Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring Triopus Net Ted Tsung-Te Lai Albert Wei-Ju Chen Kuei-Han Li Polly Huang Hao-Hua Chu National Taiwan University
Feb 23, 2016
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.
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 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
Sensor placement algorithm
branch 1
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faucet 2
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waterinlet
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Sensor placement algorithm
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Sensor placement algorithm
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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– 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
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
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
Avg. node-to-node distance
Avg. node-to-node distance
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
MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion
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
MotivationTriopusNet System DesignEvaluationLimitationsRelated WorkConclusion
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)
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 You