the permasense project af jan beutel, eth zurich
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16.7.2003
Foto: Bruno Jelk
Rockfall release mechanisms and their connection to time and climate (change) are not understood
PermaSense – Aims and Vision
Geo-science and engineering collaboration aiming to:– provide long-term high-quality sensing in harsh
environments
– facilitate near-complete data recovery and near real-time delivery
– obtain better quality data, more effectively
– obtain measurements that have previously been impossible
– provide relevant information for research or decision making, natural hazard early-warning systems
Understanding Root Causes of Catastrophes
Eiger east-face rockfall, July 2006, images courtesy of Arte Television
PermaSense Deployment Sites 3500 m a.s.l.
A scientific instrument for precision sensing and data recovery in environmental extremes
PermaSense – Key Architectural Requirements
• Support for ~25 nodes
• Different sensors– Temperatures, conductivity, crack
motion, ice stress, water pressure
– 1-60 min sensor duty-cycle
• Environmental extremes– −40 to +65° C, ΔT ≦5° C/min
– Rockfall, snow, ice, rime, avalanches, lightning
• Near real-time data delivery
• Long-term reliability– ≧99% data yield
– 3 years unattended lifetime
Relation to other WSN projects
• Comparable to other environmental monitoring projects
– GDI [Szewczyk], Glacsweb [Martinez], Volcanoes [Welsh], SensorScope [Vetterli], Redwoods [Culler]
• Lower data rate
• Harsher, higher yield & lifetime
• Data quality/integrity
PermaSense – System Architecture
• Support for multiple sensor types
• Wireless sensor network– Ultra low-power data gathering (Dozer)
• Base station– Embedded Linux (Gumstix)
– 4 GB local storage, data duplication
– WLAN/GPRS connectivity, backup modem
– Solar powered
• Data backend– Streaming interface with metadata (GSN)
– Standard internet services for monitoring
At the Core – Low-power Wireless Sensors
• Static, low-rate sensing (2 min)
• Temperature profiles, crack meters, resistivity
• 3 years operation
• < 0.1 Mbyte/node/day
Based on Recent Research Achievements
• Dozer ultra low-power data gathering system– Beacon based, 1-hop synchronized TDMA
– Optimized for ultra-low duty cycles
– 0.167% duty-cycle, 0.032mA
• System-level, round-robin scheduling– “Application processing window” between data transfers and beacons
– Custom DAQ/storage routine
time
jitter
slot 1 slot 2 slot k
data transfercontention
window beacon
timeslot 1 slot 2 slot k
Application processing window
[Burri – IPSN2007]
PermaSense – Sensor Node Hardware
• Shockfish TinyNode584– MSP430, 16-bit, 8MHz, 10k SRAM, 48k Flash
– LP Radio: XE1205 @ 868 MHz
• Waterproof housing and connectors
• Protective shoe, easy install
• Sensor interface board
– Interfaces, power control
– Temp/humidity monitor
– 1 GB memory
• 3-year life-time
– Single Li-SOCl2 battery, 13 Ah
– ~300 A power budget
Computer Engineering and Networks
Technische Informatik und Kommunikationsnetze
Infrastructure &
Data Management
Long-haul Communication – Directional WLAN
• 7.5 km from weather radar on Klein Matterhorn
• Leased fiber/DSL from Zermatt Bergbahnen AG
• Commercial components (Mikrotik)
• Weatherproofing
Base Station - Embedded Linux & WLAN Router
Gumstix Verdex
TinyNodeGSM
WLAN Router
EMP Protectors
IP68 Enclosure and Connectors
Basic On-Site Support – Power, Weather, Camera
• Mobile power/deployment box– 12V photovoltaic system
– Surge protection
– Remote switchable power channels (reset)
– Internal humidity/temperature monitor
– 220V converter for deployment work
• Weather station
• Webcam
Data Management – Online Semantic Data
• Global Sensor Network (GSN)– Data streaming framework from EPFL
– Organized in “virtual sensors”, i.e. data types/semantics
– Hierarchies and concatenation of virtual sensors enable on-line processing
– Translates data from machine representation to SI values
– Adds metadata
Private PublicMetadata
==============
Position
Sensor type
…
Import from field GSN GSN Web export
Geoscience: Fast Localized Thaw by Advection
Near-surface temperature/conductivity
Combination with lab experiments and models
Installation Work on Matterhorn 09/2007
PermaSense installation 2007, images courtesy of Arte Television
Geoscience: Cryogenic Rock Movement/Weathering
Dilatation data with cleared thermal signal
Temperature [°C]
Distance [mm]
Temperature [°C]
Dis
tance
[m
m]
Resi
stance
[M
Ohm
]
Temperature [°C]
Moisture saturation and freezing dynamics captured by sensor rod
Physical Reality Impacting Performance
Watchdog Resets
time
Storage Duration
DAQ Duration
Ambient Temperature
Experiences – First Behavioral Data from the Field
Battery Voltage & Temperature
# Lost Packets
System Outage
Loss of Connectivity
3 Months Later – Increasing Runtime Errors
Node Reboot
System Outages# Lost Packets
Loss of Connectivity
Data Quality and Integrity
• Since 07/2008: 95„874„376 data points
• Inconsistencies– Between timestamps and sequence numbers
• Duplicates
• Data gaps– Sporadic
– Systematic
Revision / Extension June 2010Service 2009Installation & Service 2008
Sensornode 20 - 22 new installiation
Key PermaSense Challenges
System Integration Correct Test and Validation
Actual Data Interdisciplinary Team
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