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Lightweight underactuated pneumatic fingers capable of grasping various objects

This paper presents the design and implementation of a lightweight and powerful fingers actuator capable of grasping various shaped objects. The proposed fingers actuator is designed on the underactuated structure formed by a thumb and an index finger, which are composed of a zigzag tube with one chamber and a soft polyurethane foam with notch. When the inside of the tube is pressurized by pneumatics, each finger joint can be bent simultaneously performing one degree of freedom motion. Due to the compliance of pneumatic and the softness of the structure, it can automatically hold various types of objects. The design parameter of each joint is illustrated in order to base on distributed grasping force evenly against the objects. The developed fingers could not only perform wide range of grasping but also realize two and half times larger force/weight ratio than general fingers actuator with electric servo motor. Lastly, as the application of the proposed fingers, it is mounted on an aerial manipulator for the door opening mission, and its validity is experimentally verified.