Velocity Sensitive MIDI Poi
This is a project from 2006 that I’ve recently migrated to my new blog.
I’ve developed a set of LED poi that are sensitive to the velocity with which they are spun. I determine their velocity by measuring their centripetal acceleration and relating that to their tangential velocity by the equation a=v^2/r
They change color from red to blue in proportion to their acceleration, and transmit that telemetry to a base station via 418/433MHz RF. The base station in turn transmits that telemetry to the host computer via RS232 serial, and generates MIDI Control Change messages. The MIDI is then used to drive visual displays or MIDI instrumentation. I’m currently driving MIDI to Ableton Live, and getting some really interesting effects by attaching the Control Change signal to various configurable effect parameters.
I’m casting them in silicone this weekend.
The brains of this project is an ATMega8. I use the on-board ADC to read one of my ADXL321 acceleration axes.
Couldn’t have exposed switches, because mechanical parts like to break on spinning objects. So there’s an embedded magnetic reed switch. The BJTs and FET are there to gate power to the 7805.
Eric Gradman is an interactive artist in Los Angeles, CA. His work often features computer vision, large-scale projections, unusual sensors, and custom electronics to produce fun environments that compel people to interact.