‘Scream if you want to go Faster’ was commissioned by Ludic rooms for their Open Citizens programme as part of Coventry City’s successful bid for ‘UK City of Culture 2021’.

Open Citizens programme of activity by Ludic Rooms explored how a playful approach to creative technologies in public space might drive new conversations around citizenship in the 21st century.

The idea came from a local school, take a Razor E300 Electric scooter and modify it so as to respond to the riders voice. The louder you scream the faster it goes.

In theory, we were going to replace the throttle switch with a variable speed controller then use a microcontroller and a digital potentiometer to control it.

The microcontroller would take the sound from the microphone and map the volume level to the digital pot over SPI.  The digital pot connected to the speed controller.

All mocked up we were ready to commence testing.  The first test runs were fun.  But then there was a failure, the motor would not stop!!!   NOT GOOD.  So we knew that it worked in theory but we needed to build in some safeguards. With the addition of a few fail-safes, some fine tuning of the code and adjustment to the microphone gain we were ready for further testing.

There were several points that needed calibration,

  • The volume levels had to be calibrated to match the acceleration of the scooter.
  • The microphone gain required careful adjustment . This was set to find the sweet spot to pick up a voice, but not be over sensitive to wind and background noise.  When it was too sensitive the sounds of the motor would increase acceleration resulting in a runaway condition.

After these things were calibrated it was a few more test runs then off to Ludic rooms for delivery.

A big thank you to Ludic rooms for giving us the opportunity to work on such an amazing project.