A Topology-Optimized 3D Printed Compliant Finger with Flex Sensor for Adaptive Grasping of Unknown Objects

Abstract

This study presents a motor-driven, two-finger compliant gripper with sensory feedback for autonomously adaptive grasping of unknown objects. The proposed compliant finger is synthesized using a topology optimization method, and prototyped by 3D printing using thermoplastic elastomer filament. Both compliant fingers of the gripper can be actuated by one displacement input and deform elastically to generate the gripping motion. A resistive flex sensor is installed on the surface of the compliant finger to determine the amount of bending for the finger. The value of resistive flex sensor reading is utilized as the feedback signal for the soft gripper. The effect of input displacement on bending angle and flex sensor reading, and the effect of object size on flex sensor reading and output force are provided in this study. The developed gripper is mounted on an industrial robot for automatic grasping of a variety of objects such as glass cup, tomato, egg, water balloon, hard disk, and paper box. The test results show the proposed design can grip objects with sizes between 30 and 141mm, and the maximum payload is measured as 2.5kg.