Navigation and Positioning Systems
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What is a requirement for determining the position of an underwater vehicle using a Long Baseline (LBL) system?

  • At least two transponders on the seafloor
  • An array of baseline transponders moored on the seafloor (correct)
  • Three or more transceivers on the ship
  • Only one transponder on the underwater vehicle

    • What is an advantage of using a Short Baseline (SBL) system for underwater positioning?

  • LBL systems are easier to use
  • Only one transponder is required on the vessel (correct)
  • It provides absolute position coordinates
  • Three or more transceivers are required on the ship

    • What is a disadvantage of using a Short Baseline (SBL) system for underwater positioning?

  • Only one transponder is required on the vessel
  • It provides accurate absolute position coordinates
  • Error based on range and water depth (correct)
  • No need to deploy transponders on the seafloor

    • What is used to determine the position of an underwater vehicle in a Long Baseline (LBL) system?

    <p>Triangulation using distance measurements</p> Signup and view all the answers

    Why is good calibration required for a Short Baseline (SBL) system?

    <p>Very good dry dock/structure calibration is required</p> Signup and view all the answers

    What is a characteristic of a Long Baseline (LBL) system?

    <p>It uses an array of baseline transponders moored on the seafloor</p> Signup and view all the answers

    What is the typical accuracy of an Underwater Positioning System?

    <p>A few cm to less than 1 m</p> Signup and view all the answers

    What is the purpose of relative calibration in LBL positioning?

    <p>To determine the shape and size of the LBL array only</p> Signup and view all the answers

    What is required for absolute calibration?

    <p>Only a relative calibration</p> Signup and view all the answers

    How are the baseline measurements used in calibration?

    <p>Combined with depth measurements and used in a least squares calculation</p> Signup and view all the answers

    What is measured in the first step of calibration?

    <p>Water sound speed</p> Signup and view all the answers

    What is the purpose of a pressure sensor on each transponder?

    <p>To determine the depth of each transponder</p> Signup and view all the answers

    What is the minimum number of baseline measurements required for calibration?

    <p>10 times in each direction</p> Signup and view all the answers

    What is the type of calculation used in calibration?

    <p>Least squares calculation</p> Signup and view all the answers

    What is the primary challenge in underwater navigation?

    <p>Absence of a reliable satellite reference</p> Signup and view all the answers

    What is the main advantage of position fixing systems?

    <p>Error is independent of the distance travelled</p> Signup and view all the answers

    What is the purpose of an integrated navigation system?

    <p>To combine several navigation methods and provide information about their accuracy and reliability</p> Signup and view all the answers

    What is the primary function of an inertial navigation system (INS)?

    <p>To estimate the initial position, velocity, and attitude</p> Signup and view all the answers

    What is the role of the inertial measurement unit (IMU) in an INS?

    <p>To measure the acceleration and angular rate of the vehicle</p> Signup and view all the answers

    What is the output of an integrated navigation solution?

    <p>The position, velocity, and attitude</p> Signup and view all the answers

    What is the purpose of the gravity model in an INS?

    <p>To account for the gravitational force affecting the vehicle's motion</p> Signup and view all the answers

    What is the minimum number of box-ins required for underwater positioning?

    <p>Two</p> Signup and view all the answers

    What is the main difference between dead reckoning and position fixing?

    <p>Position fixing estimates the location using external references</p> Signup and view all the answers

    What is the title of the 2006 publication by Schmidt, Chayes, Caress, and Aquarium?

    <p>The MB-System Cookbook</p> Signup and view all the answers

    What is the principle of Block Shifting in underwater positioning?

    <p>Attachment of transponder positions to known positions</p> Signup and view all the answers

    What is the advantage of combining an INS with other navigation methods?

    <p>It provides a more accurate position solution</p> Signup and view all the answers

    Which of the following researchers published a master's thesis on Multisensor Microbathymetric Habitat Mapping in 2017?

    <p>Dreutter</p> Signup and view all the answers

    What is the characteristic of GIB systems in underwater positioning?

    <p>Inverted LBL devices with self-positioned buoys</p> Signup and view all the answers

    What is the advantage of LBL systems in underwater positioning?

    <p>High position accuracy (depth independent)</p> Signup and view all the answers

    What is the name of the system used for multisensor microbathymetric habitat mapping?

    <p>OFOBS</p> Signup and view all the answers

    What is the disadvantage of LBL systems in underwater positioning?

    <p>Complex system requiring expert operators</p> Signup and view all the answers

    In which year was the publication 'The handbook of sidescan sonar' published?

    <p>2009</p> Signup and view all the answers

    Who are the authors of the 2019 workshop paper on 'Overview of current methods of underwater positioning'?

    <p>Dufek and Sternberg</p> Signup and view all the answers

    What is the characteristic of the field of application of GIB systems?

    <p>Areas of regular use</p> Signup and view all the answers

    What is the method used in Box-in for position determination?

    <p>Trilateration of vessel offsets</p> Signup and view all the answers

    What is the name of the company that produces the High Precision Acoustic Positioning system?

    <p>Kongsberg Maritime AS</p> Signup and view all the answers

    What is the characteristic of the transceiver in GIB systems?

    <p>On the underwater vehicle</p> Signup and view all the answers

    What is the title of the 2018 paper by Jinwu, Xiaosu, Tao, Liang, and Yao?

    <p>Study on installation error analysis and calibration of acoustic transceiver array</p> Signup and view all the answers

    What is the topic of the 2002 conference paper by Faugstadmo, Jacobsen, and Gunhildstad?

    <p>Transducer alignment and LBL calibration</p> Signup and view all the answers

    Study Notes

    • Position fixing: Measurement of distance and/or direction to known objects using identifiable external information (signals: GNSS, features: rivers, terrain height, buildings, etc.)
    • Dead reckoning: Approximation of the location of an object using direction/course and distance traveled, with errors increasing over time

    Integrated Navigation System

    • Combines several navigation methods to provide accurate and reliable information
    • Provides information about the accuracy and reliability of the navigation methods ("integrity")

    Inertial Navigation System (INS)

    • Uses accelerometers and gyros to measure the acceleration and orientation of the vehicle
    • Calculates the position, velocity, and attitude of the vehicle based on the measurements
    • Requires initial position, velocity, and attitude to be set

    Integrated Navigation Solution

    • Combines the INS with other navigation methods (e.g. USBL, DVL) to provide a more accurate and reliable position solution
    • Uses an estimation algorithm to correct the position solution based on the measurements

    Underwater Positioning

    • The most obvious challenge with underwater navigation is that a continuously updated position fix must be estimated without a robust and dependable satellite reference (GNSS)
    • Accuracy depends on the distance between the transceivers and the mounting method

    Short Baseline (SBL)

    • Advantages:
      • Only one transponder on the vehicle
      • Easy to use and ship-based – no need to deploy transponders on the seafloor
      • Good range accuracy
    • Disadvantages:
      • Three or more transceivers on the ship are required
      • Error based on range and water depth (SVP required)
      • Accuracy dependent on the vessel's motion reference units

    Long Baseline (LBL)

    • An array of baseline transponders is moored on the seafloor at fixed locations and used as reference points
    • Position determination by triangulation (distance measurements between the vehicle and each transponder of the baseline array)
    • Advantages:
      • Highest possible accuracy (theoretical)
      • High position accuracy (depth independent)
      • Wide area of coverage
    • Disadvantages:
      • Complex system requiring expert operators
      • Several transponders necessary
      • On-site installation time/costs
      • Calibration of baseline transponders necessary

    Calibration

    • Relative calibration: Determination of the shape and size of the LBL array, no absolute positioning in real-world coordinates
    • Absolute calibration: Requires first a relative calibration, then the array is placed into real-world coordinates with one of many methods (e.g. Box-in, Block shifting)

    GPS Intelligent Buoys (GIB)

    • GIB systems are inverted LBL devices
    • An array of baseline transponders is replaced by floating buoys, self-positioned by GPS
    • Position determination by triangulation (distance measurements between the vehicle and each buoy)

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    Description

    This quiz covers navigation and positioning systems, including dead reckoning, position fixing, and measurement of distance and direction to known objects.

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