Analysis of Grinding Motion using Force/Tactile Sensation

Understanding human movements is essential for teaching skills to novices and enabling robots to learn. Traditional movement analysis often relies on visual data, but incorporating force/tactile information is vital for object interactions. The spring-mass-damper model, used to represent force/tactile data, assumes continuous contact and consistent material properties, which are limitations when analyzing grinding actions that frequently alternate between contact and non-contact. This study proposes analyzing grinding by quantifying force/tactile sensations as the ratio of the root mean square (RMS) values of force to speed, using absolute impedance to measure sensations irrespective of contact. Findings indicated that operators typically initiate a pressing motion several seconds after detecting contact, and their reactions to samples of varying hardness differ significantly. These observations suggest a detailed breakdown of human grinding skills is feasible, highlighting the potential of force/tactile information in enhancing skill transfer to beginners and robots.