PROJECT: InterpretedSpace

Final circuit(work with 2 1.5v AA battery)

Prototype

Example of visualization

Right from the start, we were very interested in doing an abstract visualization of a defined space. Our first idea was to mount a camera in a room and track the movements of people in this room to create a drawing with it. However, after talking to Elio about it we became aware that the communication part in this project would be very simple and would not need an Arduino or a similar transmitter.

To create a more meaningful visualization, we decided to sense different parts of a room and visualize the changes over time in an abstract animation.

Therefore we built three sensing stations that each consist of an XBee wireless radio transmitter that has three sensors connected: a temperature sensor, a brightness sensor and a vibration sensor. Everything is soldered onto a little breadboard and connected to a battery holder that contains two AA batteries that provide 3 volts to the XBee.

We put these sensing stations in the big studio/lounge opposite to the sensor lab and collected the data for one day. The fourth XBee was put into the sensor lab and connected to a laptop running Processing that collected the data.

The sensing station send their values twice a second to the receiver. We used an XBee library for Processing recognize the data that the XBees sent into their API mode. In Processing, the data is gathered and the values for five measurements are averaged and saved to a text file. To create a more meaningful visualization, we decided to sense different parts of a room and visualize the changes over time in an abstract animation.

As a result, we collected 12 hours of data from each sensor, and mapped each values to our visualization based on parameters we made. It creates 3 random particles every time program runs, and changes color based on changes in temperature, transparency based on brightness value, and vibration rate based on vibration sensor’s changes in value. 

Credit to :
Hyun Cho & JanKo Hofmann

Processing Library for Xbee
Processing visualization from Openprocessing.org and modified to work with our data.

We have a single-sided communication here, which means we have three transmitters and one receiver, so the receiver does not respond to the transmitters; it just collects the data, but thereby is able to distinguish where the data comes from. The quality of their connection is determined by the distance and the amount of objects between transmitter and receiver. Since all XBees are located in a fixed position, you could only interrupt the communication by other RF signals or if you placed a lot of objects between them (or if you remove the batteries :D ).

[Protocol]
We used the XBee API mode that already has a defined protocol (see image below). We read the data using functions from the XBee Processing library.

The following data is transmitted:

• ID of the sensor 
• Value on analog pin 0
• Value on analog pin 1 
• Value on analog pin 2

[example of log file]

TIME – SENSOR – PIN 1 – PIN 2 – PIN 3

08:42:37 1 712 252 231
08:42:40 1 702 253 238 
08:42:42 1 702 253 241 
08:42:45 1 702 253 241 
08:42:48 1 702 253 239

…

15:52:22 1 820 323 250 
15:52:24 1 820 322 245 
15:52:27 1 820 323 243 
15:52:37 1 820 322 242 
15:52:39 1 820 323 235