Modeling of Viscoelastic Contact and Grasping Stability of Hemicylindrical Fingertips for Robotic and Prosthetic Hands

Abstract

Viscoelastic contact problems are one of the most important problems in mechanical and robot engineering. These problems become more tedious when one of the contacting bodies carries a viscoelastic and soft material. In this study, the mathematical model of contact interface and limit surface for viscoelastic contact which can be applied to robotic and prosthetic hemicylindrical fingertips has been proposed. The new achievement of this research comprises the integration of the time-dependent nature of viscoelastic contact into the modeling of grasping and manipulation. Specifically, two conjugation equations to get together the two significant parameters of contact modeling (the half-width of the rectangular contact area and the profile of pressure distribution across the contact interface) have been suggested. Additionally, two cases viable for prosthetic and robotic hands for grasping have been studied: constant rectangular contact area and constant normal contact force. The results show that the control of the grasp contact forces (case 2) when employing viscoelastic contacts is most advantageous because it promotes the stability of grasping through the enlargement domain of the limit surface as time terminates. Finally, the viscoelastic limit surface results proved that the new mathematical model is more effective (18-22%) than previous models.