Fiber-reinforced flexible joint actuator for soft arthropod robots

The flexible joints are the fundamental building blocks of modular soft robots. However, the investigation on flexible joints made entirely of soft material is still in its infancy, with complex structure, small rotation range and insufficient driving force output. Bio-inspired from the hydraulic joints of spider legs, a dexterous fiber-reinforced flexible joint actuator was proposed. For the irregular shape joint actuator with fiber-reinforced structure, its fabrication process and modeling method are discussed. And the advantages of fiber reinforcement are demonstrated in terms of rotation angle, driving torque and efficiency experiments. Compared with the joint actuator without fiber layer, the actuator with a fiber angle of 30° can increase the rotation angle by up to 36% and the driving efficiency by up to 19.6%. The maximum inflation pressure can reach 120 kPa, and the force density 3.56 mN/mm3, which demonstrates extremely high pressure tolerance capacity and force density, and shows the wide applicability of the fan-shaped flexible actuator to enable lightweight, mobile, multifunctional soft robots.