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New Generation DVLs for Underwater Vehicle Navigation
New Generation DVLs for Underwater Vehicle Navigation
Claire Cardy
Director, Nortek UK
Subsea Expo, Aberdeen, 7-9 February 2018
What is a DVL?
Doppler Velocity Log
Navigation aid - measures velocity relative
to the bottom
Step 1: Detect the bottom
Step 2: Estimate the relative velocity to the
bottom
Why use a DVL? - Prevents drift
A B C D
• Transmit pulse reflects from scatterers in the water as well as bottom
•How to distinguish?
• Look for loud returns similar to transmit pulse
Bottom Detection
A BC D
How is Nortek’s DVL different
Reduced size, weight and power
consumption
Supports legacy data formats
Easier to use
Figure of merit (FOM)
Improved time synchronization with INS
Improved bottom detection
Highly accurate!
Typical Causes for Loss of Bottom Lock
Range
Soft bottom
Bottom slope /
underwater structure
Processing method
Oslo Fjord, 1 MHz
DVL…
Oslo Fjord – 13m range
1 MHz DVLNortek Detection
Match Filter Detection
Oslo Fjord – 52m range
Nortek Detection
Match Filter Detection
1 MHz DVL
Oslo Fjord – 66m range
Nortek Detection
Match Filter Detection
1 MHz DVL
Oslo Fjord – 81m range
Nortek Detection
Match Filter Detection
1 MHz DVL
Range Test Results, 1 MHz
How does this look ping after
ping?
Standard 1.2 MHz acheives
25-50 meters
Present range is 50m
Increased this to 75m
Range Test Results, 500 KHz
300 kHz
Can you get the range
of a 300 kHz with a 500
kHz DVL?
Yes!
One DVL to rule them
all!
600 kHz
Kongsberg
High end AUV – Industry
standard
Two years of testing
Positive feed back – new data
products
Evaluated long term accuracy
Reference paper
Validation of a New Generation DVL for Underwater Vehicle Navigation
Kongsberg – Performance Evaluations
Validation of a New Generation DVL for Underwater Vehicle Navigation
Long term comparisons
Exceptional Accuracy
0.2%
0.02%
So where is this taking us?
http://noc.ac.uk/projects/oceanids
Fusion ROV Artemis
Thank [email protected]
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