Versatile Rigid-Flexible Coupling Modules: Enhancing Soft Origami Structures with Cable-Driven Parallel Mechanisms

Abstract

Soft robots have garnered significant attention due to their adeptness in addressing challenges that traditional rigid robots struggle to effectively manage, including adaptability to unstructured environments and safe human–robot interactions. However, these modular soft robots always show limitations in coping with application requirements due to the defects of their building blocks, including limited motion patterns, poor repetitive positioning accuracy, and weak load-bearing capacity. Herein, a rigid parallel structure on the exterior of a soft origami structure is introduced, developing a rigid-flexible coupling building block. In this combined theoretical and experimental study, the geometric parameters to realize the coupling synergy between the two structures in terms of kinematics are adapted. Then, diverse experiments are conducted to characterize the performance of this building block, indicating that this building block not only has all basic motion patterns (i.e., contraction ΔH_max = 30.78 mm, bending ${\theta }_{\text{max}}$ = 59.96°, and twisting ${\phi }_{\text{max}}$ = 33.67°) but also exhibits high repeatable positioning accuracy and strong load-bearing capacity. Based on this building block, a soft continuum robot that showcases its versatility, such as flexibly twisting light bulbs and using bending motion pattern to grasp items of varying weights is developed.