Bio-inspired origamic pouch motors with a high contraction ratio and enhanced force output

Abstract

The range of motion and force output of soft actuators are important characteristics that determine the capacities of soft robots. Pouch motors are a family of soft fluidic actuators featuring a simple mechanical structure and easy fabrication process, but their relatively small contraction ratio constrains their potential applications. Inspired by the origami membrane in the lobster leg joint, we propose two types of origamic pouch motors in which origami structures are integrated into the longitudinal edges of traditional pouches. As a uniform and large degree of transverse expansion can be facilitated by unfolding the origami structures, a significantly larger contraction ratio and enhanced force output can be achieved. The complete workflow of origamic pouch motors is presented including the design principles, fabrication process, theoretical modeling, and experimental characterization, and multiple pouches can be conveniently assembled to realize different motion profiles with a larger range of motion as well. For application demonstrations, we develop different grippers based on origamic pouch motors for safe and forceful grasping. The results of this study can provide guidance for the development of robotic systems featuring easy fabrication, safe actuation, lightweight, a large motion range, and high force output.