Analyzing time-series changes of the contact surface by touching is important to elucidate the touching skills of Humanitude as one of the pervasive multimodal comprehensive care methodologies. However, the transparent flat plates to capture contact surfaces used in the previous studies are far from the actual surfaces of care receivers because the surfaces of humans consist of curved shapes. In this paper, we propose a Frustrated Total Internal Reflection (FTIR) sensing system using a transparent curved plate for the purpose to capture contacting state by using a surface more similar to the human body. We evaluate the equivalent performance between data from the proposed FTIR sensing system and an FTIR sensing system using a transparent flat plate by calculating time-series contact areas and the quantitative indices representing theHumanitude's touching motion. Through these experiments, we conclude that the proposed system can obtain the same data quality for the contact areas and the indices as the FTIR system using the flat plate.
