Underwater Network Localization

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24 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Underwater Network Localization

Patrick Lazar,
Tausif

Shaikh
, Johanna Thomas,
Kaleel

Mahmood


University of Connecticut

Department of Electrical Engineering

Outline


Background


Objective


Hardware/Software


Methods


Synchronous


Asynchronous


Range Test


Noise Test


Budget


Future Work


Division of Roles


Timeline



Background


Cannot use GPS because electromagnetic signals
cannot propagate well through water


Use acoustic signals


Signal strength independent of conductivity of medium


Currently four commercial underwater localization
techniques


Two research methods


Synchronous


Asynchronous

Objective


Design a highly accurate localization system capable of
being used on underwater vehicles
.



Implement localization algorithms for real time
testing.



Provide the AUV
senior design group
with
an effective
localization
schematic that can be integrated into the
AUV for underwater tracking.


Hardware/Software


Six digital processing boards


Four anchor nodes


One tracking node


Six hydrophones


Six transducers


Four GPS tracking devices


Waterproof housing


Software : Code Composer Studio 5.1


DSP boards in waterproof housing.

Synchronous Localization
Method


Synchronous Localization


Advantages of synchronous localization:


Able to service multiple AUV at once


Does not require continuous GPS signal to synchronize
surface nodes


Disadvantages of synchronous localization:


Nodes must be on the surface initially to receive a GPS
signal initially.


Any missed node signal means position can not be
computed if working with the minimum node
schematic.

Synchronous Code Flow Diagram

Start

(nodes)

Init

Modem

Send Call


Wait for
other
nodes

Start

(AUV)

Init

Modem

Listen for
node
calls


when 4
calls
received


Position algorithm

Asynchronous Localization
Method


Asynchronous Localization


Advantages of Asynchronous Localization:


Node clocks do not require synchronization with each
other.


Extra timing measurements sent from other nodes can
be factored into to calculations to provide better
position accuracy.


Disadvantages of Asynchronous Localization:


The initiator signal must send out a delay factor long
enough so no nodes send out signals at the same time.


Never field tested so actually accuracy improvement is
unknown.

Asynchronous Code Flow Diagram

Start

(nodes)

Init

Modem

Wait for
AUV call

Record
time

Send
Response

Start

(AUV)

Init

Modem

Call
N1

Call
N2

Call
N3

Call
N4

Record N1
response

Record
N2
response

Record N3
response

Record
N4
response

Localize

Position algorithm

Range Test


The speed of sound travels at a faster rate in water than
air.


It depends on water properties of temperature, salinity,
and pressure.


As temperature of water increases, the speed of sound
increases.


On average, the speed of sound travels at
approximately 1500 m/s under water.


Range Test Diagram

Swimming Pool

Noise Test


The range of the signal can be affected by the ambient
noises and man made noises.


The variance calculated from the noise test is used to
calculate the Time of Arrival (TOA) of the signal.



Swimming Pool


Budget


Currently all our hardware needs are handled by the
Underwater Sensor Network Lab.


In terms of software the version of Code Composer
studio we use is a free license version provided by the
company.


At this time we have no plans to use the $1000 budget
but in the future we may consider using funding to buy
additional digital signal processing boards from
Spectrum Digital if necessary.


Future Work


Analyze the modem code supplied by UWSN Lab


Create
algorithm
code for both Asynchronous and
Synchronous
methods in C.


Implement tracking algorithms for localization of
moving
objects (if needed)


Conduct pool testing:


Range test of equipment


Determine delay time
for more accurate calculations


Determine pool
interference

Project Roles


Tausif

Shaikh

(EE)

Synchronous and
Asynchronous
algorithm
implementation
in C

Analysis of pool
test results

Website
maintenance and
updates

Johanna
Thomas
(EE)

Synchronous and
Asynchronous
algorithm
implementation
in C

Analysis of pool
test results


Coordinator of
data and results
collected by each
part of the team

Patrick
Lazar
(EE)

DSP Board
Programming

Hardware setup

Website
maintenance and
updates

Kaleel

Mahmood

(EE)

DSP Board
programming

Hardware setup

Main
communication
between design
group and advisor

September



Project
Statement.


Background
research in
existing
Localization
methods.

October


Project
specifications.


Additional
localization
research.


Coding DSP C

November


Code composer
studio setup and
completion of
tutorial on
coding in DSP C.


Finalize
implementation
plans.

December


Ranging and
noise pool tests
using two nodes.


Coding DSP C
algorithms.

Timeline

January


Ranging and
pool tests using
two nodes.


Hardware setup
of remaining
nodes.


Field testing of
algorithms .

February


Field testing of
algorithms.


Algorithm
comparison
analysis.

March


Field testing of
algorithms.


Algorithm
comparison
analysis.

April


Integration of
localization with
other groups.


Algorithm
comparison
analysis.

May


Complete
integration of
localization
with an AUV.

Questions?