A Novel Variable Stiffness Soft Gripper With Optimized Pneumatic Actuator for Robust Grasping

This is the authors' abstract. We don't add key points for this paper.

Soft grippers have emerged as a significant advancement in the realm of adaptive grasping operations. However, they often suffer from unstable grasp issues during practical applications due to the unchangeable stiffness of their fingers. To address this problem, this article proposes a novel variable stiffness method for the three-fingered soft gripper by a controllable jamming force mechanism. Each finger is equipped with a pneumatic soft actuator and a tendon-driven multijoint chain mechanism. In the absence of tendon force, the fingers exhibit remarkable pliability, enabling them to adeptly conform to objects of assorted geometries. Conversely, upon the application of tendon force, the fingers can instantaneously attain a high level of rigidity even at extreme flexion angles, thereby ensuring a secure and reliable grasp. To augment the scientific robustness of this innovation, kinematic and static models are established to analyze the variable stiffness, bending angle and contact force of the gripper. The pneumatic actuator structure is optimized through a finite element model to enhance finger flexion scope. The gripper, fabricated through a combination of 3-D printing and molding techniques, has yielded outstanding experimental results. A remarkable 7.1-fold enhancement in stiffness variability is achieved. It has been demonstrated that the gripper can proficiently manipulate a wide array of objects, and pick-and-place trials under high-acceleration conditions have validated its robust grasping capabilities, signifying substantial potential for real-world implementation.