Elastomer-constrained flat tube actuators (EFTAs)

Abstract Ethylene–vinyl acetate (EVA) flat tube has been widely used in designing soft wearable robots because of low-cost material, easy fabrication, and large deformation. However, only a bending-type flat tube actuator was proposed in previous studies, and more deformation modes are required to satisfy diverse robot design requirements. Herein, we propose elastomer-constrained flat tube actuators (EFTAs) with five actuation modes, extending, bending, helical, twisting, and contracting motions. Flat tubes are folded into various patterns, which are secured by silicone rubbers with different hardness. The silicone rubber fixes the arrangement of flat tubes for programmable deformation while providing resilience force. The bending angle, output force, load capability, and dynamic response tests of the EFTA-B are conducted. In addition, the deformation capability and force output of the other four actuators are also introduced in this study. We also compare our design with conventional fiber-reinforced actuators with five basic motions. EFTAs present comparable deformation performances and can be fabricated in easy processes.