A Soft-Rigid Gripper for Safe Handling and Transportation

The automatic handling of perishable items like food and agricultural products requires robotic grippers that not only can perform gentle grasps but can also transport grasped objects safely and reliably. This result can be obtained by assuring that the contact between the grasped object and the gripper is as extended as possible, to avoid stress concentration in small areas, that could lead to local damage. In this study, a soft-rigid gripper is presented and designed to grasp and hold objects and to distribute the contact pressure over a large surface, limiting its maximum value and avoiding localized peaks. The gripper has four fingers and an extendable soft palm that wraps around the object, resembling a soft pocket. The palm is composed of two soft parts, whose geometrical characteristics have been evaluated using a shape optimization process and can be easily detached from the fingers to be changed or washed. The gripper is characterized with mechanical tests and evaluated in grasping and transporting tasks with real objects.