At the beginning of the summer, our intern cohort was told that IDEO has a history of summer pranks. Inspired, we got together, threw around a few ideas, and settled on building a musical staircase, one that would play different sounds when you walk up and down the steps.
Over the course of three weeks, we brainstormed and prototyped a variety of implementations and consequently took over the Toy Lab over the weekends to build, solder, and assemble. We tried to be stealthy and keep the project a secret, though it soon became clear that designers in the Toy Lab had been thinking about building something similar for a few years.
Click through for build details and source files for building your own!
Our approach involved using IR sensors and a single Arduino Mega 2560 inspired by Sparkfun’s Illumitune project. We considered using pressure sensors but were concerned about the possibility that if they caused slippage or tripping in any way, there would no longer be an intern program at IDEO.
Unfortunately, our first attempt at using IR LEDs and detectors did not work reliably, and we spent many hours trying to calibrate and ensure that one pair of working sensors could scale reliably to sixteen sensors working in concert. We eventually switched to slightly more expensive Sharp distance emitter-sensor pairs, which a local hobby store fortuitously carried. These were considerably more reliable, though reliability came at a price — 5 times as much at $15 a piece! Luckily, the Arduino Mega has exactly 16 analog inputs for 16 stairs, and after assembling cables for the better part of the evening, we were ready to install. The Mega happily works with a 9V power supply.
We designed a custom foamcore housing to hide the cables that run along the side of the stairs as well as laminated graphics to add more fun. While in the video, the participants are standing fairly close to the railing to trigger the sensors, we have since improved the threshold for triggering the stairs, which feed into a Processing script that handles the playback of audio. There are two audio tracks currently available – piano notes and clapping, with the possibility of easily adding more. The last stair of the clapping track includes pretty much everyone from the Toy Lab!
To build your own
The code for the sensor set on the Arduino is available here
The code for the audio using Processing here
The sensors we used were the Sharp GP2D12 30″ type. The processing code has been shortened somewhat, but the essentials are there. Add as many mp3 files as needed, and run the Processing code to read the Serial output from the Arduino device using the same baud rate.
(L-R) Rio Akasaka, Haemi Chang, Engin Kapkin, Lucas Hartman, Silvia Boscolo, Tiffany Tseng, and also Corina Yen, Valerie Willis, Aaron Peck, Anne Riechart