Design, performance analysis and applications of pneumatic bellows actuator for building block soft robots

Currently, there are some new challenges for pneumatic soft robots brought by complex application environments and variable task objectives. To address these challenges, inspired by the building blocks, we develop a novel pneumatic soft actuator named pneumatic bellows actuator (PBA) that can generate bidirectional deformation, and propose a building block design concept for the soft robots based on the developed PBA. The PBA consists of three parts: a soft rubber layer (SRL), a fiber-reinforced layer (FRL) and some rigid joints. We design the SRL as a bellows-like shape so the PBA can generate bidirectional deformation, and weave an FRL as the coating of the SRL to prevent the significant radial expansion of the SRL that may affect the application of the PBA. The rigid joints include sealing glands and connectors. The sealing glands are used to seal the SRL, while the connectors having interfaces on their five surfaces are used to connect the PBAs through the customized plugs corresponding to these interfaces. Moreover, the experimental results indicate that the PBA can generate large deformation and driving force, while it has the advantages of good repeatability and approximate rate-independent under low frequency. Based on the building block design concept for the soft robots, we construct three PBA-based soft robots: a soft crawling robot, a soft gripper, and a soft manipulator, to demonstrate that we can easily use the PBAs to construct various soft robots.