Wireless distributed sensor networks have become a highly active research area due to their potential applications across many industries. VERHAERT will demonstrate a phased approach towards developing a distributed sensor network for body area networks and security applications. Distributed sensor networks allow for flexible deployment of sensors, mobility of sensing objects, and interaction between sensor nodes for added value. However, low power consumption is a critical design driver due to the need for long battery life in wireless sensor networks.

1. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
VERHAERTINNOVATIONDAY – OCTOBER 12th, 2007
www.mastersininnovation.com
WIRELESS DISTRIBUTED
SENSOR NETWORKS
Koenraad Rombaut
koenraad.rombaut@verhaert.com
www.verhaert.com
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CONFIDENTIAL 12.10.2007 Slide 1

2. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Distributed Sensor Networks, enabling
Technology in Development
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Distributed sensors networks have become a highly active research area
because of their potential of providing diverse services to a broad range of
applications, not only on science and engineering, but equally importantly
on issues related to critical infrastructure protection and security, health
care, the environment, energy, food safety, and the potential impact on the
quality of all areas of life. VERHAERT will demonstrate a phased approach
towards a distributed sensor set-up for local body area networks and their
potential in security applications. Furthermore, other potential applications
will be discussed while the current status of technology is being outlined.
CONFIDENTIAL 12.10.2007 Slide 2

3. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Content
• Introduction
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• Swans: a Verhaert inertial sensor network
• The applications
• Architecture and building blocks
• How to select or define a wireless sensor network
• Low power as a critical design driver
• Conclusion
CONFIDENTIAL 12.10.2007 Slide 3

4. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
What’s in a name ?
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• Wireless =
– wireless data transmission
– autonomous: on board power source (e.g. battery)
– often: on board intelligence
• Sensor =
– sensing physical parameters, e.g. temperature
• Network =
– added value of multiple nodes, due to cooperation,
e.g. Swans skeleton, inter vehicle communication
• e.g. Swans: a body area network (BAN) of
wireless inertial sensors for motion capturing
CONFIDENTIAL 12.10.2007 Slide 4

5. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Market trends for wireless sensor networks
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CONFIDENTIAL 12.10.2007 Slide 5

6. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
European research on wireless sensor
networks
Wireless sensor networks
www.mastersininnovation.com
= a very active research area
– Swans: Silicon platforms for
Wireless Advanced Networks of Sensors
– Stella: stretchable electronics
– E-Cubes: stacking technology
– Witness: security wireless sensor network
– MyHeart: medical smart wireless sensors
– Mimosa: Microsystems platform for MObile
Services and Applications
– Vibes: vibration energy scavenging
– Eyes: self organizing networks
Applications need mature technology
CONFIDENTIAL 12.10.2007 Slide 6

7. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Swans: a European cooperation
www.mastersininnovation.com
• SWANS = Silicon platforms for
Wireless Advanced Networks of Sensors
• a Medea+ European project
• Partners:
– silicon design companies (Atmel, STM, NXP, Ansem)
– research institutes (IMEC, CEA-Leti)
– application oriented companies (Verhaert, LMS, EADS, France Telecom)
• Verhaert’s role & interest:
development of a wireless body area network for motion tracking
sensors for health and fitness applications
CONFIDENTIAL 12.10.2007 Slide 7

8. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
The Verhaert inertial sensor body area network
• Inertial sensor (iTrack)
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per limb, capturing IMU sensor
platform personal
3D orientation
hub
• Wireless data link
communication
from limb hub - station communication
to personal hub sensor-hub
• Virtual skeleton
reconstruction
in personal hub
• Wireless communication
of skeleton motion base
from BAN hub station
to base station
CONFIDENTIAL 12.10.2007 Slide 8

9. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Wireless technology for RT motion capturing
Skeleton & Virtual model
Motion capture suit on wireframe with texture and
Virtual model
real world body representation
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representation
with skin surface
of virtual model of sensors
Swans
CONFIDENTIAL 12.10.2007 Slide 9

10. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
A sensor network for pedestrian navigation
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• Motion capturing
• Step detection
• Step distance & direction
CONFIDENTIAL 12.10.2007 Slide 10

11. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
From a good sensor node to a sensor network
Full body Single sensor Single sensor Sensor network
wired dev. kit (COTS) node (custom) demonstrator
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+
CONFIDENTIAL 12.10.2007 Slide 11

12. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Other Verhaert sensor network applications
• Healthcare:
– revalidation
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– activity monitor
– fall detection
– ergonomics
• Security
– track & trace
• Sport:
– training
– technique improvement
– activity monitoring
• Animation
– motion data capturing
– game controller (cf. Wii)
– virtual reality controller
CONFIDENTIAL 12.10.2007 Slide 12

13. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Typical healthcare & fitness applications & trends
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• Verhaert motion capturing
• Elderly: fall detection, activity
monitoring, track & trace
=> low power / long range
• EMG, EEG, ECG on flex pcb
• SiP: 3D BGA stacking
full system on 14 x 14 x 12 mm³
low power 15 mW @ 1 Mbps / 50 m
• geo-fencing / track & trace
• Man overboard tracking
similar for location based services
=> on board intelligence important
CONFIDENTIAL 12.10.2007 Slide 13

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Wireless distributed sensor networks
Typical industrial & environmental applications
• Building automation: domotics, metering
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• Industrial automation, e.g. process
monitoring, object tracking
• Asset management: track & trace
• Automotive, e.g.traffic monitoring, traffic
control, LBS
=> long lifetime (10+ year)
• Security
• Military, e.g. battlefield surveillance
• Environmental monitoring, e.g.
agriculture, habitat, seismic, marine
=> deployment in large quantities and
over large areas
CONFIDENTIAL 12.10.2007 Slide 14

15. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Added value of wireless sensor networks
• Deployment cost
Wired = high infrastructure cost ~ number of sensors & application area [m²]
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=> large application areas or high number of sensors
• Flexibility
sensor location can be changed easily,
network is easily expandable (10 => 10 000 sensors)
• Mobility
=> moving objects (e.g. automotive, people)
• Track & trace for moving objects
• Network = interaction between nodes
• Constraints
– Low power
– Lack of standardisation
CONFIDENTIAL 12.10.2007 Slide 15

16. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Sensor node hardware architecture
Motion node hardware
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Case: motion node
Antenna
COTS radio
UART
MEMS sensors
Generic
ADC
µC
SPI
Power circuit
Battery
CONFIDENTIAL 12.10.2007 Slide 16

17. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Software architecture and building blocks
Swans building Description
blocks
OSI network layer model
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Base station / Data logging &
pers. hub visualisation
application
Embedded Inertial: strap-
algorithms down, Kalman
OS Scheduler
Data acquisition Sensor interface
Wireless Proprietary
communication
Data transfer Proprietary
Base station / Proprietary
pers. hub
communication
CONFIDENTIAL 12.10.2007 Slide 17

18. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Parameters for a sensor network configuration
Parameter Target Typical value Swans full motion
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Lifetime / Autonomy high days to years 2 h sufficient
Number of sensors high 10 – 10 000 16
Data update interval long interval: days to sec 100 Hz
Bandwidth low 1 – 100 kbits/s 250 kbits/s
Range medium m to km 10 m
Sensor cost low 1 – 5000 € 3000 € acceptable
• Quality of Service
• Deployment
• Communication medium
• Mobility
• Sensor homogeneity
• Infrastructure & topology
• Certification
• Coverage
• Standardisation / interoperability
• Connectivity
CONFIDENTIAL 12.10.2007 Slide 18

19. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
What about a standard ?
Established
standard
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WiMax
Power
Non mature
standard
Wifi Proprietary
gsm
6lowpan
UWB
BTnode
Target area
Bluetooth
WirelessHart
Greenpeak
Wavenis Wisa Zigbee /Ubiwave
Wibree IMEC
Number of sensors
CONFIDENTIAL 12.10.2007 Slide 19

20. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Low power is essential for low cost deployment
www.mastersininnovation.com
• Dynamic power management:
duty cycling, external event trigger (e.g. radio, piezo-sensor for step
counter), shutting down / switching off functions like sensing, radio,
processor, deep sleep mode, …
• Dynamic Scaling:
Voltage or frequency reduction, adaptive depending on workload,
asynchronous logic, …
• Data reduction: intelligent algorithms reduce data transfer volume
e.g. compression, only sending relevant events, on board interpretation, …
• Ultra low power building blocks: processor architecture, memory,
transceiver, sensors, ADC, …
CONFIDENTIAL 12.10.2007 Slide 20

21. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Power sources: overview Classics
Wireless Sheet-like
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Batteries
sensors
New chemicals
Solar
Power
Energy
source Thermal
harvesting
Vibration
Fuel cells
Fuel combustion
Microturbine
CONFIDENTIAL 12.10.2007 Slide 21

22. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Power sources : battery evolution
• Classics: NiCd
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• Improved: Ni-MH
=> commodities
• Current standard: Li
• Li-ion
• Li-polymers
=> mobile phones
• Latest state-of-the-art
• Li-S: dense, lightweight,
high voltage, high current
• Battery = limited lifetime +
waste problem
CONFIDENTIAL 12.10.2007 Slide 22

23. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Power sources: some other trends
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• Micro fuel cells
• Flexible batteries
• Thin film solar cells
• Electro-mechanical conversion
• Ultra-capacitors
CONFIDENTIAL 12.10.2007 Slide 23

24. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Power source: vibration energy scavenger
• Working principle
• MEMS element picks up environmental vibration
www.mastersininnovation.com
• transforms vibration into electrical energy
• capacitive or piezo-electrical or electro-magnetic
• Specifications
• from 10 µW average up to 1 mW peak
• some mm³
• Applications
• Motors & rotating equipment
• Wearables
• Vehicles (distribute sensing)
• Status
• technological demonstrators
CONFIDENTIAL 12.10.2007 Slide 24

25. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Power source: thermal scavenger
• Working principle
• Seebeck / Peltier effect
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V ~ ΔT
•
• Specifications & advantages
• from 10 µW average up to 1 mW peak
• some mm³
• human body: ~10 mW/cm2
• Applications
• Motors
• Wearables
• Cooling / heating devices
• Status
• technological demonstrators
CONFIDENTIAL 12.10.2007 Slide 25

26. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
The future: challenges & trends
www.mastersininnovation.com
• Low power building blocks: sensor, radio, processor
• On board intelligence to reduce radio transmission, e.g. triggered by events
• Efficient bandwidth use
• Long lasting power supply, e.g. energy harvesting
• Standardisation / Interoperability
• Robust and fault tolerant protocols
• Self configuring (dynamic) network configuration
• Security / privacy
• Synchronisation
• Services
CONFIDENTIAL 12.10.2007 Slide 26

27. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
Conclusion
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• Opportunities for wireless sensor network applications are numerous
• However, the enabling technologies are not yet mature
• A multi-disciplinary approach and optimization is a key factor for succes
• Continued effort in development is critical for gaining maturity
CONFIDENTIAL 12.10.2007 Slide 27

28. © MASTERS IN INNOVATION ®
Wireless distributed sensor networks
www.mastersininnovation.com
Verhaert New Products & Services nv
Hogenakkerhoekstraat 21
9150 Kruibeke
Belgium
Tel +32 (0)3 250 19 00
Fax +32 (0)3 254 10 08
www.verhaert.com
info@verhaert.com
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CONFIDENTIAL 12.10.2007 Slide 28