Variable Stiffness, Sensing, and Healing in FESTO's FinRay Gripper

Abstract

The rising popularity of soft grippers in industry is due to their impressive adaptability. Yet, this adaptability requires flexibility, which often sacrifices grip firmness and complicates sensor integration. This article introduces two additional innovations, variable stiffness and pneumatic sensing, into a FinRay adaptive gripper. The approach and design for incorporating these innovations are guided by requirements outlined by Festo. Regarding this, a layer-jamming-based variable-stiffness skin broadens gripper applications, manipulating objects of varying hardness and weight, while a pneumatic sensor skin detects contact and loss of contact. Both functionalities rely on the airtightness of the skins, which is compromised if damaged. To address this, both the skins and the gripper were crafted using self-healing polymers. The sensing capability and modulated mechanical performance of the gripper were evaluated experimentally and through simulations, and the self-healing ability was assessed by recharacterization after a damage healing. This work showcases the promising synergy between robotics and self-healing materials, demonstrating mutual reinforcement to a highly efficient gripping system.