automating wireless sensor network deployment and replacement in pipeline monitoring ted tsung-te...

Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring

TriopusNet

Ted Tsung-Te Lai Albert Wei-Ju Chen

Kuei-Han LiPolly Huang

Hao-Hua Chu

National Taiwan University

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

Water pipelines are everywhere people live

Pipelines carry important resources (gas, oil…etc.)

Pipelines carry very important resources (beer pipeline!)

•Motivation

leaking

leaking

Pipeline monitoring is essential

Water contamination (Boston, 2010)

Difficult sensor deployment

WSN challenges (Deployment and maintenance)

• Deployment challenges– Difficult to access pipelines to place sensors (often hidden

inside walls or underground)

– May need to break pipes to install sensors inside

• Maintenance challenge– Difficult to replace out-of-battery sensors

• Real pipeline environment– Difficult to ensure network connectivity during sensor

placement and replacement

Research question

• Can we automate WSN sensor placement and replacement in pipeline?– While minimize the number of sensor nodes– Good sensing and networking coverage

• Reduce the human effort bottleneck for long-term, large-scale WSN deployment & maintenance.

Single-Release Point the enabling concept

Place sensors at a single release pointSensors automatically place themselves in the pipes

Single-release point

How to realize single-release point?

• Sensor placement– Mobile sensors– Sensor latch mechanism– Sensor placement algorithm– Sensor localization

• Sensor replacement– Sensor replacement algorithm

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

TriopusNet automate WSN deployment in pipeline

Triopus nodethree arms for latching

Gateway node

Gateway node

Gateway node

Single-release point

• Sensor placement– Mobile sensors– Sensor latch mechanism– Sensor placement algorithm– Sensor localization

• Sensor replacement– Sensor replacement algorithm

TriopusNet automate WSN deployment in pipeline

Mobile sensor (components)

Localization sensors (SenSys’ 10)

water pressure + gyro

Actuatorpull/push a mechanical arm

Sensor mote

• A Telosb-like platform, TinyOS compatible• Smaller form-factor, only CPU board is needed

= +

Kmote CPU board USB board

Mobile sensor (kmote)

(data processing) (program uploading)

Mobile sensor (latch & delatch mechanism)

Linear actuator, off-the-shelf from marketA motor with gear inside to control the armSpec:• Stroke: 2cm• Weight: 15gram• Arm extending speed: 2cm/sec 0cm

1cm

2cm

Prototype #1 (8cm diameter)

Prototype #2 (one motor, three arms)

Prototype #2 (6cm diameter)

Sensor placement algorithm

• Where are the optimal locations to place sensors in pipes (after releasing them from the single-release point)?

– Networking coverage• Interconnectivity among all nodes

– Sensing coverage• Each pipe segment has at least one sensor

– Minimize # of sensor nodes for deployment

Sensor placement algorithm

branch 1

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Sensor placement algorithm

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Sensor placement algorithm

branch 1

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waterinlet

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

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Sensor placement algorithm

Post-order traversal : n1 -> n2 -> … n7

Reasons:1. Assure nodes cover all pipes2. Allow blockage-free movement (bottom-up placement)

Testing packet received ratio

Good link quality, placement completedBad link quality

Sensor placement algorithm

Gateway node

Gateway node

Gateway node

Single-release point

Sensor localizationPressure graph

• Previous PipeProbe system [SenSys’10]

– cm-level positional accuracy

• Vertical pipe location– Water pressure changes at different height levels

• Horizontal pipe location– Node distance = node velocity * node flow time

• Pipe turn detection– Gyroscope

Data Collection

• Collection Tree Protocol (CTP) in TinyOS• Multi-sink tree to balance network load

Gateway node

Gateway node

Gateway node

Single-release point

Low Battery…

Sensor replacement algorithm

Gateway node

Gateway node

Gateway node

Single-release point

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

Testbed

150cm

200cm

200cm 200cm

200cm 200cm

Testbed spatial layoutSingle-release point

Evaluation metrics

• Automated sensor placement– # Nodes for pipeline deployment– Data collection rate– Energy consumption

• Automated sensor replacement– Data collection rate

Scenario 3

Scenario 1

Scenario 4

Scenario 2

Experimental procedure (4 test scenarios)

5 tests for each scenario

gateway gateway

gateway

Single-release point

# Deployed Nodes (Static v.s. TriopusNet deployment)

TriopusNetATriopusNetBTriopusNetC

Avg # of nodes deployed-Static: 7.5-TriopusNet: 4.4

Avg. node-to-node distance: 173cmStd: 58cm

Static (90cm)

Avg. node-to-node distance

Avg. node-to-node distance

Avg. node-to-node distance

Avg. node-to-node distance

Data collection rate

Each node sent 1000 packets to gateway-80% nodes achieve 99% packet receive rate-All nodes > 87% rate

Energy consumption (node placement)

Each node requires 2.4 actuations on average(1 actuation consumes ~1J)

Evaluation metrics

• Automated sensor placement– # nodes for sensing/networking coverage– Data collection rate– Energy consumption

• Automated sensor replacement– Data collection rate

Test scenario and result for replacement

Set these two nodes to low battery level and trigger replacement

Data collection rate

Initial deployment

After replacement

Without replacement

0.99 0.98 0.80

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

automatic faucet

Limitation: Lack automatic faucets

Limitation: Node size

Low Battery…

Limitation: Node sizeSingle-release point

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

Detect and localize leakage by pressure and ultrasonic sensors

PipeNet (IPSN’07, pipeline monitoring)

NAWMS (SenSys’08, water flow sensing)

toilet

kitchen sink

shower

HydroSense (Ubicomp’09, water event sensing)

Single-point pressure-based sensor of water usage

Multi-pointsensing

Single-pointsensing

Single-release point

NAWMS HydroSense TriopusNet

PipeNet

Comparison to related work

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

Conclusion

Automated sensor placement and replacement to reduce human deployment and maintenance effort: mobile sensors with self-latching mechanism from a single-release point

Results show smaller number of sensor nodes with good sensing/networking coverage

TriopusNet: automating WSN deployment and replacement in pipeline monitoring

Thank shepherd (Prof. Gian Pietro Picco) & reviewers for valuable comments

Questions & Answers

TriopusNet: Automating WSN Deployement and Replacement in

Pipeline Monitoring

Ted Tsung-Te Lai, Albert Wei-Ju Chen, Kuei-Han LiPolly Huang, Hao-hua Chu

Ubicomp labhttp://mll.csie.ntu.edu.tw

National Taiwan University