PHOTON: Non-Invasive Optical Tracking of Key-Lever Motion in Historical Keyboard Instruments

Fuente: arXiv
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Auteurs principaux: Jaffe, Noah, Burgoyne, John Ashley
Format: Preprint
Publié: 2026
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author Jaffe, Noah
Burgoyne, John Ashley
author_facet Jaffe, Noah
Burgoyne, John Ashley
contents This paper introduces PHOTON (PHysical Optical Tracking of Notes), a non-invasive optical sensing system for measuring key-lever motion in historical keyboard instruments. PHOTON tracks the vertical displacement of the key lever itself, capturing motion shaped by both performer input and the instrument's mechanically imposed, time-varying load. Reflective optical sensors mounted beneath the distal end of each lever provide continuous displacement, timing, and articulation data without interfering with the action. Unlike existing optical systems designed for modern pianos, PHOTON accommodates the diverse geometries, limited clearances, and non-standard layouts of harpsichords, clavichords, and early fortepianos. Its modular, low-profile architecture enables high-resolution, low-latency sensing across multiple manuals and variable key counts. Beyond performance capture, PHOTON provides real-time MIDI output and supports empirical study of expressive gesture, human-instrument interaction, and the construction of instrument-specific MIDI corpora using real historical mechanisms. The complete system is released as open-source hardware and software, from schematics and PCB layouts developed in KiCad to firmware written in CircuitPython, lowering the barrier to adoption, replication, and extension.
format Preprint
id arxiv_https___arxiv_org_abs_2604_21682
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle PHOTON: Non-Invasive Optical Tracking of Key-Lever Motion in Historical Keyboard Instruments
Jaffe, Noah
Burgoyne, John Ashley
Audio and Speech Processing
This paper introduces PHOTON (PHysical Optical Tracking of Notes), a non-invasive optical sensing system for measuring key-lever motion in historical keyboard instruments. PHOTON tracks the vertical displacement of the key lever itself, capturing motion shaped by both performer input and the instrument's mechanically imposed, time-varying load. Reflective optical sensors mounted beneath the distal end of each lever provide continuous displacement, timing, and articulation data without interfering with the action. Unlike existing optical systems designed for modern pianos, PHOTON accommodates the diverse geometries, limited clearances, and non-standard layouts of harpsichords, clavichords, and early fortepianos. Its modular, low-profile architecture enables high-resolution, low-latency sensing across multiple manuals and variable key counts. Beyond performance capture, PHOTON provides real-time MIDI output and supports empirical study of expressive gesture, human-instrument interaction, and the construction of instrument-specific MIDI corpora using real historical mechanisms. The complete system is released as open-source hardware and software, from schematics and PCB layouts developed in KiCad to firmware written in CircuitPython, lowering the barrier to adoption, replication, and extension.
title PHOTON: Non-Invasive Optical Tracking of Key-Lever Motion in Historical Keyboard Instruments
topic Audio and Speech Processing
url https://arxiv.org/abs/2604.21682