CS HONORS UNDERGRADUATE RESEARCH PROGRAM - FINAL PROJECT TALKTingyu Thomas LinAdvisor: Professor Deborah EstrinDate of Presentation: Thursday, June 7, 2007

AN INVESTIGATION OF ACOUSTIC SOURCE LOCALIZATION IN A HETEROGENEOUS NETWORK

OUTLINE Overview of system Design Simulation Experimentation and Results

OUTLINE Overview of system Design Simulation Experimentation and Results

OVERVIEW OF SYSTEM Two tiered distributed sensing network:

ENSBox + Lots of resources, precise - Expensive in cost, resources, to deploy in large

numbers Mica2 Mote

+ Cheap to deploy in large numbers - Resource constraints, poor resolution in measurements

Why? To leverage the advantages respective

advantages General context of acoustic source localization

OUTLINE Overview of system Design Simulation Experimentation and Results

SYSTEM GOALS Functionality to support acoustic localization:

Wireless Communication Time synchronization Self-calibration

ENSBox Already have functionality

Mica2 Mote Extend functionality to motes

WIRELESS COMMUNICATION & TIME SYNC Mote-Mote communication

Mica2 motes - onboard 433 MHz radio BMAC Transport/Routing Protocols

Mote-ENSBox communication ENSBox – tethered mote

Time Synchronization Flooding Time Synchronization Protocol (FTSP) Time translation between ENSBox & Motes

SELF-CALIBRATION How to determine positions of motes w/o any

prior knowledge of location? ENSBox acoustic source localization facilities

Equip motes with speakers

Process: Schedule the motes to emit a signal ENSBoxes localize signal Localization results => mote locations

DOA-BASED LOCALIZATION Determine Direction of Arrival (DOA)

Combine DOAs

DOA LIKELIHOOD PLOTS

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LOCALIZATION, CONT’D The Mica2 Motes now support:

Wireless Communication Time synchronization Self-calibration

OUTLINE Overview of system Design Simulation Experimentation and Results

GOALS OF SIMULATION Modeling System

Rapid Simulation Controllable

Self-Calibration Accuracy of localizing Motes w/ ENSBoxes

SIMULATING LOCALIZATION Field

60x60 m, no obstructions

ENSBox placement and self-calibration Errors in self-calibration

Gaussian errors: 4 cm for position, .96 degrees in orientation

Mote Localization Sound wave DOA and pseudo-likelihood maps

SIMULATING LOCALIZATION

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OUTLINE Overview of system Design Simulation Experimentation and Results

EXPERIMENT #1 Questions:

Frequency of call? More ENSBoxes = better?

Scenario: 20 motes randomly but uniformly generated in

field Initially: 5 ENSBoxes Localize motes using different frequency calls

1 KHz, 4 KHz, 10 KHz

Increase ENSBox count up to 8

EXPERIMEN

T #1, CO

NT’D

Squares = ENSBoxes

Blue = Motes

Red = Estimated mote positions

Call: 1 KHz

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EXPERIMENT #1 RESULTS Table of mean errors ± standard deviation,

units in cm In this particular simulation setting:

Frequency of call, no effect Increasing ENSBox count, no effect

Frequency of Call  1 KHz 4 KHz 10 KHz

5 47±23 47±23 47±24Number

of 6 38±23 38±23 39±22ENSBoxes 7 40±35 39±35 36±31

8 39±25 40±25 38±23

EXPERIMENT #1 EXTENSION For 1 KHz call

localization results for 9 and 10 ENSBoxes Indicates > 5 ENSBoxes != >accuracy

Frequency of Call  1 KHz 4 KHz 10 KHz

5 47±23 47±23 47±24Number of 6 38±23 38±23 39±22ENSBoxes 7 40±35 39±35 36±31

8 39±25 40±25 38±239 44±19 - -

10 35±30 - -

EXPERIMENT #2 Question:

Least amount of ENSBoxes w/o losing accuracy?

Scenario: Same 20 motes 5 ENSBoxes to start from, 1 KHz calls from motes ENSBoxes removed, motes localized with

remaining boxes

EXPERIMEN

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Same 5 ENSBoxes, 20 motes.

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EXPERIMENT #2 RESULTS1 ENSBox Removed,

4 left Error in Measurement

ID Mean Std. dev

1 46 18

2 32 15

3 52 24

4 50 24

5 51 32

2 ENSBox Removed, 3

left Error in Measurement

IDs Mean Std. dev

1,2 52 33

1,3 77 71

1,4 60 22

1,5 86 73

2,3 40 19

2,4 46 40

2,5 33 21

3,4 68 42

3,5 63 32

4,5 62 33

3 ENSBox Removed, 2

left Error in Measurement

IDs Mean Std. dev

1,2,3 138 114

1,2,4 87 84

1,2,5 73 50

1,3,4 148 157

1,3,5 160 152

1,4,5 133 170

2,3,4 106 257

2,3,5 40 21

2,4,5 88 104

3,4,5 173 242

EXPERIMENT #2 RESULTS, CONT’D In simulation framework:

< 5 ENSBoxes = < accuracy

Suggests: At least 5 ENSBoxes in the 60x60 m yields most

accuracy w/ errors about 40±25 cm Comparable to other mote acoustic localization

schemes