ITP Thesis Week 2009
Monday, May 4 - Friday, May 8

Irregular Incurve

Xiaoyang Feng

Irregular Incurve is a MIDI Controllable robotic string instrument composed of twelve independent single stringed units.

Irregular Incurve has a similar construction structure as acoustic guitar. Instead of mounting strings on the neck, each string is mounted on an independent steel pipe. The steel pipes are fixed onto a curved shower rod by 3 pieces acrylic panels. Twelve controllable arms are mounted on the shower rod as well, which can pluck the strings by moving guitar picks. A homemade bridge transfers the vibration of the string to a spruce-wood sound box that sits under all the steel pipes. There are no nuts for different frets on each string. It only produces 12 simple tones. With the ability to change different strings and tuning manually, it can be used to perform different music.

'Absolut Quartet', a music-making machine, by Jeff Lieberman and Dan Paluska.
‘Acoustic Curve’ of Animusic
Guitarbots from

anyone who loves classical music.

User Scenario
User can use it as a tool to performance in real time with MIDI input source or compose music for it. As a performance tool, user can simply click a key on a midi keyboard to trigger the instrument to play.

In order to generate better sound, I designed a long sound box. Not like original guitar body, this sound box is made to fit the shape of whole structure. To make the curved edge of the sides, I cut 4 pieces of plywood as a frame and bent the side wood by holding the wood pieces in the position in a moist environment in three days.
The acrylic holding panel laser-cut and screwed together. The steel pipes are bent using both a pipe bender and a clamp. The length of them is calculated with fret-placement calculator for string instrument. It’s twelve tones in one octave. The steel pipes are mounted by screws with felt washer between them. In order to keep the pipes in position on the shower rod, I glued one of the three acrylic panels with a nylon spacer to enlarge the contact area in order to add the fraction between them. I also tapped a hole on the spacer and the shower rod, screwed them together better hold them in position. Twelve rubber foam spacers are put under each arm as a cushion pad as well. Felt is also added between guitar picks and aluminums arm rod to reduce noise.
Every components of this instrument are designed, refined and developed under hundred of experiments. It’s a combination of science and art.

Irregular Incurve began as an attempt at designing and creating a new acoustic musical instrument to be played by itself. It breaks the limitation of designing an instrument to fitting human's hands/mouth. It's designed to generate acoustic sound instead of using electronic pick-up. It continues to this end, a blend of the accessible and the experimental.