Data Collection Storage, and Retrieval with an Underwater Sensor Network SENSYS 2005

1. Data Collection Storage, and Retrieval with an Underwater Sensor NetworkSENSYS 2005 I. VasilescuK. KotayD. Rus MIT CSAIL, Cambridge, MA M. DunbabinP. Corke CSIRO ICT Centre, Brisbane, Australia Speaker: Steven

2. Outline • Introduction • Hardware architecture • Experiment • Conclusion • Concluded my own way

3. Introduction • A platform for long-term monitoring of coral reefs and fisheries • Consists of both static and mobile nodes • Cameras, water temperature, and pressure • Optical and acoustic communication model

4. Introduction-problems • Power efficiency, deployment and repair are harder in the underwater environment • Mobile node • Radio communication is no longer practical • Radio waves are attenuated strongly in salt water • Optical and acoustic communication instead

5. Introduction-optical and ultrasonic • Optical • Capable of higher data transmission rates • Propagation speed is closer to the speed of the light • Essentially directional • Ultrasonic • A shared media that supports broadcasting • Low propagation rate poses a challenge for carrier-sense transmission strategies

6. Hybrid communication approach-optical and acoustic • Optical system • shot-range line-of-sight data transfer • communication between a sensor node and an AUV • Acoustic system • signal events • Notify the AUV about the exception situation • transmit small amounts of data

7. Optical transmitter • Luxeon 5 LXHL-PM02, a 532nm green LED with approximately 700mW radiated power while consuming 6W of input power • The choice of the light frequency is based the sensitivity of the photodiode and the attenuation of light

9. Acoustic communication system • They build their own system to fit the demand • Shorter communication range, 25m • Panasonic EFR-RQB40K5(receiver) and EFR-TQB40K5(transmitter)

11. Introduction-static and mobile nodes • The advantage of mobile nodes • Provides means for deploying, reconfiguring, and retrieving the nodes in the network • Permits large area coverage with sparse networks • Can act as data mules to collect data

12. Outline • Introduction • Hardware architecture • Experiment • Conclusion • Concluded my own way

13. Hardware infrastructure • Static underwater sensor node • Aquaflecks • Mobile underwater sensor node • Also known as Autonomous Underwater Vehicles (AUV) • Amour • Starbug

14. Hardware infrastructure-Aquafleck • ATmega128 processor, 128kbyte programming flash memory, 4kbyte RAM,512kbyte flash memory for data logging • Contained in a 170x100x90 mm watertight yellow box up to 30m • 532nm light, capable of a range of 2.2m/8m3, within a cone of 30 degrees, maximum data rate of 320kbits/s • 30kHz FSK modulation with a range of 20m omnidirectional, data rate of 50bits/s • 4 days of continuous operation with all hardware fully powered

16. Hardware infrastructure-Amour AUV • Used to dock and transport the Aquafleck nodes, and data muling • 4 external thrusters • Pressure sensor as depth feedback, magnetic compass as orientation feedback • 8bits microcontroller with 64kbyte of program memory and 2kbyte of RAM • Can dock with any mate whose docking element is a 15.24 cm long rod of 1 cm diameter • Optical communication

18. Hardware infrastructure-Starbug AUV • Used to locate the aquafleck nodes by vision, data muling and to dock with Amour in order to provide visual control feedback • 2 stereo vision heads, downward for sea-floor altitude and speed estimation, forward for obstacle avoidance • Acoustic communication

20. Outline • Introduction • Hardware architecture • Experiment • Conclusion • Concluded my own way

21. Experiment of data collection • Long term collection of temperature and pressure data (Tingalpa Creek) • Sensor nodes were deployed approximately 1 km for a period of 3 days • Log data every 150 sec

22. Data retrieval using mobility • A relative position of the network can be preloaded in the mobile node to locate the static node • Starbug located the next node using visual odometry while Amour locates the node using the magnetic compass

23. Data retrieval using mobility • Mobile node sends a request for data • The data is transmitted either packet by packet or in a groups of packets • Depends on the quality of communication link • If any packet is lost • Time out and request again • Transmission is completed • Reset and erase the data • Adjust the clock of a static node to the clock of a mobile node • For long term monitoring, clock need to be synchronuzed

24. Outline • Introduction • Hardware architecture • Experiment • Conclusion • Concluded my own way

25. Conclusion • The first prototype for an underwater sensor network • Still many technical challenges to be solved • How to control the mobile node in the presence of currents • Mobile node helps a lot

26. Outline • Introduction • Hardware architecture • Experiment • Conclusion • Concluded my own way

27. Concluded my own way • Just an application use the idea of sensor network yet it’s the first one • Relatively new compared to e-home, military purpose, etc • It continuously collect data for several days nevertheless I think the transfer in underwater environment is gradually, not in a sudden • I can not believe that Aoyama will put her hand in Densha Otoko’s

28. Thank you 