Automating Wireless Sensor Network Deployment
and Replacement in Pipeline Monitoring
Ted Tsung-Te Lai
Albert Wei-Ju Chen
Kuei-Han Li
Polly Huang
Hao-Hua Chu
National Taiwan University
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
Water pipelines are everywhere people live
Pipelines carry important resources (gas, oil…etc.)
Pipelines carry very important resources (beer pipeline!)
Pipeline monitoring is essential
•Motivation
leaking
leaking
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 point
Sensors 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
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
TriopusNet automate WSN deployment in pipeline
Triopus node
three arms for latching
Single-release point
Gateway node
Gateway node
Gateway node
TriopusNet automate WSN deployment in pipeline
• Sensor placement
–
–
–
–
Mobile sensors
Sensor latch mechanism
Sensor placement algorithm
Sensor localization
• Sensor replacement
– Sensor replacement algorithm
Mobile sensor (components)
Sensor mote
Actuator
pull/push a mechanical arm
Localization sensors (SenSys’ 10)
water pressure +
gyro
Mobile sensor (kmote)
+
=
Kmote
CPU board
(data processing)
USB board
(program uploading)
• A Telosb-like platform, TinyOS compatible
• Smaller form-factor, only CPU board is needed
Mobile sensor (latch & delatch mechanism)
Linear actuator, off-the-shelf from market
A motor with gear inside to control the arm
Spec:
• Stroke: 2cm
• Weight: 15gram
• Arm extending speed: 2cm/sec
2cm
1cm
0cm
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
root
water
inlet
branch 2
n7
branch 1
faucet 1
branch 3
n6
n1
faucet 4
faucet 3
n4
n5
faucet 2
n2
n3
Sensor placement algorithm
root
water
inlet
branch 2
n7
branch 1
faucet 1
branch 3
n6
n1
faucet 4
faucet 3
n4
n5
faucet 2
n2
n3
Sensor placement algorithm
root
water
inlet
branch 2
n7
branch 1
faucet 1
branch 3
n6
n1
faucet 4
faucet 3
n4
n5
faucet 2
n2
n3
Sensor placement algorithm
root
water
inlet
branch 2
n7
branch 1
faucet 1
branch 3
n6
n1
faucet 4
faucet 3
n4
n5
faucet 2
n2
n3
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
n6
n1
n4
n2
n5
n3
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
1st
n6
n1
n4
n2
n5
n3
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
1st
n6
n1
2nd
n2
n4
n5
n3
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
1st
n6
n1
2nd
n2
n4
3rd
n3
n5
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
1st
n1
4th
2nd
n2
n4
n6
3rd
n3
n5
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
1st
n1
4th
2nd
n2
n4
n6
3rd
n3
5th
n5
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
n7
6th
1st
n1
4th
2nd
n2
n4
n6
3rd
n3
5th
n5
Sensor placement algorithm
root
Post-order traversal : n1 -> n2 -> … n7
7th
n7
6th
1st
n1
4th
2nd
n2
n4
n6
3rd
n3
5th
n5
Sensor placement algorithm
Post-order traversal : n1 -> n2 -> … n7
root
Reasons:
1. Assure nodes cover all pipes
2. Allow blockage-free movement
(bottom-up placement)
7th
n7
6th
1st
n1
4th
2nd
n2
n4
n6
3rd
n3
5th
n5
Sensor placement algorithm
Single-release point
Gateway node
Testing packet received ratio
Bad link quality
Good link quality, placement completed
Gateway node
Gateway node
Sensor localization
Pressure 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
Single-release point
• Collection Tree Protocol (CTP) in TinyOS
• Multi-sink tree to balance network load
Gateway node
Gateway node
Gateway node
Sensor replacement algorithm
Single-release point
Gateway node
Gateway node
Low Battery…
Gateway node
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
Testbed
Testbed spatial layout
Single-release point
150cm
200cm
200cm
200cm
200cm
200cm
Evaluation metrics
• Automated sensor placement
– # Nodes for pipeline deployment
– Data collection rate
– Energy consumption
• Automated sensor replacement
– Data collection rate
Experimental procedure (4 test scenarios)
Single-release point
5 tests for each scenario
gateway
Scenario 3
Scenario 2
Scenario 4
Scenario 1
gateway
gateway
# Deployed Nodes (Static v.s. TriopusNet deployment)
Avg # of nodes deployed
-Static: 7.5
-TriopusNet: 4.4
Avg. node-to-node distance: 173cm
Std: 58cm
Static (90cm)
TriopusNetA
TriopusNetB
TriopusNetC
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
Data collection rate
Initial
deployment
After
replacement
Without
replacement
0.99
0.98
0.80
Set these two nodes to low battery level
and trigger replacement
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
Limitation: Lack automatic faucets
automatic faucet
Limitation: Node size
Limitation: Node size
Single-release point
Low Battery…
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
PipeNet (IPSN’07, pipeline monitoring)
Detect and localize leakage by pressure and ultrasonic sensors
NAWMS (SenSys’08, water flow sensing)
HydroSense (Ubicomp’09, water event sensing)
Single-point pressure-based sensor of water usage
toilet
kitchen sink
shower
Comparison to related work
Multi-point
sensing
Single-point
sensing
Single-release
point
NAWMS
HydroSense
TriopusNet
PipeNet
Outline
Motivation
TriopusNet System Design
Evaluation
Limitations
Related Work
Conclusion
Conclusion
TriopusNet: automating WSN deployment
and replacement in pipeline monitoring
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
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 Li
Polly Huang, Hao-hua Chu
Ubicomp lab
http://mll.csie.ntu.edu.tw
National Taiwan University