Development of a Self-Weight Gripper Suitable for Flexible and Heavy Bagged Objects

Abstract

A social issue owing to the aging of society in recent years is the daily removal of garbage by the elderly. This study proposes a gripper that can grip large, flexible, and heavy objects such as garbage bags as well as small and light objects such as plastic bottles, with the aim of automating the garbage-collection process. The proposed gripper consists of an opening/closing mechanism with a rhombic link structure and a contact area that makes contact with the object to be gripped. This mechanism is characterized by its power-saving effect as it converts the weight of the waste into gripping force through the rhombic structure. Therefore, minimizing power consumption is important for automating garbage collection with battery-driven mobile manipulators. This study describes the principle of operation of the rhombic link structure of the proposed gripper and compares it with conventional motor-torque gripping. Furthermore, by incorporating a flexible structure in the form of the gripping contact area, we verified that the proposed gripper is capable of gripping and operating a total of six types of garbage depending on the size (large or small), content (bottles or cans), and material of the garbage bags. The results show that the proposed gripper uses 60% less electricity than a parallel open/close type gripper and improves the success rate of gripping large garbage bags by 20% owing to the flexible structure of the contact area.