Hardware Design Experiences in ZebraNet

[ZSLM04] - Princeton University Sensys ‘04

Presented By: Jay Taneja

Mpala Research Centre

• Application: Animal Tracking - Use collars with GPS to take periodic readings in order to support biologists monitoring the walking patterns of zebras in Kenya

ZebraNet Design Space

• Mobile Sensor System• Sparse Network Coverage• High Energy Sensors (GPS)

ZebraNet is unlike any other deployment, requiring custom hardware and software

Goals for ZebraNet

• Three Primary Goals• Collect detailed, accurate position logs of each

zebra• Have a high data recovery rate (Redwoods?)• Autonomous Operation

Moo.

Hardware Evolution

Another Important Evolution

• Change of -controller• Lower power usage (switching clocks)

• 750 mA-hr/day, 20 MHz Hitachi SH1 too greedy• TI MSP430F149 allows multiple clocks (32 KHz, 8

MHz) • Ease of software development (16-bit)• Ability to have 100% duty cycle

• 32 KHz clock consumes 0.05 mA more than sleep

Important Features

• Nodes obtain GPS reading every 8 minutes• GPS can sync to global clock allowing for

efficient TDMA scheme• Nodes attempt to send

information over radio (multi-hop) every 2 hours

• All data logged to onboard flash (local as well as received - latency, shmlatency)

% of Successful Receive vs. Distance

No spell checkon figures

Solar Power Analysis

A Thousand Words

GPS Data for 1 Zebra Over 24 Hours

Conclusions

• Hardware choice worked very well for sparse node-to-node communication

• Simplicity of software environment dictated -controller choice

• Details matter in WSN power management