Optimal Design of a Highly Self-Adaptive Gripper with Multi-Phalange Compliant Fingers for Grasping Irregularly Shaped Objects

Abstract

The development of a robotic gripper for handling objects of various sizes, shapes, weights, and degrees of hardness is a challenging problem in the field of robotics. In order to design a highly self-adaptive gripper capable of conforming to a wide range of objects, this article presents an innovative topology-optimized design of a compliant finger consisting of several multi-material phalanges connected by flexure hinges. The prototype was produced by means of a metamaterial approach, which utilizes 3D-printed infill structures (periodic cells) with different infill densities to represent regions with different equivalent mechanical properties. Adaptability tests were conducted to demonstrate the effectiveness of the proposed design in grasping circular, rectangular, trapezoidal, and concave objects. The results were compared with those of the fingers with single infill densities and a commercially available Festo MultiChoiceGripper, which features a Fin Ray structure. The total contact length between the fingers and the grasped object was used as a measure of the grippers' adaptability. The test results demonstrate that this novel self-adaptive gripper is comparatively highly adaptable for grasping irregularly shaped objects and is able to carry a maximum payload of 6.76 kg.