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
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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
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
