Wireless Mesh Networking - A development path

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A brief introduction in applying wireless mesh networking to the geotechnical industry. Presented at the Field Measurements in Geomechanics symposium, Boston, MA in 2007.
[Apologies for the malformed animations]

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Wireless Mesh Networking - A development path

  1. 1. An Introduction to Wireless Monitoring Systems By Daniel Scott Technical Development Manager ITM-Soil Group [email_address]
  2. 2. <ul><li>Introduction to the principles of Monitoring, Field Measurements and the Site Environment </li></ul><ul><li>Why go Wireless? </li></ul><ul><li>Wireless Mesh Networks Tutorial </li></ul><ul><li>Soil Instruments Wireless Network Module </li></ul><ul><li>Intelligent Monitoring System Example </li></ul>
  3. 3. Goal of the Monitoring System <ul><li>The goal of a monitoring system is to detect changes in physical parameters that are of decision-making importance </li></ul>
  4. 4. Goal of the Monitoring System <ul><li>The system is a functional success if the </li></ul><ul><li>information generated from it is: </li></ul><ul><li>Consistent, accurate and valid </li></ul><ul><li>Represented in some form of standardised unit </li></ul><ul><li>Of engineering significance </li></ul><ul><li>The system is financially sustainable if the </li></ul><ul><li>Information obtained from it is of more value </li></ul><ul><li>than the cost of the systems implementation: </li></ul><ul><li>Decrease the cost of implementation </li></ul><ul><li>Increase the value of the data </li></ul>
  5. 5. Goal of a Monitoring System 0001100111001 Operators, Engineers, Consulting Engineers, Risk Ans, Neural Networks Spread Sheet, Software, Web Based Manual, CAN, RS485/Short Haul Modems, TCP/IP Binary, Hex, ASCII Voltage, Current, Frequency, Count, Digital mm, Hz , N, Pa, V, A, Ω , °C Observer Presentation Transport Data Signal Sensor Physical Phenomenon
  6. 6. Why Monitor? <ul><li>Risk analysis </li></ul><ul><li>Design verification </li></ul><ul><li>Development of new constitutive laws </li></ul><ul><li>Project management </li></ul><ul><li>Process control and optimisation </li></ul><ul><li>Asset and infrastructure management </li></ul><ul><li>Post-construction problem diagnosis </li></ul>
  7. 7. Alternatives <ul><li>Assumptions </li></ul><ul><li>Ignorance </li></ul><ul><li>Over design </li></ul><ul><li>Adoption of greater risk </li></ul>
  8. 8. The Challenge <ul><li>Providing detailed information about the real world that is of importance to engineers and practitioners </li></ul><ul><li>Lab-Level metrology within the field environment </li></ul>
  9. 9. Extreme environments
  10. 10. Extreme environments
  11. 11. Extreme environments
  12. 12. Why Wireless?
  13. 13. … manpower Cabling sensors… <ul><li>Finding: </li></ul><ul><ul><li>Committed </li></ul></ul><ul><ul><li>Good </li></ul></ul><ul><ul><li>Skilled people </li></ul></ul>Intricate Systems
  14. 14. … disruptive environments Cabling sensors…
  15. 15. … machinery Cabling sensors…
  16. 16. … Problems with Safety … cable susceptible to damage Cabling sensors…
  17. 17. … Inter-Cable signal Interference Cabling sensors… … Cable Management … Complex Wiring Requirements … Difficult Access
  18. 18. … high cost of installation Cabling sensors…
  19. 19. <ul><li>Wireless monitoring using </li></ul><ul><li>Mesh Networks </li></ul>
  20. 21. Network Sensor Module (Node)
  21. 22. Network Sensor Module (Node) Sensors and nodes are put in place
  22. 23. Wireless Data Link The network collects, stores and shares sensor data
  23. 24. Network Gateway Wired Data Link Wireless Data Link A node is selected as the gateway Wired or wireless loggers are connected to the gateway
  24. 25. A data path may become blocked The network will reroute the data via a different node Network Gateway Wired Data Link Wireless Data Link
  25. 26. Network Gateway Rerouted Wireless Data Link Data are again rerouted when the obstruction is cleared This is a “Self Healing Network”
  26. 27. Network Gateway Wired Data Link Wireless Data Link Access to the network can be made from any node
  27. 28. Network Gateway If connection to the logger is lost… Data are stored within the network until connection with the logger is restored
  28. 29. Network Gateway When connection is restored, the logger can collect data from network
  29. 30. New wireless sensor nodes are installed in a nearby location The nodes are out of range of the working network … and a brick wall is in the way Placing two nodes as repeaters, the new sensors are able to connect to the existing network
  30. 31. Placing two nodes as repeaters, the new sensors are able to connect to the existing network
  31. 32. Wireless Network Module
  32. 33. Wireless Network Module <ul><li>IP68 Box </li></ul><ul><li>Interface for any sensor </li></ul><ul><li>9V battery </li></ul><ul><li>75x119x58mm </li></ul><ul><li>395g </li></ul><ul><li>RS232 serial connection </li></ul><ul><li>External power control </li></ul>
  33. 34. Sensor Reading <ul><li>Multiplexed </li></ul><ul><li>Voltage Output </li></ul><ul><li>Electrolevel </li></ul><ul><li>Solid State </li></ul><ul><li>Vibrating Wire </li></ul><ul><li>Thermistor </li></ul><ul><li>4-20mA </li></ul><ul><li>Pulse Counter </li></ul><ul><li>Digital </li></ul><ul><li>Piezometers </li></ul><ul><li>Pressure Cells </li></ul><ul><li>Inclinometers </li></ul><ul><li>Extensometers </li></ul><ul><li>Load Cells </li></ul><ul><li>Weather Stations </li></ul><ul><li>Settlement Cells </li></ul><ul><li>Thermometers </li></ul><ul><li>Etc </li></ul>
  34. 35. Datalogging <ul><li>1,000,000+ Readings per Module </li></ul><ul><li>Upgradeable Memory </li></ul><ul><li>User Configurable Reading Intervals </li></ul><ul><li>Alarm Functions </li></ul><ul><li>Threshold-Based Reading Intervals </li></ul><ul><li>Request Specific Date/Time Information </li></ul><ul><li>Instantaneous Readings </li></ul><ul><li>Cal factors </li></ul><ul><li>Engineering Notes </li></ul>
  35. 36. Telemetry <ul><li>PC/Laptops </li></ul><ul><li>Handheld Computers </li></ul><ul><li>Existing Dataloggers </li></ul><ul><li>Short-Haul Modems </li></ul><ul><li>GSM/GPRS modem </li></ul><ul><li>Satellite modem </li></ul><ul><li>IP Addressable (Access over the Internet) </li></ul><ul><li>Access every Sensor from one Gateway </li></ul>
  36. 37. Battery Life <ul><li>Battery Type </li></ul><ul><li>Type of Sensor </li></ul><ul><li>Frequency of Readings </li></ul><ul><li>Frequency of Radio Transmission </li></ul><ul><li>Processing Requirements </li></ul><ul><li>Temperature </li></ul><ul><li>External Energy Sources </li></ul>This is a Dynamic System, Battery Life depends on:
  37. 38. Sensor Performance <ul><li>Absolute: </li></ul><ul><li>24bit ADC </li></ul><ul><li>± 0.05mV 0-2.5V dc </li></ul><ul><li>Resistance <1% in 100-50k Ohms Range (~0.15ºC) </li></ul><ul><li>Vibrating Wire 0.5Hz Accuracy @ 400-5000 Hz </li></ul><ul><li>Engineering [100mm Linear Potentiometer] </li></ul><ul><li>Stability 0.003mm </li></ul><ul><li>0.1mm Accuracy </li></ul><ul><li>0.01mm Accuracy w/ Calibration </li></ul>
  38. 39. 2.4 GHz Radio <ul><li>Pros: </li></ul><ul><li>Operates Globally, Licence Free </li></ul><ul><li>High Data throughput (<250kb/s) </li></ul><ul><li>Short Wake times </li></ul><ul><li>High complexity of Network organisation </li></ul><ul><li>Optimised at a Suitable Range </li></ul><ul><li>1-100mW output allowed (30m-1Km+) </li></ul><ul><li>Cons: </li></ul><ul><li>Higher attenuation than lower frequencies </li></ul><ul><li>Greater power drop off </li></ul>
  39. 40. <ul><li>Wireless monitoring on Dams using Mesh Networks </li></ul>
  40. 42. Network Sensor Module (Node)
  41. 43. Wireless Data Link Network Sensor Module (Node)
  42. 44. Network Sensor Module (Node) Wireless Data Link
  43. 45. Network Sensor Module (Node) Wireless Data Link
  44. 46. Network Sensor Module (Node) Wireless Data Link
  45. 47. Network Sensor Module (Node) Wireless Data Link
  46. 48. Network Sensor Module (Node) Wireless Data Link
  47. 49. Network Gateway Wireless Data Link
  48. 50. Network Gateway Wireless Data Link
  49. 51. <ul><li>Speed of Installation </li></ul><ul><li>Flexibility </li></ul><ul><li>Scalability </li></ul><ul><li>Access to Data </li></ul><ul><li>Inherent Lightening Protection </li></ul><ul><li>Reduction in need for </li></ul><ul><ul><li>Multiplexers </li></ul></ul><ul><ul><li>Terminal Boxes </li></ul></ul><ul><ul><li>Dataloggers </li></ul></ul>
  50. 52. Intelligent Monitoring <ul><li>Automatic optimisation of read/report cycles </li></ul><ul><ul><li>Event monitoring </li></ul></ul><ul><ul><li>Power saving </li></ul></ul><ul><li>Automatic notification of maintenance Requirements </li></ul><ul><li>Flagging of extraordinary readings for Engineering analysis </li></ul><ul><li>Collaboration between sensors </li></ul>
  51. 53. Intelligent Wireless Sensors A Case Study
  52. 54. Flood Monitoring
  53. 55. Flood Monitoring
  54. 56. SOLID STATE PRESSURE TRANSDUCER
  55. 57. TRANSDUCER IS INSTALLED INTO SLOTTED HDPE TUBE…
  56. 58. … AND INSTALLED BELOW THE WATER
  57. 59. GPRS MODEM LOGGER IS USED TO STORE AND COMMUNICATE DATA…
  58. 60. … AND IS CONNECTED TO THE PRESSURE TRANSDUCER
  59. 61. AT NORMAL WATER LEVELS, DATA TRANSMSSIONS NEED ONLY TO BE SENT ONCE A DAY Data sent every day
  60. 62. WHEN WATER LEVEL RISES TO PRECONDITIONED LEVELS, THE SENSOR DATA CAN BE TRANSMITTED MORE OFTEN Data sent every 10 minutes
  61. 63. IF FLOOD CONDITIONS ARE DETECTED, ALARMS CAN BE SENT AND SENSOR DATA TRANSMITTED MORE FREQUENTLY Alarms sent and data transmitted every 2 minutes
  62. 64. Future Developments <ul><li>Over Air Programming </li></ul><ul><li>Onboard Math / FFT’s </li></ul><ul><li>Integrated Telemetry </li></ul><ul><li>Energy Harvesting </li></ul><ul><li>Security Encryption </li></ul><ul><li>Continual Advancement of Sensor Functions </li></ul><ul><li>Development of further system intelligence </li></ul>
  63. 65. The Future What do you want to do?

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