Triopusnet automating wireless sensor network deployment and replacement in pipeline monitoring
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TriopusNet : Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring. IPSN 2012 Ted Tsung-Te Lai, Wei- Ju Chen, Kuei -Han Li, Polly Huang, Hao-Hua Chu NSLab study group 2012/03/26 Reporter: Yuting. Previously….

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Triopusnet automating wireless sensor network deployment and replacement in pipeline monitoring

TriopusNet: Automating Wireless Sensor Network Deployment and Replacement in Pipeline Monitoring

IPSN 2012

Ted Tsung-Te Lai, Wei-Ju Chen, Kuei-Han Li, Polly Huang, Hao-HuaChu

NSLab study group 2012/03/26

Reporter: Yuting


Previously
Previously…

  • PipeProbe: A Mobile Sensor Droplet for Mapping Hidden Pipeline

  • Jeffery reported it at study group last year

    • http://nslab.ee.ntu.edu.tw/NetworkSeminar/index.php?action=schedule&year=2010_Fall&pattern=

  • http://mll.csie.ntu.edu.tw/papers/PipeProbe_Sensys10.pdf

  • http://mll.csie.ntu.edu.tw/papers/PipeProbe_Sensys10.pptx (Best Presentation Award)


The overview of triopusnet
The overview of TriopusNet

  • Sensor network data is wirelessly transmitted to nearby gateway nodes

  • The gateway is a (laptop) computer wired to a Kmote node


Outline
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Outline1
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Abstract
Abstract

  • Autonomous sensor deployment

    • For pipeline monitoring

  • Centralized repository at pipeline’s source

    • Automatically releasing nodes

  • Placement:

    • Nodes will latch itself in pipeline

  • Replacement:

    • Source will send new nodes to replace failed one, ex: low battery level; experiences a fault


Abstract1
Abstract

  • Evaluated on testbed

  • Advantage:

    • Less sensor nodes to cover a sensing area

    • High data collection rate

    • Recover from the network disconnection


Outline2
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Motivation
Motivation

  • Flow assurance

    • A major safety concern

    • Ex: clean and uncontaminated water

  • Traditional method:

    • Manually placing, but it’s hard and waste time

  • TriopusNet

    • Automated

    • Scalable

    • Human effort strictly needed only at the start to deposit mobile sensors


Sensor deployment
Sensor Deployment

  • Sensor deployment algorithm depends on:

    • Sensing coverage

    • Network connectivity

    • Deployment location

  • Upon arrival at its deployment location, a traveling sensor activates its latching mechanism


Sensor replacement
Sensor Replacement

  • Upon detection of low battery level (or a fault), the sensor node retracts its mechanical arms to detach itself

    • Flow in the pipes carries it out

    • System releases a fresh sensor node and runs the sensor replacement algorithm

    • And adjust the locations of existing ones


Main contributions
Main Contributions

  • Automates sensor deployment and replacement by leveraging natural water propulsion to carry sensor nodes throughout pipes

  • Real prototype and pipeline testbed show that this quality deployment using no more sensor nodes

  • Successfully replaced a battery-depleted sensor node with a fresh sensor node while recovering data collection rate from the departure of a battery-depleted sensor node


Outline3
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


System overview
System Overview

  • Pipelines interconnect a set of vertical and horizontal pipes, starting with a single water inlet and ending at multiple water outlets

  • Pipelines form a virtual tree!

  • The inlet also serves asthe storage point wheresensor nodes are depositedinto a dispatch queueat the start of deployment


Triopusnet node
TriopusNet node

  • A significant size reduction in 2nd type - 6 cm in diameter

    • May still get stuck in some pipes

  • (a~d): gyro, water pressure sensors, relays, Kmote(TelosB-like w/o USB)

    • In water, sonar and light are better than radio -> they leave the choice in future

  • One customized motor drives three arms in 2nd type


Four steps
Four Steps

  • Preparation Step

  • Sensor Deployment Step

  • Sensor Latching Step

  • Sensor Replacement Step


1 preparation step
1. Preparation Step

  • Pipeline spatial topology must be measured a-priori as an input for automated sensor deployment

    • PipeProbe system (their previous work)

  • Inlet must be filled with sensor nodes

  • Faucets in the pipeline are turned on

    • Manually or automatically (by installing a remote-control actuation device)

  • One-time manual effort


2 sensor deployment step
2. Sensor Deployment Step

  • Runs the sensor deployment algorithm prior to releasing

  • Then sends the “release” message including the deployment position, to the head sensor node


3 sensor latching step
3. Sensor Latching Step

  • Sensor node continuously computes its current location as it travels

  • When the node approaches its deployment position:

    • Latch itself

    • Report the completion

    • Triopusnet releases the next (repeat step2)


4 sensor replacement step
4. Sensor Replacement Step

  • Some sensor node may report low-battery to the system

    • Detach itself, carried out by the water

    • Triopusnet releases fresh one


Gateway nodes
Gateway Nodes

  • Must be installed prior to any sensor node deployment inside the pipelines

  • Must have wireless communication with at least one in-pipe sensor node

  • Must also have a network connection to a computer for:

    • Remote control

    • Data logging

    • Automated sensor deployment and replacement algorithms


Outline4
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Some information not all here
Some Information (Not All Here)

  • Linear actuator controls a mechanical arm

    • Push: SW1&4, pull: SW2&3

  • Motor calibration was achieved by adding a spiral gear that connects and pushes three separate gears


Outline5
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


1 sensor deployment order
1. Sensor Deployment Order

  • Placing nodes close to the releasing point early may result in blockage

    • Transforms the layout of the pipelines into a tree

    • Subsequently runs a post-order traversal of the tree

    • Deploying nodes in the above sequence will:assure covering all pipes without blocking others


2 sensor deployment position
2. Sensor Deployment (Position)

  • Before sensor nodes can be released, the sensor deployment algorithm computes first the coarse-grain positions:

    • The pipe segment

    • The approximate latching point

  • Assume a simple coverage function (but not limited)

    • Circle with radius R

    • “Subtracting 2*R distance from the most recently deployed sensor node in segment S gives the position of the new one”

    • “If segment S is not long enough to accommodate the new sensor node, the new sensor node is placed in the next segment”


3 sensor movement faucet turn on order
3. Sensor Movement (Faucet Turn-On Order)

  • The sensor movement algorithm computes first the flow paths from the inlet to each outlet

  • Then selects a path intersecting the pipe segment the node is positioned to


4 sensor localization
4. Sensor Localization

  • There are both vertical and horizontal pipes

  • Adopts the pipeline localization technique from the PipeProbesystem [4]

  • Sensor node tracks its location by:

    • Counting the number of turns with:

      • pressure and gyroscope sensors

    • Segment offset distance from the last run:

      • Vertical: the change in water pressure

      • Horizontal: multiplying velocityby traveled time

        • Buoyancy? -> the sensor node was designed with its weight density equal to the water density


5 sensor latching
5. Sensor Latching

  • Turning on radio after latching and measures the packet received rate for the link quality

  • Upon detecting a low packet received rate, the sensor node moves one increment closer to its downstream sensor node

  • Until a pre-defined link quality threshold is met, sends a “latching completion” packet

    • May be tricky to ensure the first sensor node of an intermediate segment is connected to the sensor nodes of all downstream segments

      • May moves into one of the unreachable downstream segment

  • Repeats until full sensing and network coverage


6 data collection
6. Data Collection

  • Collection tree protocol (CTP) implemented in TinyOS2.1

  • Use anycast (provided by CTP) to multiple sinks(gateway nodes) in order to balance traffic load


7 sensor replacement
7. Sensor Replacement

  • Battery-depleted node (determined simply by voltage)

    • Informs the downstream gateway

    • Faucet can be turned on

    • Downstream nodes are also flushed out

    • Fishing net is inserted at the ends of pipelines

  • Good nodes

    • Each upstream node repeats:detachment, movement, localization, reattachment

    • Until the uncovered area reaches the root location

    • System then releases fresh nodes

  • With a smaller prototype in the future, it will be easier and save more energy!


Outline6
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Experimental testbed
Experimental Testbed

  • 6 “transparent” pipe tubes (10 cm in diameter)

  • 2 water valves control the volumetric flow rate on each flow path


Performance metrics
Performance Metrics

  • And:time to replacementenergy consumption (2 cases)


Experimental procedure
Experimental Procedure

  • System parameter:

    • PRR threshold = 95%

    • Water flow velocity = 12.5 cm/sec

    • Each node’s sensing range R >= radio range

  • 4 scenarios * 5 runs/scenario = 20 test runs

  • Data was logged during both:

    • node deployment and data collection

  • Replacement performance is measuredin scenario #4

    • 20 test runs of node replacement


Deployment node locations
Deployment - Node Locations

  • Static deployment: a good baseline for performance comparison

    • Nodes are 90 cm apart ( average radio range between two sensor nodes in a straight pipe )

    • Might have better DCR, but more redundant nodes (DCR: Dada Collection Rate)


Deployment node locations1
Deployment - Node Locations

  • The radio range can reach up to 170 cm for nodes placed in different tubes

  • Benefits of using online deployment


Deployment data collection rate dcr
Deployment - Data Collection Rate (DCR)

  • Indicate whether a network is well connected

  • 80% of the sensor nodes show a data collection rate exceeding 99%

    • And all are above 86.5%

  • Each sensor node sent 1000 data packets to a gateway node


Deployment positional accuracy
Deployment - Positional Accuracy

  • 18,20,20,30 location estimates for scenario 1~4, respectively

  • Overall median: 7.14cm

  • 90% of the errors are less than 20.45 cm

  • Sufficient for most pipeline applications,ex: pinpointing the location of pipe leakage


Deployment time to deployment
Deployment - Time to Deployment

  • Time to manually turn on/off faucets is not included here

  • If the flow velocity is set at 12.5 cm/sec, the average time to deploy nodes is less than 2.5 minutes


Deployment energy consumption
Deployment - Energy Consumption

  • Primary energy consumer in the sensor node is in the motor and relays that drive the three mechanical arms

    • (Note: energy consumption: motors > radio > MCU)

  • A single act of latching:

    • 1.01W * 2 sec < 1% * 600mAh = 2.16J

  • # of latching:

    • average is: 2.35; 90% of nodes required less than 5


Replacement data collection rate dcr
Replacement – Data Collection Rate(DCR)

  • DCR before a node reported low-battery level and after the node was replaced:

    • 0.989 and 0.984 respectively

    • Small difference, effective!

    • [YT] But which node are they use? ( last or 2nd last )

  • DCR without automated replacement: 0.81


Replacement time to replacement
Replacement - Time to Replacement

  • Depends on the location of the node and the size of the network


Outline7
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Before practical deployment
Before Practical Deployment

  • Several assumptions and limitations require extensions before practical deployment

    • Node is too big to be flushed out independently

      • [YT] If the size is reduced, there may be extra works on gryo measurement

    • Node placement requires controlling or obtaining the direction of the water flow in the pipes

      • Automatical method:attaching a sensor-trigger node to activate/deactivate the infrared sensor in each automatic faucet


An opportunistic node placement scheme
An Opportunistic Node Placement Scheme

  • Nodes are equipped with a water flow sensor

  • Can infer the current flow path

  • May Releases new nodes whose destinations must match the current water flow path


Outline8
Outline

  • Abstract

  • Introduction

  • System Overview, Assumptions and Limitations

  • Hardware Design

  • System Design

  • Experiment

  • Discussion

  • Conclusion


Conclusion
Conclusion

  • Pipeline monitoring

  • Autonomous sensor deployment

  • Scales down human effort

  • Real pipeline testbed

  • No more nodes than non-automated static sensor deployment

  • Restore sensing and network coverage from the departure of a battery-depleted node


Comments
Comments

  • Strength

    • Save lots of nodes using online deployment method

    • Successfully replaced a battery-depleted sensor node with a fresh one

  • Weakness

    • Not adaptive with varying water flow rate now

    • No automatically water faucet now

    • Will the mechanical arms be reliable under strong water flow?

    • For high traffic load, the deployment performance may not be as good as now

    • Evaluation for DCR in replacement is not clearly enough



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