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 DiagramReal Environment

• Object Detection• Boat Detection• Multiplexing (MUX)

Software Environment• Signal Processing• Intelligent System• Logging

Presentation Overview

Development StagesStage 1: Lab EnvironmentStage 2: Portable SystemStage 3: Real Environment

Future ImprovementsWake Height DetectionPressure Sensing

Bo

at

Bo

at

P/R

MUX

Real Environment

SignalProcessing

Intelligent System

Echo signal

Logging System

•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)

Data after Signal Processing Logged data

System Level Block Diagram

Software Environment on System

MUX: MultiplexerP/R: Pulser/Receiver

Real Environment Design

The following slides will depict the system’s operation in the canal setting, including:

Boat DetectionTransducer Multiplexing

Object

Pulser/Receiver(P/R)

Beam Path

Transducer

Electric pulse sent by P/R to transducer

Object

Pulser/Receiver(P/R)

Ultrasound pulse

Transducer

Transducer reacts by sending ultrasound pulse

Object

Pulser/Receiver(P/R)

Echoed pulse

Transducer

Pulse hits object and echoes

Real Environment: Object detection

Object

Pulser/Receiver(P/R)

Echoed pulse

Transducer

Echo reaches transducerThe transducer turns echo into electric pulse and sends it to P/R

Pulser/Receiver(P/R)

Transducer

Electric pulse sent to the signal processing unit

Signal Processing unit

Real Environment: Object detection

Boat

Boat

Ultrasound Beam

Canal

Canal

Transducer

Transducer

• Boat is not intersecting the path of either ultrasound beam• System is idle

• Boat is intersecting the path of left ultrasound pulse• System starts tracking the boat

0t

Tt

Real Environment: Basic Boat Detection method

Canal

Transducer

• Boat just cleared off of the left ultrasound pulse• A boat just passed by!• Length of the boat can be calculated by:Boat

2Tt

)/()()( 2 smvsml boatboat

Canal

Transducer

• Boat is intersecting the path of both ultrasound pulses• Calculate speed of the boat:Boat

1Tt

rs transduceobetween tw distance:

)()()/(

1

d

smdsmvboat

d

Real Environment: Basic Boat Detection method

Multiplexer

Switch signal from PC

Pulser/Receiver(P/R)

Connected to P/R

Disconnected from P/R

After receiving one switch signal from PC

Multiplexer

Switch signal from PC

Pulser/Receiver(P/R)

Disconnected from P/R

Connected to P/R

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

Real Environment: Multiplexer

Boat

Real Environment: To the next step

Time

Echo from transducer A Echo from transducer AEcho from transducer B

The signals received from the transducer by the pulser receiver are sent to the PC in the form of Electrical signals to be processed by Signal Processing Unit

Multiplexer

Switch signal from PC

Pulser/Receiver(P/R)

Transducer A

Transducer B

Software Environment

The following slides will describe the software used in this system including the:

Signal ProcessingIntelligent SystemLogging System

Signal Processing

This begins the outline of the Signal Processing Section

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

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

Multiple PulsesMultiple Pulses

Individual PulseIndividual Pulse

Transducer System

Transducer System

When the pulses strike an object, echoes are reflected back towards the transducer.

When the pulses strike an object, echoes are reflected back towards the transducer.

TransducerTransducer TransducerTransducer

Pulses TransmittedPulses Transmitted Pulses ReturningPulses Returning

Water Water

Side Of

Boat

Side Of

BoatSide Of

Boat

Side Of

Boat

Canal Wall

Canal Wall

Canal Wall

Canal Wall

If this pulse is sent:

The returning echo will look the same:

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

PulsesPulses

This is a possible setup of the transducer system

This is a possible setup of the transducer system

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

PulsesPulses

This represents what is being transmitted into the canal

This represents what is being transmitted into the canal

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

PulsesPulses

This represents what is being reflected from the canal

This represents what is being reflected from the canal

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

PulsesPulses

When the canal is empty, there is nothing for the pulses to reflect off of. Thus, the return is empty

When the canal is empty, there is nothing for the pulses to reflect off of. Thus, the return is empty

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

EchoesEchoes

When a boat travels in front of the transducer system, echoes begin returning.When a boat travels in front of the transducer system, echoes begin returning.

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

Returning From Canal

Returning From Canal

EchoesEchoes

As the boat continues to pass, more and more echoes are recordedAs the boat continues to pass, more and more echoes are recorded

Canal Wall

Transducer System

Transmitted Into Canal

Transmitted Into Canal

PulsesPulses

When the boat passes, the transducer system stops receiving echoes.

When the boat passes, the transducer system stops receiving echoes.

Returning From Canal

Returning From Canal

At this point, the system has recorded a series of echoes, such as this:

At this point, the system has recorded a series of echoes, such as this:

When we receive an echo, we are measuring its:When we receive an echo, we are measuring its:

Presence

Is there an echo or not?

Is there an echo or not?

When we receive an echo, we are measuring its:When we receive an echo, we are measuring its:

Signal Width

How wide the echo is

How wide the echo is

When we receive an echo, we are measuring its:When we receive an echo, we are measuring its:

Amplitude

The maximum strength of the

signal

The maximum strength of the

signal

When we receive an echo, we are measuring its:When we receive an echo, we are measuring its:

Time Delay

Time spent traveling in the

water

Time spent traveling in the

water

Correlation

How much the echo resembles the original pulse

How much the echo resembles the original pulse

This graph represents the output of the correlation function, a complex signal processing algorithm. The height of the solid line represents the similarity between pulse and echo. The higher the line, the more resemblance that exists.

When we receive an echo, we are measuring its:When we receive an echo, we are measuring its:

PresencePresence

AmplitudeAmplitude

Time DelayTime Delay

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

CorrelationCorrelation

Echo ValidityEcho Validity

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

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

Pulse Echo Received

Same?

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

Echo Validity

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

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

Pulse Echo Received

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

Same?

Echo Validity

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

smooth, hard sides.

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

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

Echo ReceivedEcho Received Validity Measurement

Validity Measurement

Thus, if a string of echoes is received, all with high validity,Thus, if a string of echoes is received, all with high validity,

Validity Measurement

Validity Measurement

It can be concluded that a boat has passed in front of the transducer.It can be concluded that a boat has passed in front of the transducer.

Validity Measurement

Validity Measurement

If the echo validity is low, no boat has passed yet.If the echo validity is low, no boat has passed yet.

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

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.

Validity Measurement

Validity Measurement

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

Validity Measurement

Validity Measurement

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

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.

Validity Measurement

Validity Measurement

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

Bad EchoBad Echo

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.

Echo 1Echo 1

Echo 2Echo 2

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

Time delay

Time delay

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.

Boat

Boat

Ultrasound Beam

Canal

Canal

Transducer

Transducer

• Boat is not intersecting the path of either ultrasound beam• System is idle

• Boat is intersecting the path of left ultrasound pulse• System starts tracking the boat

0t

Tt

Real Environment: Basic Boat Detection method

Canal

Transducer

• Boat just cleared off of the left ultrasound pulse• A boat just passed by!• Length of the boat can be calculated by:Boat

2Tt

)/()()( 2 smvsml boatboat

Canal

Transducer

• Boat is intersecting the path of both ultrasound pulses• Calculate speed of the boat:Boat

1Tt

rs transduceobetween tw distance:

)()()/(

1

d

smdsmvboat

d

Real Environment: Basic Boat Detection method

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 mNote: 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.

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.

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.

Digitizer(LeCroy9400)

GPIB

Fish Tank Pulser/Receiver

PC with test software

First Generation

Test of Theory in lab controlled environment•Test that the method works•Refine method of detection and data collection•Establish a detection software

Toy Boat

Development Stages: First Generation

Laptopwith digitizer cardand test softwareTest Object

(i.e. real boat)

Pool Pulser/Receiver

Second Generation

Field testing•Test theory established in first generation•Deal with any irregularity of the real environment•Finalize detection and data collection software

Development Stages: Second Generation

Venice Canals Pulser/Receiver

Final Generation

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

StandaloneEmbedded

System

Boat

Research Team

Data TransferVia Network

orRemovable Media

Development Stages: Third Generation

Lateral Wave Force

Wake Height

Boat

Accelerometer or Pressure

Transducer

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

Future Improvements: Wake height and pressure detection

Time Boat Type Wake height (cm) Pressure (?)* Speed (km/h) Length (m)

2003-7-15-11:23:42 Motor-boat C 35.5 23 14.3 6.1

2003-7-15-11:24:32 Gondola A 9.3 10 6.2 5.5

2003-7-15-11:25:35 Freight D 11.6 18 8 8.2

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

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