Full Speed Ahead!
Last week for NIME I completed my first fully working prototype of the yet-to-be-named plate spinning instrument. My sensing strategy for both the individual plate IDs and rotation has changed greatly since their initial inception. At first I had planned on using computer vision to get the rotational and ‘fingerprint’ data from the individual plates, but after trying several different algorithms, the frame rate proved too slow for the fine grained data I wanted… So next I leapt into the hardware world. In the very beginning I assumed I would be using hardware for data collection, but decided to try the CV stuff because it would allow me to divorce the sensing from the physical stick setup… which would make the instrument portable, repairable, and clean looking… so I am a little disappointed that did not work out; but on the bright side, the hard ware solution will be MUCH more robust.
The sensing setup work like this:
On the bottom of each plate there is a small white plastic disc glued to the center. On the disc there is a grove in the center, one magnet strategically placed, and five sections that can be colored black or left white. The magnet is used in conjunction with a reed switch to track rotational frequency, and the black and white sections are used as a binary rotary encoded via a black/white sensor. With the combination of the B/W sensor and the reed switch, I am able to get accurate IDs (5 digit byte) and rotational speed serially out of an Arduino. That data is sent to the computer and fed into PD where it controls playback speed of a granulated loop.
The next step is really just fabrication of the full system. I am going to make six sensing sticks and place them on a three piece platform (for ease of portability)… hopefully I can have this by next week’s prototype presentation.