A dual-mode soft gripper for food packaging

Robotics and automation in the food industry is not as widely applied as in other industries, such as automotive and electrical industries, due to the large variations in the shape and properties of food materials and the frequent alterations of food products. Robotic end effectors that can adapt to these variations and handle multiple types of food materials are in high demand. Therefore, we propose a dual-mode soft gripper made of rubber material that can grasp and suck different types of objects. The gripper consists of four soft fingers, fabricated with rubber material using casting process, each of which is designed as a combination of a PenuNet bending actuator and a suction pad located at the fingertip. We introduce a new design for the air paths, which play an important role in the proper function of the soft finger. Finite element (FE) simulations were performed to confirm the finger design. Experimental tests were conducted to evaluate single finger bending, gripper lifting force, and grasping and sucking actions for various types of food materials. Results show that the soft gripper can lift a 273.97-g hot dog in the grasping mode, as well as a 512.62-g bagged Kernel corn and a 1072.65-g Macbook Air in the suction mode. It can adapt to approximately circular and square targets, such as a piece of fried chicken and an orange, when the soft fingers are in a perpendicular configuration. While in a parallel configuration, the gripper can successfully handle elongated targets, such as a hot dog. An experiment is also presented to demonstrate the automatic packaging of a Japanese boxed lunch, which requires both grasping and suction modes to be employed. (C) 2020 Elsevier B.V. All rights reserved.