A Robotic End-Effector for Screwing and Unscrewing Bolts From the Side

Abstract

This letter presents a novel robotic end-effector for screwing and unscrewing bolts. In many industrial scenarios, it is required to manipulate bolts from the side using robots with end-effectors. Besides, the reaction torque during tightening needs to be balanced to the stability of the robot. To address these challenges, we design a robotic end-effector that can realize side screwing and torque counteraction. Specifically, through an open gear set and a width-adjustable screwing mouth, the end-effector can approach the bolt from the side in any direction and then screw and unscrew it. A gripper with force-magnification and self-locking drive is equipped to counteract the reaction torque during screwing and unscrewing. Considering the extensions for different application scenarios, a method to extend the end-effector by switching screwing mouths is given, and the extended end-effector is able to screw a variety of objects. After further analysis and optimization of the force and size, experiments are carried out. The results show that the end-effector can screw and unscrew the target bolt robustly and counteract the reaction torque. It is also applicable in different scenarios.