DESIGN OF A RECONFIGURABLE MODULAR CHAIN FOR FOLDING 3 D LATTICE STRUCTURES

A wide range of engineering applications, ranging from civil to space structures, could benefit from the ability to construct material-efficient lattices that are easily reconfigurable. The challenge preventing modular robots from being applied at large scales is mainly the high level of complexity involved in duplicating a large number of highly integrated module units. We believe that reconfigurability can be more effectively achieved at larger scales by separating the structural design from the rest of the functional components. To this end, we propose a modular chain-like structure of links and connector nodes that can be used to fold a wide range of 2D or 3D structural lattices that can be easily disassembled and reconfigured when desired. The node geometry consists of a diamond-like shape that is one twelfth of a rhombic dodecahedron, with magnets embedded on the faces to allow a forceful and self-aligning connection with neighboring links. After describing the concept and design, we demonstrate a prototype consisting of 350 links and experimentally show that objects with different shapes can be successfully approximated by our proposed chain design. INTRODUCTION Self-reconfigurable modular robots contain a number of identical unit modules and are generally intended to change shapes and functions through reconfiguring their modules with respect to different applications. However, this desirable reconfiguration ability comes with a high cost since each individual module requires independent actuation, communication, power, and even sensing. We believe that the benefit of the reconfigurable ability does not have to be bonded to complicated modular robot designs that generally require a high degree of integration and miniaturization of both mechanical and electronic components. Instead, we argue that some of the intended benefits can be achieved by developing low-cost, light-weight, and reconfigurable modular materials that can be repeatedly used to construct the skeleton of different structures without requiring individual sensing/actuation, but can instead be robotically assembled/disassembled. The general approach of our proposed method is based on a concept in which a continuous prefabricated chain of links is deposited and connected to itself at joint nodes, producing structural lattices in nearly arbitrary configurations that can be disassembled and reconfigured when desired. Our design concept can be seen as a sort of 3D printer for sparse lattices, in which a robotic manipulator arm/small construction robot lays down/carries the links of a passive (non-robotic) continuous chain to create programmed truss lattices using a hierarchy of sub-modules all formed from a single chain of links and joints. The concept will be similar to modern 3D printers that lay down a heated and extruded thread of ABS thermoplastic (i.e. Fused Deposition Modeling) onto a substrate to create arbitrary 3D structures. Instead, we will lay down a chain of rigid links Proceedings of the ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference IDETC/CIE 2016 August 21-24, 2016, Charlotte, North Carolina