Grasping Force Modeling of Granular Food for Robotic Application

This study explores a method for modeling contact forces during granular food grasping at a low cost. Through experiments and numerical simulations, the interactions between particles during the grasping process were investigated. Specifically, the discrete element method (DEM) was employed as a high-accuracy yet computationally expensive approach to study the internal particle flow. In contrast, the shallow resistive force theory (S-RFT) was applied as an efficient alternative. Grasping tests were conducted using a simplified gripper jaw consisting of two plates, with adzuki beans and corn kernels as representative food materials. Material properties were measured for DEM simulations, and the necessary parameters for S-RFT were determined through preliminary tests. To assess the applicability of S-RFT, its predictions were compared with experimental and DEM results under varying gripper sizes, velocities, rotation angles, and food materials. Although S-RFT does not fully account for particle flow dynamics, it provides an efficient means of estimating the contact forces experienced by the gripper jaw at a significantly lower computational cost.