The ukulele, often viewed as a quaint instrument, is no less legitimate than any other, requiring considerable practice to play well. However, Zeroshot, a maker with a knack for building innovative projects, decided to bypass the practice and instead create a robotic ukulele that plays itself.
Much like a guitarist, a ukulele player can produce sound by strumming multiple strings simultaneously or by picking individual strings. While more complex techniques exist, they are beyond the scope of this project. The heart of Zeroshot’s creation lies in a mechanism capable of both picking and strumming. This is achieved using two actuators: a servo motor to lift and lower the pick, and a stepper motor to move the pick back and forth perpendicular to the strings.
An Arduino UNO Rev3 board serves as the brain of this operation, controlling the motors via a HiLetgo L293D motor shield and a TMC2208 driver module for the stepper. The Arduino can either strum across all the strings or move the pick to a specific string to pluck it individually.
To avoid being limited to playing only open strings, Zeroshot added hardware that presses the strings down on the fretboard. Solenoids were chosen for this task, mounted in a 3D-printed holder. Powered by the motor shield, the Arduino can engage the solenoids to produce the required notes.
Zeroshot designed the mount to hold up to 16 solenoids, covering the first four frets across the four strings. Including the open strings, this setup provides the robotic ukulele with up to 20 playable notes. As Zeroshot demonstrated by performing Celine Dion’s “My Heart Will Go On,” many songs can be played with just a few solenoids.
