Measurement of Tractive Rolling of the Fingertip

Stable contact is essential for dexterous object manipulation, as it enables reliable force transmission and prevents unwanted slip. When subjected to tangential loading, the contact interface is subjected to localized partial slip but the contact interface also shift along the fingertip surface, a phenomenon known as tractive rolling. While fingertip rolling could provide additional manual compliance and may contribute to grip stability, it remains poorly quantified. To address this gap, we used a state-of-the-art imaging system to experimentally characterize the fingertip rolling under progressive tangential loading. Preliminary results indicated that rolling dynamics was significantly influenced by both the direction of the tangential loading and the applied normal force. Ongoing work will examine the relationship between tractive rolling and slip dynamics, with the aim of clarifying its functional role in contact stabilization during manipulation.