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The Hitchhiker’s Guide to Successful Residential Sensing

Deployments

Timothy W. Hnat, Vijay Shrinivasan, Jiakang Lu, Tamim I. Sookoor, Raymond

Dawson, John Stankovic, and Kamin Whitehouse

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Sensing in Homes

MedicalMonitoring

HomeAutomation

EnergyManagement

People spend 65% of time in their homes

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Sensing in Homes

Extreme Environments Indoors is hard too!

Photo courtesy of: Jan Beutel

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Sensing in Homes

1200 sensors Over 20 homes Up to 1 year/home

Diffi

culty

#Sensors

#Sen

sors

< #Out

lets

#Sen

sors

> #Out

lets

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Sensing in Homes

1200 sensors Over 20 homes Up to 1 year/home

Diffi

culty

#Sensors

#Hom

es <

#Res

earc

hers

#Hom

es >

#Res

earc

hers

#Homes

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Sensing in Homes

1200 sensors Over 20 homes Up to 1 year/home

Diffi

culty

#Sensors

#Day

s < ~1

mon

th

#Day

s > ~1

mon

th

#Homes

#Days

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Outline Deployment Overview Reliability and Failure Analysis A Hitchhiker’s Guide

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Deployments Overview

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Deployments Overview

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Deployments Overview

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Our DeploymentsDeployment

# Homes

Weeks

Motion

Object Use

Door Heights

Wearable Tracking

Light Switch

Power (Plugs)

Power (Circuits)

Power (Mains)

Water Mains

Custom Thermostat

Active Register

Light/Temp Humidity

A 11 1-2 25-30

12-20 - - - - - - - - - -

B 1 1 - - 12 12 - - - - - - - -

C 3 3-4 15-25 - - - - - - - - - - 12-

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D 1 2 4 - - - - 2 - - - - - -

E 1 2 5 - - - - - 1 - - - - -

F 1 28 65 13 13 16 22 - - 1 1 1 12 86

G 1 44 54 7 31 14 22 8 37 1 1 1 12 29

H 1 39 15 7 14 - 11 4 - 1 1 - - -

I 1 32 25 10 30 - 31 3 48 1 1 - - 8

J 1 25 14 5 17 - 7 2 - 1 1 - - -

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Outline Deployment Overview Reliability and Failure Analysis A Hitchhiker’s Guide

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Fault Analysis

…

Time

Sens

ors

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Failure Analysis

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Fault Analysis Power Outage

Time

Sens

ors

…

Sensor-Days – down time × number of sensors

Fault Analysis

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Reinstall

Hard drive failure

Sub-system failure Plug disconnections

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Outline Deployment Overview Reliability and Failure Analysis A Hitchhiker’s Guide

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Homes are Not a Power Panacea 30-40 outlets per house Long wires 2.3x more down time than

batteries More maintenance calls

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Homes Have Poor Connectivity Wireless connectivity

Power line communications Wires 180bit/s 5 min polling rate Exploiting Home Automation Protocols

for Load Monitoring in Smart Buildings

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Homes are Hazardous Environments

Children Mobile objects Roomba Guests and

cleaning services

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Homes are Remote Environments Minimize installation time

Scout Lab assembly and

configuration Checklists

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Expect Limited User Participation Button Tracking Wearable Tracking Self-reporting Surveys

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Aesthetics Matter in Homes Disappear into the

woodwork Leave no trace No LEDS at night Noise

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Simplify the Architecture

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Similar Work Infrastructure-based

Neural Network House, Aware-Home, MavHome, PlaceLab

Infrastructure-less Tapia, Cook, Kasteren

Lessons Learned Edwards and Grinter – 7 challenges “Hitchhiker’s guides for WSN deployments”

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Summary AC Power is not abundant or reliable Wireless connectivity is worse than expected Unexpected environmental hazards Houses are remote environments User participation is limited Aesthetics are important COTS are a double-edged sword

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Thank You

Any questions?

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Root FailuresRoot Cause House G House H House I House J

Sensing sub-system 4107 642 4757 274

Gateway Down 5596 0 3 136

Plug Disconnected 509 30 474 10

Battery Dead 452 17 168 0

Wireless Link Loss 410 0 122 1

Internet Down 251 97 178 9

Power Outage 21 0 87 2