The touchquilt is the first piece in my visual instrument series. I undertook it as a means of solving some of the problems I had run into involving projection interaction with the wiimote whiteboard setup in performance. The wiimote whiteboard approach often required sensitive calibration, placement, and lighting, the touchquilt can just be plugged in via ethernet. Here’es a schematic for the first implementation of the quilt:
As the video suggests, with this resistor ladder approach I was able to get a fairly accurate reading on which button was being pushed if I held the button for long enough, but associated with each press was a significant amount of electrical noise which made the quilt unpredictable. As an installation piece the unpredictability was interesting, but as a visual instrument it was problematic. I later modified the quilt to utilize a time based method for much more stable results. I found that by attaching each column to a digital row I could scan a voltage across the surface of the quilt allowing me to test each individual button to determine if there was contact. This enabled 16 point multi-touch ( 1 press per row ) as well, which is nice. Here’s a shot of it opened up from the back:
Shoot me an email at brian@ec2-54-91-147-104.compute-1.amazonaws.com if you’d like more information on this project. If you’d still like to see the code or more details on the construction prior to the time-based changes I made, you can also check out my post on the arduino forum. To download the code for the stable version of the quilt click here.