String Theory: Exploring Human-Impossible Techniques Through a Machine Aesthetic for Robotic Guitar

Abstract

Robotic Musicianship (RM) is the implementation of machines that listen to, interact with, and improvise music. RM often aims to design systems that listen like humans but play with the techniques and capabilities that are humanly impossible. Robots such as Shimon [1] play like a machine by leveraging humanly impossible playing speeds and multiple arm morphologies that allow for sonorities unachievable by humans. Other robots such as the Expressive Robotic Guitarist (ERG), successfully emulated human performance but have yet to fully exploit its own mechanical embodiment. This paper introduces the latest version of the ERG, which navigates unexplored musical landscapes by leveraging physically impossible or difficult techniques for a human to execute. We detail the implementation of augmented guitar techniques, including complex polyrhythms, variable speed tremolo, and asynchronous glissandi, which transcend human physiological constraints. To evaluate the musical and interactive potential of these techniques, we conducted online surveys with 30 guitarists and performed in-person workshop sessions with 4 professional guitarists. Participants evaluated the system based on its perceived creativity and its ability to provoke collaborative musical experiences. We contribute a practical application of the Cooperative-Creative Index by evaluating the perceived Trust, Collaboration, Creativity, and Stability of the system. Although qualitative results from the online format indicate mixed responses, quantitative responses and in-person responses indicate that our augmented techniques show potential to foster innovative human-robot collaboration. By leveraging objective technical limits as musical strengths, we demonstrate a model for asymmetric human-robot collaboration that fosters creative synergy and a path for the future development of human-robot musical interaction.