Commonalities of Vehicle Data

The data package is delivered per cruise, with contained products grouped on a per-dive basis.

Navigation Data Sets

All NDSF vehicles are equipped with high precision Doppler Velocity Log
(DVL) navigational systems (dead reckoning) that can be
supplemented with acoustic Long-BaseLine (LBL) navigation. Bottom-lock
DVL sonar is used to compute vehicle displacement,
and LBL acoustic ranges are used to place the DVL displacement data in
a geographical coordinate frame. Real-time positioning uncertainties
of these systems used individually can be significant, as much as
hundreds of meters, but the post-processing of LBL and DVL and
high-precision gyro compass data results in a more precise navigational
track [1,2,3,4].

First-order processing of LBL and DVL navigation data, which can be
performed at sea, removes the most extreme positioning errors and also
utilizes gyrocompass attitude to constrain vehicle position. This level
of processing is provided as a standard data product for most NDSF
vehicles. Second-order processing can be performed post-cruise by
experienced specialists to further improve navigational data quality.
Vehicle positioning
accuracy can range from less than one meter to tens of meters depending
on deployment geometry, operational conditions and the nature of the
post-processing.

DVLNav is used
to collect data from navigation, vehicle, and ship’s systems and also
provides a
real-time display of estimated position and track history. DVLNav produces the following, which are included in the standard
deliverables from each of the vehicles:

  • Simple comma-delimited 1-second data file:

    .csv suffix, logs time-stamped navigation and sensor data at 1 second intervals. One file per day. 1 MB/hour. Compresses 5:1.

  • Comprehensive DSL Format Data file:

    .dat suffix, logs ALL sensor and processed data, timestamped to 0.001 second. One file per hour, 60 MB/Hour. Compresses 10:1.
    Requires awk/grep and MATLAB to process.

  • Screen Shot JPEG File:

    .jpeg suffix. Timestamped (to the second) screen shot image of the DVLNAV screen. 500 KB/Image. Created by a DVLNav screenshot
    button.

  • Hourly system configuration (INI file):

    Logs the internal DVLNAV configuration once an hour. 6 KB.

See vehicle specifics for more information about the navigation data deliverables for that vehicle.

Video

On Alvin, in which pilot and science observers have a limited field of view through portholes,
video cameras and recorders augment
visual observations. On Jason, video cameras
are the only source of real-time
visual information. Some of these are utility units while others are
high quality units that provide images suitable for detailed
observation
and for recording. Video is recorded in two forms: a pristine version
that is transferred to the WHOI Data Library, and a single working copy
that is
delivered to the Chief Scientist at the conclusion of the dive. In both
forms, time and real-time vehicle position data (position, altitude,
depth)
data are recorded in audio tracks using the SMPTE standard.
Information contained in the
audio channels can be used to generate a customized video overlay.
Working copies are overlain with user-defined parameters at the time of
recording.

Bathymetric Sonar

All NDSF vehicles are capable of carrying a bathymetric sonar, available by pre-cruise request.
See vehicle specifics for more information about the sonar data deliverables for that vehicle.

Digital Still Photography

Each of the vehicles carries a digital camera for capturing still photography. Images are downloaded and archived
in JPEG format, with date and time information denoted in the filename.

Autosnaps and Event Logging

Autosnaps are framegrabbed images that are extracted from video automatically at a customizable time
interval and are coregistered with sensor data. On Alvin this is done with the Framegrabber system and
on Jason this is done with the Virtual Van.

Additionally, an Eventlogger system gives Jason science
users the ability to record dive event commentary that is coregistered
with user-triggered autosnaps.

Additional Sensors

All vehicles carry sensors such as CTD, altimeter, compass, and
gyroscope. AUVs ABE and Sentry each routinely carry a magnetometer.
Alvin and
Jason can be fitted with one if requested prior to your cruise. Note: Proper use of a
magnetomoter requires mid-water column calibration of the sensor at each new location.


Alvin
, Jason, and ABE each carry a forward-looking sonar unit for
target detection and obstacle avoidance. We do not offer a standard
product from these systems.

Science-provided equipment can be carried by each of the vehicles as
long as the equipment doesn’t exceed the vehicle’s limits of size,
weight,
and power usage. Please allow significant lead time prior to your
cruise to contact
NDSF planning personnel and vehicle managers.

Contact the NDSF Data Manager

References
  1. Whitcomb, L., D. R. Yoerger, and H. Singh (1999a), Combined
    Doppler/LBL based navigation of underwater vehicles, paper presented at
    the 11th International Symposium on Unmanned Untethered Submersible
    Technology, Autonomous Undersea Syst. Inst., Durham, N. H.
  2. Whitcomb, L. L., D. R. Yoerger, and H. Singh (1999b),
    Advances in Doppler-based navigation of underwater robotic vehicles,
    paper presented at the IEEE International Conference on Robotics and
    Automation, Detroit, Mich.
  3. Ferrini, V.L., L. Whitcomb, J. Howland, D. Fornari, S.M.
    Carbotte, D. Kelley, T. Shank, M. Tivey, (2005). Navigation of UNOLS
    National Deep Submergence Facility (NDSF) Vehicles: Status Report and
    Guidelines for Data Acquisition. Ridge 2000 Community Progress and
    Planning Workshop, Vancouver, B.C., Canada.
  4. Kinsey, J.C., L.L. Whitcomb, D.R. Yoerger, J.C. Howland, V.L.
    Ferrini, O. Hegrenas, (2006). New Navigation Post-Processing Tools for
    Oceanographic Submersibles. Eos Trans. AGU, 87(52), Fall Meet. Suppl.,
    Abstract OS33A-1678.