Evaluation of sensor technologies for the rulers, a kalimba-like digital musical instrument

Selecting a sensor technology for a Digital Musical Instrument (DMI) is not obvious specially because it involves a performance context. For this reason, when designing a new DMI, one should be aware of the advantages and drawback of each sensor technology and methodology. In this article, we present a discussion about the Rulers, a DMI based on seven cantilever beams fixed at one end which can be bent, vibrated, or plucked. The instrument has already two sensing versions: one based on IR sensor, another on Hall sensor. We introduce strain gages as a third option for the Rulers, sensor that are widely used in industry for measuring loads and vibration. Our goal was to compare the three sensor technologies according to their measurement function, linearity, resolution, sensitivity and hysteresis and also according to real-time application indicators as: mechanical robustness, stage light sensitivity and temperature sensitivity. Results indicate that while strain gages offer more robust and medium sensitivity solution, the requirements for their use can be an obstacle for novice designers.