05-Embedded Systems&Wireless Sensor Networks 3

Embedded Systems & Wireless Sensor Networks

Emil SlusanschiUniversity Politehnica of Bucharest

Computer Science and Engineering [email protected]

Romanian real – virtual communication Seminar. Brussels October 20, 2009Emil Slusanschi

Why ES & WS(A)Ns?

“Smart Dust”


WSN Present & Future

Today’s WSNs are Tomorrow’s WS&ANs areHighly specialised and purpose built for

• One user• One application• One business case

Highly specialised and purpose built BUT for• Many users• Many application• Many business cases

Only Sensors Sensors & Actuators

Applications are still coarse Intelligent dynamic applications (many M2M)

Statically configured Dynamically reconfigured including the protocol stack

Based on many proprietary technologies Based on a few standardised solutions

Island technologies, not openly connected and accessible

Still islands, but openly connected to the Internet and reusable

Sparsely deployed Ubiquitously deployed - scalability


Sparrow

• WSN node optimized for low-power applications

• Built around the Atmel ZigBit

• Contains:• On-board sensors• Memory• Speaker • Battery management

circuitry• Contiki OS


Sparrow Power

• Measures the energy consumption of any appliance• Voltage• Current • Active power

• Easy integration with other WSN nodes to form heterogeneous networks

• Monitored data is sent to online repository


Bird Watch• WSN monitoring software• Allows real-time monitoring of

heterogeneous multi-hop networks• Graphic display of real-time data• Log historical sensor data in a

database• Sends commands over the

network• Uploads acquired data to

online repositories


WSN Energy Considerations• Limited available energy – batteries• Trade-off: performance vs. availability • Processor – most nodes have low power CPUs• Sensing subsystem – low power usage• Radio transceiver – main energy overhead


Energy Harvesting

• Technology opening new possibilities in device portability and application functioning time

• Well suited for powering WSN nodes• No dependency on battery-life• Functioning time can be

prolonged indefinitely


Energy Harvesting Sources• Vibration Harvesting

– Cantilever structure attached to a vibration source

– Maximum energy at resonance frequency• Thermic Energy Harvesting

– Uses the Seebeck effect– Works well in an environment

with temperature differentials • Photovoltaic Conversion

– Affordable PV cells– Has the best efficiency over the two other

methods

P

A

VT0

T1


Monitoring & Reprogramming

• Heterogeneous WSN monitoring/reprogramming platform

• All nodes run ported versions of Contiki OS• Measured parameters can be visualized online using

MonALISA• Allows data aggregation from multiple WSN

networks that may even be geographically distinct

ClientRepository

Control Module

ApMon

WSNGather

WSNControl

WSN Gateway

MonALISA Server PC

Data

Commands


TestbedNodesGatewaysMonitoring

Sparrow

Avr-Raven

Sparrow Power

NGW100

PC+RavenUSB

Sensinode


SENSEI FP7 IP

www.sensei-project.eu


Intelligent City Example

Other sensor-rich application spaces: Transport, Building & Home, Asset Management, Security, Entertainment, Healthcare & Wellbeing


?Thank you

www.cs.pub.ro

05-Embedded Systems&Wireless Sensor Networks 3

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