39 Questions
What is a requirement for determining the position of an underwater vehicle using a Long Baseline (LBL) system?
An array of baseline transponders moored on the seafloor
What is an advantage of using a Short Baseline (SBL) system for underwater positioning?
Only one transponder is required on the vessel
What is a disadvantage of using a Short Baseline (SBL) system for underwater positioning?
Error based on range and water depth
What is used to determine the position of an underwater vehicle in a Long Baseline (LBL) system?
Triangulation using distance measurements
Why is good calibration required for a Short Baseline (SBL) system?
Very good dry dock/structure calibration is required
What is a characteristic of a Long Baseline (LBL) system?
It uses an array of baseline transponders moored on the seafloor
What is the typical accuracy of an Underwater Positioning System?
A few cm to less than 1 m
What is the purpose of relative calibration in LBL positioning?
To determine the shape and size of the LBL array only
What is required for absolute calibration?
Only a relative calibration
How are the baseline measurements used in calibration?
Combined with depth measurements and used in a least squares calculation
What is measured in the first step of calibration?
Water sound speed
What is the purpose of a pressure sensor on each transponder?
To determine the depth of each transponder
What is the minimum number of baseline measurements required for calibration?
10 times in each direction
What is the type of calculation used in calibration?
Least squares calculation
What is the primary challenge in underwater navigation?
Absence of a reliable satellite reference
What is the main advantage of position fixing systems?
Error is independent of the distance travelled
What is the purpose of an integrated navigation system?
To combine several navigation methods and provide information about their accuracy and reliability
What is the primary function of an inertial navigation system (INS)?
To estimate the initial position, velocity, and attitude
What is the role of the inertial measurement unit (IMU) in an INS?
To measure the acceleration and angular rate of the vehicle
What is the output of an integrated navigation solution?
The position, velocity, and attitude
What is the purpose of the gravity model in an INS?
To account for the gravitational force affecting the vehicle's motion
What is the minimum number of box-ins required for underwater positioning?
Two
What is the main difference between dead reckoning and position fixing?
Position fixing estimates the location using external references
What is the title of the 2006 publication by Schmidt, Chayes, Caress, and Aquarium?
The MB-System Cookbook
What is the principle of Block Shifting in underwater positioning?
Attachment of transponder positions to known positions
What is the advantage of combining an INS with other navigation methods?
It provides a more accurate position solution
Which of the following researchers published a master's thesis on Multisensor Microbathymetric Habitat Mapping in 2017?
Dreutter
What is the characteristic of GIB systems in underwater positioning?
Inverted LBL devices with self-positioned buoys
What is the advantage of LBL systems in underwater positioning?
High position accuracy (depth independent)
What is the name of the system used for multisensor microbathymetric habitat mapping?
OFOBS
What is the disadvantage of LBL systems in underwater positioning?
Complex system requiring expert operators
In which year was the publication 'The handbook of sidescan sonar' published?
2009
Who are the authors of the 2019 workshop paper on 'Overview of current methods of underwater positioning'?
Dufek and Sternberg
What is the characteristic of the field of application of GIB systems?
Areas of regular use
What is the method used in Box-in for position determination?
Trilateration of vessel offsets
What is the name of the company that produces the High Precision Acoustic Positioning system?
Kongsberg Maritime AS
What is the characteristic of the transceiver in GIB systems?
On the underwater vehicle
What is the title of the 2018 paper by Jinwu, Xiaosu, Tao, Liang, and Yao?
Study on installation error analysis and calibration of acoustic transceiver array
What is the topic of the 2002 conference paper by Faugstadmo, Jacobsen, and Gunhildstad?
Transducer alignment and LBL calibration
Study Notes
Navigation and Positioning
- 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)
This quiz covers navigation and positioning systems, including dead reckoning, position fixing, and measurement of distance and direction to known objects.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
