Organizations: Department of Systems Innovation, Graduate School of Engineering Science, The University of Osaka, 1-3 Machikaneyama, Toyonaka, Osaka, Japan. · Industrial Cyber-physical Systems Research Center, The National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo, Japan.
Modular reconfigurable robots require reliable mechanisms for automated module exchange, but conventional rigid active couplings often fail due to inevitable positioning and orientational errors. To address this, we propose a misalignment-tolerant tool-changing system. The hardware features a motor-driven coupling utilizing passive self-alignment geometries, specifically chamfered receptacles and triangular lead-in guides, to robustly compensate for angular and lateral misalignments without complex force sensors. To make this autonomous exchange practically feasible, the mechanism is complemented by a compact rotating tool exchange station for efficient module storage. Real-world autonomous tool-picking experiments validate that the self-aligning features successfully absorb execution errors, enabling highly reliable robotic tool reconfiguration.
Figures & tables
Fig. 1 : CAD representation of the reconfigurable robot with integrated module changer and rotating table.
Fig. 2 : Exploded CAD representation of the motor-driven coupling with component table indicating part numbers, quantities, and names.
Fig. 3 : Comparison between the CAD representation and the 3D printed, motor-driven coupling.
Fig. 4 : Cross-sectional illustration of the coupling showing the lock-pin positions in the unlocked and locked states.
Fig. 5 : Exploded CAD representation of the 3D printed rotating tool exchange station with component table indicating part numbers, quantities, and names.
Fig. 6 : Comparison between the CAD representation and the 3D printed rotating tool exchange station.
Fig. 7 : Illustration of rotational misalignment.
Fig. 8 : CAD representation and the 3D printed of the examined receptacle.
Fig. 9 : Step-by-step insertion of the motor-driven coupling under three conditions: (A) no lead-in guide feature as a baseline, (B) right-angle triangle with chamfered wall, and (C) isosceles triangle with chamfered wall. Images from left to right show the states before, during, and after insertion.
Fig. 10 : Illustration of lateral misalignment.
Fig. 11 : Insertion sequence under different receptacle conditions: (A) isosceles triangle with chamfered wall, (B) baseline with correct alignment, and (C) baseline with lateral misalignment. Images from left to right show the states before, during, and after insertion.
Fig. 12 : Time-lapse sequence of the simulation environment. The 6-axis modular arm executes a planned trajectory from a fully extended initial pose (left) to the tool exchange position (right).
Fig. 13 : Autonomous tool exchange sequence showing disengagement, receptacle rotation to introduce misalignment, re-insertion with passive self-alignment, and lifting after successful locking.
Modular small-scale robots offer the potential for on-demand assembly and disassembly, enabling task-specific adaptation in dynamic and constrained environments. However, existing modular magnetic platforms often depend on workspace collisions for reconfiguration, employ bulky three-dimensional electromagnetic systems, and lack robust single-module control, which limits their applicability in biomedical settings. In this work, we present a modular magnetic millirobotic platform comprising three cube-shaped modules with embedded permanent magnets, each designed for a distinct functional role: a free module that supports self-assembly and reconfiguration, a fixed module that enables flip-and-walk locomotion, and a gripper module for cargo manipulation. Locomotion and reconfiguration are actuated by programmable combinations of time-varying two-dimensional uniform and gradient magnetic field inputs. Experiments demonstrate closed-loop navigation using real-time vision feedback and A* path planning, establishing robust single-module control capabilities. Beyond locomotion, the system achieves self-assembly, multimodal transformations, and disassembly at low field strengths. Chain-to-gripper transformations succeeded in 90% of trials, while chain-to-square transformations were less consistent, underscoring the role of module geometry in reconfiguration reliability. These results establish a versatile modular robotic platform capable of multimodal behavior and robust control, suggesting a promising pathway toward scalable and adaptive task execution in confined environments.
Erik Garcia Oyono, Jialin Lin, Dandan Zhang
Department of Bioengineering, Imperial College London, London, United Kingdom.
Robotic construction systems often treat the material system and the robot as separate design problems, locating intelligence primarily in hardware, sensing, motion planning, and control. This project instead investigates how geometric intelligence can be encoded within architected material systems to simultaneously address requirements for robotic grasping, self-alignment, reversible connection, structural performance, and three-dimensional aggregation. We introduce a self-aligning compound nested lattice module composed of conjoined cuboctahedral-octahedral units. The cuboctahedral features of the modules provide defined surfaces for robotic grasping and alignment, while the octahedral features incorporate screw-releasable snap-fit connectors and corresponding receptors. Additionally, we present a nested arrangement that enables interlocking aggregation along the x, y, and z axes. We demonstrate the system through furniture and architectural scale structures assembled using both a robotic arm and mobile assembler. The resulting configurations include seating, spanning structures, surfaces, and vertical frames. Compression testing of the compound module produced a stiffness of 4,556 N/mm, a maximum load of 3,445 N, and a compressive modulus of 17.5 MPa. The modules can also be disassembled and reused across different configurations, supporting reconfigurable and circular construction.
Alexander Htet Kyaw, Miana Smith, Paul Richard +1
Massachusetts Instittue of Technology (MIT) · École Polytechnique Fédérale de Lausanne (EPFL)
Continuum robots enable smooth shape morphing and safe interaction in confined environments. However, most existing systems are task-specific and depend on external sensing infrastructure, limiting their adaptability and real-world deployment. This paper presents a self-contained modular continuum robotic platform that combines mechanical reconfigurability with onboard pose estimation. The robot is constructed from interchangeable continuum joints with analytically precomputed stiffness, allowing rapid assembly and direct programming of the robot shape. Proprioceptive sensing is achieved using magnetic sensors and a modular learning-based framework, where a single model is trained per joint and reused across configurations. The system is experimentally validated in real world, demonstrating self-sensing capabilities and adaptation without external tracking.