A closed-loop control system for robotic hi-hats

While most musical robots that are capable of playing the drum kit utilise a relatively simple striking motion, the hihat, with the additional degree of motion provided by its pedal, requires more involved control strategies in order to produce expressive performances on the instrument. A robotic hi-hat should be able to control not only the striking, timing, and velocity to a high degree of precision, but also dynamically control the position of the two cymbals in a way that is consistent, reproducible and intuitive for composers and other musicians to use. This paper describes the creation of a new, multifaceted hi-hat control system that utilises a closed-loop distance sensing and calibration mechanism in conjunction with an embedded musical information retrieval system to continuously calibrate the hi-hat’s action both before and during a musical performance. This is achieved by combining existing musical robotic devices with a newly created linear actuation mechanism, custom amplification, acquisition and DSP hardware, and embedded software algorithms. This new approach allows musicians to create expressive and reproducible musical performances with the instrument using consistent musical parameters, and the self-calibrating nature of the instrument lets users focus on creating music instead of maintaining equipment.