Getting a reality check at iMAL codes & craft workshop

Given the problems we had with the biosensors, we have decided to limit our first installation to making the visitors feel a different sound based on their position in the room. Well, there is more than that, but technically speaking we’ll stop there.

We need to find a way to understand the position of a person inside a totally dark room, so thought of using 4 sonars, and triangulate the different readings in order to pinpoint the position of the object in the room. To try and get some more help on the technical problems of using sonars, and also to understand how to possibly get rid of the breadboard and build a nice and tidy arduino board, we participated to a workshop about arduino shields, organized by the iMAL and held by Wendy from Ellentriek.

This two day workshop was very useful: we found out about the problems that might arise when using multiple sonars, and we got to play a bit with various shields (especially the motor shield) and we realized that the MP3 Shield is not enough for what wanted to do.


The biggest problem of sonars is that they cannot be used in combination with other sonars, because the waves from one can be “read” by another sonar, thus causing unreliable readings. Also sonars don’t work super well with people because they might wear woolen clothing that absorbs waves. So we tried and build a scanning sonar: we put a sonar on the shaft of a stepper motor and we created a funnel to try and reduce the width of the sonar’s beam. And at the end we had a nice rotating sonar that was tracking the distance while scanning the area.

[Pictures taken at the iMAL Code, Arts and Craft meets Ellentriek #2 by iMAL]

Actually everybody suggested we skip entirely this attempt at using sonars for people tracking, and that we directly go to using a Kinect or doing triangulation with IR cameras.


Also here we got a reality check: apparently the MP3 Shield is not advanced enough to play two songs at the same time, mixing them like the minim library on Processing does, so apparently for this we will have to use a computer running Processing. That is something we wanted to avoid, and that we’ll do for our first exhibition at the Académie, but we’ll have to find a better way to deal with that problem.


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