Designing an Expressive Pitch Shifting Mechanism for Mechatronic Chordophones

The exploration of musical robots has been an area of interest due to the timbral and mechanical advantages they offer for music generation and performance. However, one of the greatest challenges in mechatronic music is to enable these robots to deliver a nuanced and expressive performance. This depends on their capability to integrate dynamics, articulation, and a variety of ornamental techniques while playing a given musical passage. In this paper we introduce a robot arm pitch shifter for a mechatronic monochord prototype. This is a fast, precise, and mechanically quiet system that enables sliding techniques during musical performance. We discuss the design and construction process, as well as the system's advantages and restrictions. We also review the quantitative evaluation process used to assess if the instrument meets the design requirements. This process reveals how the pitch shifter outperforms existing configurations, and potential areas of improvement for future work.