1. 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

2. 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-Hua Chu Graduate Institute of Networking and Multimedia Department of Computer Science and Information Engineering

3. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

4. Water pipelines are everywhere people live

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

6. Motivation leaking Pipeline monitoring is essential- clean water

7. Water contamination (Boston, 2010)

8. Difficult sensor deployment - traditional monitoring

9. 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

10. 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.

11. 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.

12. Single-Release Point the enabling concept Place sensors at a single release point Sensors automatically place themselves in the pipes Single-release point

13. How to realize single-release point? Sensor placement – Mobile sensors – Sensor latch mechanism – Sensor placement algorithm – Sensor localization Sensor replacement – Sensor replacement algorithm

14. 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.

15. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

16. TriopusNet automate WSN deployment in pipeline Triopus node three arms for latching Gateway node Single-release point

17. Sensor placement – Mobile sensors – Sensor latch mechanism – Sensor placement algorithm – Sensor localization Sensor replacement – Sensor replacement algorithm TriopusNet automate WSN deployment in pipeline

18. Mobile sensor (components) Localization sensors water pressure + gyro Actuator(motor) pull/push a mechanical arm Sensor mote(Kmote) Water proof case Verticalhorizontal Pipepipe

19. 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)

20. 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 0cm 1cm 2cm

21. Prototype #1 (8cm diameter)

22. Prototype #2 One motor driving the three arms. Replace 3 AAA with lithium battery.

23. Prototype #2 (6cm diameter)

24. 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

25. Sensor placement algorithm branch 1 branch 2 branch 3 faucet 2 faucet 1 faucet 3 faucet 4 water inlet n7 n6 n5 n2 n4 n3 n1 root

26. branch 1 branch 2 branch 3 faucet 2 faucet 1 faucet 3 faucet 4 water inlet n7 n6 n5 n2 n4 n3 n1 root Sensor placement algorithm

27. branch 1 branch 2 branch 3 faucet 2 faucet 1 faucet 3 faucet 4 water inlet n7 n6 n5 n2 n4 n3 n1 root Sensor placement algorithm

28. branch 1 branch 2 branch 3 faucet 2 faucet 1 faucet 3 faucet 4 water inlet n7 n6 n5 n2 n4 n3 n1 root Sensor placement algorithm

29. Post-order traversal : n1 -> n2 -> … n7 n7 n6 n5 n2 n4 n3 n1 root Sensor placement algorithm

30. n7 n6 n5 n2 n4 n3 n1 root 1st Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

31. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

32. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

33. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd 4th Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

34. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd 4th 5th Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

35. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd 4th 5th 6th Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

36. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd 4th 5th 6th 7th Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7

37. n7 n6 n5 n2 n4 n3 n1 root 2nd 1st 3rd 4th 5th 6th 7th Sensor placement algorithm Post-order traversal : n1 -> n2 -> … n7 Reasons: 1. Assure nodes cover all pipes 2. Allow blockage-free movement (bottom-up placement)

38. Testing packet received ratio Good link quality, placement completed Bad link quality Sensor placement algorithm Gateway node Single-release point

39. Sensor localization Pressure 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

40. Data Collection Collection Tree Protocol (CTP) in TinyOS Multi-sink tree to balance network load (reduce the hope count and packet loss) Gateway node Single-release point

41. Low Battery… Sensor replacement algorithm Gateway node Single-release point

42. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

43. Testbed

44. 150cm 200cm Testbed spatial layout Single-release point

45. Evaluation metrics Automated sensor placement – # Nodes for pipeline deployment – Data collection rate – Energy consumption Automated sensor replacement – Data collection rate

46. Scenario 3 Scenario 1 Scenario 4 Scenario 2 Experimental procedure (4 test scenarios) 5 tests for each scenario gateway Single-release point

47. # Deployed Nodes (Static v.s. TriopusNet deployment) TriopusNetA TriopusNetB TriopusNetC Static (90cm) Real node location of three test runs from scenario 4. It shows the dynamic of each deployment.

48. # 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: 173cm Std: 58cm

49. Avg. node-to-node distance

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

53. 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

54. CDF of Positional Errors Overall median error 7.14 cm 90% of errors are less than 20.45 cm 18 20 30 Location Estimates: Node positional accuracy is important for achieving sensing coverage in node deployment.

55. Energy consumption (node placement) The energy consumed by a single act of latching is 1.01 W,2 seconds The average of latching is 2.35 90% required less than 5

56. Evaluation metrics Automated sensor placement – # nodes for sensing/networking coverage – Data collection rate – Energy consumption Automated sensor replacement – Data collection rate

57. 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 0.9890.9840.81 The effectiveness of the automated replacement The reason of high data loss rate: 1-some sensors change route 2-isolated nodes report zero

58. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

59. automatic faucet Limitation: Lack automatic faucets The TriopusNet gateway control each faucet by sending signals to the sensor trigger node.

60. Limitation: Node size

61. Low Battery… Limitation: Node size Single-release point

62. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

63. Breadcrumb System Liu Mobile WSN Deployment SensorFly System Purohit

64. Detect and localize leakage by pressure and ultrasonic sensors PipeNet (pipeline monitoring)

65. NAWMS (water flow sensing)

66. toilet kitchen sink shower HydroSense (Ubicomp09, water event sensing) Single-point pressure-based sensor of water usage

67. PipeProbe (determining the spatial topology)

68. Motivation TriopusNet System Design Evaluation Limitations Related Work Conclusion Outline

69. 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

70. Thank You