A Self-Locking Tendon-Driven Robotic Arm Inspired by Cubic Origami

• Self-locking of FC-ori is revealed through geometry and singularity analysis. • Novel tendon path enables folding FC-ori despite self-locking behavior. • Multi-module FC-ori robotic arm can be actuated by a single motor. • The reconfiguration process of the robotic arm requires only several seconds. • A programmable deployment sequence is achieved among parallel modules The ability to transition between load-carrying and readily foldable states enables deployable structures to satisfy diverse functional requirements, such as compact storage, adaptive shape transformation, and stable load-bearing performance. Self-locking origami structures, which utilize geometric constraints to prevent the structure from collapsing under external loads, offer an effective solution for achieving these capabilities. In this study, we investigate the self-locking behavior of a Foldable Cube Origami (FC-ori) structure in its cubic configuration by analyzing its geometry and singularity. To address self-locking constraints, a tendon-driven mechanism is developed with tendons routed through the side panels, in contrast to conventional designs where tendons pass only through the top and bottom panels. By optimizing the tendon path, we reduced the maximum friction by approximately 20%. Moreover, we design and implement two multi-unit tendon-driven FC-ori robotic arms configured in series and parallel arrangements. These systems allow for programmable deployment sequences and achieve rapid transitions between folded and deployed configurations within several seconds, driven by only a single motor. By integrating a tunable stiffness origami structure with efficient actuation, this work offers enhanced potential for applications in space exploration, foldable shelters, reconfigurable robotics, and other engineering domains.