The PermaSense ProjectWireless Sensor Networks for

Extreme Environments

Jan BeutelETH Zurich

19.11.2008

16.7.2003

Photo: Bruno Jelk

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

Our patient does not fit into a laboratory

So the laboratory has to go on the mountain

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

Sensor Network Technology

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

The Big Picture – Network System Integration

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

Sensors Contribute to Power Consumption

Ruggedized for Extreme Environments

PermaDozer – Total Power Performance Analysis

1/30 sec

1/120 sec

148 uA average power

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

PermaSense – Base Station Situation

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

Multi-Site, Multi-Station Datenmanagement

Central Web-based Data Access

PermaSense Sensors – Sensor Rod Example

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

PermaSense Sensors – Crack Meter Example

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

Experiences…

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

Interested in more?

http://www.permasense.ch

• ETH Zurich– Computer Engineering and

Networks Lab

• University of Zurich– Department of Geography

• University of Basel– Department Computer Science