Harbour Sea Floor Clearance (5A MAST 2009)

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Harbour Sea Floor Clearance (5A MAST 2009)

  1. 1. MAritime Systems and Technology 2009 Sweden, Stockholm 21-23 October 2009 HARBOUR SEA-FLOOR CLEARANCE: “ HD” HIGH DEFINITION MAGNETIC SURVEY PERFORMANCE Faggioni O., Soldani M., Leoncini D., Zunino R., Gastaldo P., Di Gennaro E., Lamberti L., Maggiani P.V. University of Genoa DIBE - SEA Lab, DGG INGV Sez. ROMA2 AOG - . App. Ocean. Group Italian Navy Davide Leoncini – University of Genoa Ph.D. Student (davide.leoncini@unige.it)
  2. 2. Agenda <ul><li>Application Context Seafloor Clearance in seafloor critical conditions </li></ul><ul><li>Problem Definition Limitations in Controlling Target-Sensor Distance and in High Accuracy Localization </li></ul><ul><li>State of the Art Acoustic, Optical and Single Sensor Magnetic Approaches </li></ul><ul><li>The Proposed Method The High Definition (HD) Magnetic Survey Protocol </li></ul><ul><li>Experimental Results Overview of the Detected Targets and Effectiveness Maps </li></ul><ul><li>Conclusions and Future Works </li></ul>
  3. 3. The History of the Project <ul><li>May 2007: Request of Italian Ministry of Defence and Autonomous Region of Sardinia </li></ul><ul><li>Italian Navy (ITN) – prime contractor – and NURC agreed to provide the marine survey of Cape Teulada (NATO firing range) </li></ul>APPLICATION CONTEXT
  4. 4. The Survey Area Isola Rossa Cape Teulada Cape Teulada and Isola Rossa (Sardinia, Italy) Overview of the survey area APPLICATION CONTEXT
  5. 5. Test Area - Environmental Conditions HIDDEN TARGETS <ul><li>Sandy sea bottom </li></ul><ul><li>Presence of Posidonia (seaweed) </li></ul><ul><li>Complex seafloor morphology </li></ul>PROBLEM DEFINITION
  6. 6. Seafloor Clearance Methods CLASSICAL METHODS NEW METHOD EMPLOYED METHODS <ul><li>Acoustic Based (Sonar) </li></ul><ul><li>Optic Based (direct-inspection) </li></ul><ul><li>Magnetic Based (single-sensor) </li></ul><ul><li>Magnetic Based (multi-sensor) </li></ul>STATE OF THE ART
  7. 7. Limitation of Magnetic Based Single-Sensor Method AUV AUV AUV MAG MAG MAG Real Detection False Detection Missed Detection Constant Magnetic Field F(t1) F(t2) Variable Magnetic Field F(t1) F(t2) Variable Magnetic Field F(t1) F(t2) Grabbed Signal Grabbed Signal Grabbed Signal STATE OF THE ART
  8. 8. The High Definition Mag Method <ul><li>Observatory (Reference Magnetometer) Displacement to Obtain Coherence Condition </li></ul><ul><li>Validation of the Observatory Displacement (TTs reduction) </li></ul><ul><li>Survey of the Area </li></ul>THE PROPOSED METHOD
  9. 9. Observatory Displacement <ul><li>Observatory site must guarantee coherence in magnetic field time variations </li></ul><ul><li>The length of coherence calculation sectors is more or less 1500 [m] </li></ul><ul><li>The 80% of survey surface is covered (in the external area there are not sources of local noise in the high frequency band) </li></ul><ul><li>I t is strictly necessary having a good verify of the space coherency of observatory time variations over the entire survey area </li></ul>THE PROPOSED METHOD
  10. 10. Validation of the Displacement Timer Tracks (TTs) Reduction 1) Perform Track T1 with sentinel sensor 2) Perform Track T2 (inverse of T1) with sentinel sensor 3) Use the signal acquired by the reference magnetometer (observatory) to compensate the time variation of the magnetic field in T1 and in T2 4) Compare T1 and the inverse sequence of T2: This two sequences of samples now should result almost equals T1 T2 70 % 0 [nT] < ΔF <= 2 [nT] 25 % 2 [nT] < ΔF <= 3 [nT] 05 % 3 [nT] < ΔF <= 5 [nT] THE PROPOSED METHOD
  11. 11. Survey of the Area Devices Utilized : proton magnetometers Number of Track : over 75 standard tracks + 19 special tracks ( for more definition) Sampling Rate : 1 [s] Distance Between Tracks : 10 [m] - 70 [m] Navigation Speed : 2-3 knots Distance Sensor-Seafloor : 1 [m] < h < 2 [m] (3 [m] in Poseidonia Area, biological damages avoidance) Measurements Sensibility : 1 [nT] (signals lower than 5 [nT] has not informative capability) Geomagnetic survey of Capo Teulada standard tracks THE PROPOSED METHOD
  12. 12. Targets Detected Examples Fish pot 2 kg Half iron barrel 15 kg Security System Cables MARK 3 (dummy) Iron shell case 4 kg EXPERIMENTAL RESULTS T.C. C.C. Date Time UTC Ti Tf Fi Ff  F    24.01 Dipole 5/23/2007 13:33:12 3303 3319 44683 44661 22 474443 4305843 25 24.02 Dipole 5/23/2007 13:34:02 3356 3410 44683 44673 10 474495 4305891 17 24.03 Dipole 5/23/2007 13:34:25 3419 3431 44582 44668 14 474520 4305913 13 27.05 Dipole 5/23/2007 15:35:26 3519 3535 44758 44698 60 475116 4306480 13 29.06 Impulse + 5/24/2007 13:58:29 5811 5858 44747 44710 37 474786 4306387 43 29.07 Impulse + 5/24/2007 14:00:16 5952 58 44762 44716 46 474680 4306290 67 60.01 Dipole 5/31/2007 10:26:36 2631 2642 45135 44601 534 474371 4306838 9 75.02 Dipole 6/1/2007 9:21:20 2116 2123 44753 44689 64 475716 4306292 5 75.03 Dipole 6/1/2007 9:21:28 2125 2132 44728 44694 34 475725 4306301 6 T.C. N° Track Contact C.I. Contact Classification Date dd/mm/yyyy Time UTC hh:mm:ss Ti UTC start signal time detection mmss Tf UTC end signal time detection mmss Fi Amplitude of field at start signal detection [nT] Ff Amplitude of field at end signal detection [nT]  F Amplitude of the signal [nT]  Longitude E Green [m]  Latitude N [m]  Signal wavelength [m]  
  13. 13. The MARK 3 mine (dummy) MK3 EXPERIMENTAL RESULTS
  14. 14. The Security System Cables Detection of artificial anomaly crossing the entire survey area not present in the official maritime map Magnetic field associated to two cables (ships’ traffic control system) inductive system (E cable active component - W cable passive component) EXPERIMENTAL RESULTS
  15. 15. Results Discussion Target Detected: 258 magnetic target signals (134 impulses positive [52%] + 93 dipoles [37%] + 28 impulses negative [11%]) Max Amp.: 574 [nT] Min Amp.: 6 [nT] Red: Target Detected Yellow: Two magnetic cables EXPERIMENTAL RESULTS
  16. 16. Maps of Effectiveness Not Explored EA = 80% SA EA = 60% SA EA = 40% SA EXPERIMENTAL RESULTS
  17. 17. Conclusions and Future Works <ul><li>This technique proves to be a great auxiliary method to the standard approaches using in sea floor survey and detection (acoustic, optic, etc…). </li></ul><ul><li>Analyzing the results obtained in Capo Teulada ITN has decided to carry on the research on MCM developing a multi sensorial system. </li></ul>CONCLUSIONS AND FUTURE WORKS
  18. 18. Organizations Involved in the Research

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