Design, Topology Optimization, and Additive Manufacturing of a Pneumatically Actuated Lightweight Robot

Soft robotics research has rapidly incorporated Additive Manufacturing (AM) into its standard prototyping repertoire. While numerous publications have highlighted the suitability of AM for producing soft pneumatic actuators, fluidic components, and lightweight structures, their integration into an industry-like robotic arm has not yet been shown. Against this background, a pneumatically actuated robot was developed that incorporates additively manufactured soft structures into rigid articulated hinges that generally allow for integration into today's industrial production lines. The development of the robot, including pneumatic soft rotary bellows and rotary vane actuators (RVAs), is summarized, and its functionality is proven. It was found that using AM can increase the structural stiffness of robot links to a significant degree as manufacturing-related constraints in topology optimization are largely eliminated. Moreover, it was found that multi-material polyjet printing of soft rotary bellows actuators allows for highly integrated designs that provide low leakage and friction. However, these soft rotary actuators are still inferior in terms of endurance and performance if compared to AM replicas of RVAs. Our work narrows the gap between soft robotics research and today's industrial applications, may realign research directions, and may provide impulses for the industry towards soft robotics and AM.