Ultrasound Boat Monitoring System

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Ultrasound Boat Monitoring System

• Worcester Polytechnic Institute
• Major Qualifying Project

Advisors Fabio Carrera Peder
Pedersen Students Alexander Gomperts Joseph
Lee Yusuke Tanefusa
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Venice Canal Traffic

• Problem
• Wall Erosion
• Caused by traffic
• Solution
• Design an instrument that can measure boat and
  wake characteristics
• Consequent Canal Policy

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Implementation Plan

• Lab testing Phase
• Using lab equipment and PC in lab.
• Pool testing Phase
• Semi-mobile system utilizing a laptop.
• Canal Phase
• All in one embedded system.

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Why Ultrasound?

• Options
• GPS, RF ID tags
• Obtrusive
• Video
• High post processing demand
• Ultrasound
• Unobtrusive
• Low post processing demand
• Proven in rugged underwater applications.

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Methodology
Acoustic System
Signal Conditioning
Echo Acquisition
Decision Making
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Echo Acquisition
Acoustic System
Ultrasound Transducers
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Why Two Transducers?
Position at t1

• Velocity Calculation
• ?tv t2 t1
• d distance between transducers
• Length Calculation
• ?tl t3 t1
• d distance between transducers

• Worst case error is 20
• Dependent upon echo sampling rate (14Hz)
• Number of A to D samples taken
• A to D sampling rate (2MHz)
• Canal Width (10m)
• Laptop performance

Position at t2
Position at t3
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Acoustic System
BOAT
Transducer
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Echo Acquisition Process
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Switching Circuit
Before receiving signal from the digitizer
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Switching Circuit
After receiving signal from the digitizer
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Relay Switch

• A switch for high voltage signals
• Connects or disconnects the pulser/receiver with
  the transducers

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Pulser / Receiver

• Triggered by the Analog to Digital Converter
• Emits a short high voltage pulse then receives
  small signals

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Signal Propagation
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Triggers

• Originate from Analog to Digital Converter
• Switching Trigger
• switches active transducer
• Pulser/Reciever Trigger
• Causes Pulser/Receiver to emit a high voltage
  pulse
• These two triggers cycle at a constant rate
  dependent on the canal width.

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Trigger Timing
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Trigger Generating Circuit Design

• 555 Timer
• Synchronization issues using two timers
• 4-bit counter
• 0001 gives first trigger A. 0010 gives second
  trigger B.
• It takes 2ms for increment time of binary number

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Signal Conditioning
Acoustic System
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Analog Filter
Passive band-pass filter
3dB Bandwidth
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Filtering Results
Without band-pass filter
With band-pass filter
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Analog to DigitalConverter

• NI-5102 PCMCIA Digitizer Card
• Converts an analog signal to an 8-bit digital
  representation at a given sampling rate.
• Trigger Source

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Digital SignalProcessing

• Cross Correlation

• Similar echoes produce a distinct high amplitude
  spike.

• Dissimilar echoes produce lower amplitude result.

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Decision Making
Acoustic System
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Data Analysis
Match Filtering
Signal Consistency
Boat?
Range Consistency
Reality Check
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Signal and Range Consistency

• A consistent train of valid echoes
• At a consistent range given the shape of a boat
  hull

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Reality Check

• Asks the Questions
• Is the object moving faster than a boat would
  (30 knots)?
• Is the object moving slower than a boat would (2
  knots)?
• Is the object longer than a boat would be
• (7 meters)?
• Is the object shorter than a boat would be
• (2 meters)?

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Data Logging

• Records
• Timestamp
• Location ID
• Boat Data
• Velocity
• Length
• Wake Height
• Wake Pressure

------------------------------------- Location
ID canal name Date Stamp April 20,
2004 Velocity 3.14159 m/s Length 4.2
m -------------------------------------
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Future Work

• Future Project Groups
• Implement wake height and pressure sensors
• Implement hydrophone boat recognition
• Implement a GUI for the software
• Implement the embedded system phase

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Testing Setup
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Questions?