Design Analysis of Flexible Rod Jamming Based Pneumatically Soft Actuator

Abstract

Soft grippers exhibit exceptional adaptability to novel objects and tasks, making them suitable for safe and effective operation in human-centered applications. To improve their stiffness and gripping force, jamming techniques has been frequently used in manipulating objects of diverse shapes and weights. However, the existing jamming based grippers suffer from significant limitations including complex and expensive fabrication, excessive weight, slow recovery response and bending instability due to requiring a high level of vacuum to achieve jamming. This paper presents a novel design of pneumatically actuated flexible rod jamming based soft gripper. It consists of zigzag-based driving chambers to allow bending of the actuator upon pressurization. Additionally, a zigzag jamming chamber filled with flexible rods, that are fabricated by activating the internal support. The design is fabricated completely from Elastic 50A resin using Stereolithography (SLA) fabrication process without the need of additional fabrication procedure. The prototype’s stiffness is achieved by regulating the vacuum inside the jamming chamber. A nonlinear static analysis based on 3rd Yeoh model is conducted to investigate the actuator performance in terms of safety and deflection under various operating conditions. The performance of the prototype is evaluated against conventional actuator, while concerning its bending repeatability and payload capacity. The experimental results show that the proposed design achieves bending angle of 178◦ and carrying external load of 200 g. Additionally, it exhibits low deflection during bending compared to traditional zigzag actuator.