Chameleon Drum Machine

Our (Grau and Rogue) final Physical Computation project is the Chameleon, a hand held drum machine.  The concept behind the object is to take the drum machine off the table and into your hands, leaving your body free to move (with the instrument) during a live performance.  It’s also intended to be an instrument in its own right, not simply a midi interface that runs whatever you want it to run. We also don’t want it to feel like a toy, but rather an instrument that is simple enough to understand it by just picking it up, but having a bit of a learning curve, for old instrument learning sake.

We wanted a hand held design that would feel like something between a table top drum machine and a game controller, but we didn’t want it to feel like a game. It needs to feel like an instrument with its own personality. Ideally, we would have pads similar to an  MPC drum machine as the buttons, but we are using arcade style buttons for the first prototype.  The design is cylindrical, inspired by the shape of an actual drum.  This design led to an unintended use on the top surface of the instrument.  During our test run in class some classmates thought to play the top of the object like a drum, as if it was the rim of a drum with a skin on it. We briefly entertained that idea but ultimately we decided to use that real estate for buttons instead.

The first design is a bit blocky. The positioning of the hands holding it gave way for tension in the shoulders, so we knew we had to re-work the design to tell the hands how to hold it in a specific manner and to spread the shoulders more to get rid of the concave angles the shoulders were resting at.

First Prototype:



We cut some fat off of the first prototype and created Prototype # 2, with an ergonomic design that is easier to hold.


The placement of the buttons is a bit more successful in directing how the hand holds it. The shape also spreads the shoulders out, creating a comfortable shoulder position that is near natural standing position or shoulder width apart.

The concept of the instrument is for it to be as dynamic and inclusive as possible in terms of the sounds it produces. Ideally each setting on the instrument is a different sound bank that is guided by the names of the settings: Africa, Middle East, Latin America, Asia, Space. Each of these settings would recall sounds from each specific region of the world.


We drew up various schematics for what the button functions would be, based on the position in the hand and how comfortable it would be to create a beat with your fingers. Taken into consideration were two main factors, which fingers were the strongest and fastest. The index, the middle, and the ring fingers were the most comfortable to use, especially the index and ring fingers for precision purposes.I also included various features like pitch-shifter and volume control, which will be additions that we will add in the future.

The end result for the prototype includes six buttons on the front, three for each hand, and four on the back, which will be played by the thumbs.

For the prototype we concentrated on programming a traditional western drum set, with finger positioning that looks like this:

We originally drew up the casing for the Chameleon thinking that we were only going to use one arduino, plus a sound shield to store all the sounds it would recall via a mini sd card. We worked on the casing and the computation simultaneously, really hoping that one arduino would be enough. One arduino wasn’t enough, however.  In order to play three sounds at once without any latency, we decided to employ three separate arduinos with three separate mini sd cards.

The final prototype of the Chameleon is still in the works. One hiccup we ran into was the size of the casing versus the amount of hardware that fits inside. We need to figure out a way to minimize the hardware. An easy way out of this dilemma is to use Max MSP to control the interface, but we are adamant about creating an instrument with it’s own sounds..without having to plug into a computer.

We also had to build a custom audio mixer to mix together the three lines of audio from the three arduinos and the three breakout chips. We also had a bit of an issue with the sounds themselves. It seems the sounds we selected for the Chameleon got lost in translation and are coming out as amorphous blobs of sound, rather than drum sounds.

It works, though!

We should have these two kinks done over the break, and as soon as they are, I plan on filming a performance piece using the Chameleon.




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