Development Note - Embedding sensors.

For the first version of the Optron (the one performed at GA-Tech), I used eMotion Wireless sensing to translate performance gestures into data for the computer processing. This was the quickest path to getting something working. Now, I am embedding these sensors directly inside of the Optron and using a separate dedicated Arduino just to process the data so it does not affect the speed and agility of the other Arduino driving the Adafruit Dotstars (the lights).

I'm upgrading the IR "strum" sensor to a Sparkfun ZX Gesture Sensor. The old IR could only detect If my hand was in front of the sensitive area and how far away it was. The ZX will detect this too, and also the position of my hand horizontally along the x-axis of the Optron (in a window of about 6 inches). This will give the Strum an idea of how fast or slow my hand moves across the area. Or I can play chords if 1-inch segments are mapped to play individual pitches as my hand moves across. Possibilities abound!

The MPU6050 was selected to translate tilt and orientation.

I'm continuing to use the SoftPot Membrane potentiometer to track my finger position along the "neck" of the Optron, and the Long FSR for finger pressure - but this time I get to optimize their sensing range. One conflict I have is choosing the resistor for the SoftPot. The original eMotion wireless sensor system uses 30k resistors by default, which provided me with an almost linear response, but sacrificing a bit over half of the resolution (500 steps over 500mm isn't bad though). With an optimal resistor value of 1k, I get a sweep range over all 1024 steps, but now I get an exponential (non linear) response from the sensor. The "curve" is also backwards from the 12th root of 2 effect you'd see on a guitar (where the frets get closer and closer together the further up the neck you go). The exponential response could be desirable, but I'd have to rip off the current sensors and turn them around. With another performance coming up soon and wanting to make more music, I'm waiting to implement this in the next Optron I build. Sticking with 30k on the SoftPot and 10K on the Long FSR for now.

Chet Udell