Variable Stiffness Woven Soft Active Textiles and Robots Using Thin McKibben Muscle

Abstract

Active woven structures are extensively utilized in wearable and soft robotics due to their exceptional body compliance, lightweight nature, long-term stability, and programmable architectures. Although existing active woven structures have been successfully applied to actuators and sensors, the fabrication of intricate variable stiffness soft robots directly through weaving methods has consistently posed challenges. To address this issue, we draw inspiration from the Chinese knot technique and employ thin McKibben muscles to weave a variety of variable stiffness textiles, including a flexible spine, flexible skin, and a bistable structure, as well as innovative soft robots such as a soft crawling robot, a soft enclosed gripper, and a continuum module. Experimental results demonstrate that the variable stiffness range of the developed variable stiffness textiles exceeds 5.4 times that of the initial stiffness. Furthermore, we also experimentally demonstrate that the woven soft crawling robot (weighing 171 g) can achieve omnidirectional movement on an ferromagnetic surface at a maximum speed of 666.7 mm/min; the woven continuum module (weighing 49 g) can reduce the impact of external forces on the motion angle by over 65% by activating the high stiffness mode; the soft enclosed gripper (weighing 175 g) can lift objects weighing up to 14.7 kg, and the variable stiffness function can enhance its multi-directional bearing capacity by ∼3.3 times. This study offers various new configurations and ideas for the advancement of complex variable stiffness soft robots based on weaving technology.