Date of Award


Document Type

Thesis (Undergraduate)


Department of Computer Science

First Advisor

Daniela Rus


Self-reconfigurable robots are designed so that they can change their external shape without human intervention. One general way to achieve such functionality is to build a robot composed of multiple, identical unit modules. If the modules are designed so that they can be assembled into rigid structures, and so that individual units within such structures can be relocated within and about the structure, then self-reconfiguration is possible. We propose the Crystalline Atomic unit modular self-reconfigurable robot, where each unit is called an Atom. In two dimensions, an Atom is square. Connectors at the faces of each Atom support structure formation (such structures are called Crystals). Centrally placed prismatic degrees of freedom give Atoms the ability to contract their outer side-length by a constant factor. By contracting and expanding groups of Atoms in a coordinated way, Atoms can relocate within and about Crystals. Thus Atoms are shown to satisfy the two properties necessary to function as modules of a self-reconfigurable robot. A powerful software simulator for Crystalline Atomic robots in two and three dimensions, called xtalsim, is presented. Xtalsim includes a high-level language interface for specifying reconfigurations, an engine which expands implicit reconfiguration plans into explicit Crystal state sequences, and an interactive animator which displays the results in a virtual environment. An automated planning algorithm for generating reconfigurations, called the Melt-Grow planner, is described. The Melt-Grow planner is fast (O(n2) for Crystals of n Atoms) and complete for a fully general subset of Crystals. The Melt-Grow planner is implemented and interfaced to xtalsim, and an automatically planned reconfiguration is simulated. Finally, the mechanics, electronics, and software for an Atom implementation are developed. Two Atoms are constructed and experiments are performed which indicate that, with some hardware improvements, an interesting self-reconfiguration could be demonstrated by a group of Atoms.


Originally posted in the Dartmouth College Computer Science Technical Report Series, number PCS-TR99-348.