Self-Forcing Mechanism of the Braided Tube as a Robotic Gripper

Abstract

Robotic grippers, which act as the end effector and contact the objects directly, play a crucial role in the performance of the robots. In this paper, we design and analyze a new robotic gripper based on the braided tube. Apart from deployability, a self-forcing mechanism, i.e., the holding force increases with load/object weight, facilitates the braided tube as a robotic gripper to grasp objects with different shapes, weights, and rigidities. First, taking a cylindrical object as an example, the self-forcing mechanism is theoretically analyzed, and explicit formulas are derived to estimate the holding force. Second, experimental and numerical analyses are also conducted for a more detailed understanding of the mechanism. The results show that a holding force increment by 120% is achieved due to self-forcing, and the effects of design parameters on the holding force are obtained. Finally, a braided gripper is fabricated and operated on a KUKA robot arm, which successfully grasps a family of objects with varying shapes, weights, and rigidities. To summarize, the new device shows great potentials for a wide range of engineering applications where properties of the objects are varied and unpredictable.