Player Fence

Background

Since summer 2020 I’ve been helping out with the Pickup Music Project which has installed a few interactive musical sculptures around the Northeast. Currently we’re working on a permanent installation for the Cambridge Crossing development. Unfortunately it’s been delayed due to COVID, but as a silver lining this gives me extra time to play around with our prototypes. Right now I have this machinery tucked next to my keyboards at home.

It’s a set of 7 aluminum chimes, tuned to a G major scale. Each chime has a solenoid actuator that can swing a lever arm to sound a note, a piezo sensor that should be able to detect when the chime is vibrating regardless of how it was struck, and a RGB LED ring tucked inside that casts a colorful glow below. The real installation will use the same hardware, but will consist of 60 chimes.

However a lot of this hardware isn’t functional at the moment (i.e. February 2021), since it’s missing a lot of electronics and the firmware/software to drive it. This is what I will be working on. In particular, the solenoid/piezo system needs some work. A dedicated electrical engineering team has developed some control boards for the system (and I’ve produced early prototypes on CBA’s pick and place machine), but we’ve uncovered some design issues that will have to be fixed.

The light system on the other hand is pretty much ready to go. I use a fadecandy device to drive the LEDs. It connects via USB to a computer running a version of Open Pixel Control.

Plans

The requirements of the system are:

• Put the actuators and sensors on a network, so that a single (local) control computer can read all data and control the actuation.
• Achieve a delay of less than 10 milliseconds between sending a message to play a chime on the computer, and having the chime sound. This is our minimum requirement; the less latency the better.
• The computer should have two core abilities: scheduling playback on the chimes of composed material, and running interactive programs that respond to user inputs (as measured by the piezo sensors). For accessibility with existing musical ecosystems, we want to accept composed pieces in the MIDI format, and develop interactive programs using Pure Data.
• The control computer must be reachable wirelessly.
• Everything has to live outside in Cambridge, and survive. This means winters, summers, humidity, hurricanes, etc.