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Ultrasound Boat Detection System PowerPoint PPT Presentation

Ultrasound Boat Detection System A Worcester Polytechnic Institute Major Qualifying Project Advisor: Fabio Carrera Advisor: Peder Pedersen Students:Mark Johnson Jonathan Lovisolo Yasuhiro Okuno Presentation Overview System Block Diagram Real Environment Object Detection

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Ultrasound Boat Detection System

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Ultrasound boat detection system l.jpg

Ultrasound Boat Detection System

A Worcester Polytechnic Institute

Major Qualifying Project

Advisor: Fabio Carrera

Advisor: Peder Pedersen

Students:Mark Johnson

Jonathan Lovisolo

Yasuhiro Okuno


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Presentation Overview

  • System Block Diagram

    • Real Environment

      • Object Detection

      • Boat Detection

      • Multiplexing (MUX)

    • Software Environment

      • Signal Processing

      • Intelligent System

      • Logging


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Presentation Overview

  • Development Stages

    • Stage 1: Lab Environment

    • Stage 2: Portable System

    • Stage 3: Real Environment

  • Future Improvements

    • Wake Height Detection

    • Pressure Sensing


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Boat

Boat

System Level Block Diagram

At the Canal

Software Environment on System

Intelligent

System

Signal

Processing

MUX

P/R

Logging

System

Echo signal

Data after Signal Processing

Logged data

  • Echo

    • Signal: TRUE

    • Delay: 2 (ms)

    • Strength: 92

    • Width: 96.2 (us)

  • Boat detected at:2003-7-15-11:23:42

  • Speed of boat: 14.1 (km/h)

  • Length:6.3 (m)

MUX:Multiplexer

P/R:Pulser/Receiver


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Operational Units

  • The following slides will describe the following different blocks of the system:

    • Signal Processing

    • Intelligent System

    • Logging System


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Signal Processing

  • This begins the outline of the Signal Processing Section


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Basic object detection using a transducer

Beam Path

Pulser/Receiver

(P/R)

Electric pulse sent by P/R to transducer

Boat Hull

Transducer

Ultrasound pulse

Pulser/Receiver

(P/R)

Transducer reacts by sending ultrasound pulse

Boat Hull

Transducer

Echoed pulse

Pulser/Receiver

(P/R)

Pulse hits object and echoes

Boat Hull

Transducer


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Basic object detection using a transducer

Echoed pulse

Pulser/Receiver

(P/R)

Echo reaches transducer

The transducer turns echo into electric pulse and sends it to P/R

Boat Hull

Transducer

Pulser/Receiver

(P/R)

Electric pulse sent to the signal processing unit

Signal Processing unit

Transducer


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Ultrasound pulses such as this are sent into the canal from the transducer

Multiple Pulses

Transducer System

Individual Pulse


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If this pulse is sent:

The returning echo will look the same:


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Boat

Measured Echoes

T = 0

Pulse sent


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Boat

Measured Echoes

T = t1

Pulse echoed


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Return Signal: When there is no boat

No return signal

Signal

T

0


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Signal

Boat

T

0

Return Signal: When there is a boat

Clean echo signifying boat


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Return Signal: When there are interferences

Noisy and weak signal

Signal

T

0


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Extracted Signal Information

Signal width

Signal strength

Signal amplitude

0

0

T

2 x t1

Signal delay

t1 is the time measured from the pulsing of transducer to when the pulse hit the boat hull

So the time a signal takes to echo back to the transducer to “hear” is 2 x t1


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Signal

T

0

T

0

Extracted Signal Information: Correlation

Sent Pulse

Signal

T

0

Received Pulse 1 (Clean)

Received Pulse 1 (noisy)

Echo is noisy and does not resemble sent pulse

Low Correlation value

Echo similar to sent pulse

High Correlation value

Correlation value of the signal, higher value means cleaner echo

High correlation value means the echo came from a solid surface and not from interference


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Once these four characteristics have been measured, Echo Validity can be determined

Presence

Correlation

Echo Validity

Amplitude

Time Delay


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Echo Validity determines if the pulse sent out is the same as the echo received.

Pulse

Echo Received

Same?

Echo Validity

In this case, the echo received is the same as the pulse transmitted. Thus, echo validity is high.


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Echo Validity determines if the pulse sent out is the same as the echo received.

Pulse

Echo Received

Same?

Echo Validity

In this case, the echo received is dissimilar from the pulse sent out. Thus, the echo validity is very low.


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So a stream of echo measurement such as below can be sent to the Intelligent System

Validity Measurement


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Echoes from the canal will only have a high validity if they are reflected off of a boat’s hard sides.

Echoes with low validity correlate to reflections off of debris, birds, etc.

If there is no echo, the echo validity is 0.


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Intelligent System & Logging

  • The following slides will depict the Intelligent System design used to gather information about the boats, as well as how that information is logged


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Basic Boat Detection Logic

Ultrasound Beam

  • T = 0

  • Boat is not intersecting the path of either ultrasound beam

  • System is idle

Boat

Canal

Transducer

  • T = 1

  • Boat is intersecting the path of left ultrasound pulse

  • System starts tracking the boat

Boat

Canal

Transducer


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Basic Boat Detection Logic

  • T = 2

  • Boat is intersecting the path of both ultrasound pulses

  • Now the system ca calculate boat speed

Boat

Canal

Transducer

d

  • T = 3

  • Boat just cleared off of the left ultrasound pulse

  • A boat just passed by!

  • Length of the boat can be now calculated

Boat

Canal

Transducer


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Multiplexer: Using 2 transducers in one channel

Connected to P/R

Multiplexer

Pulser/Receiver

(P/R)

Switch signal from PC

Disconnected from P/R

Multiplexer Allows one P/R to alternately read from 2 transducers

After receiving one switch signal from PC

Disconnected from P/R

Multiplexer

Pulser/Receiver

(P/R)

Switch signal from PC

Connected to P/R


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Boat

The Information passed to Intelligent System

Transducer A

Multiplexer

Pulser/Receiver

(P/R)

Switch signal from PC

Transducer B

Into Signal processing

Echo from transducer B

Echo from transducer A

Echo from transducer A

Into Intelligent System

Echo from transducer B

Echo from transducer A

Echo from transducer A

Distance:2.2 (m)

Validity:35

Distance:2.0 (m)

Validity:67

Distance:2.15 (m)

Validity:44

Time


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The intelligent system then takes the signal data and makes final determinations on the presence of a boat.

It looks at how many valid echoes are received consecutively with similar time delays.

If there are enough valid echoes then a boat has passed.


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There are enough valid echoes here. Therefore there is a boat

Validity Measurement


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This only has a few valid echoes. This was probably not a boat.

Validity Measurement


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Because debris, bubbles, or other factors can affect a signal we need to make the system allow for some invalid echoes.

If a there is one invalid echo amidst a string of valid echoes we ignore it and go on.


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Single bad echoes can be ignored. They could be caused by interference.

Validity Measurement

Bad Echo


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If signals return with very different time delays then they are probably reflecting off of different boats.

The system uses the time delay as a means of distinguishing between boats in the canal.


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The two echoes had different delays because they hit different boats.

Echo 1

Time delay

Time delay

Echo 2


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The system sends pulses every 0.01 seconds. The system can keep track of how many pulses happen between when the boat hits Transducer A and Transducer B.

The number of pulses tells the system how much time it took a boat to move a fixed distance. From this information we can calculate the speed of the boat. This was depicted earlier.


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Boat Speed & length calculation

Ultrasound Beam

  • Boat is not intersecting the path of either ultrasound beam

  • System is idle

Boat

Canal

Transducer

  • Boat is intersecting the path of left ultrasound pulse

  • System starts tracking the boat

Boat

Canal

Transducer


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Boat Speed & length calculation

  • Boat is intersecting the path of both ultrasound pulses

  • Calculate speed of the boat:

Boat

Canal

Transducer

d

  • Boat just cleared off of the left ultrasound pulse

  • A boat just passed by!

  • Length of the boat can be calculated by:

Boat

Canal

Transducer


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When the system stops receiving valid echoes from a boat the speed is calculated. This was also shown earlier.

Once this happens the information for the boat is logged. This information is printed in the log file like this:

Timestamp: Sun Feb 16 14:30:07 2003

Speed: 9.7 km/h

Length: 2.8 m

Note: The length of this boat may be inaccurate due to other boats in the system!

The note is shown when another boat interferes with the data for this boat.


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Once the data is logged to a file it can be retrieved at any time. The system will be capable of retrieval by either disk or remotely through the internet when it is complete.

Sample Entry in the log


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Development Process

The next few slides will depict the development process of this project

By the end of the academic year, this group will have completed the second stage of development, ready for testing in Venice.


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Toy Boat

Development Stages: First Generation

First Generation

Fish Tank

Pulser/Receiver

Digitizer

(LeCroy9400)

GPIB

PC

with test software

  • Test of Theory in lab controlled environment

  • Test that the method works

  • Refine method of detection and data collection

  • Establish a detection software

No new investment

Using equipment available at WPI


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Test Object

(i.e. real boat)

Development Stages: Second Generation

Second Generation

Pool/Venice

Pulser/Receiver

Laptop

with digitizer card

and test software

  • Field testing

  • Test theory established in first generation

  • Deal with any irregularity of the real environment

  • Finalize detection and data collection software

Investment:

Laptop $1500

Digitizer card $1300

P/R$2000

Transducer (x2)$800

* These Prices are rough estimates


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Boat

Development Stages: Third Generation

Final Generation

Standalone

Embedded

System

Venice Canals

Pulser/Receiver

Data Transfer

Via Network

or

Removable Media

Research Team

  • Deployment

  • Implement all functionality developed in 2nd generation in a single standalone system.

  • Test all functionality in field

  • Deploy system for usage in Venice canals

Price per Unit:

Platform Hardware$500 - 800

Digitizer card $1300

P/R$2000

Transducer (x2)$800

* These Prices are rough estimates


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Future Improvements: Wake height and pressure detection

  • In the Future…

  • Use Accelerometer or Pressure Transducer to measure force exerted on the wall.

    • This data can be used to relate traffic and canal damage

Lateral Wave Force

Boat

Wake Height

Accelerometer or Pressure Transducer

With all the information, the log may look like the following for each station:

(note: the values in the table is a sample and may not resemble real data)

* The pressure measurement unit is unknown at the point of this writing, and the values may be unreasonably off


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Conclusions

  • The project is currently in the second phase of development.

  • The second phase will be completed by May 2003, ready for testing in Venice

  • The system will be able to log:

    • Boat Traffic

    • Speed of Boats

    • Boat Size


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