Real-Time Calculation of Strain Energy Density in a Fingertip for Haptic Distribution Rendering

Considering the neural signals generated by mechanoreceptors in response to haptic stimuli when contacting virtual objects is essential to display spatial haptic distributions on the skin in virtual reality applications. This study focuses on reproducing the neural activities of Merkel cells, which are known as slowly adapting type-1 mechanoreceptors. The firing activity of these receptors is known to respond to strain energy density (SED). We developed a real-time SED calculation method using a specially designed finite element (FE) model of a fingertip, which features a simplified layer structure of skin and nail. We validated the model by comparing its calculation results with those of a detailed model and a homogeneous model, using reliable FE analysis software. We demonstrated that modeling the layered structure of the skin is effective in improving the reproducibility of the SED distribution at the locations of Merkel cells.