Contact Area-Based Modeling of Robotic Grasps Using Deformable Solid Mechanics

In robotic grasp analysis, contact between an object and a hand is described using point contact models and soft contact models. Although soft contact models estimate both contact area and contact force for grasp analysis, most of the approaches use point contact models to analyze the stability of grasp because of the simplicity involved in computation and modeling. However, grasps suggested by these approaches are not intuitive to execute with and often fail in experiments. Since the hand-object interface is modeled using points, their physical characteristics are not taken into account in the analysis, thereby resulting in failed grasps. In this work, the contact models related to robotic grasping are briefly reviewed, and the discrepancies present in them are identified from a solid mechanics standpoint. Using the constitutive equations available in solid mechanics, these contact models are then reformulated based on contact areas for both deformable hard as well as soft fingertips. By performing Finite Element (FE) simulations of the contact situation considered, the contact models are validated. The proposed models are validated using robotic grasp experiments as well.