A Compliant Hinge Joint Driven by the PneuNets Bending Actuator for Enhancing the Performance of Soft Robots

摘要

Abstract While soft robots enjoy the benefits of high adaptability and safety, their inherent flexibility makes them suffer from lower load-carrying capacity and low motion precision, which limits their applications to a broader range of fields. In this paper, we propose an active hinge joint with a hard backbone combined with soft pneumatic actuators to overcome this challenge. We detail the design, theoretical modeling, and experimental testing of a novel compliant hinge joint driven by two pneumatic networks (PneuNets) bending actuators. The joint is constructed by attaching the two actuators to a cross-spring pivot’s two flexible leaf springs. Pressurizing one of the actuators can drive the joint to rotate clockwise or counterclockwise about the central axis. A Pseudo-rigid-body model is developed to analyze the kinematics and statics of the joint. FEA simulation and experimental experiments have been developed to validate the model. The results show that the joint can achieve ± 43° under 0.276 MPa, and the pressure-displacement curve is close to linear. Experiments are also conducted to measure the joint’s in-axis and the other three off-axis stiffness. After calculating the stiffness ratio, the results show that the three off-axis stiffness (Kθx, KY, KZ) are 16.74, 471.75, and 627.63 times the in-axis stiffness (Kθz), respectively. It means our hinge joint can carry a high payload off-axis while maintaining the in-axis flexibility.