Soft origami gripper with variable stiffness via textile jamming for gentle manipulation

This thesis presents a proof-of-concept for integrating variable stiffness (VS) technology, specifically textile jamming, into a soft origami actuator. The goal was to design a soft gripper capable of operating in confined spaces, unlocking applications such as exploration and minimally invasive surgery, where conventional soft grippers, often limited to controlled environments, fall short. The proposed gripper is designed to navigate narrow openings while folded and expand to grasp objects, with VS technology to enhance grasping performance. A finger-based morphology was chosen for dexterity, and pneumatic actuation was selected for its safety, payload, and responsiveness. The actuator, sized like two human fingers, incorporated an origami structure to enable passage through narrow openings. Textile jamming was adopted as the VS mechanism due to its compliance, and capability of the fabric to fold without permanent deformation and thus, to follow origami kinematics. State-of-the-art methods were used to evaluate the most suited material and layers combination for integration of textile jamming. Following these design choices, the gripper's fingers were fabricated and tested. Tests assessed the impact of textile jamming on actuator’s kinematics, exerted force, and shape-locking. Results demonstrated that textile jamming provides shape control and shape-locking, validating its benefits. Finally, a three-fingered gripper was assembled. It successfully passed through 75 mm openings and grasped objects (20-85 mm diameter, 0-660 g weight). In its soft state, it excelled in power grasps, while activating the VS enabled pinch grasps. In conclusion, this work demonstrates a novel soft gripper design for confined spaces, proving the integration of textile jamming with a soft origami pneumatic actuator achieves shape control, shape-locking, and multimodal grasp.