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TriopusNet. 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. Ted Tsung-Te Lai Albert Wei- Ju Chen Kuei -Han Li
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TriopusNet 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
Ted Tsung-Te Lai Albert Wei-Ju Chen Kuei-Han Li Department of Computer Science and Information Engineering Polly Huang Graduate Institute of Networking and Multimedia Department of Electrical Engineering Hao-HuaChu Graduate Institute of Networking and Multimedia Department of Computer Science and Information Engineering
Outline Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion
Pipeline monitoring is essential-clean water • Motivation leaking leaking
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: • Preparation Step • Knowing the spatial topology(turning faucets on one after another). • Sensor Deployment Step • Compute deployment location then send “release” message and position to node. • Sensor Latching Step • Compute location, attach itself, completion message. • Sensor Replacement Step • Consume battery power during the data collection phase. • Detach itself, go to faucet, exit.
Single-Release Point the enabling concept Single-release point Place sensors at a single release point Sensors automatically place themselves in the pipes
How to realize single-release point? • Sensor placement • Mobile sensors • Sensor latch mechanism • Sensor placement algorithm • Sensor localization • Sensor replacement • Sensor replacement algorithm
Limitations • The spatial topology of pipeline must be known. • Manual effort is required to open faucets.(at the beginning, at battery replacement) • Current sensor measures 6 cm in diameter.
Outline Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion
TriopusNetautomate WSN deployment in pipeline Triopus nodethree arms for latching Single-release point • Gateway node • Gateway node • Gateway node
TriopusNetautomate 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(Kmote) Actuator(motor) pull/push a mechanical arm Localization sensors water pressure + gyro Water proof case Vertical horizontal Pipe pipe
Mobile sensor (kmote) • A TelosB-like platform, TinyOS compatible • Smaller form-factor, only CPU board is needed + = Kmote CPU board USB board (program uploading) (data processing)
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 #2 • One motor driving the three arms. • Replace 3 AAA with lithium battery.
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 n6 n1 branch 3 faucet 4 n4 n5 faucet 3 faucet 2 n2 n3
Sensor placement algorithm root water inlet branch 2 n7 branch 1 faucet 1 n6 n1 branch 3 faucet 4 n4 n5 faucet 3 faucet 2 n2 n3
Sensor placement algorithm root water inlet branch 2 n7 branch 1 faucet 1 n6 n1 branch 3 faucet 4 n4 n5 faucet 3 faucet 2 n2 n3
Sensor placement algorithm root water inlet branch 2 n7 branch 1 faucet 1 n6 n1 branch 3 faucet 4 n4 n5 faucet 3 faucet 2 n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 n6 n1 n4 n5 n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 1st n6 n1 n4 n5 n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 1st n6 n1 n4 n5 2nd n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 1st n6 n1 n4 n5 3rd 2nd n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 1st n6 n1 4th n4 n5 3rd 2nd n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 1st n6 n1 5th 4th n4 n5 3rd 2nd n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 n7 6th 1st n6 n1 5th 4th n4 n5 3rd 2nd n2 n3
Sensor placement algorithm root Post-order traversal : n1 -> n2 -> … n7 7th n7 6th 1st n6 n1 5th 4th n4 n5 3rd 2nd n2 n3
Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7 Reasons: 1. Assure nodes cover all pipes 2. Allow blockage-free movement (bottom-up placement) root 7th n7 6th 1st n6 n1 5th 4th n4 n5 3rd 2nd n2 n3
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 PipeProbesystem • 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 (reduce the hope count and packet loss) • 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 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 (4test scenarios) Scenario 2 Single-release point 5 tests for each scenario gateway Scenario 3 Scenario 4 Scenario 1 gateway gateway
# Deployed Nodes(Static v.s. TriopusNet deployment) Real node location of three test runs from scenario 4. It shows the dynamic of each deployment. TriopusNetA TriopusNetB Static (90cm) TriopusNetC
# Automated Sensor Deployment Avg # of nodes deployed -Static: 7.5 -TriopusNet: 4.4 Avg. node-to-node distance: 173cm Std: 58cm • The overall large variation implies that the Radio range varies significantly from location to location.