robow I/O

A robotic stringed instrument that can be controlled with software or with a variety of different sensors.

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robow I/O is a robotic string instrument that can be controlled with software or with physical sensors. This project is currently in an early-stage prototype and so far the x axis can be controlled to draw the bow across the strings; future iterations will likely include additional motors and controls to apply pressure, tilt the instrument and depress individual strings. I'm using an electric violin for the initial prototype, but robow could be used on any bowable string instrument.

robow is not designed to be a robot that plays violin as a human would -- instead I am using the advantages that computational control affords to play an instrument in ways that humans cannot. This presents an opportunity to create a new kind of sound. What can a robot do that a human can't? What kinds of new sounds could it make and how would you write music for it? These are complex and interesting questions that I will attempt to answer throughout the duration of this project.


I'm an artist that uses technology as my primary medium for expression. As a physical interaction designer, I think musical instruments are an ideal interface to explore expressive gestures -- both kinetic and tactile -- and how they correlate to sounds and inform music composition. 

Although I am not a violinist, I sometimes work with composers that are searching for new sounds and innovative ways to create them. I am using computer software and alternative interfaces to control a traditional (or modern) stringed instrument in ways that a human cannot.

Interaction Design

The player uses software, their smartphone, or another wireless sensor to control the bow’s rate and length of travel across the strings. On the instrument, this is driven by a motor with an old-timey rotary-to-linear gear driver. The bow’s pressure will be controlled by a stepper motor attached to a lead screw along the z-axis. When paired with a smartphone, the IMU senses tilting and will control the angle of the bow across the strings by rotating the violin with a second stepper motor. Additional motors will move the violin along the "z" axis and depress individual strings.

Visual Design & Mechanics

The design of the instrument is influenced by 19th century automata and by machines such as the mechanical turk, an “automaton” secretly controlled by a human. A rotary-to-linear driver is constructed from plywood gears and is a replica of Movement 329 of 507 Mechanical Movements.  The device is designed to accommodate any bowable stringed instrument. 


Open Sound Control is a format for streaming real-time audio control messages. It’s a binary encoding that uses URL-style naming schemes and timestamps high resolution data. Data is transferred over UDP because musical instruments require real-time actuation and feedback. This also allows multiple devices to control the instrument, or one device to control multiple instruments.


Max is a visual and dataflow programming language and I am using it in this project to either program the movements or tap into the data stream before it reaches the hardware so that I can translate sensor data into mapped values appropriate to motors. Max is a full programming language designed for controlling audio and allows me to rapidly prototype ideas and features and implement them live without compiling. 


The gears are milled in plywood and the cranks and mounts are 3D printed in PLA. I'm utilizing hardware that is commonly used in open source CNC equipment. 

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AVR wrote 10/09/2018 at 19:35 point

cool project! Very focused and elegant design in all the engineering here, looking forward to more from you!!!

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Hunter wrote 10/11/2018 at 15:36 point

that is the best compliment, thanks AVR!! It's been a lot of fun to build :D

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