Two-DoF adaptive unit enabling multi-functionality in modular robot

Abstract

Modular reconfigurable robots (MRRs) can achieve diverse morphologies and functions through dynamic reassembly. MORI, an origami-inspired modular robot with a triangular lattice structure, demonstrates exceptional reconfigurability; however, its ability to actively interact with external objects remains limited. To address this limitation, we introduce a complementary Two-DoF modular unit with a Linear-to-Rotary (TDLR) mechanism that extends the multi-functionality of modular origami robots. The TDLR employs a linkage structure that converts linear actuation into rotary motion, providing two additional degrees of freedom at the end-effector without requiring extra actuators or sensors. Kinematic and static analyses were conducted to derive optimal design parameters, maximizing angular range, ensuring stable torque transmission, and maintaining mechanical robustness. Through experiments, the multi-functionality of the TDLR as a heterogeneous end-effector was validated, demonstrating adaptive object grasping, dual-object manipulation, crawling locomotion, and motion teaching enabled by inter-module data transfer. These results show that introducing heterogeneous modules like the TDLR not only expands MORI’s workspace but also provides a generalized approach to overcoming structural and functional limitations of MRRs, paving the way toward more versatile and adaptive robotic platforms.