Over The Air 2013 @ Bletchley Park

This is always a great event thanks to the organisers’ skill and persistence. All hail @mobilemaggie, @torgo, @matthewcashmore, sponsors etc. This year was no exception with plenty of great talks and workshops plus hacking. As usual, I wanted to do something with hardware and had brought a big bag of parts.

“Airsome” – Protecting Cyclists from Pollution

This idea came via keen cyclist Hugh Knowles of F4F. We had not got round to it until now (for reasons see to-dos below) but this seemed like the ideal opportunity to do air quaility measurement using wireless communications. The We in this case included Stephen @millipedia (aka Sooper) Cooper who is a dab hand with mobile software.

The general idea is as follows:

Airsome

A sensor board is mounted on the bike. This has a bluetooth transmitter and sends periodic readings of gas concentration (CO and NO2) to the phone. The phone knows its location and sends this and the measurements to a cloud-based data store. The phone can then pull down a time-averaged dataset and plot a heatmap of the polution level.

airsome_bike

This gets much more interesting when you can multiple bike inputs, supplemented by offical data from government AQ networks. This was beyond what we had time for in this 24-hour hack.

The sensor setup for this hack used an Arduino with AQE Shield and Bluetooth module. Not enough accuracy for a real-life solution and not robustly packaged but it did produce readings and showed the effects of driving around a local traffic island compared to the environment in the park.

map_real_data

The sensor module was powered by 4 AA rechargeables.  Fine for short-range use.  We assumed within this hack that we always had a mobile data connection from the phone.

We were pleased that we had enough hardware parts and could get this all working in the time available. We used Phonegap’s Bluetooth plugin which seemed to work fine for the most part, although we had to filter out some extraneous characters.

To-Dos

  • Sensor devices with better accuracy and professional calibration are needed. Ideally sense more than gases, particulates being a greater health risk.
  • The packaging for the sensor unit needs to be robust and suited to bike mounting in such a way that air passes over the sensors.
  • Need to think further about battery life or adding a battery and/ or charging system.
  • It should not be assumed that there is always a mobile signal.  Relatively little storage on the phone would avoid data loss.  We could use SMS as a fallback for alerting the rider when maps cannot be used.
  • The solution should be secured to that location data is not exposed.
  • It would be good if the whole solution could be open-sourced.

As usual, watch this space.

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