Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring

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

Ted Tsung-Te Lai Albert Wei-Ju Chen

Kuei-Han LiDepartment of Computer Science and Information Engineering

Polly HuangGraduate Institute of Networking and Multimedia

Department of Electrical EngineeringHao-Hua Chu

Graduate Institute of Networking and MultimediaDepartment of Computer Science and Information Engineering

MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion

Outline

Water pipelines are everywhere people live

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

•Motivation

leaking

leaking

Pipeline monitoring is essential-clean water

Water contamination (Boston, 2010)

Difficult sensor deployment-traditional monitoring

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.

The system involves the following:

1. Preparation Step• Knowing the spatial topology(turning faucets on one

after another).

2. Sensor Deployment Step• Compute deployment location then send “release”

message and position to node.

3. Sensor Latching Step• Compute location, attach itself, completion message.

4. Sensor Replacement Step• Consume battery power during the data collection

phase.• Detach itself, go to faucet, exit.

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

Limitations

1. The spatial topology of pipeline must be known.

2. Manual effort is required to open faucets.(at the beginning, at battery replacement)

3. Current sensor measures 6 cm in diameter.


Outline

TriopusNet automate WSN deployment in pipeline

Triopus nodethree arms for latching

Gateway node

Gateway node

Gateway node


• 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 sensorswater pressure + gyro

Actuator(motor)pull/push a mechanical arm

Sensor mote(Kmote)

Water proof caseVertical horizontal

Pipe pipe

• 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 driving the three arms.• Replace 3 AAA with lithium battery.

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


branch 1

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faucet 2

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waterinlet

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waterinlet

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waterinlet

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

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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


Gateway node

Gateway node

Gateway node


Sensor localizationPressure graph

• Previous PipeProbe system– 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(reduce the hope count and packet loss)

Gateway node

Gateway node

Gateway node


Low Battery…

Sensor replacement algorithm

Gateway node

Gateway node

Gateway node



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


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

TriopusNetATriopusNetBTriopusNetC

Static (90cm)

Real node location of three test runs from scenario 4.It shows the dynamic of each deployment.

# Automated Sensor Deployment

• The overall large variation implies that the Radio range varies significantly from location to location.

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

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

Avg. node-to-node distance




• I-shape radio signal travel through water which absorb energy and limits its range.

Data collection rate-cumulative density function

Each node sent 1000 packets to gateway-80% nodes achieve 99% packet receive rate-All nodes > 86.5% rate

CDF of Positional Errors

• Overall median error 7.14 cm• 90% of errors are less than 20.45 cm

18

20

20

30

LocationEstimates:

• Node positional accuracy is important for achieving sensing coverage in node deployment.

Energy consumption (node placement)

The energy consumed by a single act of latching is 1.01 W ,2 secondsThe average of latching is 2.3590% required less than 5

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

0.989 0.984 0.81

The effectiveness of the automated replacement

The reason of high data loss rate:1-some sensors change route2-isolated nodes report zero


Outline

automatic faucet

Limitation: Lack automatic faucets

The TriopusNet gateway control each faucet by sending signals to the sensor trigger node.

Limitation: Node size

Low Battery…

Limitation: Node sizeSingle-release point


Outline

Breadcrumb SystemLiu

Mobile WSN Deployment

SensorFly SystemPurohit

Detect and localize leakage by pressure and ultrasonic sensors

PipeNet (pipeline monitoring)

NAWMS (water flow sensing)

toilet

kitchen sink

shower

HydroSense (Ubicomp’09, water event sensing)

Single-point pressure-based sensor of water usage

PipeProbe (determining the spatial topology)


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 You

Documents

Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring