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Solar walker

Justin Downs

The solar walker, is a GPS unit conceived and design for long periods of use away from power supplies and data recording facilities.

http://www.johnhenryshammer.com/projects/solarGPS/solarGPS.html

Classes Sustainable Energy

Solar walker >>>>> A solar powered GPS unit

This solar powered GPS unit was conceived and is being developed to fill the needs of the Lion Guardian organization in Kenya: http://www.lionconservation.org/

This organization uses a combination of social and electronic technologies to track and care for the lion populations of southern Kenya. The GPS unit would specifically be used by the Lion Guardians (trained scouts from the surrounding villages) to record the walking routes used in monitoring the bush and lion prides. The gathered GPS data is later crossed referenced with their recorded observations, producing data visualizations, which represent change in the lion’s environment.

This device address the problems of design and functionality associated with:

Long periods of time away from a centralized power source.
Robust functionality, in terms of weather conditions and ruggedness.
Making a tailored device with no excess functionality that would hinder data collection, power needs or weight of the device.

The device consists of a Trimble GPS unit paired with a SD card reader/writer. The device operates by taking a GPS reading at a set interval and recording it to a SD card with up to 1MG of memory, This card is retrieved at the end of the trip and the data is downloaded as a text file.

Currently we have the GPS working and writing to the SD card using only solar power we now have to design a storage system for the power and refine the casing.
The power is supplied from 6 small (4 x 2.5cm) solar cells. Below is an overview of the power specifications for the device.

Power usage overview:
Trimble GPS + antenna mA< 54mA at 3.0-3.6 v
Arduino mA< 30mA at 3.0-5.0v
SD cardreader Active current 5mA @ 3.3V
Total< 89 mA at 3.3v =(3.3v)(89mA)=(.2937 watts)(1sec)=. 2937 joules

Power supply from solar cells: full sun solar cell MAX 23mA at 4.6V (times 6 cells) = (4.6v)(138mA)= (.634 watts)(1sec) = .6348 joules

So full sun power supply gives us .634 joules with a constant draw of .2937 joules (ideally).



Background
This device address the problems of design and functionality associated with:

Long periods of time away from a centralized power source.
Robust functionality, in terms of weather conditions and ruggedness.
Making a tailored device with no excess functionality that would hinder data collection, power needs or weight of the device.


The device consists of a Trimble GPS unit paired with a SD card reader/writer. The device operates by taking a GPS reading at a set interval and recording it to a SD card with up to 1MG of memory, This card is retrieved at the end of the trip and the data is downloaded as a text file.
The power is supplied from 6 small (4 x 2.5cm) solar cells. Below is an overview of the power specifications for the device.

Power usage overview: 

Trimble GPS + antenna mA< 54mA at 3.0-3.6 v

Arduino mA< 30mA at 3.0-5.0v
SD cardreader Active current 5mA @ 3.3V
Total< 89 mA at 3.3v =(3.3v)(89mA)=(.2937 watts)(1sec)=. 2937 joules


Power supply from solar cells: full sun solar cell MAX 23mA at 4.6V (times 6 cells) = (4.6v)(138mA)= (.634 watts)(1sec) = .6348 joules

So full sun power supply gives us .634 joules with a constant draw of .2937 joules (ideally).

Currently we have the GPS working and writing to the SD card using only solar power we now have to design a storage system for the power and refine the casing.



Audience
The GPS unit would specifically be used by the Lion Guardians (trained scouts from the surrounding villages) to record the walking routes used in monitoring the bush and lion prides.

User Scenario
The GPS unit would specifically be used by the Lion Guardians (trained scouts from the surrounding villages) to record the walking routes used in monitoring the bush and lion prides.

Conclusion
I wish i had more time in the week.