPECIFICATIONS .............................. 102
`
`TABLE 3-13.
`
`LASER LINE SCAN SURVEY SYSTEM SPECIFICATIONS ............ 104
`
`TABLE 3-14.
`
`COMMERCIALLY AVAILABLE SIDE-SCAN SONARS ............... 11x
`
`TABLE 3-15.
`
`COMMERCIALLY AVAILABLE FORWARD-LOOK SONARS .......... 125
`
`TABLE 3-16.
`
`SPECIFICATIONS FOR RESON’S SEABAT 9001 ............
`
`.
`
`.
`
`.
`
`.
`
`131
`
`TABLE 3-17.
`
`LIZARD"l EDDY CURRENT INSPECTION
`SYSTEM OPERATING SPECIFICATIONS ....................... I44
`
`TABLE 3-18.
`
`LIQUID LEVEL SENSOR CHARACTERISTICS .................... 151
`
`TABLE 4-1.
`
`SUMMARY OF VEHICLE A'I'I'RIBUTES ........................ 163
`
`TABLE 4-2.
`
`SUMMARY OF VEHICLE AT'I'RIBUTES ........................ 167
`
`LIST OF FIGURES
`
`FIGURE 1-1.
`
`CONCEPTUAL DESIGN DEVELOPMENT FLOW DIAGRAM ..........
`
`4
`
`FIGURE 2-1.
`
`NINE ZONES OF US. COASTAL WATERS ......................
`
`10
`
`FIGURE 2-2.
`
`MAJOR OIL SPILLS FROM TANKERS AND CAUSES: NUMBER OF
`
`INCIDENTS AND VOLUME—WORLD, 1976-1989 ..................
`
`16
`
`FIGURE 2-3.
`
`MAJOR OIL SPILLS FROM TANKERS AND CAUSES: NUMBER OF
`INCIDENTS AND VOLUME—U5. WATERS .....................
`
`FIGURE 2-4.
`
`HISTOGRAM 0F DAMAGE LOCATION AS A FUNCTION OF SHIP
`LENGTH FOR 135 GROUNDINGS REPORTED ON
`IMCO DAMAGE CARDS
`.................................
`
`FIGURE 2-5.
`
`LONGITUDINAL LOCATION AND EXTENT OF DAMAGE FOR
`220 VESSEL ACCIDENTS
`................................
`
`FIGURE 2-6.
`
`GRAPH SHOWING DISTRIBUTION OF DAMAGE INCIDENT
`INCIDENT LOCATION ALONG BARGE BY TYPE OF DAMAGE .......
`
`FIGURE 2-7.
`
`FREQUENCY OF DAMAGE IN MAJOR BARGE AREAS .............
`
`FIGURE 3-1.
`
`SAMPLE MFEP EVALUATION ..............................
`
`l6
`
`I9
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`20
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`22
`
`24
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`32
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`LIST OF FIGURES (Continued)
`
`Baa:
`
`0
`
`FIGURE 3-2.
`
`SAMPLE SCORING CURVE FOR CURRENT EFFECTS ..............
`
`33
`
`FIGURE 3-3.
`
`MAJOR ROV SUBSYSTEMS ................................ 36
`
`FIGURE 3-4.
`
`JASON REMOTELY OPERATED VEHICLE ...................... 38
`
`FIGURE 3-5.
`
`CHAZLENGER REMOTELY OPERATED VEHICLE ................. 39
`
`FIGURE 3-6.
`
`STA'I'E-OF-THE-ART DC-BRUSHLESS-
`MOTOR CONFIGURATION ................................ 41
`
`FIGURE 3-7.
`
`FIGURE 3-8.
`
`MINIMUM OPERATING DEPTH FOR VEHICLES
`WITH GIVEN THREE AXIS SPEED CAPABILITY ................. 42
`CONTROL PANEL FUNCTIONAL BLOCK DIAGRAM ............... 46
`
`FIGURE 3-9.
`
`TYPICAL LAUNCH AND RECOVERY SYSTEM ................... 4s
`
`FIGURE 3-10.
`
`UNTETHERED ROV SYSTEM FUNCTIONAL DIAGRAM ............ 50
`
`FIGURE 3-11.
`
`GENERAL ARRANGEMENT OF ODYSSEY ...................... 52
`
`FIGURE 3-12.
`
`POWER DENSITY AS A FUNCTION OF ENERGY DENSITY
`FOR VARIOUS BATTERY CHEMISTRIES ....................... 54
`
`FIGURE 3-13.
`
`RANGE AS A FUNCTION OF SPEED FOR DIFFERENT HOTEL
`LOADS FOR ODYSSEY FOR so RG OF ALKALINE—
`MANGANESE DIOXIDE BATTERIES AND LITHIUM BATTERIES ......
`
`55
`
`FIGURE 3-14.
`
`FUNCTIONAL CONTROL BLOCK DIAGRAM FOR AUV ............. 57
`
`FIGURE 3-15.
`
`EXAMPLE OF AUV LAYERED CONTROL HIERARCHY ............. 57
`
`FIGURE 3-16.
`
`FIGURE 3-17.
`
`FIGURE 3-18.
`
`FIGURE 3-19.
`
`TYPICAL SMALL AUV CONFIGURATION (SEA SQUIRD ............ 64
`
`XP—ZIB OPERATING CONFIGURATION
`(APPLIED REMOTE TECHNOLOGY) .......................... 65
`MANTA TOWED VEHICLE .................................
`69
`
`ASIROS 200 STRUCTURALLY RELIANT VEHICLE (Travocean) ........
`
`72
`
`'
`
`.
`
`'
`
`0
`
`.
`
`FIGURE 3-20.
`
`THE ATTENUATION OF ELECTROMAGNETIC
`ENERGY IN SEAWATER ..................................
`
`FIGURE 3—21.
`
`THE SELECTIVE TRANSMISSION OF LIGHT BY
`DISTILLED WATER
`
`76
`
`77
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`Page 10 of 324
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`FIGURE 3-22A. EXTINCTION COEFFICIENT OF VISIBLE WAVELENGTHS
`IN VARIOUS OCEAN ENVIRONMENTS
`
`FIGURE 3-22B.
`
`IMAGING RANGE VS. ATTENUATION LENGTH
`FOR VARIOUS IMAGING SYSTEMS .........................
`
`80
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`
`LIST OF FIGURES (Continued)
`
`Bax:
`
`FIGURE 3-23.
`
`VARIOUS CAMERA-LIGHT PLACEMENTS FOR THE
`REDUCING OF BACKSCATI'EIUNG EFFECTS ................... 81
`
`FIGURE 3-24.
`
`BASIC ELEMENTS OF A TELEVISION CAMERA .................. 83
`
`FIGURE 3-25.
`
`MINIMUM OBJECT SIZE (RESOLUTION) THAT CAN BE
`RESOLVED BY CAMERA SYSTEM AT VARYING AL'ITI'UDES
`ABOVE THE SEA FLOOR IN CLEAR WATER .................... 87
`
`FIGURE 3-26.
`
`NECESSARY LIGHT FOR USABLE IMAGE
`AT GIVEN ALTITUDE ABOVE SEA FLOOR ..................... 88
`
`FIGURE 3-27.
`
`FIGURE 3-28.
`
`REQUIRED NUMBER OF EXPOSURE DEPENDING 0N
`SURVEY AREA AND ALT. I‘UDE ABOVE SEA FLOOR .............. 89
`
`A PROPOSED METHOD OF PROVIDING ADJUSTABLE AND
`CLOSELY-SPACED PARALLEL LASER BEAMS FOR SMALL-SCALE
`INSPECTION AND MEASUREMENT TASKS ..................... 96
`
`FIGURE 3-29.
`
`AN APPLICATION OF LASERS AND TRIANGULATION
`TO MEASURING THE DISTANCE FROM THE CAMERA TO
`A TARGET ...........................................
`
`97
`
`FIGURE 3-30.
`
`NCEL/HBOI 3D IMAGING SYSTEM—PRINCIPLE OF
`OPERATION .......................................... 100
`
`FIGURE 3—31.
`
`SYNCHRONOUS SCAN CONCEPTUAL DIAGRAM ................. 103
`
`FIGURE 3-32.
`
`EXPERIMENTAL TV] 11!:- AGING SYSTEM ...................... 106
`
`FIGURE 3-33.
`
`SIGNAL-TO-NOISE-RATIO IMPROVEMENT THROUGH
`RANGE GATING ....................................... 108
`
`FIGURE 3-34.
`
`THEORY OF OPERATION FOR A LASER RANGE-GATED IMAGING
`SYSTEM ............................................. 108
`
`FIGURE 3-35.
`
`SET-UP FOR TWO—CAMERA PROJECTION MOIRE ................ 110
`
`FIGURE 3-36.
`
`DIMPLED PIPE ........................................ 111
`
`FIGURE 3 ‘37.
`
`IMAGE OF DIMPLED PIPE ................................ 112
`
`FIGURE 3-38.
`
`SONAR SYSTEM ELEMENTS ............................... 113
`
`FIGURE 3-39.
`
`METHODS OF ACOUSTIC IMAGING .......................... 116
`
`FIGURE 340.
`
`ACOUSTIC BEAMS VOLUME COVERAGE .
`
`.
`
`. .................. 119
`
`FIGURE 341.
`
`ARTIST’S SKETCH OF A TOWED SIDE-SCAN SONAR .............. 120
`
`FIGURE 3—42.
`
`SEQUENCE OF SIGNAL LEVELS FOR A NEGATIVE DISPLACEMENT
`CONTOUR (A); RECTIFIED OUTPUT SIGNAL (B) ................. 122
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`LIST OF FIGURES (Continued)
`
`En:
`
`FIGURE 3-43.
`
`TYPICAL FAN-SHAPED BEAM AS USED ON IMAGING SONARS .....
`
`126
`
`FIGURE 3-44.
`
`FAN-SHAPED SONAR BEAM INTERSECTS WITH A FLAT BOTTOM AND
`TARGETS ............................................ 127
`
`FIGURE 345.
`
`ECHO STRENGTH VS TIME WHEN FAN-SHAPED SONAR BEAM
`INTERSECTS WITH A FLAT BOTTOM AND TARGETS ............. 128
`
`FIGURE 3-46.
`
`CORRECT ECHO STRENGTH FOR CHANGES DUE TO RANGE .
`
`.
`
`.
`
`.
`
`.
`
`.
`
`. 130
`
`FIGURE 3-47.
`
`BATHYMETRIC SONAR .................................. I32
`
`FIGURE 348.
`
`CONFIGURATION FOR DAMAGE ASSESSMENT USING A PROFILING
`SONAR .............................................. 134
`
`FIGURE 349.
`
`PENCIL SHAPED SONAR BEAM SCANS IN A VERTICAL PLANE TO
`MEASURE BOTTOM PROFILE .............................. 135
`
`FIGURE 3-50.
`
`FIGURE 3-51.
`
`ECHO RETURN FROM PENCIL BEAM ......................... 136
`PLOT DIGITIZED ECHO RETURNS TO SHOW PROFILE
`(CROSS SECTION) OF BOTTOM ............................. 137
`
`FIGURE 352.
`
`CSARS SYSTEM VOLUMETRIC FIELD OF VIEW ................ 140
`
`FIGURE 3-53.
`
`3D CONTOUR PLOT OUTPUT OF CSARS SYSTEM ................ 140
`
`0
`
`O
`
`.
`
`.
`
`FIGURE 3—54.
`
`FIGURE 3-55.
`
`LEVEL MEASUREMENT METHODS .......................... 146
`
`Q
`
`APPARATUS FOR DETERMINING LIQUID/GAS INTERFACE
`THROUGH A SHIP WALL ................................. 154
`
`FIGURE 3-56.
`
`LIQUID LEVEL SENSOR WITH OPTICAL FIBERS ................. 155
`
`FIGURE 4-1.
`
`REMOTELY OPERATED HULL INSPECTION VEHICLE ............. 168
`
`O
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`C
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`O
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`EXECUTIVE SUMMARY
`
`Currently, the U.S. Coast Guard performs vessel damage assessment by placing
`
`divers in the water or by using fairly simple free-swimming remotely operated vehicles (ROVs). The
`
`capabilities of underwater vehicles and the sensors they carry have advanced significantly over recent
`
`years. As discussed in this report, the implementation of these advances into an inspection system
`
`should allow the Coast Guard to carry out vessel damage assessments more thoroughly efficiently,
`
`and safely.
`
`This report consists of the following:
`
`a An analysis of the Coast Guard damage assessment mission.
`
`0 A technical overview of the underwater vehicle and sensor technologies.
`
`0 An evaluation of how well each vehicle system would be able to meet operational
`and environmental requirements for sensor delivery.
`
`0 An evaluation of how well each sensor would be able to meet the overall
`
`inspection requirements.
`
`0 The development of a conceptual system which integrates a vehicle, sensors, and
`navigation system for the performing damage assessment.
`
`0 Recommendations for research and development which will enhance the Coast
`Guards ability to perform damage assessments in the future.
`
`This project found that a hull-crawling ROV with free-swimming capabilities would
`
`most adequately meet the Coast Guard's mission requirements. Such a system should be able to
`
`operate in a wide variety of sea-state conditions, and would provide the operators with operational
`
`flexibility for optimizing the damage assessment process. This conclusion must be tempered with the
`
`understanding that other vehicle types might perform specific missions more ably (e.g., towed
`
`vehicles for side-only inspections or AUVs for long standoff/hazardous environments).
`
`As described in this report, the selection of "optimum" sensors for installation on the
`
`vehicle depends greatly on the specific inspection scenario. Operators should be provided with as
`
`much flexibility as possible with respect to sensor selection. Providing a suite of sensors that can be
`
`placed on the vehicle in a modular fashion provides the operator this flexibility. For example, two
`
`viable sensor modules that could be interchanged on a combination hull-crawler/ROV are depicted in
`
`
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`ES— 1
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`a conceptual drawing; here, one sensor module (consisting of sonar sensors) would be suitable for
`
`imaging in extremely low visibility conditions, while the other module (range-gated laser) would be
`
`suitable for enhanced imaging under less limiting visibility conditions.
`
`Recommendations for future development include:
`
`0 Testing sensors in a laboratory environment to assess performance capabilities as
`they relate to damage detection and damage characterization.
`
`0 Development of a vehicle test bed for field testing sensors.
`
`0 Analyzing sensor performance in an oil/water environment.
`
`0 Developing or monitoring the development of specific sensors and vehicles to
`allow enhancement of the damage assessment mission as they become available.
`
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`1.0 INTRODUCTION
`
`1.1 Statement of the Problem
`
`Large spills of crude oil or chemicals have focused attention on the need for a capability
`
`to rapidly assess damage to vessels that have run aground, been involved in a collision, or suffered
`
`structural failure. The primary goals in the management of a vessel casualty are timely, complete and
`
`accurate assessment of damage, prevention of further spilling of oil or chemicals, mitigation of the
`
`effects of the spill, and assurance of crew and vessel safety. Equipment and instrumentation for
`
`rapidly determining the extent and location of tank damage is necessary for assisting the Coast Guard
`
`in making strategic response management decisions. The information provided serves as critical input
`
`for the Coast Guard to use when formulating the hazard assessment and response tactics. Knowing
`
`the volume of water and oil in a hold—along with the location, size, and nature of damage to the
`
`hull— the Coast Guard can make important casualty control decisions. Such information, coupled
`
`with knowledge of the vessel’s design characteristics, allows stability and residual strength to be
`
`determined. Knowing the stability and strength status of a vessel allows the Coast Guard to make
`
`educated decisions regarding the various actions that could or should be taken (e.g., towing,
`
`lightering, or evacuating personnel).
`
`The Coast Guard and industry presently have extremely limited capability to assess
`
`underwater damage. When conditions allow, scuba divers can perform the assessment very
`
`adequately. When environmental conditions are too severe for the safe placement of divers. or when
`
`the casualty itself precludes the placement of divers in the water, the ability to gather accurate damage
`
`information is severely hindered. Recent technological advances in underwater sensors and
`
`underwater vehicles make unmanned damage assessment a viable option.
`
`in many cases, unmanned
`
`inspection systems may be able to provide better quality information more quickly than scuba divers
`can.
`
`1.2 Objectives
`
`The primary objectives of this study are to:
`
`(1)
`
`Define the mission requirements for an underwater damage assessment operation.
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`
`
`(2)
`
`(3)
`
`(4)
`
`(5)
`
`Perform a technical evaluation of underwater vehicle systems, sensors, and
`methodologies for use in vessel damage assessment. Events that may require
`vessel damage assessment include collision, grounding. fire/explosiOn, or
`structural failure.
`
`Establish conceptual designs that will most effectively make use of the
`technologies that are currently available (or being developed) to meet the Coast
`Guard mission requirements.
`
`Recommend areas where research and developments efforts are required to bring
`underwater vehicle or sensor technologies to the point where they can meet the
`mission requirements more effectively.
`
`Provide a method of evaluating future technologies that might be suitable for
`vessel damage assessment.
`
`1.3 Organization
`
`This report is organized into six sections. Section 1, introduction. sets the problem. and
`
`describes the goals, objectives, and methodologies involved in the performance of system analysis and
`
`definition.
`
`Section 2, Mission Analysis, presents an investigation of the
`
`oceanographic/environmental conditions that could be expected during the performance of a damage
`
`assessment. an operational analysis resulting from a questionnaire completed by Coast Guard
`
`personnel, characterization of vessel damage that is likely to be encountered, and a description of both
`
`the operational flow and inspection system performance requirements.
`
`Section 3, Subsystem Evaluation Methodology and Technology Overview, presents the
`
`method of evaluation for the underwater vehicle and sensor technologies. An overview of the
`
`technology is given, methods of applying the technology to the damage assessment task are discussed,
`
`and the strengths and weaknesses of that technology are presented.
`
`Section 4, Vehicle and Sensor System Multifactor Evaluation Process (MFEP) and
`
`Conceptual System Development, evaluates the compatibility of the different underwater vehicle and
`
`sensor systems. This section concludes with a conceptual design that addresses the mission
`
`requirements under the various environmental and operational scenarios that are lllrely to be
`
`encountered.
`
`0
`
`.
`
`.
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`0
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`0
`
`Section 5, Recommendations, presents recommendations for testing, evaluation, system
`
`.
`
`integration, and future research and development activities.
`
`Section 6, Conclusions, presents a summary of the analysis performed herein.
`
`1.4 Investigation and Analysis Techniques
`
`1.4.1 Literature Search and Market Survey
`
`A literature search and a market survey were performed to identify and compile
`
`information on the vehicle and sensor technologies that are either commercially available or under
`development. A keyword list was developed for searching various databases. The reports, articles,
`
`books. and technical papers obtained through these searches were used as the primary source material
`
`for this report. These items are listed in the Bibliography.
`
`The market survey consisted of surveying and interviewing commercial manufacturers
`and collecting and analyzing product literature. Research findings and system development status
`
`were discussed with the scientists and engineers involved in the development of technologies that are
`
`not commercially available. The commercial availability of the technologies addressed in this study is
`
`discussed in the appropriate sections.
`
`1.4.2 Conceptual Design Development
`
`A process flow diagram for the conceptual design development is shown in Figure 1-1.
`The flow process used for this study is bued on a Systems Engineering approach taught at the
`
`Defense Systems Management College. The approach is often used for the development of complex
`
`
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`0
`
`.
`
`.
`
`0
`
`.
`
`0
`
`O
`
`.
`
`

`

`Detine System
`Operating
`Re - uirements
`
`-
`Define
`Problem
`
`Problem .
`ldsntrlication
`
`.
`99"“
`at:
`gszmmb
`
`Parlorm
`Preliminary
`Sizing
`
`Penorm
`.
`VehICIo. and
`Sensor MFEP
`
`
`
`Develop
`
`Parametric
`
`Perl. Data
`
`
`
`'Best' Subsystem
`5’81““
`',
`s a
`l
`50'”le
`
`y em
`
`
`Develop Subsys
`Requirements
`Interactions
`
`
`
`
`
`Evaluation
`
`Criteria
`
`Development
`
`
`
`
`'
`Update Requrrements.
`Revise Interaction
`
`Excercise Concepts
`Against Operational
`Scenarios
`
`
`
` Development
`Operationally Acceptable
`
`Concepts
`Recommendations
`.-___.—..—-—-——————_—_.-—._——_—-—-——-——.———.——_____——._.————__
`
`
`
`
`
`Evaluate
`
`
`Determine
`
`
` Retina Concepts
`Concepts Against
`Perlormance
`
`
`
`all Selection Criteria
`
`
`Baseline Design(s)
`(Based on Penonnance Conpared to Selection Criteria)
`
`
`
`
`
`FIGURE 1-1. CONCEPTUAL DESIGN DEVELOPMENT FLOW DIAGRAM
`
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`

`systems. The point at which the subsystems are evaluated by the multifactor evaluation process
`
`(MFEP) is shown on the flow diagram. The MFEP is discussed in the following section, and in
`
`greater detail in Section 3. As illustrated in the flow diagram, the conceptual design development
`
`process requires that the following steps be performed:
`
`Problem Definition. The objectives for system performance are
`developed. The stated objectives must generally be accomplished within a specified
`operating environment.
`
`Fatablish Measures of Performance. Quantitative measures of performance that will
`be used to guide and evaluate th