Estimation of Violin Bow Pressure Using Photo-Reflective Sensors

The violin is one of the most popular instruments, but it is hard to learn. The bowing of the right hand is a crucial factor in determining the tone quality, but it is too complex to master, teach, and reproduce. Therefore, many studies have attempted to measure and analyze the bowing of the violin to help record performances and support practice. This work aimed to measure bow pressure, one of the parameters of bowing motion. The proposed method uses a regression model to estimate bow pressure based on bow deformation. First, the deformation of the bow hair is measured by photo-reflective sensors attached to the bow stick. Next, the regression model is trained based on the correspondence between the bow deformation and the true value of bow force measured by a load cell. The adjusted coefficient of determination was 0.84, with an average mean absolute error of 0.11 N and an average mean absolute percentage error of 19.1%. We also present an example of an application for real-time bow pressure estimation and visual feedback during violin playing.